Qtractor Manual & How-To’s
Qtractor Wiki
Qtractor Wiki
rncbc et al. 2018-03-10 09:50+0000
Manual - Table of Contents
This wiki version of the manual is based on a document originally authored by
Rui Nuno Capela, James Laco Hines and Stephen Doonan.
Table of Contents
1. Introduction
• 1.1. Abstract
• 1.2. Introduction
2. Installing and Configuring Qtractor
• 2.1. Compiling Qtractor
• 2.2. Build dependencies
– 2.2.1. Mandatory packages
– 2.2.2. Optional packages
• 2.3. Downloading Qtractor
– 2.3.1. Official releases
– 2.3.2. Qtractor for the experienced and adventurous
• 2.4. Compiling and installing Qtractor
– 2.4.1 Standard compilation and installation
– 2.4.2. Compiling with Steinberg Linux VST Support (optional)
– 2.4.3. Compiling Qtractor with debugging support
• 2.5. Qtractor’s Configuration Settings File
• 2.6. QJackCtl
• 2.7. Audio and MIDI Input
3. Learning Qtractor–An Example Session
• 3.1. Preparation
• 3.2. Importing an Audio File
• 3.3. Connecting the MIDI data source to Qtractor
• 3.4. Creating a MIDI track
• 3.5. Recording and Playback
• 3.6. Next Steps
4. Qtractor–An Overview
• 4.1. Routing–Connections, Ports, Tracks and Buses
– 4.1.1. Routing–General Concepts and Information
– 4.1.2. Routing in Qtractor
– 4.1.3. Routing–Technical Notes
• 4.2. Qtractor’s Main Window and Work Area
• 4.3. Understanding a Qtractor Session (recording or editing)
– 4.3.1. Session Audio Sample Rate
– 4.3.2. Session Properties
– 4.3.3. Session Options
• 4.4. Files
• 4.5. Clips
Clips Summary
Copying, Cutting, Splitting and Merging
Fades and Cross-Fades
Clip Properties
• 4.6. Qtractor Main Workspace–Tracks Area
Tracks Summary
Track States
Making Selections - Select Modes
Making Selections - Edit Markers
– 4.6.6. Paste Repeat
– 4.6.7. Punch In/Out
– 4.6.8. Automation
• 4.7. Mixer
– 4.7.1. Mixer Summary
– 4.7.2. Setting Levels
– 4.7.3. Panning
• 4.8. Signal Flow
Signal Flow Summary
Aux Sends
Connection Persistence
• 4.9. Plugins
Plugins Summary
VST (Linux Native)
• 4.10. Working with MIDI
MIDI Summary
Importing MIDI Data
Creating MIDI Data with a MIDI Controller
Creating MIDI Data with the MIDI Editor
Additional MIDI Editor Features
MIDI Instruments
Soft Synths
Soft Synths as Plugins
Stand-alone Soft Synths
• 4.11. Working with Audio
Audio Summary
Importing Audio Files
Recording Audio
Recording from Line-In
Recording from USB
Recording Takes
• 4.12. Audio / MIDI Export
• 4.13. Snapshots, Templates and Archives
– 4.13.1. Snapshots
– 4.13.2. Templates
– 4.13.3. Archives
• 4.14. Other Qtractor Features
– 4.14.1. Metronome
– 4.14.2. Keyboard Shortcuts Editor
5. Qtractor Menus
• 5.1. Main Workspace
• 5.2. MIDI Editor
• 5.3. View / Options
6. Appendixes
• 6.1 References
Manual - 1 Introduction
Manual - Table of Contents
1. Introduction
1.1. Abstract
Qtractor is a multi-track audio and MIDI recorder and editor. The program is
written in C++ and uses the Qt toolkit for the GUI (graphical user interface)
elements. Qtractor is free and open source software, licensed under the GNU
General Public License version 2 or later.
Qtractor runs exclusively under GNU/Linux and depends upon ALSA (Advanced
Linux Sound Architecture) and JACK (the Jack Audio Connection Kit) to
provide its MIDI and audio IO infrastructure. It currently has one developer,
the originator of the project, Rui Nuno Capela. Development was started in
April of 2005, initially as a Qt 3 application. Since October 2015, it is officially
a Qt 5 application.
Main GUI window showing audio & MIDI tracks, Mixer & Connections windows
The project began as a sequencer intended mainly to be used with MIDI hardware
devices but has since developed comprehensive support for plugins and gained
moderately powerful audio recording and editing facilities. It now aims to be a
lightweight but reasonably powerful solution for hobbyist and semi-pro musicians.
It does not aim to be a “do-it-all monolith DAW” (such as you may find in
the commercial world), nor is it completely “modular” - rather, it should be
considered something of a “hybrid”, which contains the kind of features that are
most likely to be useful for its intended user-base. In the words of its developer,
rather than a fully-fledged DAW, Qtractor is a sequencer with DAW-like features.
If your intention is to mimic the functionality of a recording studio, conducting
a great deal of live audio recording and performing complex routing operations,
something like Ardour may be more suited to your needs.
1.2. Introduction
Whilst Qtractor is still in its beta phase of development, it can already be
comfortably used by hobbyists as a personal home recording studio or “bedroom studio”. It can record, import, arrange and edit both digital audio and
MIDI data. Its interface will be familiar to users of other popular multi-track
recording/editing applications.
In addition to recording digital audio and MIDI, Qtractor provides an environment for multi-track clip-oriented composing techniques common in modern
music-making and aims to be intuitive and easy to use, yet powerful enough for
the serious recording enthusiast.
Qtractor is a non-destructive audio editor. This means that your session’s audio
files remain unchanged on disk after you have edited them. Instead, all edits to
audio files are stored within the Qtractor session file.
As part of the GNU/Linux audio and MIDI ecosystem, Qtractor relies on other
projects to provide functionality in various areas. Due to this approach, the user
must consider his/her needs in areas such as synths, samplers, drum machines,
effects processors and sounds (audio samples, sample packs (sf2/sfz/gig etc.),
synth patches and so on) and use these other projects in tandem with Qtractor
by referencing the information in this wiki. If you have no idea where to start
and find the information in the wiki lacking, try searching online or checking
sites such as the Linux Audio Wiki and LinuxMusicians. There are also various
projects on Rui Nuno Capela’s site which should enable you to get up and
running reasonably quickly.
Manual - 2 Installing and Configuring Qtractor
Manual - Table of Contents
2. Installing and configuring Qtractor
2.1. Compiling Qtractor
If Qtractor is not available from your Linux distribution’s package manager/repository and nor can you find a standalone package (such as a .deb
package for Debian, Ubuntu or other Debian-based system or an .rpm package
for Red Hat, Fedora, SUSE, etc.), then you will have to build it from source.
Doing so requires you have both a C++ compiler (such as g++, the GNU C++
compiler) as well as several other dependencies, the most important of which
are listed below.
Those with experience in compiling Linux/UNIX software using autoconf should
find the build process straightforward. Building Qtractor is fairly easy but both
the compilation process and setting up a build environment (a collection of
programs necessary for compiling software) can be a bit daunting to those new
to Linux. You don’t need to be a programmer to compile software but you will
at least need to know the basics of using the Linux command line and how to
use your distribution’s package manager.
2.2. Build dependencies
In order to compile Qtractor you are required to have at least all the packages
listed under section 2.2.1 installed. Everything listed under section 2.2.2 is
optional but recommended to get the most out of Qtractor.
Note that some Linux distributions (such as Arch) include the development files
in their packages whereas other distributions split packages up into binary and
dev components. For example, the ALSA library under Debian and Ubuntu
is contained in the package libasound2 but its development files are contained
within libasound2-dev.
If you are compiling Qtractor under a Debian or Ubuntu-based distro you can
install all the required build dependencies with one command by running:
sudo apt-get build-dep qtractor
2.2.1. Mandatory packages
• Qt 5 (core, gui, xml) - C++ class library and tools for cross-platform
development and internationalization http://www.qt.io/
• JACK - JACK Audio Connection Kit http://jackaudio.org/
• ALSA - Advanced Linux Sound Architecture http://www.alsa-project.org/
• libsndfile - C library for reading and writing files containing sampled
sound http://www.mega-nerd.com/libsndfile/
• LADSPA - Linux Audio Developer’s Simple Plugin API http://www.
2.2.2. Optional packages
• libvorbis (enc, file) - Ogg Vorbis audio compression http://xiph.org/
• libmad - High-quality MPEG audio decoder http://www.underbit.com/
• libsamplerate - Secret Rabbit Code; C library for audio sample rate
conversion http://www.mega-nerd.com/SRC/
• librubberband - Rubber Band Audio Time Stretcher; audio timestretching and pitch-shifting library http://breakfastquay.com/
• liblo - Lightweight OSC implementation (required for DSSI GUI and NSM
support) http://liblo.sourceforge.net/
• DSSI - API for soft synth plugins with custom user interfaces http://dssi.
• VST-SDK - Steinberg’s Virtual Studio Technology plugin format. Note
that Qtractor can still use most VST plugins when using the included
VeSTige reverse-engineered VST headers instead http://www.steinberg.
• LV2 - Audio plugin standard; extensible successor to LADSPA http:
• liblilv - Lightweight LV2 implementation stack http://drobilla.net/
• NSM - Non Session Management http://non.tuxfamily.org/nsm/
2.3. Downloading Qtractor
2.3.1. Official releases
Qtractor is considered to be in its beta stage of development but is already
fully functional. The latest official releases are publicly available from the
qtractor.sourceforge.net project web site:
2.3.2. Qtractor for the experienced and adventurous
The latest “bleeding-edge” source code can be obtained from the qtractor git
repository with the following command:
git clone git://git.code.sf.net/p/qtractor/code qtractor-code
Prepare the configure script on the just created qtractor-code source tree
cd qtractor-code
make -f Makefile.git
You should now be ready to configure, build and install Qtractor.
NOTE: After the initial checking-out of the source code, if you want to update
to the latest version in future you can fetch/merge the latest changes by using
the following command from within the qtractor-code directory:
git pull
2.4. Compiling and installing Qtractor
2.4.1. Standard compilation and installation
The installation procedure follows the autoconf standard. From within the
Qtractor source directory, run:
./configure [--prefix=<prefix>]
NOTE: To see all configuration options before entering the command sequence
above, type:
./configure --help
and optionally, as root:
make install
This procedure will end by installing the following files:
Just launch <prefix>/bin/qtractor and you’re off, hopefully! Note that the
default installation path prefix is /usr/local.
2.4.2. Compiling with Steinberg Linux VST Support (optional)
VST is the “Virtual Studio Technology” effect and instrument plugin format
developed by Steinberg Media Technologies GmbH. Using the official VST headers
could result in higher plugin compatibility than using the reverse-engineered
VeSTige headers included with Qtractor. Steinberg VST support is not very
easy to accomplish and is recommended for experienced users only.
Due to licensing issues for this proprietary software, one must download the
VST SDK (software development kit) from the third-party developers section of
the Steinberg Media Technologies GmbH website. Ensure you download either
the 2.3 or 2.4 VST SDK. Do not use VST 3.0. It will not work!
In order to download the VST SDK zip archive you will have to accept the
license and supply some personal data, then download and unpack the pertinent
program header files, which are found in one of the directories listed below.
VST SDK 2.3:
VST SDK 2.4:
It is recommended that you copy those files into a standard “include” directory
(eg. /usr/local/include or /usr/include), so that the Steinberg VST header
discovery process will be handled “automagically” by the ./configure script.
Otherwise you’ll need to supply the path yourself, like so:
./configure -with-vst=/path/to/vstsdk2.x/include
Qtractor searches for VST plugins within /usr/local/lib/vst and /usr/lib/vst. If
you wish to use VST plugins installed anywhere else then you will need to add
and export their location to your VST_PATH environment variable.
export VST_PATH=/path/to/vst_plugins
To set the VST_PATH permanently, you will have to add the above line to
the file where your distribution declares environment variables. This is usually
achieved by adding it to /etc/environment or creating a new .sh file under
/etc/profile.d .
A number of Linux VST plugins can be found on the following web sites:
• http://www.linux-vst.com/
• http://linux-sound.org/linux-vst-plugins.html
2.4.3. Compiling Qtractor with debugging support
If you find and report a bug in Qtractor, you may be asked to provide some
debugging information. This short guide will explain how to build Qtractor with
debugging enabled, making it easier to pinpoint the problematic code.
Rebuild it all from scratch, with:
./configure --enable-debug && make
Enable core dumps in a shell session:
ulimit -c unlimited
From the same shell command line, run the program until it crashes. You’ll see
something like this in the output when it happens:
Segmentation fault (core dumped)
Locate the dumped core file. Depending on your environmental settings it might
be named just core, or something like core.1234 (1234 is the process-id number
of the crashing program), located in the last directory where the program was.
Load the core dump file into gdb:
gdb ./qtractor /path/to/core
At the gdb prompt just enter:
gdb> bt
gdb> thread apply all bt
2.5. Qtractor’s Configuration Settings File
Qtractor keeps its settings and configuration file in:
Normally, there is no need to manually edit this file. Most of Qtractor’s options
can be adjusted from the Options window under the View menu.
2.6. QJackCtl
In order to use Qtractor, JACK must be running in the background. JACK is a
kind of patchbay for Linux (technically a “sound server”), enabling you to route
audio and MIDI data between Qtractor and other JACK applications.
Some distributions may configure Qtractor such that JACK starts automatically
when Qtractor is launched; others may not. If you launch Qtractor from your
application menu and receive JACK errors in the message log at the bottom of
the main workspace, quit Qtractor, start JACK manually, then launch Qtractor
The easiest way to start JACK is with QJackCtl (“Q JACK Control”), a control
panel and global, synchronized timecode display. If this is not installed, install
it from your distribution’s repository or from the project’s site.
If necessary, launch QJackCtl and click the Start button. This should begin a
global, synchronized timecode clock that will allow Qtractor to use all available
inputs and outputs just like a studio mixing board.
QJackCtl in operation
2.7. Audio and MIDI Input
Qtractor can record both digital audio and MIDI data, but it does not magically
know what audio or MIDI data you wish to record; you must route audio and
MIDI data to it manually. This can be done with QJackCtl, via the command
line or using Qtractor’s Connections window, pictured below.
Qtractor depends upon ALSA and JACK to utilize your audio hardware. It uses
ALSA to communicate with MIDI hardware and JACK to route audio to/from
various hardware and software “ports”.
Qtractor’s Connections window, showing both the Audio and MIDI tabs. “Readable” ports are sources of data (where audio or MIDI data can come from, e.g. a
microphone input or a MIDI keyboard controller) while “Writeable” ports are
places that data can be routed to, such as a track, an audio output or a MIDI
Manual - 3 Learning Qtractor–An Example Session
Manual - Table of Contents
3. Learning Qtractor–An Example Session
This chapter is written for those who may not be very familiar with digital
audio recording or MIDI “sequencing” applications, or who wish to gain a quick
overview of how Qtractor works. It can be used before exploring the program
in greater depth and learning its features in detail. It describes an example
Qtractor session and serves as a basic walk-through of the program.
3.1. Preparation
You’ll use Qtractor to import a pre-recorded audio file and record a MIDI
track. A MIDI-triggered tone generator (in this case, a hardware tone generator
outside the computer, although it could just as easily be a “soft synth” inside
the computer) will produce the sound for the MIDI track as Qtractor plays it
To begin:
1. Start the QJackCtl application (recommended), or start jackd from a
shell. After launching QJackCtl, press the Start button to start JACK
2. Launch Qtractor from your applications menu, dock, or launcher
3. It’s good practise to start every session by saving. It might seem
strange to save an as-yet empty session, but it’s better to save an empty
session than to start creating your masterpiece and have data files and
MIDI files scattered all throughout your hard drive. Saving first is a good
way to instantiate an environment in which you can keep all of your files
and sounds organized and consolidated
To save, click the File menu and select Save As. This opens the Session
Properties window.
In the Name field, name your session. For the Directory field, click the
directory icon to create a new, empty directory for your session files and click
OK. Save your session by clicking the OK button; a Save Session dialogue
will open so that you can navigate to the directory you’ve created and name your
session file, which will appear as a .qtr file. Click the Save button to confirm.
Now that the session has been saved, open the Session Properties window
again using the menu item File / Properties. This time, click the Properties
tab and set both the time signature and the tempo so that you can use the
metronome to help you keep MIDI parts synchronized as you record them.
3.2. Importing an Audio File
The first thing you may like to do is import a pre-recorded audio file of drums
and other percussion, to form the basis of the recording session. To bring audio
into your project file, right-click in the Files pane on the right hand side of the
main workspace and select Add Files, then choose the file or files you wish to
import from the Open Audio Files window that appears. If the Files pane
isn’t visible, you can enable it by clicking on the yellow file icon, the one without
an arrow above it. To place an audio file in a track, drag and drop it from the
Files pane into the workspace. You can add it to an existing track, or drop it
directly into an empty area and a new track will be created automatically.
3.3. Connecting the MIDI data source to Qtractor
Your MIDI piano-like keyboard normally routes its MIDI data (created when
you strike the keys, for example) to its own internal tone generator, which then
sounds like you’re playing a real piano, or electric piano, harpsichord, bass
guitar, etc. However, for this project in Qtractor you want to route the external
keyboard’s MIDI data to Qtractor. So, using a standard MIDI cable (or perhaps
a MIDI to USB converter, depending on your set-up), connect the keyboard’s
output to the input of your sound card. Inside the computer, you will route the
MIDI data from the sound card to a Qtractor MIDI input bus.
Next, open Qtractor’s Connections window by clicking on the red icon near the
top of the main workspace.
Connections icon
In the Connections window’s MIDI tab, connect the MIDI output of the sound
card (in the left pane, marked Readable Clients / Output Ports) to Qtractor’s
listing in the right pane (marked Writable Clients / Input Ports). If your sound
card doesn’t appear in the list, click the Refresh button in the bottom right to
update the list of connections.
You can connect an output port (the source of the data, MIDI or audio) to an
input port (the port that will receive the data) in several ways. One method
is to left-click a port in the left pane, left-click a port in the right pane, then
either left-click the Connect button or right-click elsewhere in the window and
select Connect from the pop-up menu. Another method is to click a port in
the left pane and, with the mouse button held down, drag the cursor to a port
in the right pane until the port is highlighted, then release the mouse button.
Regardless of the method you use, a line representing a “virtual cable” will
appear between the two ports in the middle section of the window.
After connecting your sound card to Qtractor, you’ll then need to connect
Qtractor’s output to your destination source, so that it can send the MIDI information back out again. Again in the Connections window, connect Qtractor’s
Master/Out listing in the left pane to your sound card in the right pane.
Once you’ve made your connections, close the Connections window by clicking
its icon once more.
3.4. Creating a MIDI track
Now that Qtractor can receive and send MIDI data, it’s time to create the first
track in order to record that data. Right-click in the blank pane on the left of
Qtractor’s main window and, from the pop-up menu, choose Add track. . . . You
can also do this via the menu item Track / Add Track. . . .
Adding a track
Qtractor’s Track Properties window will then open.
Track Properties window
In the Track Properties window, click the MIDI radio button: you want this
track to be used for MIDI, rather than audio, data. As soon as you click the
MIDI button, the track is automatically connected to Qtractor’s Master MIDI
input and output buses. These can be changed by using the drop-down lists
and the ellipsis button in the Input / Output area of the Track Properties
window, but there is no reason to do so right now. You can replace the default
name “Track 1” with, for instance, “Piano comp.”
You can leave the MIDI Channel at the default “1” for now, as this channel
designation is mainly for output. That is to say, when the track is played back
and its MIDI data is sent to somewhere outside Qtractor (in this case, a hardware
tone generator) that data will be sent on the MIDI channel specified here (there
are 16 possible channels). However, you’re going to record now, so the eventual
output MIDI channel doesn’t matter at the moment - it can easily be changed
later before you play your MIDI tracks back.
What does matter however is the Omni checkbox. If enabled, Qtractor will
record MIDI information received on any MIDI channel (omni means all). If
disabled, it will record only information it receives on the channel number
specified in the Channel setting, to the right of the Omni checkbox. Your MIDI
keyboard might be set to transmit MIDI data on only one channel (e.g., MIDI
channel 1), so you need to make sure that each of the MIDI tracks you plan to
record on will receive data either from the correct channel, or from all channels.
Click the OK button and a new empty track appears in Qtractor’s main window.
3.5. Recording and Playback
In order to record, you must arm the track by clicking on the “Record” button
for that track. This is the “R” button that is present on every track strip, besides
the other “M” and “S” buttons (respectively for “Mute” and “Solo” track state
settings). You can also do this via the menu item Track / State / Record.
Either way, the “R” button will turn red (or become highlighted, depending on
your GUI settings) and the track is then set armed and ready for recording.
Next, turn on session recording mode by clicking on the Record button in the
main transport toolbar (big red circle). You can also do this via the menu item
Transport / Record.
Now you’re ready to record your first MIDI track. Take a little breath and. . .
press “Play” (blue triangle next to the transport’s Record button), the space
bar or choose the Transport / Play menu item: you’re rolling. Hit the MIDI
keyboard and see a brand new MIDI clip taking shape while you’re performing.
When done, press “Play” again to stop.
As previously mentioned, when playing back a MIDI track its data is sent on
the channel number specified in the Channel setting of the Track Properties
window. In order for your hardware tone generator to play back the MIDI data
from Qtractor as actual sound, you’ll need to make sure that this channel tallies
with your hardware set-up.
3.6. Next Steps
This chapter has been merely an introduction to what is a fairly far-reaching
subject. More detailed information on the above topics, plus many other aspects
of Qtractor, can be found in the next chapter. Specifically, see here for more
information on working with MIDI and here for audio. A sample MIDI workflow
tutorial using a soft synth can be found in this How To.
Manual - 4 Qtractor–An Overview
Manual - Table of Contents
4. Qtractor–An Overview
4.1. Routing–Connections, Ports, Tracks and Buses
4.1.1. Routing–General Concepts and Information
Qtractor can record and play digital data, specifically audio and MIDI data.
To record, Qtractor must get the data from somewhere; to play the data,
Qtractor must send it to somewhere that can understand the data stream and
produce sound. The process of directing such data to and from – and through –
software and hardware is called routing. In Qtractor, not much routing is done
automatically. Most of it is left to the user, because it is the user’s preferences,
desires and goals in any specific project that determine how the audio and MIDI
data should be routed.
In order to route data, one must have an understanding of the various connections
and pathways that are available. A bus is like a pipeline through which one or
more streams of data can travel. A port is like a valve at one or both ends of a
bus. A port is normally closed, not allowing any data to flow through, but once
a connection is made to it, it opens to allow data to pass through it from one
bus to another. However, simply because a connection is made and the port is
open doesn’t mean that data is flowing through it: the data flow is initiated by
the software or hardware at one or both of the ends of the bus.
A track can be thought of as a place where digital audio or MIDI data is deposited,
rather than a pathway through which such data moves. Data can be deposited
in various ways, such as recording, pasting or importing. Tracks are, however,
still part of the signal or data flow, as they can “pluck” a copy of their data and
send it to one or more buses (and, through those buses, to other destinations).
In concrete terms:
• During recording, a track becomes the destination for audio or MIDI data
entering Qtractor’s input bus(es)
• During playback, a track becomes the source of audio or MIDI data, which
is then sent through a Qtractor output bus to a destination, such as a
sound card and its attached speakers
Below is a representation of the connections (ports), buses and routes in Qtractor
through which audio or MIDI data can flow.
Audio & MIDI data flow, in, through and out of Qtractor
Routing in Qtractor is very flexible and therefore signal/data flow can become
very complex. Data streams can merge and flow through the same bus, or split
and go through separate buses to different destinations. They can likewise flow
through different buses to the same destination, whilst passing through other
intermediate software or hardware in which the data is possibly manipulated
in some way. Because of this complexity it is beneficial to develop a solid
understanding of the issues related to routing, the many possible routes that
data can take and the many possible connections that can be made.
4.1.2. Routing in Qtractor
Routing can be accomplished in several ways, including:
• Using the Connections window to connect Qtractor’s input and output
buses to outside sources (for “reading” and, possibly, recording data) and
destinations (for “writing” data to, for example, a sound card)
• Using the Track Properties window to assign a track’s input and output
• Setting the state of a track, from among Record, Mute, Solo and Monitor
(some of which are mutually exclusive)
• Adding Plugins, Aux Sends or Inserts to tracks or buses. Aux Sends are
used to route audio to internal destinations, i.e. Qtractor buses; Inserts
are used for external destinations, i.e. applications outside of Qtractor
4.1.3. Routing–Technical Notes
Qtractor is a fairly massive multi-threaded application. For instance, each audio
clip has a dedicated disk I/O executive thread, which synchronizes with the
master engine, and to the central JACK real-time audio processing cycle, through
a lock-free ring-buffer. These audio file ring-buffers are recycled (filled/emptied)
at a one second threshold and have a maximum streaming capacity of 4-5 seconds
of audio sample data. Smaller clips are permanently cached in a RAM buffer.
Audio thread scheduling is mastered and mandated through the JACK callback
API model. MIDI clip events are queued in anticipation through one MIDI
output thread, which feeds an ALSA sequencer queue, synchronized on one
second periods to the JACK process cycle. A single thread is responsible for
listening (polling) for MIDI input, and multiplexes all incoming events through
record-armed MIDI tracks. Time stamping is done through the ALSA sequencer
Looping is made possible through the audio file buffering layer, right at the disk
I/O thread context. The same consideration is adopted for MIDI output queuing.
Audio frame relocation is accounted from successive JACK client process cycles
(i.e. buffer-period resolution).
In this particular design, JACK and ALSA sequencer ports are logically aggregated as buses with respect to the audio and MIDI signal routing paths,
functioning as fundamental device interfaces. Input buses, through exposing
their respective input ports, are the inlets responsible for capture and recording.
Output buses are the main signal outlets and are responsible for providing
playback and, more importantly, mix-down connections.
Buses are independently assigned to tracks. Each track is assigned to one input
bus for recording, and to one output bus for playback and mix-down. The
assigned bus determines the number of channels the track supports. Clips bound
to disparate multi-channel audio files, for which the number of channels does
not match the track’s, are automatically resolved on mix-down. The illustration
in the above section shows one typical signal flow block diagram.
4.2. Qtractor’s Main Window and Work Area
Qtractor’s graphical user interface follows a standard design of most modern
digital audio and MIDI workstations. The interface is easy and intuitive enough
to easily interact with in order to discover the potential of the underlying inner
core of the application where its functionality is implemented.
The following illustration shows an overall view of the GUI with an example
session loaded into the workspace.
Qtractor’s main window and work area
The main Qtractor window is initially laid out in this fashion:
Top - Menus and toolbar icons, with navigation window in bottom-right
Left - Tracks area, showing name, state, buses etc.
Middle - Audio and MIDI clips area, with timeline above
Right - Files pane
Bottom - Messages window
To move around the work area use the horizontal/vertical scroll bars at the
bottom/right of the windows, or the mouse wheel to move up/down and
Shift+mouse wheel to move left/right. You can also click on the navigation
window (above the timeline) to jump to specific areas of the session.
The navigation window, situated between the main toolbar icons and timeline
To zoom in/out horizontally and vertically use the magnifying glass buttons in
the bottom-right of the main view. Shift-clicking these allows you to zoom in
greater increments and Ctrl-clicking will zoom to the maximum/minimum. You
can also zoom in/out horizontally using Ctrl+mouse wheel.
“Magnifying glass” zoom buttons, situated in the bottom-right of the main view
The clips area in the middle is where most of the action takes place. It contains
visual displays and representations of audio waveforms or MIDI data. This
section is used for editing Clip objects (portions or all of any particular audio
or MIDI file, recorded or imported) and for navigation within the project or
The very bottom-right of the screen shows the Session total time and Session
sample rate. To the left of these is a panel which provides information on the
session’s current state. From left to right, the indicators and their meanings are:
MOD - session state has been modified since last save
REC - session is set to record when transport next starts
MUTE - at least one track is muted
SOLO - at least one track is soloed
LOOP - session is set to loop when transport next starts
XRUN - an x-run has occurred
Session state, total time and sample rate information
Qtractor also has other useful windows, such as the Mixer window and the
Connections (patch-bay) window. These can be opened via the View / Windows menu, or by pressing F8 for Connections or F9 for the Mixer. Three
utility windows are additionally featured: the Messages window, for general
information and debugging purposes; the Files pane, where audio and MIDI
files are organised and selected; and the File System browser, which provides
access to your file system in a manner similar to a file manager (such as Dolphin,
GNOME Files, Thunar and so on).
Dialog windows for editing session, track and clip properties are also accessible
in their proper context, which will be discussed in their respective sections.
Finally, session and application configuration options are assisted through respective customizing dialogs: Buses, Instruments and Options. . . , available from
the View menu in the main menu bar.
4.3. Understanding a Qtractor Session (recording or editing)
A Qtractor session project contains all the information about your Clips and
their placement, Mixer set-up, plugins, tempo, time signature and Connections
patch-bay. When creating or saving a project, all this and any related settings
are saved on your hard disk within this session project file.
To create a new session, simply start Qtractor and begin working. If you already
have a session loaded and want to start a new one, choose File / New or click
the New session icon (blank piece of paper) in the upper-left of the screen. To
open a session, either use the File / Open. . . menu command or drag your
session file (.qtr or .qts, which are essentially the same) into the left or middle
4.3.1. Session Audio Sample Rate
It is important to note that Qtractor sessions are locked to a session project
sample rate. This is dependent on the sample rate of the JACK server running
at the time the session is created.
Any attempt to convert non-matching sample-rate sessions will result in a
recommendation warning message.
However, individual audio clip files are automatically converted on playback in
real-time to the host sample-rate (via libsamplerate). This method, while it
works very well, is not the recommended method due to possible errors in the
real-time sample rate conversion. Real-time sample rate conversion is also going
to use quite a bit more valuable CPU resources.
Rui Nuno Capela is working toward eliminating this shortcoming by taking
control of JACK from within Qtractor, and restarting it using the session’s
project parameters. This will ultimately reconnect any plugins, set the proper
sample rate, etc. Until this feature is available, please follow the recommendations
listed above.
4.3.2. Session Properties
To access the session properties, choose the File / Properties menu item. Here,
you can name your Qtractor session, set the tempo, time signature (how many
beats per bar) and decide how many “ticks” (the smallest time unit in a session)
will be within the time span of each beat.
Session properties window showing both Session and Properties tabs
Tempo and time signature can be changed during the course of your composition
using the Tempo Map / Markers window. This is accessed via the View
menu or by double-clicking the region directly above the tracks which displays
the bar numbers. Determine where you wish your tempo/time signature change
to occur in Location, input the details of the change in Node, then click either
Add to add a new node, or Update to make changes to a previously created
one. If desired, you can also add descriptive text in Marker, plus a colour, by
clicking the palette icon next to the text field. Markers may be assigned to
tempo/time signature changes, or independent of them. Once you’re happy with
the content of your Marker, click Add to add it to the map. The other option
in this window is Tempo scale factor, which allows you to scale the entire
Tempo Map (speeding up/slowing down the whole composition) by an arbitrary
Tempo Map / Markers window showing tempo/time signature changes and
There are two limitations to be aware of with regard to tempo and time signature
changes. Firstly, changes must occur at the start of a bar - there is no facility to
add changes within one. If you, for example, need to insert a change into the
middle of a 4/4 bar, create two 2/4 bars and add the change to the start of the
second of these. Secondly, there is no facility to “ramp” between two different
tempos (gradually increase/decrease tempo over a defined period). Hopefully,
such a feature will be added in the future, though whether this will happen or
not is currently unclear.
4.3.3. Session Options
Access the Options windows via the View / Options. . . menu item. This
window allows you to control the global parameters of Qtractor. These are global
settings which are not saved within your session file.
Session Options window, showing General tab
The window is divided into five tabs: General, Audio, MIDI, Display and
Plugins. Most of the settings are self-explanatory, and there are tool tips to
guide you, but some which require more explanation are covered elsewhere in this
chapter. The default options should largely be fine to begin with, but if you’re
having trouble seeing parts of the GUI you may wish to adjust the options in
the Display tab. Qtractor takes its look-and-feel from your system settings by
default, but on this tab you can disable Use desktop environment native dialogs
(which should be off by default) and choose your preferred Color theme and
Style theme. You may also wish to run qtconfig to perform configuration for
all Qt applications (of which Qtractor is one).
If you experience problems with Qtractor when using a desktop environment
based on GTK+ (GNOME, Xfce etc.), try a Qt-based theme for Style theme
and make sure that Use desktop environment native dialogs is disabled.
4.4. Files
Sound file selection is made available through a tabbed mini-organizer, known
as the Files pane, which lists all the files contained in the current session. Audio
and MIDI file lists are kept separate on their respective tabs. Audio file format
support is provided by libsndfile, enabling the use of wav, aiff, flac, au, etc. The
optional libraries libvorbis and libmad provide support for ogg and mp3 formats
respectively. MIDI file support covers the usual SMF formats 0 and 1, through
a native, home-brew implementation.
Files can be imported using the menu command Track / Import Tracks /
Audio. . . or MIDI. . . , or by right-clicking in the relevant tab of the Files pane
and choosing Add Files. . . . If the Files pane is not visible, you can enable it
via View / Windows / Files. The default position for the Files pane is to the
right of the clips area, but it can be detached and docked elsewhere (such as to
the left of the Tracks pane) if needed. You can preview files by double-clicking
them, or by selecting them and either clicking the play button on the lower right
hand side of the pane or choosing Play from the right-click menu.
The Files pane of Qtractor’s main workspace. Both Audio and MIDI tabs are
When importing a MIDI file, note that the file’s tempo map will be reproduced
in Qtractor only if it is the first MIDI content to be loaded into the current
session. If the current session already has one or more MIDI tracks (even if the
tracks contain no actual clips), the tempo map from the imported MIDI file
will be discarded. This also means that if a New session template containing
tracks has been enabled via the View / Options. . . / General menu, the
tempo map of any imported MIDI file will be automatically discarded.
Individual and multiple files can be drag-and-dropped from the desktop environment and within the file list. Dropping a file into a blank region of the tracks
area will create a new track and add the clip (which represents the file) to it.
Dropping a file into an existing track will create a new clip within it. When
dropping an audio file into an existing track you can drag the file itself, but with
a MIDI clip you must drag your desired Track/Channel (displayed when clicking
the file name in the Files pane), rather than the file itself. Finally, dragging a
session file (.qtr or .qts, which are essentially the same) into the left or middle
pane will load that session.
After working on a project for a while you’ll probably find that the Files pane
contains files which you no longer need. To remove anything not currently
referenced in the tracks area, right-click the Files pane and choose Cleanup.
Note that this merely cleans up the list of files - it does not delete the files
themselves from your hard drive. If you wish also to remove non-needed files
from your session directory, save the session as a .qtz archive and use this in
place of your previous session. See here for details on archives.
For convenience, a File System browser with tree-view is also available. This
can be enabled via View / Windows / File System. Its default position is
to the left of the Tracks pane, but like the Files pane it can be detached and
docked elsewhere. For instance, you may choose to have both windows on one
side of the screen, with one above the other.
File System browser, docked to the left of the Tracks pane
4.5. Clips
4.5.1. Clips Summary
Clip objects are the elemental items of a session arrangement, and can contain
either audio or MIDI data. A clip represents either a region of, or the entirety
of, an actual audio or MIDI file. MIDI clip objects are representations of a
sequence of events of one single MIDI channel, as extracted from an SMF format
0 file, or of one single track from an SMF format 1 file. Clips can be copied,
truncated, lengthened/shortened (by dragging their edges) and time-stretched
as if they were actual audio/MIDI data; editing a clip object in these ways is a
non-destructive process.
Clips are placed on tracks either by importing audio or MIDI files as new tracks
or by dragging and dropping files into the main track window. Empty clips
may also be created by right-clicking on a track and choosing Edit / Clip /
New. . . .
4.5.2. Copying, Cutting, Splitting and Merging
To copy or cut a clip, select the clip, then right-click and choose Copy or Cut
from the menu. Next, choose Paste from the right-click menu, position the box
outline where you want to paste the clip and left-click. Note that when copying
a MIDI clip within the same track, the two clips become linked, meaning that
any change to one of them will automatically affect the other. If you select a clip
which is currently linked to another, any such linked clips will be highlighted
with a dashed outline, enabling you to see which other clips will be affected by
changes made to the selected one. To unlink a clip, thus disabling automatic
changes, select it and choose Clip / Unlink from the right-click menu.
A linked clip highlighted with a dashed outline
To split a clip, select the clip, then position the playhead (red vertical line) where
you want to split it and choose Clip / Edit / Split from the right-click menu.
If you use this operation often, it is far more convenient to assign a keyboard
shortcut for it. Since Qtractor never affects the original file it is referencing, any
split you make to a clip is reversible. You can undo a split via the Edit / Undo
menu, or by clicking and dragging the edge of the clip then extending it to its
original length. Note that when dragging audio files to hide/reveal portions of
them, the waveform may appear to “move” slightly. This is just a visual artefact
- the position of the actual audio in the track is not affected.
To merge clips and so consolidate a number of them into one file on your hard
1. Select the clips within a track that you want to merge into one
2. Choose Clip / Merge, either via the main toolbar or the right-click menu
3. In the Merge/Export window, enter a new name for the merged file and
save it to a logical location on your hard drive (preferably within your
session folder)
4. The merged clip immediately replaces the old clips in your project
4.5.3. Fades and Cross-Fades
Fading a clip in or out is a common enough operation that there is a quick
shortcut to achieve the effect. Notice that in the top corner of any audio or
MIDI clip there is a semi-transparent square node. Clicking and dragging this
node further into the clip will create a fade-in (if done at the beginning of the
clip) or a fade-out (if done at the end).
The actual method of audio volume (gain) and MIDI velocity change can be one
of linear, quadratic or cubic types. You can set your desired type via the clip’s
Properties window (see next section).
An audio clip, with left and right upper corner fade handles drawn inward to
create a fade-in and fade-out
When two clips overlap you may wish to cross-fade them, simultaneously fadingout the first and fading-in the second. You can do this manually, by dragging
the fade handles to the desired lengths (they can still be manipulated even if
clips overlap). Alternatively, you can select either clip and choose Clip / Cross
Fade - Qtractor will then add a cross-fade, determined by the length of the
overlap. Once you have your cross-fade you can fine-tune its length and type if
needed, as per the information above. If you have trouble clicking on a particular
clip because it’s obscured by another, try selecting it from the Files pane.
Two audio clips cross-faded together
4.5.4. Clip Properties
A clip’s properties can be accessed by double-clicking the clip (for audio clips),
or by opening the clip and choosing File / Properties (for MIDI).
Audio clip properties include its Name (the label the clip is known by within
the session); File path; Start time (location), Offset and Length; Gain; Panning;
Format (Frames, Time or BBT); Fade-in/out length and type; Time Stretch
percentage; and Pitch Shift amount (in semitones) and options. Time-stretching
is applied in real-time at the buffering level, as a custom WSOLA algorithm
based on and derived from the SoundTouch library.
MIDI clip properties include its Name; File path; Track/Channel; Start time,
Offset and Length; Volume; Format (Frames, Time or BBT); and Fade-in/out
length and type.
Audio clip properties window
4.6. Qtractor Main Workspace–Tracks Area
4.6.1. Tracks Summary
MIDI and audio tracks in the main workspace of Qtractor
Tracks are arranged as a sequence of one or more clips of the same file type,
either audio or MIDI. The tracks window is the main application workspace,
serving as a virtual canvas of a multi-track composition arranger. Most of the
editing operations are performed here.
The tracks area has two panes: the left one displays the list of tracks with their
respective properties and the middle pane is the audio and MIDI clips area,
where multi-track composition and arranging is performed. Column widths in
the left pane can be adjusted to allow for long track names etc. by dragging their
edges; double-clicking resets them to their defaults. Track height can be adjusted
by dragging up/down in the Nr column of the left pane, or by right-clicking and
using the Height menu. If desired, meters showing volume levels can also be
added to the left pane. To enable these, open the View / Options. . . menu
and enable Show meters on track list/left pane in the Display tab.
Audio and MIDI tracks with meters enabled
Note that information regarding global UI settings, such as column widths
and Mixer set-up, is stored in ~/.config/rncbc.org/Qtractor.conf (and so
restored upon re-loading Qtractor), while track height is stored in the session
file (and so restored upon re-loading a session).
To create a new track either right-click in the left pane and choose Add Track,
or right-click in the right pane and choose Track / Add Track. In the Track
window which appears, choose a name in the Name: box, choose a Type (Audio
or MIDI ), adjust any other options desired, such as the track’s colour and icon,
then click OK.
Track window for a MIDI track
You can also duplicate an already-existing track by right-clicking the track in
the left pane and choosing Duplicate Track.
As is usual, tracks are stacked on horizontal strips and clips are layered on a
bi-dimensional grid, in time sequence for each track strip. Time is modeled on
the horizontal axis and pictured by a bar-beat scale ruler at the top of the track
view. Clips may be conveniently aligned to discrete time positions, depending
on the current Snap mode setting, which is set via either its icon on the toolbar
or the View / Snapping menu. When set to “None”, snapping is carried out
to MIDI resolution, quantized to ticks per quarter note granularity.
Each track has its own user assignable colors for better visual identification.
Audio clips are displayed with approximate waveform graphic, with peak and
RMS signal envelopes as read from the respective audio file segment. MIDI
clips are shown as a piano roll-like graphic, with note events shown as small
rectangles, depicting pitch, time and duration.
All session, track and clip editing operations are undo/redo-able. Discrete view
zooming is also available.
The red vertical line in the tracks area is the playhead. This shows the point at
which playback/recording will begin when you start the transport rolling and
its time corresponds to the clock towards the top-left of the screen. You can
control the position of the playhead via the transport controls (to the left of
the clock), by dragging the top of the playhead, or by Ctrl/Shift-clicking in
the horizontal bar above the tracks which houses the bar numbers or in an area
of the Tracks pane which contains no clip (Ctrl/Shift-clicking on a clip will
select the clip). Alternatively, you can Ctrl/Shift-middle click on either the
horizontal bar or anywhere in the Tracks pane (with or without a clip).
Transport controls (left box) and clock (right box) showing current position of
The blue vertical lines are Edit Markers. See below for information on these.
4.6.2. Track States
A track’s state is controlled via the R, M, S and A buttons in the left pane.
Their meanings are as follows:
• Record - arm the track for recording, ready for creating new audio or
MIDI clips with captured material
• Mute - silence the track so that it produces no sound
• Solo - set only this track to produce sound, silencing all the others (though
those already solo-ed will too produce sound)
• Automation - automatically control various parameters of a track or its
plugins. See the Automation section for details
When muting/solo-ing a track, holding down Shift or Ctrl while clicking the
M or S buttons produces the following effects:
• Shift-click - Enable/disable state on all tracks. If the button clicked is
currently disabled, all tracks will be enabled; if it is currently enabled, all
tracks will be disabled
• Ctrl-click - Enable/disable state on this track only. For example, Ctrlsolo-ing a track with other tracks already solo-ed will un-solo those other
tracks, leaving just the target track solo-ed
Mute, Solo, Record & Automation buttons for individual tracks
It is possible to select more than one track at a time in order to mute/solo/monitor
them all simultaneously, by using the following commands:
• Add tracks - Shift+left-click/mouse drag; Shift+Home/End keys;
Shift/Ctrl+up/down arrow keys
• Toggle tracks - Ctrl+left-click/mouse drag; Ctrl+Home/End keys
In Qtractor parlance, though there is only ever one current track at any one time
for editing purposes, there may be one or more selected tracks, invoked by the
above commands, on which an operation can be performed. The current track is
always displayed with a slightly darker background, whilst the colour of selected
tracks is determined by the current palette scheme or theme (the default being
that of the desktop environment). Once you have your desired tracks selected,
you can mute/solo/monitor them using the relevant icons, menus or keyboard
shortcuts. It is also possible to Shift/Ctrl-click the M or S icons (as discussed
above) with multiple tracks selected in order to apply these operations to the
entire “set” of selected tracks.
Tracks can also be muted and solo-ed on mix-down, which will then apply when
exporting, enabling you to export specific tracks only.
4.6.3. Making Selections - Select Modes
The mouse cursor has four select modes: Clip, Range, Rectangle and Automation.
Choose your desired mode via Edit / Select Mode from the main toolbar, or
by right-clicking in the track area and choosing Select Mode.
Select Mode context menu (right-click menu)
• Clip - allows you to select whole clips, click and drag them within and
between tracks, and extend/shorten their lengths. The precision with
which you perform these operations is determined by the current Snap
mode setting
• Range - spans all tracks in your workspace and allows you arbitrarily to
select any portion of clips, irrespective of their beginning/end. You can,
for example, select a range in the very middle of a clip and all other clips
above and below it, because you are selecting a block of time, rather than
a particular clip
• Rectangle - is similar to Range, but is track-specific. This allows you to
draw an arbitrary “box” area over one or more tracks, the extent of which
becomes your selection
Once you’ve made your selection, you can then perform the usual cut, copy,
paste etc. operations.
Making a selection using the Range* select mode*
For the final select mode, Automation, see its section.
4.6.4. Making Selections - Edit Markers
In addition to using select modes, you can select a range in your workspace by
using the Edit-head and Edit-tail markers. These are the two blue vertical lines
which are present in the tracks area and which are independent of the playhead.
The Edit-head and Edit-tail markers
To set the in-point of your selection, left-click in the bar/tempo area of the
workspace, where the top of the blue lines are situated. To set the out-point,
right-click in the same area. You can also drag the lines. Middle-clicking will
bring both lines together at that point.
Once you’ve set your markers, you can use them to make a selection. To do
so, from the main toolbar, choose Edit / Select and one of Track or Track
Range. You can also right-click in the track area to access the same menu.
4.6.5. Loops
Looping a section is a common operation, often used to enable a musician to
practise a particular passage, or a mix engineer to focus on a specific area. To
play a section of your composition in a loop:
1. Select a range, using one of the methods described above
2. From the Transport menu, select Loop Set. Alternatively, click the Loop
button (pair of blue, circular arrows) on the main toolbar
3. Move the transport into the loop range, or somewhere before it, then press
the Play button or the space bar. Once the transport reaches the end
of the loop range, it will return to the in-point and seamlessly continue
playing until stopped
It is also possible to record using a loop, but such an operation would more
commonly be handled by Qtractor’s Takes feature. See its section for details.
4.6.6. Paste Repeat
In electronic music especially, there’s often a need to record one or two bars
and then loop them to create standardised bass lines or drum beats. For drum
tracks, you may prefer to handle them by using a specialist drum machine, such
as Hydrogen, which would play the same data (either pure MIDI data or audio
samples) for as many bars as you program it to. However, the same effect can be
achieved in Qtractor by using a Paste Repeat. This allows you to copy an audio
or MIDI clip and then paste it back-to-back for as many repetitions as you wish.
There are two ways to perform a Paste Repeat - one quick and one slightly more
detailed. The quick method is to Ctrl-click and drag a clip’s left or right edge.
This will replicate the clip as many times as fits into the desired area. The more
detailed method is as follows:
1. Check your snapping settings in the View / Snap menu (when pasting
clips for a loop, the user generally wants precision snapping to the clips’
2. Select the clip you want to copy using the Clip select mode (or use Range
mode, Rectangle mode, or the Edit Markers to select a portion of a clip)
and use Edit / Copy to copy it
3. Click Edit and choose Paste Repeat
4. In the Paste Repeat window, enter the desired number of iterations in
Count and, if needed, the duration (in frames, time or BBT) between the
start of each iteration in Period. Click the OK button to confirm
5. Position the box outline where you want to paste the clips and left-click to
anchor them in their track
Note that any clips copied in this way will become linked to the original, as
covered in the Clips section.
4.6.7. Punch In/Out
If one or two bars of a track don’t quite measure up to your standards, you
might want to re-record just those bars without having to record the entire track
over again. This process is called punching in/out.
To perform a punch in/out:
• Use the Range or Rectangle selection mode, or the Edit Markers, to define
the region of your timeline that you wish to re-record
• Once your range is set, click the Punch in/out button in the main toolbar
(pair of up/down arrows), or use the Transport menu and select Punch
• Arm the recording destination track by clicking its “R” button in the track
properties pane, on the left hand side of the main workspace
• Press the Record button in the main toolbar, position the playhead somewhere before your selected region, then press the Play button or the space
bar. Qtractor will play back your piece and you can play along, but nothing
will actually be recorded unless it is within the punch range
• To stop playback, click the Stop button in the main toolbar, or use the
space bar
Punch in/out range (purple markers) inside a loop range (green markers)
4.6.8. Automation
Qtractor features automation of nearly any aspect of any plugin, as well as basic
track functions like volume and panning. It is only possible to automate tracks;
buses cannot be automated.
• In the track you wish to automate, click the Automation button in the
track list. From the pop-up menu, select the attribute of the track that
you wish to automate first (here, we’re automating “wave Volume”). An
overlay is placed on the track.
Automation pop-up menu
• Click the Edit menu to go into the Select Mode category, and choose the
Automation selection tool. Alternately, click the Automation Selection
Tool icon from the top menu bar
• Armed with your automation selection tool, click on the automation overlay
on your track to create a node. Node placement is constrained by the
Snap/beat setting, so set this to None if you wish to place a node at an
arbitrary point
• Adjust the volume of this node to be the initial volume. You can either
drag the node or double-click it and enter a precise value
• Click again on the automation overlay to create a second node, and move it
to another volume level. For the space between the two nodes, the volume
will change from the starting node level to the ending node level
• You can drag multiple nodes left/right, maintaining their values (vertical
positions), by first selecting the nodes then dragging them whilst holding
Ctrl or Shift. It is not currently possible to drag multiple nodes up/down
Adding automation nodes
If you need a less gradual change, move the nodes closer together, or use more
nodes to shape different movements.
Adjusting automation nodes
The type of transition used between automation nodes can be customized via
the track’s Automation button, within the Mode category. Hold places the
automation nodes into absolute values until otherwise changed.
“Hold” automation mode
• Linear - represents the automation as even linear progression from one
node to the next. This is the default automation mode.
“Linear” automation mode
• Spline - same as linear, except with b-splines instead of completely linear
progress between nodes.
• Logarithmic - same as spline except that the degree of the bezier curves
change proportionately to the difference between nodes.
“Spline” automation mode
• Color - when you automate volume, panning and effects all on one track
it can get confusing. Use Color to change the shade of the automation
overlay so that you can distinguish one set of controls from another. Lock
prevents accidental changes to automation; this is especially useful when
working on a different automation function on the same track.
Automation node values are stored as plain MIDI controller values, which
means a default 7-bit resolution; on save/load, the values are quantized to this
resolution. Because of this, you may find that the values you originally entered
change very slightly upon reloading a session. Despite this, Qtractor should
still handle the automation correctly. If you want a higher resolution, you can
enable High resolution plugin automation from View / Options. . . / Plugins
/ Experimental, which will give a 14-bit resolution.
If you are a skilled live mixer and want to record your performance in real-time,
you can override existing automation decisions, or record new ones, in two
different ways, each available in the Automation menu:
• Play - with this enabled, you may make real-time changes to existing
automation, and upon release of the slider or knob that you are automating,
the value returns to the pre-existing value. This may be combined with
the Record option.
• Record - with this enabled, you may make real-time decisions for automation and every move will be recorded, in real-time, as a node in your track.
They can be manually changed later, if needed.
4.7. Mixer
4.7.1. Mixer Summary
The Mixer window serves for session control, monitoring, recording and assistance
in mix-down operations. It is divided into three panes: the left accommodates
all input buses; the centre, individual track strips (either MIDI, with a yellow
“plug” icon, or audio, with a green “waveform” icon); and the right, output buses.
These are marked as Inputs, Tracks and Outputs respectively. Right-clicking in
this area allows you to toggle the Inputs/Outputs’ displays on and off; you can
also left-click and drag & drop them both within and outside of the Mixer.
The Mixer window can be accessed via the View / Windows / Mixer menu.
It opens as a separate window, making it a prime candidate for occupying a
second screen if you have a multiple-head set-up.
The Mixer window
Each vertical mixer strip offers a volume slider (MIDI tracks) or gain control
(audio tracks and buses), panning slider, Mute/Solo/Record state buttons (tracks
only), monitor button, connections button (buses only) and output event activity
LED (MIDI tracks only).
Right-clicking in the panel directly underneath each strip’s name allows you to
perform a variety of operations. For instance, you can add plugins, or set up
dedicated outputs via Audio / Dedicated. A dedicated output is an audio
output specifically for that track, which can be connected via JACK (in Qtractor’s
Connections window, or QJackCtl, it will appear in the Audio tab, under
Qtractor). You can also choose whether to Auto-connect the dedicated output
via the same right-click menu - doing so means that it will automatically be
connected to system:playback_1 and 2.
At the extremities of the Mixer window are the Master In and Master Out buses.
These are independent of any one track and control everything coming into or
going out of the Mixer. Here, you can adjust the master input/output levels and
place any effects processors you want to apply globally (such as a compressor to
prevent peaks on outgoing audio).
Monitoring is presented in the form of peak level meters for audio and note
event velocity for MIDI, both with fall-off eye-candy. Audio volume is presented
on a dBFS scale (IEC 268-10) and pan is applied in approximated equal-power
effect (trigonometric weighting). For MIDI tracks, volume control is implemented
through the respective channel’s Controller 7 and system-exclusive master volume
for output buses. MIDI pan control is only available for track strips and is
implemented through the channel’s Controller 10. MIDI input buses have
volume and pan controls disabled.
4.7.2. Setting Levels
When monitoring the levels of your tracks, make sure that the sound does not
enter the red zone on the volumeter. In audio production, any sound that goes
above 0dB hits its peak and can cause distortion. It’s not uncommon to flirt
with 0dB to truly maximize the impact of important sounds, but leaving sounds
above 0dB in your final mix can ruin your project.
Using the volume level slider, adjust your track volumes to safe settings while
listening to your project. Then, listen to your project again to refine the levels
in relation to one another. If the sound source is too low (or too loud), you can
add (or subtract) gain at the input point with the Gain adjustment at the very
bottom of the Mixer window. This adds or subtracts gain level at the point of
the sound’s entry, meaning that you are changing the amount of sound reaching
any effects processors. Generally, gain adjustment is avoided and other tools,
like a Compressor or Equalizer, are favoured.
The Mixer’s gain adjuster
Remember that Track levels don’t exist in a vacuum; the levels are cumulative.
So, if you have two tracks with near-maximum levels that produce very loud
sounds at the same time, the Master Out level will peak even if each track was
“safe” independently.
There is no authoritative way of achieving a balanced mix. Some professional mix
engineers favour an additive mix, in which they start all levels at a reasonable
and safe level and then accentuate important parts by adding volume to tracks.
Others favour a subtractive method, starting everything at the highest safe (or
unsafe) level and then bringing volumes down so that everything falls into place.
Predictably, still others prefer a combination of these methods.
4.7.3. Panning
By default, tracks are set to play from the center point of the stereo space,
meaning that the sound will feel as if it’s situated directly in front of the listener,
or spaced evenly between his/her ears. To diversify the sound, perhaps in order
to emulate a live set-up, to suggest that an instrument is just next to the listener,
or simply to broaden the scope and impact of the piece, you can pan tracks
between the left and right speakers using the panning slider.
The Mixer’s panning slider
When panning a track, “less” is often “more” and an even spread is usually best.
In other words, instead of arbitrarily assigning tracks in stereo space just to
give a spread to your sound, try to consider their overall balance. Avoid moving
sounds to the extreme stereo positions (also known as hard left/right), since, in
real life, sounds are rarely only heard in one ear and not the other. The sound
of extreme stereo separation was common in early stereo mixes from the 1960s,
in which the drums might only be heard in the right ear and the guitar only in
the left; the effect was revolutionary at the time but is largely considered utterly
unnatural now.
Generally, important tracks (vocals, lead etc.) and low frequency/groove tracks
(bass, kick drum etc.) are positioned in the middle, while other parts are panned
to the sides in various degrees. The extreme edges are often used for atmosphere,
emphasis, or effect.
4.8. Signal Flow
4.8.1. Signal Flow Summary
For anything other than the simplest of projects, you will likely want to manipulate the flow of MIDI and audio data, routing it into, out of and through
Qtractor in a variety of ways. You may want to drive an external sound module,
accept input from a MIDI controller to record performance data, group together
similar tracks to share the same plugin, or perform some other kind of processing
before final export. In Qtractor, Connections, Buses, Aux Sends and Inserts are all used to control “what goes where”. There are many different ways
to approach the process of routing and exactly what you’ll need will depend on
your set-up. With this in mind, this section will give a general overview of the
options available so that you can decide what best fits your requirements.
4.8.2. Connections
The Connections window serves to establish the audio and MIDI port connections
between the internal core layer input and output buses (ports), and the external
devices or client applications. It can also be used to connect external client
application ports - either JACK clients for audio or ALSA sequencer clients for
MIDI. All active connections on the existing input and output buses are saved
and restored upon session recall. To open the Connections window, select View
/ Windows / Connections, or click on its icon.
Connections icon
A window similar to the below will then open. Its features and usage are almost
identical to those of QjackCtl.
Qtractor’s Connections window, showing both the Audio and MIDI tabs. “Readable” ports are sources of data (where audio or MIDI data can come from) while
“writable” ports are places that data can be routed to (sent to)
Once you’ve decided how to approach the routing for a particular project, you
can then make the necessary connections between Qtractor and whatever other
programs or external devices you’re using. You can connect a Readable/Output
port (left pane) to a Writable/Input port (right pane) in several ways. One
method is to left-click a port in the Output pane, left-click a port in the Input
pane, then either left-click the Connect button or right-click elsewhere in the
window and select Connect from the pop-up menu. Another method is to click a
port in the Output pane and, with the mouse button held down, drag the cursor
to a port in the Input pane until the port is highlighted, then release the mouse
button. Regardless of the method you use, a line representing a “virtual cable”
will appear between the two ports in the middle section of the window.
The System input ports playback_1/2 represent your default left/right stereo
output (e.g. your first-configured sound card). If you wish to use alternative
destinations for playback, monitoring etc., you can connect them up here.
4.8.3. Buses
As explained at the start of this chapter, a bus is like a pipeline through which
streams of data can travel. Qtractor has Input, Output and Duplex buses for
both audio and MIDI. Input buses receive data streams from particular sources
(inside Qtractor, or from other software or hardware), Output buses send streams
to other destinations and Duplex buses both receive and send streams.
How many and what kind of buses you need will depend on what you want to
achieve, but the basic steps to follow are:
1. Create a bus
• Assign it as an Input or Output for a track
• Connect it via the Connections window
To open the Buses window, click on the View / Buses menu.
The Buses window, showing one MIDI and three audio buses
The left pane contains a list of the session’s buses; clicking on one of these will
display its information in the right pane. The right pane has three tabs:
• Properties - Name, Mode (Input, Output or Duplex), Monitor (Duplex
buses only), Channels and Auto-connect (Audio buses only) and Instrument
and SysEx (MIDI buses only)
• Input Plugins - plugins processed on input (Input and Duplex buses
• Output Plugins - plugins processed on output (Output and Duplex buses
The method of creating a bus may not be immediately apparent. To create
a new MIDI or audio bus, select any bus of the desired type in the left pane
(if you’re working on a clean session, the only choices will be MIDI and Audio
Master) in order to display its properties in the right pane. Next, change the
text in the Name field; this will enable the Create and Update buttons. To
create a new bus, click Create.
Before clicking Close, you may wish to change other options in the right pane.
For audio buses, a commonly used option is the Channels setting. Its default is
2, which, for an Input bus, will give you a stereo recording. However, you may
want to set this to 1 to create a mono input bus in order to record, for example,
an external source via a single microphone. With a bus’ Channels set to 1 and
the bus assigned as the Input to a track, any recording on that track will then
be in mono.
If you’ve made any changes, click Update, then Close. (If you don’t click
Update a reminder dialogue box will appear in any case.)
Once you’ve created your bus, you’ll need to assign it to the relevant track(s). To
do so, select a track and choose the Track / Track Properties. . . menu, or
double-click the track in the left pane of the main view. This will open the Track
window. In the Input / Output area, assign your bus via the drop-down box
(whether it appears in Input, Output or both will depend on what type of bus it
Track window for a MIDI track
The final step is to connect the bus up to its destination - a task which is achieved
via the Connections window. Again, exactly what you need to do will depend
on your set-up, but if you wanted, for example, to send a particular MIDI track
to an external software or hardware synth, you would connect its output bus’
Output connection in the left pane to your synth’s Input in the right pane. One
thing you should not do is route the output of one Qtractor bus to the input of
another, as this will give unpredictable results.
Buses are an extremely valuable tool and their use is almost essential for any
reasonably sized project and when using Qtractor with external inputs and
outputs. They enable you to use the full 16 MIDI channels through each bus,
giving you much more flexibility than if you were using the Master MIDI bus only.
You can, for example, have a dedicated MIDI bus routed to a multi-instrument
synthesizer, sound module or soft synth, giving you 16 separate channels to
control different instruments within the synth. Buses can also be used to route
the audio output of external synths into Qtractor audio tracks for recording. For
more information on this topic, see this How To.
4.8.4. Aux Sends
Aux Sends are used to route audio or MIDI from a track or input bus to another
destination within Qtractor - specifically, to a bus. To create one, open the
Mixer, right-click under the name of your track or bus, then choose Inserts /
Audio or MIDI / Add Aux Send. In the window which appears, set the Aux
Send to “Active” (top right button), choose your destination bus in the Aux
Send Bus combo box (bottom left) and choose the amount you want to send
via the Send Gain slider.
The Aux Send window for a MIDI track
What value to set Send Gain to will depend on the purpose of your destination
bus. For example, you may want to send several tracks to the same bus in order to
share that bus’ plugin(s). This is a reasonably common requirement, particularly
for reverb, where you would have an “overall” setting in the destination bus’
plugin, then adjust the amount you send to this via each track’s Send Gain
slider. In this way, you can control the amount of reverb applied, in order, for
example, to mimic an instrument’s placement on the stage.
4.8.5. Inserts
Inserts are similar to Aux Sends, but are used to route audio or MIDI externally
of Qtractor. They can be added to tracks, or to input or output buses. You can
even route your entire mix to an external destination, such as JAMin, before
routing it back into Qtractor for export.
To create an Insert, first, launch your external application. Then, open Qtractor’s
Mixer, right-click under the name of your track or bus and choose Inserts /
Audio or MIDI / Add Insert. In the window which appears, set the Insert to
“Active” (top right button) and adjust Send Gain, Dry Gain and Wet Gain
as necessary.
The Insert window for an audio track
Next, use the Sends button to connect the Insert to your external application
and the Returns button to connect the application back to the Insert (these
buttons open up the same Connections window discussed above). The signal
will now flow from your track/bus out to the external application, then return
to the same track/bus and continue on from the point below the Insert.
4.8.6. Connection Persistence
When working with purely internal sources and destinations (plugin soft synths,
Aux Sends etc.) Qtractor will automatically restore any connections you have
made upon re-loading the session. With external applications, however, things
are slightly different: Qtractor will only restore such connections if they are
present when the session is saved. For example, if you save and close your session
with everything correctly connected, upon restarting both Qtractor and your
external application, the connections will be correctly restored. However, if you
close the external application, then make a change in Qtractor and save (i.e. with
Qtractor and the application in a “non-connected” state), upon restarting, the
connection will be lost and you’ll need to make it again.
This behaviour can be avoided by always ensuring that you have your external
connections in order before closing Qtractor (easier said than done when using
many external applications). It can also be mitigated somewhat by using
QjackCtl’s Patchbay feature to make the connections persistent; however, this
too is rather unwieldy as it means adding each item manually to the Patchbay.
A third approach would be to use a session manager, such as QJackCtl’s Session
feature (which employs “JACK session”), or NSM.
4.9. Plugins
4.9.1. Plugins Summary
There are four types of plugins supported within Qtractor: LADSPA, DSSI,
VST and LV2. They can be added to both buses and tracks and are aggregated
seamlessly as one single instance on a multi-channel context. To add a plugin,
open the Mixer, right-click in the panel below the name of the desired track and
select Add Plugin.
Mixer window showing plugin area at top. Plugins are added, removed, activated/deactivated, moved in the processing chain and their settings edited using
a right-click context menu
In the Plugins window which then appears, select the plugin type - (Any),
LADSPA, DSSI, VST, or LV2 (see the following sections for information on
the different types) - in the top-right box. Next, select your plugin from among
those installed and, if desired, tick Activate in the bottom-left corner to enable
the plugin as soon as it’s added to the mixer strip. If you have a long list of
plugins to choose from, you can use the top-middle box to search for what you
Plugins window, showing LADSPA plugins currently installed
Qtractor will look in the most likely installation directories for plugins and
display any found in the above window. If, however, you have plugins installed
in non-standard directories, you should specify their paths in the Plugins tab
of the View / Options. . . window. Once you’ve made your selection, click the
OK button to add the plugin.
Specifying the locations (paths) of plugins in the View / Options. . . window
Plugins are processed in order from top to bottom and can be individually selected,
activated and moved (by dragging/dropping) within the plugin chain order. They
can also be copied or moved to other mixer strips by dragging/dropping and
choosing your desired option from the pop-up menu which appears; a faster way
to accomplish this is Ctrl+drag to copy and Shift+drag to move. There are a
couple of things to note about plugins, which may affect your workflow.
• All plugins are pre-fader - that is, they are processed before the Mixer’s
Gain fader. If you want them to behave as though they were post-fader
you can insert any plugin which controls gain at the start of the chain
(i.e. before your pseudo post-fader plugins) and use that, rather than the
Mixer fader, to control the track’s gain
• There is no plugin delay compensation, so if a plugin adds latency to the
signal chain this won’t be corrected for. If you do need to correct for this,
the only option is to do so manually by adjusting a clip’s timing via the
Offset value in its Properties window
Individual plugin control parameters can be modified in real-time through
provided dialog windows and maintained as named presets for re-usability. To
create a preset, once you have your desired settings ready, enter a name in the
box at the top left of the generic plugin GUI (it will say “(default)” to begin
with), then click the save icon next to it. You can select from among your saved
presets by clicking the arrow next to the preset name or, when in the Mixer, by
right-clicking the plugin and choosing Preset.
Generic plugin GUI, showing preset box and save and delete icons
Note that certain plugin-specific GUIs, such as Calf LV2, may not display the
presets information even though the functionality itself is there. In such cases,
you can access the generic GUI by right-clicking the plugin in the Mixer and
choosing Properties. . . , then create presets from there. When more than
one GUI exists for a plugin, you can also opt to choose which you want by
enabling Select plugin’s editor (GUI) if more than one are available in the View
/ Options. . . / Plugins menu.
4.9.2. LADSPA
LADSPA has been a Linux audio plugin standard for many years. There are
literally hundreds of LADSPA plugins available for Linux, providing a huge
variety of processing effects, such as equalization, filtering, reverb, chorus, amp
and speaker simulation and so on. Well-known LADSPA plugins include the
swh package by Steve Harris and the tap package by Tom Szilagyi. These may
already be present in your distro’s repositories.
4.9.3. DSSI
DSSI plugin support is available for instrument and effects plugins. You must
have the core DSSI subsystem installed in order for this type of plugin to function.
Well-known DSSI plugins include the fluidsynth soft synth for working with
soundfonts (.sf2/.sf3) and Sean Bolton’s WhySynth. Again, these may already
be present in your distro’s repositories.
4.9.4. VST (Linux Native)
Native Linux VST plugins are supported, but there are only a few native Linux
VSTs available. Please see section 2.4.2 for complete information on building
Qtractor with native VST support.
Note: Native Linux VST support does NOT include running of Windows® VST
plugins. Please use the DSSI-VST wrapper when attempting to use this type
of plugin, and make sure your Windows® VST plugins are located within your
DSSI path environment variable (the variable name is VST_PATH).
4.9.5. LV2
LV2 is the extensible successor to LADSPA and offers many improvements over
it. A wide variety of plugins are available, such as the synthv1 synth, by Rui
Nuno Capela (author of Qtractor), and the Calf set of effects. If you have the
choice of using an LV2 plugin over a LADSPA or DSSI one, it’s generally better
to use the LV2 one. Doing so will ensure that when saving a Qtractor archive
file (.qtz), all the relevant information is correctly included in the archive.
4.10. Working with MIDI
4.10.1. MIDI Summary
MIDI is a versatile format for triggering sounds. It can be used to trigger
hardware synths external to your computer, software synth applications on your
computer, samples, loops, automation functions and more. Some music programs
bundle your MIDI data into your project file, which can make it difficult to share
one MIDI loop between projects. However, Qtractor saves all MIDI tracks as
independent files, meaning that you can easily re-use them.
There are basically three ways to get MIDI data into your Qtractor session and
they are each covered in the sections below:
• Import MIDI data from an existing file
• Play in MIDI data via a USB MIDI keyboard controller
• Enter MIDI data into the MIDI Editor (sometimes called a “piano roll” or
“matrix editor”)
Before beginning with MIDI, unless you’re using Qtractor to drive an external
hardware synth you should make sure that you have some software synthesizers
installed on your system. If you’ve just installed soft synths now you should
relaunch Qtractor so that it will detect the newly available plugins.
Note that with each successive MIDI track you add, you must increment the
MIDI Channel used (Qtractor will do this by default), otherwise key presses
on your MIDI controller, or playback from Qtractor, will use the same MIDI
channel to trigger different sounds. In other words, if Track 1 and Track 2 are
both using MIDI Channel 1, then a note played on Track 2 will also trigger the
instrument assigned to Track 1. To change a track’s Channel, double-click on
the track in the left hand pane of the main view then, in the Track window
which appears, select the Channel number underneath MIDI / Instrument.
If you run out of channels, you can use multiple buses.
Track window for a MIDI track, where the MIDI Channel can be selected
4.10.2. Importing MIDI Data
Since MIDI data consists of nothing more than digital signals to activate and
deactivate sounds at certain times, MIDI files are small and easily distributed
online. A simple internet search for MIDI files will result in thousands of files
for nearly any song you can name. Taken alone, MIDI files are useless; imported
into Qtractor and assigned instruments, however, the files come to life like a
player piano. The MIDI file you import into Qtractor could be from the internet,
one you created yourself in another application, or even a data dump from a
MIDI-capable hardware synth. In this example, we will use one from the internet:
1. Download a MIDI file, such as JS Bach “Invention in C minor, BWV 773
(Canon)” and save it to your hard drive - preferably in your Qtractor’s
session directory, to keep your project self-contained
2. In Qtractor, go to the Track menu and select Import Tracks / MIDI.
Alternatively, you may open the Files pane, click on the MIDI tab and
use the right-click menu to import the MIDI file without automatically
adding it to a track (if you do this, you’ll need to drag the file into the
workspace manually). Please also see the note in the Files section regarding
importing MIDI files
3. The MIDI tracks will appear in your Qtractor session. Imported tracks
will often have embedded General MIDI instrument assignments, as is the
case with this example. General MIDI was an effort to standardize a set
of 128 instruments to provide similar playback results across all systems
If you have a soft synth installed and assigned to the relevant track(s) you can
press the Play button in the top toolbar of Qtractor to hear the MIDI file. If
you’re using a General MIDI-compliant soft synth bank you should get a good
approximation of how the original author of the file wanted the tracks heard.
4.10.3. Creating MIDI Data with a MIDI Controller
A MIDI controller is a piece of hardware to help you play the software-based
synthesizers in your computer. Typically, it is a piano keyboard with a few
octaves and no built-in sounds of its own. It usually plugs into the USB port
of your computer and, once configured, will pass on any key press to Qtractor,
allowing you to play a software synth in real-time as well as record the key
presses themselves.
MIDI and USB are two technologies that, fortunately, have been kept universal
enough that you almost don’t need to question whether any given USB MIDI
controller will work with your system. There are perfectly capable USB MIDI
controllers being offered from vendors like Akai, Roland/Edirol, Digidesign/MAudio and many others. If you require realistic, weighted keys with high
resolution touch-sensitivity then look at the upper price-range of controllers
and go to a music store to audition them. However, if all you require are a few
octaves of piano keys so that you can get a tune into the computer quickly and
easily, the basic controllers will be enough.
To use your USB controller to input MIDI data:
1. Plug the USB MIDI controller into your computer
2. Launch QJackCtl and start it
3. Launch Qtractor and click on the View menu, then select Connections
from the Windows category
4. In the Connections window, click on the MIDI tab. Find your USB
controller device from those listed on the Readable Clients/Output Ports
column on the left hand side. Open its category to see the available outputs
5. Connect the output of your MIDI device to Qtractor in the Writable
Clients/Input Ports column
6. Create a new track, then double-click the track in the left pane of the main
view. In the Track window which appears, make sure that the Channel
value (underneath MIDI / Instrument) corresponds to the channel your
MIDI device is transmitting on. Alternatively enable Omni alongside this
to tell Qtractor to receive input on all channels
7. In the Mixer, enable the track’s Monitor button (so that it turns green)
In Step 4, if you do not see your USB controller listed in the left column, check
to ensure that your controller is powered on (some require external power; others
are powered by the USB port) and check the cable connection. If you still cannot
see the device in the left column make sure your computer sees the controller by
checking dmesg | tail. If your computer registers the device but you are not
seeing it in Connections click Refresh* in the bottom right of the window. If
it still doesn’t appear try restarting both QJackCtl and Qtractor.*
Presuming you have a soft synth installed and assigned to the track, pressing
the keys on your USB controller should now trigger the soft synth in Qtractor,
generating sound. To record MIDI data, arm your track by clicking its “R”
button in the left pane of the main view, click the Record button in the top
menu, then click the Play button to start the transport recording - every key
press you make on your USB controller should now be recorded in real-time.
Depending on the feature set of your controller, velocity, pitch and other data
may also be recorded
If you re-record over a clip, Qtractor will create a new, overlapping clip (which
can, if desired, be merged with the original clip using Clip / Merge). If you’d
rather overdub the original clip, adding extra notes directly to it instead of
creating a separate clip, select the desired clip and choose Clip / Record from
the main menu, or File / Record from the MIDI Editor. Once selected, the
clip will change colour and any data recorded in its region of the timeline will
be added to it.
You may wish to control particular settings of a plugin by sending MIDI controller
messages to it from your USB controller. Although assigning MIDI controllers
to LV2 plugins is not permitted by the LV2 specification, Qtractor offers another
way of handling this which works for all plugin types. To assign a controller,
first open the plugin’s generic GUI, by right-clicking on its name in the Mixer
and selecting Properties. . . . A window such as the below should appear, the
content of which will be defined by the plugin’s exposed settings.
A plugin’s generic GUI
Next, right-click on the name of the setting you want to control and, in the
dialogue box which appears, choose MIDI Controller. The below window
should then appear.
MIDI Controller window, where controller messages can be assigned to plugin
If you have not already done so, connect your hardware MIDI controller up,
using the Inputs button. Then, choose which controller message to use via the
Type and Parameter options, together with your desired MIDI channel in the
Channel box. There are also several other options below these:
• Logarithmic - the linear scale of the MIDI controller (rotary knobs, sliders,
etc.) is mapped to a logarithmic scale value on the target controlled subject.
This is usually applicable to audio volume, dB scales or even frequency
spectrum ranges
• Feedback - causes any change in the state value of the controlled subject
to be sent/fed-back to the MIDI controller, to allow the latter to reflect and
sync its state accordingly. This is mostly applicable to MIDI controllers
with visual (e.g. LEDs) and/or mechanical (e.g. motorized faders) feedback
• Invert - the minimum-maximum range of the MIDI controller is inversely
mapped to the maximum-minimum scale values on the target controlled
subject (and vice-versa)
• Hook - the MIDI controller and its controlled subject state/value are
always in sync (hooked to each other); otherwise a deferred sync mode
is in effect, with both ends playing catch-up to each other’s from either
direction until they match their states/values
• Latch - this is used only for on/off toggle parameters and relates to Latch
vs Momentary modes of switches. These are the opposite of each other, so
latch=OFF is the same as momentary=ON and vice-versa. This option
is mostly applicable to foot-switches or pedal controllers. Latch (=ON)
mode is the default setting for most such controllers, but a controller
that operates in Momentary mode will usually send an event when you
depress the switch (0 -> 1) and another when you release it (1 -> 0).
(This is the meaning of “momentary”: the switch state is only signalled to
be momentarily on while the switch is depressed, returning to its former
state upon release.) Setting the Latch option to OFF for this latter case
will simulate a toggle switch, meaning that the target subject state will
only change to ON or OFF when the switch is either being depressed or
released, respectively
Note that MIDI controller assignments are applicable only to the session you
create them in. If you want to use the same assignment in a different session
you’ll need to create it again.
You can also create and manage generic MIDI controller mappings, plus import/export these mappings as a .qtc file, via the View / Controllers menu.
The Controllers window, where generic MIDI controller mappings can be managed
4.10.4. Creating MIDI Data with the MIDI Editor
If you have no USB MIDI controller, you can still create MIDI data using
Qtractor’s MIDI Editor (sometimes called a “matrix editor” or “piano roll”
in other music programs). Data is edited on a grid through the usual GUI
operations, such as selection, drag-and-drop, move, cut, copy, paste and deletion.
The MIDI Editor can be invoked either for raw entry or to modify existing MIDI
data that you’ve imported or played into Qtractor.
The MIDI Editor is very intuitive. The main, upper pane is the Editor Grid,
which represents the notes being played. Vertically, the grid corresponds with
notes on the chromatic keyboard (pitched as per the keyboard on the left of
the window); horizontally, it corresponds with beats per bar. The lower pane
is the Value Grid, which controls extra MIDI data, such as velocity, program
changes, pitch bends and so on. The data represented here changes according to
the Value menu setting in the upper menu bar.
MIDI Editor window, showing notes in a familiar “piano roll” display (above)
with their velocities (below)
You move around the MIDI Editor in the same way as the main work area using the horizontal/vertical scroll bars at the bottom/right of the window, the
mouse wheel/Shift+mouse wheel, or the navigation window (at the bottom of
the MIDI Editor window itself).
The MIDI Editor’s navigation window, situated at the bottom of the MIDI Editor
window itself
To zoom in/out, again, as per the main work area use the magnifying glass
buttons at the bottom-right of both the Editor Grid and Value Grid (Shift68
clicking or Ctrl-clicking if needed), or Ctrl+mouse wheel.
“Magnifying glass” zoom buttons, situated towards the bottom-right of the MIDI
Editor window
All MIDI editing operations are available and processed in real-time. Several
MIDI Editor instances may be active and open at any one time, provided each
one refers to its own clip. All MIDI content may be saved as standard MIDI files
(SMF) Format 0 (all tracks reduced to one track, preserving channel assignment
data) or Format 1 (multi-track). The format for the SMF files may be set in
View / Options. . . / MIDI.
To create new MIDI data:
1. Create a destination track, if you don’t have one already
• Right-click within the track and choose Clip / New. The MIDI Editor
window will appear
• Click the Edit on (pencil) icon in the menu bar and draw notes in the
upper pane of the grid. You can also click the Edit Draw (pencil with wavy
line) icon to draw multiple notes “free-hand” by dragging the mouse
• In the bottom Value Grid pane you can adjust a variety of parameters.
The default view shows Note Velocity, but this can be changed via the
Value type and Parameter type combo boxes just below the pencil icons.
Drag the bars up/down to increase/decrease their values, or click in a
blank area (with one of the Edit modes enabled) to add new data
Below is a summary of the MIDI Editor’s main tools:
• Arrow - select/move notes in the Editor Grid (or values in the Value Grid)
and increase/decrease their length. To select all the notes of a particular
pitch, left-click the desired key of the piano keyboard on the left hand side
of the window and drag the cursor right, into the editor area
• Edit on (pencil) - draw notes or values, with their spacing determined by
the Snap/beat setting (see below). You can also hold down Ctrl or Shift in
this mode to put the Edit cursor into select mode temporarily - this is useful
for quickly switching between inputting and selecting notes/information, as
it avoids having manually to switch between the Edit and Arrow (described
above) cursor modes
• Edit Draw (pencil with wavy line) - dynamically draw multiple notes/values
with a click-and-drag of the mouse. This is, again, governed by the
Snap/beat setting, but the faster you move the cursor the fewer the lines
that will be drawn
• Note Type - “Note On” indicates that the notes you draw in the grid
represent the length of the note. “Key Press” indicates that the notes
represent a MIDI event without a defined duration, such as triggering an
external MIDI sequence to begin playing
• Value - determines the information shown in the Value Grid. This may be
note velocity, program changes, pitch bend or other extra MIDI data
• Parameter type - only available when certain Values are selected, such as
Controller. Provides further information for the Value setting
• Snap/beat (musical note) - determines the resolution when drawing and
editing notes/values. In a 4/4 session, for instance, a setting of Beat would
cause a click in the Editor Grid to produce a crotchet (quarter note),
Beat/2 would produce a quaver (eighth note) and so on. Regardless of the
default note length, a note can be lengthened/shortened by clicking and
dragging one of its edges to increase/decrease its length. The resolution of
such changes is also determined by the Snap/beat setting
• Value ramp - allows you to draw a continuous, linear slope of MIDI events
in the Value Grid. This can be useful for operations such as creating
crescendos/diminuendos or adjusting pitch bend
To use the value ramp: 1. Choose your desired Snap/beat setting 2. Enable Edit
on and Edit Draw, then draw a series of events in the Value Grid (lower pane)
3. Hold down Shift or Ctrl (or switch to Edit off ) and highlight these events
4. Disable Edit Draw (leaving Edit on enabled), then hold down the left mouse
button and drag the dotted line over the events to set the angle of the slope.
You can not only shave the tops off the bars but extend their heights too. You
should see something like the below as you drag
Adding a diminuendo using the value ramp
You can also use the tools detailed in Additional MIDI Editor Features with
MIDI events such as these. For example, if you wish to make your diminuendo
longer/shorter you can do so easily using the Rescale tool. With the MIDI
events highlighted, right-click and choose Tools / Rescale, then adjust the
Time percentage value accordingly.
4.10.5. Additional MIDI Editor Features
In addition to input and editing tools, the MIDI Editor features functions such
as Quantization, Transposition, Timeshifting and more to make it easy to modify
your composition. To access these features, open the Tools menu via the MIDI
Editor toolbar, or by right-clicking within the window. If no notes are selected,
the Tools will be unavailable; select a note or block of notes with the Arrow tool
to make them available. Many of these tools are also very useful for adjusting
MIDI event data in the Value Grid.
• Quantize - allows you to automatically structure notes in stricter uniformity
with your time signature. This is especially helpful if you’ve played the
notes in and were not perfectly on the beat. You can quantize notes such
that the notes occur on the beat (or divisions thereof); such that the
durations of notes are extended to be on the beat (or divisions thereof);
such that notes play with some degree of “swing”; and even such that the
notes played match a specific scale, from Minor to Major to the extremely
• Transpose - allows you to transpose the pitch of, or shift the timing of, a
note/notes, or reverse a sequence of notes
• Normalize - adjusts note velocity by either a percentage or an absolute
value. A percentage value will adjust the velocity of the notes equally by
the percent given in relation to the original velocity, while an absolute value
adjusts velocity of each note to that value regardless of original velocity
• Randomize - provides random changes to the Note, Time, Duration, or
velocity (Value). You may adjust how extreme the changes will be with
percent values
• Resize - allows you to control the duration of notes to any number of beats
(or divisions thereof), or the Velocity to any value
• Rescale - changes the selected notes by some percentage. You may alter
the time that the notes are triggered, the duration for which they sound
and the velocity at which they are played
• Timeshift - alters the timing of the selected notes on a curve, such that the
acceleration from the beginning note to the ending note is either increased
or decreased
The MIDI Editor’s Tools menu
In order for Qtractor to know how to accelerate the timing of the notes, you must
define a range of time for the acceleration to occur. Do this with the Edit-head
and Edit-tail markers (the blue markers in the timeline above the MIDI Editor
grid). Mark the out point (tail) of your range by right-clicking on the timeline,
and then set the in point (head) of the time range by left-clicking somewhere
to the left of the original marker. Once the range is defined, select the notes
you wish to timeshift with the Arrow tool. Open the Tools menu and select
Timeshift. Use the slider to cause either an acceleration, or a deceleration, in
your selected notes over the course of the defined time range and then click OK
to commit the change.
The View menu provides customization for how the MIDI Editor is laid out and
how the notes are presented to you. The default layout is clean and pleasingly
minimalist, but take a look at some of the other options to see what works best
for you:
• Menubar - turns off the top menu bar; use Control+m to toggle it on or off
• Statusbar - turns off the status bar at the bottom of the window
• Toolbars - defines what information is visible in the window. Choose from
File (file opening and saving icons), Edit (cut, paste, undo), View (preview
modes, snapping, quantization), Transport (fast forward, rewind etc.),
Scale (key signature and scale information) and Thumb (thumb view at
the bottom of the window)
• Windows - toggles on or off event information, a panel which provides
detailed information on each MIDI event in the MIDI Editor grid
• Tool Tips - toggles whether tool tips are visible
• Note Duration - defines whether the note’s duration is reflected in the
length of the velocity bars at the bottom of the grid
• Note Color - assigns differing colours to each note; if this is not active, all
notes appear as one colour
• Value Color - assigns the colours of the corresponding notes to the velocity
bars; helpful when you have many overlapping notes but want to adjust
their velocities
• Zoom - zoom in or out on the grid
• Snap - define what division of the beat your notes snap to, or turn snapping
off entirely
• Scale - change the key signature or type of scale being used
• Refresh - causes the MIDI Editor to redraw in the event of latent images
• Preview Notes - toggle whether or not you hear the notes of the scale as
you input or move notes on the grid
• Follow Playhead - define whether the MIDI Editor grid scrolls with the
playhead when you are playing the track
4.10.6. MIDI Instruments
There are many MIDI hardware tone generators available from a variety of
manufacturers such as Yamaha, Roland and Korg. In Qtractor, information
about the sound patches and sound banks of these tone generators is obtained
from “instrument definition” (.ins) files. Qtractor supports instrument definition
files used by the Cakewalk/Sonar MIDI sequencer software, offering a convenient
MIDI bank-select/program-change mapping for existing MIDI instrument patch
names and easier, intelligible selection of MIDI track channels. Files for many
popular MIDI tone generators and synthesizers can be downloaded from the
Cakewalk site.
.ins files are imported via the View / Instruments. . . window. You can
also import MIDI Name XML files (.midnam) in the same way. Once you’ve
imported a file, select your desired patch via the Bank and Program options
in the MIDI / Instrument area of the Track window. After clicking OK,
the information will appear in the main view. Instrument patches can also be
assigned via several other menus:
• Track / Instrument in the main toolbar
• File / Track / Instrument in the MIDI Editor
• Right-clicking a track in the left pane of the main view and selecting
• In the GUI of the plugin itself
When working with soundfonts (for example, via the FluidSynth DSSI, or Calf
Fluidsynth LV2, plugins), you can also use the View / Instruments. . . window
to import their patch names. Simply select the desired .sf2/.sf3 file and its
patch names will be imported. For DSSI plugins, changing the patch information
in the Track window should update the relevant information in the plugin’s
GUI automatically and vice-versa. However, this may not be the case for LV2
plugins (due to the LV2 spec, rather than any issue with Qtractor) - if there
is a mismatch between the patch set in the plugin and the information in the
Track window, upon re-loading the session the patch in the track may override
that of the plugin. To avoid this behaviour, in the Track window set MIDI
/ Instrument to (No instrument) and Bank and Program both to (None),
then perform all patch selections directly in the plugin.
Instruments window, where MIDI instrument definition files, MIDI Name XML
files and soundfont patch names can be imported, exported and moved
4.10.7. Soft Synths
Strictly speaking, software synths, or “soft synths”, are not part of Qtractor.
However, it is common to use them within Qtractor. Acquiring free soft synths
online is a simple matter of locating them via the project’s homepage, your
distribution’s repositories, or sites such as sourceforge.net.
Soft synths for GNU/Linux come in a few varieties:
• Standalone synth applications that launch separately from Qtractor, but
which plug into JACK so that they can be used as sound sources within
Qtractor. One such example is Qsynth, written by the same programmer
as QJackCtl and Qtractor
• DSSI Plugins, which are launched and controlled entirely from within
Qtractor. For example, Fluidsynth DSSI
• LV2 Plugins, which are launched and controlled entirely from within
Qtractor. For example, synthv1
• VST Plugins. The format from Steinberg does in fact support Linux
technically, but there are few Linux-native VST synths
synthv1 - a soft synth available in both standalone and LV2 plugin forms
Once your synth of choice is installed, the method of launching it will depend on
what form it is. If it’s a standalone application, it can be launched like any other
application on your system. If it’s a plugin for Qtractor, launch Qtractor and
create a new MIDI track, then choose your soft synth for the MIDI Instrument,
as described here.
4.10.8. Soft Synths as Plugins
Using soft synths as LV2 or DSSI plugins is probably the easiest model, as it
does not require any additional routing through JACK. The synth is integrated
into Qtractor’s interface, the sound is directed to the appropriate track, and the
fact that you are using a separate application is almost entirely abstracted away
from you. For more information on using plugins, see the Plugins section.
Most soft synths have some level of control over the sounds they produce. To
edit a synth’s properties:
1. Choose View / Windows and open the Mixer
2. In the panel towards the top, locate your synth and make sure it’s on
(designated by a green lamp on the left of its name). If the lamp is black
(synth turned off), click it so that it turns green
3. Double-click on the soft synth to open its settings window and change the
desired parameters. The actual information presented will differ depending
on the synth
Whether you use LV2, DSSI or VST plugins, the process for using a soft synth (or
plugin effect) is the same. In addition, all parameters provided by the interface
can be automated, enabling attributes like LFO or resonance to change over
time during playback. For more information on this see the Automation section.
4.10.9. Stand-alone Soft Synths
The other kind of software synth you might use is a stand-alone synthesizer, such
as Qsynth. To use such a synth, launch QJackCtl and Qtractor, then launch the
synth the same as you would any other application on your system.
Once you’ve launched your synth it will become a source for audio and a
destination for MIDI signals in Qtractor. However, you must first verify that
your settings are correct:
1. Open the View / Windows / Connections menu
2. The Audio tab contains all possible sources of audio. If you’ve launched
QSynth, for example, it will be listed in the left column. Also listed will
be Qtractor itself, since it too produces sound. In the right column are the
audio destinations available. At the very least, you should see Qtractor’s
Master In and your computer speakers (labelled as System > playback).
By default, the sound from Qtractor’s Master Out is patched to System >
playback so that you can hear everything that Qtractor’s Mixer manages
3. This is where the workings of your own studio set-up should be considered.
The audio from your synth can logically be patched into either Qtractor’s
Master In, so that its sound can be recorded into an audio track, or System
> playback, if you have an external mixer or recording device that will
be recording it. To patch the sound from the synth to its destination,
click the left channel of the synth output (in the left column), then the
left destination channel (in the right column), then the Connect button.
Repeat this for the right channel if stereo is required
This takes care of routing the audio; now you must route the MIDI signals
controlling the synth. Here again, there is no “right” way to route the flow of
data - you must be somewhat familiar with the equipment and workflow you
are implementing and decide for yourself how you want it all to work together.
However, a general method of working is described below:
1. Open the View / Windows / Connections menu
2. The MIDI tab contains all possible sources of MIDI signals. At the very
least, your stand-alone soft synth will be listed in the left column. If you
have a USB MIDI controller, it too will be listed. Qtractor itself and a
MIDI Through channel will also be listed. In the right column are the
sound destinations available. At the very least, you should see Qtractor’s
Master and MIDI Through, together with any soft synths you are running
3. Connect the MIDI signal from Qtractor (in the left column) into your
soft synth (in the right column) so that the data in your MIDI tracks will
trigger the synth’s sounds
4. If you are using an external USB MIDI keyboard controller, you will also
likely want to route its signal into Qtractor’s MIDI input so that you can
input notes directly into your Qtractor MIDI tracks
4.11. Working with Audio
4.11.1. Audio Summary
There are two typical scenarios for dealing with audio in Qtractor and, indeed,
for most digital audio workstations:
• Import existing audio files from your hard drive, a recording device, or a
loop collection
• Record audio into Qtractor via your computer’s built-in microphone or an
external microphone
These methods of acquiring sound for your work can be, and very often are,
combined to create a richer audio production.
4.11.2. Importing Audio Files
The easiest way to get sound into Qtractor is to import an audio file from your
hard drive. Whether you are using sampled loops to construct a new musical
piece, or importing a performance transferred from a recording device, importing
audio in this way does not involve recording sound directly into Qtractor.
To bring audio into your project file, right-click in the Files pane and select
Add Files or use Ctrl+F. Choose which file or files you wish to import from
the file chooser window that appears. To place an audio file in a track, drag and
drop it from the Files panel into the workspace. You can add it to an existing
track, or drop it directly into an empty workspace area and a new track will be
created automatically.
Note that when importing an mp3 file and adding it to the timeline, you may
find that the waveform shows extraneous silence at the end. This is a known
problem with mp3 files and it is especially prevalent with those encoded in VBR
(variable bit rate) mode. To fix this, just delete the file from the timeline, then
re-drag it back onto the timeline and the waveform should display correctly.
4.11.3. Recording Audio
Recording audio into Qtractor requires a microphone and at least one audio
input channel. Many laptops and webcams have built-in microphones, so, in
theory, you could use this as an input source, but for best quality, purchase an
external microphone and use it as your audio capture device.
For simultaneous multi-track recording, rarely will the sound card that was
bundled with your computer be sufficient. Almost all sound cards embedded on
motherboards are set to mix the input signals down to a stereo mix. If you wish
to record three separate musicians at the same time, each to a separate track in
Qtractor, you will require a sound card with separate, dedicated inputs.
The way that Linux displays available sound inputs and outputs can be daunting
at first, until you understand the logic behind it. A Linux system displays sound
devices the same way it displays hard drives and available network interfaces:
the first device (regardless of actual inputs or outputs available via that device)
is labeled hw0, the next hw1, the next hw2, and so on. It is safe to assume that
hw0 would be the built-in sound card on the system; being embedded in the
motherboard would certainly qualify it as being the first available sound device.
So, hw0 represents, in almost every case, your built-in sound card. hw1 might
represent, for instance, a webcam that you keep plugged into your desktop, and
hw2 could represent, perhaps, a USB microphone or a USB interface that you’ve
plugged in. You can usually determine which device is which by looking at the
vendor name associated with the hw labels; for example, if you have two devices
plugged into your system and one is labeled Blue and the other H4, then you
would know from these terms that one is your Blue USB microphone and the
other your Zoom Studio H4n.
With regard to outputs, these can sometimes be confusing due to the many
possible ways you may wish to output your sound. Typically the stereo mix of
your system sound is available as the first two output devices. If you have more
than just two speakers and you wish to split your sound to each, then utilize the
outputs labeled appropriately (Front, Center and so on). If the sound input and
output labels confuse you, take a few minutes to learn them by playing sound on
your computer and plugging speakers into each output on your computer. For
the inputs, plug a microphone into your different inputs and see where they are
received and how they are labeled. It won’t take long before you understand the
logic behind the labels, and you’ll be able to use Qtractor all the more fluidly.
4.11.4. Recording from Line-In
There are many kinds of microphones, each intended for certain kinds of sounds
and situations, but on a purely technical level, without the question of aesthetics
and microphone design, there are only about three scenarios you will encounter:
• Microphones with an 8th-inch (also called a mini) jack
• Microphones with a quarter-inch or XLR jack
• Microphones with USB connectors
The recording process is different, depending on your input type.
If your microphone has an 8th-inch jack, then you can plug it directly into
the line-in of your computer. No external sound interface is required. Your
built-in sound card is JACK’s default input, so no changes are necessary. If your
microphone can easily and cleanly adapt to the standard 8th-inch input with a
cable or a simple plug adapter, then you can use this method of recording, as
To record from the line-in of your computer into Qtractor:
• Go to the View menu and select Windows / Connections to verify
that the Capture devices on your System are routed to the Master/In of
Qtractor and that the Master/Out channels are routed to the Playback
channels of your System
Connections window, set up to capture audio
• Go to the Track menu and choose Add Track or use Ctrl+Shift+N. In
the Track dialogue box, give the track a name, set the Type to Audio, and
set the Input/Output to Master. Click the OK button to proceed
• Arm the new track for recording by clicking the “R” button in the track
listing on the left of the main Qtractor window. This sets the destination
for the recorded sound
• Click the Record button in the top toolbar
• Click the Play button in the top toolbar
4.11.5. Recording from USB
A USB microphone plugs directly into the USB port of your computer. If you
input sound through USB, then (obviously) you are utilizing a different interface
than your computer’s built-in sound card. This must be set via QJackCtl for
appropriate sound routing to occur:
• In QJackCtl, stop the sound server by clicking the Stop button
• If you have not already plugged in your USB audio interface or USB
microphone, then do so. Make sure it’s on
• Click the Setup button. In the Settings tab, locate the Input Device
setting and click the “>” button to see your choices
QJackCtl settings window showing Input Devices
• Click the Start button to activate
Now your USB interface, whether it is a single USB microphone or a 4-channel
Audio-to-USB conversion box, is managing your input sources. Plug your XLR
microphone into your USB interface, set the interface’s input source as your
XLR jack, and then create a new track in Qtractor and begin recording:
• Go to the View menu and select Windows / Connections to verify
that the Capture devices on your System are routed to the Master/In of
Qtractor and that the Master/Out channels are routed to the Playback
channels of your System.
Connections window, set up to capture audio
• Go to the Track menu and choose Add Track or use Ctrl+Shift+N. In
the Track dialogue box, give the track a name, set the Type to Audio, and
set the Input/Output to Master. Click the OK button to proceed
• Arm the new track for recording by clicking the “R” button in the track
listing on the left of the main Qtractor window. This sets the destination
for the recorded sound
• Click the Record button in the top toolbar
• Click the Play button in the top toolbar
4.11.6. Recording Takes
Aside from one-take recordings, you can create multiple, continuous takes by
using the Loop recording mode. To enable the Loop recording mode, go to View
/ Options. . . and, on the General tab, set Loop Recording mode (takes) to
either ‘First’ or ‘Last’. This will control whether Qtractor chooses the first or
the last take by default.
After you have enabled the Loop recording mode, select a loop range. To do
so, position the Edit markers by left-clicking on the timeline where you want
your loop range to start and right-clicking where you want it to end. Now select
Transport / Loop (or press Ctrl+Shift+L). This will create a loop range out
of your edit range and enable the loop mode as well. Just arm the track you
want to record to, press Record, then press Play. Qtractor will start recording,
but when it reaches the end of your loop range it will wrap around and start
recording a new take of your loop range. You can record as many takes as you
wish and decide later which one you like the most.
After having recorded some takes, select your new clip and go to Clip / Takes
/ Select to choose between the different takes. You can also press Shift+T to
iterate through the recorded takes.
It is also possible to combine Punch in/out recording with looped takes recording.
Just create a new Loop range as before, then create a Punch in/out range inside
your loop range. Recording now starts as soon as the playhead enters your
Punch in/out range. Recording stops once the playhead leaves the range, but
it will start again, recording another take, as soon as your loop starts over and
reaches the punch in point again.
Punch in/out range (purple markers) inside a loop range (green markers)
Takes are implemented in such a way that they are appended to each other. In
other words, multiple recorded takes will result in a single clip that contains all
takes appended to each other. By having activated the takes mode, Qtractor
will show you only a section of this clip with the size of the selected loop range.
If you go to Clip / Take / Select and choose ‘None’, Qtractor will ‘unfold’
your takes and show the recorded clip at its full length.
Once you know how takes are implemented, you can create them from any clip
you like. For example, select a clip and place the edit markers within a fraction
of your clip. If you have a clip that is four measures long, place the first edit
marker at the beginning of the clip and the last at the beginning of the second
measure. Now go to Clip / Take / Range. In the dialog box which appears,
choose ‘Edit’. The box on the right of this will show the resulting number of
takes - in this case it will create four takes (one for each measure). Just click on
the take you want to select. As you can see, takes can be created with a variety
of ranges - just use the one that fits your needs best.
Finally, be aware that take state information is kept only for the original recording
track location. If you change or cut any of the folded clip-takes all take state
information will be lost (though such operations can be undone, as normal). If
you move a clip to another area of the same track, then select a different take,
the clip will “snap” back to its original position. If you move a clip to another
track, take state information will be lost. Note that even if information has been
lost in whatever way, you can still drag the clip’s edges to access any hidden
takes manually.
4.12. Audio / MIDI Export
All or part of the session may be exported to one audio or MIDI file. To export
a file, select Track / Export Tracks / Audio. . . or MIDI. . . , or right-click
in the tracks area of the main view to access the same menu. This will open
either the Export Audio or Export MIDI window.
Export Audio window, where the tracks in a session can be exported as a single
audio file in the format previously specified by the user in View / Options. . .
The Range options enable you to specify how much of your session to export.
You may export the whole Session; any Loop, Punch or Edit range you have
previously denoted with its markers; or an arbitrary Custom period (the format
of which can be expressed in Frames, Time or BBT).
The Outputs box allows you to choose which buses to export. Ctrl-click to
select more than one. Note that when exporting multiple buses, because the
buses’ outputs are added together, the exported file can become clipped. To
address this, you may choose to:
• Lower the level of the output buses, so that their combined output level
does not exceed 0dBFS (monitoring this combined output via an external
meter if necessary)
• Export to a float sample file format, by selecting one via the Capture
/ Export section of the View / Options. . . / Audio menu. This way,
even if the exported file does become clipped, no data will be lost. You
can then simply reduce the level of the file later using an editing tool, such
as Audacity
Enabling the Add new track(s) option will automatically import a copy of
your exported file into a new track below the currently selected one. This can be
useful to “freeze” all or part of your session, mixing down several tracks to one
new track in order to lighten CPU load or simply to tidy your workspace up.
MIDI export pertains to MIDI material only and results in the merging and
concatenation of the selected MIDI tracks and clips into a single file of either SMF
Format 0 (all tracks reduced to a single track) or SMF Format 1 (multi-track).
Audio export is implemented through the special JACK freewheel mode and is
thus faster than real-time, resulting in a complete and exact mix-down of the
selected audio material into a designated audio file of the selected format (wav,
aiff, flac, au, ogg etc.). It is also possible to export the output of MIDI tracks
directly as audio (with standard audio tracks also included in the exported file, if
desired) using the same Export Audio window, provided that the MIDI tracks’
audio is generated by plugin instruments. For MIDI tracks which are used to
send data to external instruments driven by JACK-MIDI or ALSA-MIDI (the
output of these instruments then being routed back into Qtractor), it is necessary
to “bounce” their output to audio tracks within Qtractor before export. The
process of bouncing is covered in this How To.
The user-preferred format for exported audio and MIDI files can be set in the
Options window (View / Options. . . ).
4.13. Snapshots, Templates and Archives
4.13.1. Snapshots
After the initial save of your project, you may find later that you want to save
multiple “snapshots” of a session to compare it at different stages. To do this,
click File / Save as. . . and Qtractor will add an incremental number to the
end of your file name. Once saved, you can then switch freely between these
snapshots by opening the relevant file.
Be aware that snapshots saved in the standard session file formats (.qtr or .qts,
which are essentially the same) save only references to clips, rather than the clips
themselves. Because of this, “destructive” edits (such as changing the notes of a
MIDI clip) will be reflected in all snapshots. For example, if you have a MIDI
clip in snapshot 1, then create snapshot 2 and make changes to the notes in that
same clip, when you re-load snapshot 1, the changes you made in snapshot 2
will now be present in snapshot 1 as well. If you wish to avoid this and preserve
all of your clips in a separate snapshot, use the .qtz archive format, which will
safely bundle its own versions of all the clips (see also 4.13.3. Archives below).
4.13.2. Templates
Templates are an extremely useful time-saving feature, which enable you to
restore many settings automatically for use in a new project, thereby eliminating
the need to re-configure tracks, buses, connections etc. each time. To create a
template, once you have your session set up the way you want it, choose File /
Save As and save the file in the .qtt format. This file can then be loaded in
the same way as a standard session. Template files reproduce all the original
session’s settings, without any MIDI or audio data, leaving you ready (or at
least part of the way ready) to begin a new project. Exactly what you include
in your template will depend on your needs, but you’ll begin to discover what
these are as you use Qtractor. You can save any number of templates to cover
whatever kind of projects you need.
If you find that you’re using the same template often, you may choose to have it
auto-loaded for every new session. To enable this, choose View / Options. . .
and, in the General tab, specify your template in New session template.
The Options window
4.13.3. Archives
Qtractor has a zipped archive format, .qtz, which collects together all the information needed to reproduce the session elsewhere, such as settings, connections,
plugins (LV2 only) and all MIDI and audio files (minus any which have been
disassociated with the session via the Cleanup option in the Files pane). This
format can be used to share your Qtractor project with other people, or simply
to tidy up a session which contains extraneous files.
Note that even if you save an archive with a different session name the original
session’s Properties will remain as they were, meaning that any clips subsequently
recorded will still bear this old name. For example, if your original session has
“Song_A” as the Name in its Properties and you save an archive of, then
work on, the new session as “Song_B”, all new clips will continue to be called
Song_A-trackName-1.mid etc. If you want the new session name to be reflected
in the new clips, open the File / Properties. . . / Session menu and update
the name in the Name: box.
4.14. Other Qtractor Features
4.14.1. Metronome
When recording audio or MIDI data in real-time, a metronome can be very
useful for keeping your performance in time. Qtractor has both audio and MIDI
metronomes. The audio metronome generates its sound within Qtractor; the
MIDI variant requires an external sound source, such as a standalone soft synth.
You can even use both metronomes at the same time if desired.
To set up a metronome, open the View / Options. . . menu.
• Audio metronome - select the Audio tab. In Metronome, tick Enable
audio metronome and point Qtractor to the files you wish to use for Bar
and Beat. You can also adjust the Gain if necessary, plus create Dedicated
audio metronome outputs (useful if you have a particular monitoring set-up
in mind)
• MIDI metronome - select the MIDI tab. In Metronome, tick Enable
MIDI metronome, select a Channel and specify the Note (bar) and Note
(beat) you wish to use. You can also adjust the Velocity and Duration of
these notes. The MIDI metronome triggers sounds via the MIDI Master
Out bus by default, but if you’d prefer to use a separate bus you can enable
Dedicated MIDI metronome output - this will then appear as Metronome
in the MIDI tab of the Connections window. Once you’ve decided which
bus to use, connect it up to your destination via the Connections window
If you’re working with noticeable latency in your system, the Offset (latency)
option, available for both audio and MIDI metronomes, allows you to compensate
for this.
Percussion sounds are often employed for a metronome, though what you use is
entirely your choice. For the audio metronome, if you have no suitable files to
hand you can search the internet or use the ones from this thread on rncbc.org.
For the MIDI metronome, if you want percussion sounds and you’re using a
General MIDI-compliant bank, set Channel to 10, which is the channel for
In order to hear either metronome while the transport is rolling you must turn
it on. To do so, click the blue triangle icon in the top menu bar, or select
Transport / Metronome.
The Metronome icon
4.14.2. Keyboard Shortcuts Editor
Keyboard shortcuts are useful for the power user, in that they provide a quick
mechanism for performing often used commands quickly, without the use of your
mouse. Shortcuts can also be assigned for MIDI Controllers.
Keyboard shortcuts may be customized to your preference by using the shortcuts
editor. This editor may be found in the Help menu (Help / Shortcuts. . . ).
Note that there are two separate shortcuts windows - a general one, accessed
from the main window and a MIDI Editor-specific one, accessed from the MIDI
Editor window.
Keyboard Shortcuts Editor window, available from the Help / Shortcuts. . .
menu item
It is very straightforward in its use. Simply find the item you want to create a
shortcut for, left-click in the shortcut cell, and choose the key you wish to be
assigned to that function. You will then see whatever key or key combination
you chose appear in the context. The “X” icon on the right of the window can
be used to undo any changes or remove a default shortcut.
Take care when using shifted combinations, as if that combination produces a
non-alphanumeric character it may not function as a shortcut. For example,
Shift+1 will likely end up as a symbol such as “!” in the menu and, upon
attempting to use this combination as a shortcut, it will not work. Alt and
Ctrl-modified shortcuts should, however, be fine.
Qtractor will display a warning message if you try to duplicate a shortcut in the
same menu, but not if you use the same shortcut in both the main and MIDI
Editor menus. Instead, a warning message will appear in the Messages window.
This warning is driven by the Qt framework and is, unfortunately, outside of
Qtractor’s control.
Manual - 5 Qtractor Menus
Manual - Table of Contents
5. Qtractor Menus
5.1. Main Workspace
• New – create a new session project
• Open. . . – open a previously created session project
• Open Recent – access a list of several of your last used session projects
• Save – save your current session project
• Save As. . . – save your current session project with naming conventions
• Properties. . . – open the session properties dialog
• Exit – exit the program
• Undo – undo the last action
• Redo – redo the last action
• Cut – delete and copy an item to the clipboard
• Copy – copy an item to the clipboard
• Paste – paste an item from the clipboard
• Paste Repeat. . . – paste an item from the clipboard multiple times,
with a user-definable period in between each
• Delete – delete the selected item
• Select Mode – select Clip, Range or Rectangle edit modes, or Automation
• Select – select All, None, Invert, Track, Track Range or Range
• Insert – insert a range or track range
• Remove – remove a range or track range
• Split – after selecting a Range or Rectangle, split according to this selection
• Track – add, remove and adjust the properties of tracks
• Clip – create a new clip, edit an existing clip, or import/export a clip
• Add Track. . . – add either a new audio or MIDI track
• Remove Track – remove a track
• Duplicate Track – create a copy of the currently selected track, directly
beneath it
• Track Properties. . . – open the track properties dialog
• Inputs – show current track inputs
• Outputs – show current track outputs
• Instrument – select the instrument name of a MIDI track, from those
defined in the View / Instruments menu
• State – set current track state: Record, Mute, Solo, Monitor
• Navigate – navigate through tracks: First, Previous, Next, Last, None
• Move – change position of current track: Top, Up, Down, Bottom
• Height – adjust the vertical height of a track
• Auto-Monitor – toggle current track auto-monitoring
• Auto-Deactivate – deactivate plugins not producing sound
• Import Tracks – import audio or MIDI file(s) as new track(s)
• Export Tracks – export audio or MIDI track(s)
• Automation – automate the parameters of a track or its plugins
• New. . . – add a new clip to the currently selected track, bounded by the
Edit-head and Edit-tail markers (blue vertical lines)
• Edit. . . – edit the currently selected clip
• Take – select from multiple takes recorded, or set a range to create a new
• Unlink – if a MIDI clip is copied within the same track, any subsequent
changes will be reflected in both the original and copied clips. This unlinks
the clips, deactivating this behaviour
• Record – set a clip to be overdubbed on the next recording operation
• Split – split the clip at the position of the play-head (red vertical line)
• Merge. . . – merge two or more currently selected clips into one
• Normalize – normalize the level of an audio clip to 0dB
• Tempo Adjust. . . – adjust the clip’s tempo and time signature
• Cross Fade. . . – cross fade two overlapping clips
• Range Set – set the edit boundaries (blue vertical lines) to the start/end
of the currently selected clip
• Loop Set – set a loop between the start/end of the currently selected clip
• Import. . . – import audio or MIDI file(s) as new track(s)
• Export. . . – export audio or MIDI track(s)
• Tools – access a variety of tools to manipulate a MIDI clip
• Menubar – toggle display of the menu bar. Restore with Ctrl+M
• Statusbar – toggle display of the status bar
• Toolbars – toggle display of various toolbars
• Windows – choose which windows are displayed: File System, Files,
Messages, Connections, Mixer
• Tool Tips – toggle display of tool tips (despite the name, these are not
tool tips for the GUI icons at the top of the screen, but for the information
seen when hovering over a clip)
• Zoom – zoom the main view: In/Out/Reset for Horizontal axis/Vertical
• Snap – change the Snap/beat setting
• Refresh – refresh the view contents
• Instruments. . . – open the instruments dialog, where you can import/export patch names etc.
• Controllers. . . – manage MIDI controllers
• Buses. . . – open the buses editor dialog
• Tempo Maps / Markers. . .
– manage tempo and time signature
• Options. . . – open the program options dialog (see below)
• Backward – move playhead backward to the beginning of a range or
• Rewind – move playhead backward at greater than usual speed
• Fast Forward – move playhead forward at greater than usual speed
• Forward – move playhead forward to the next edit marker or end of the
• Loop – repeatedly play the range marked as a loop
• Loop Set – mark selected range as a loop
• Stop – stop the transport when rolling
• Play – move playhead forward at normal speed to play all un-muted tracks
• Record – prepare to record audio or MIDI on record-enabled tracks
• Punch – prepare to record the selected punch range
• Punch Set – mark the selected range for punch recording
• Metronome – turn the metronome’s audio or MIDI output on or off
• Follow Playhead – enable view scrolling so that the playhead is always
• Auto Backward – have the playhead return to the beginning of a range
or session automatically when it stops
• Continue Past End – have the playhead continue to move forward even
after it reaches the end of the session
• Mode – set the JACK Transport mode: None, Slave, Master, Full
• Panic – stop any MIDI notes that may be playing
• Shortcuts. . . – list the keyboard key combination equivalents for various
menu items, commands and MIDI Controllers. The content of this menu
differs from that of the MIDI Editor’s shortcuts menu
• About. . . – view information about Qtractor
• About Qt. . . – view information about Qt, the graphics toolkit used for
Qtractor’s user interface
5.2. MIDI Editor
• Save – save the current clip
• Save As. . . – save the current clip with naming conventions
• Unlink – if a MIDI clip is copied within the same track, any subsequent
changes will be reflected in both the original and copied clips. This unlinks
the clips, deactivating this behavior
• Record – set a clip to be overdubbed on the next recording operation
• Properties. . . – open the clip properties dialog
• Range Set – set the edit boundaries (blue vertical lines) to the start/end
of the currently selected clip
• Loop Set – set a loop between the start/end of the currently selected clip
• Track – set the inputs, outputs and properties of a track
• Close – close the current clip
• Undo – undo the last action
• Redo – redo the last action
• Cut – delete and copy an item to the clipboard
• Copy – copy an item to the clipboard
• Paste – paste an item from the clipboard
• Paste Repeat. . . – paste an item from the clipboard multiple times,
with a user-definable period in between each
• Delete – delete the selected item
• Select Mode – select On, Off or Draw edit modes
• Select – select All, None, Invert or Range
• Insert – insert a range
• Remove – remove a range
• Tools – access a variety of tools to manipulate the clip
• Menubar – toggle display of the menu bar. Restore with Ctrl+M
• Statusbar – toggle display of the status bar
• Toolbars – toggle various toolbars on and off
• Windows – toggle display of the Events window
• Tool Tips – toggle display of tool tips (despite the name, these are not
tool tips for the GUI icons at the top of the window, but for the information
seen when hovering over a note/MIDI controller data)
• Note Duration – visualise note durations in the bottom pane
• Note Color – set notes/values to be displayed in different colors according
to pitch
• Note Type – display either Note On or Key Press events
• Value Color – set notes/values to be displayed in different colors according
to velocity value
• Value Type – determine the information to be displayed in the bottom
• Zoom – zoom the view: In/Out/Reset for Horizontal axis/Vertical axis/All
• Snap – change the Snap/beat setting
• Scale – lock the addition/editing of notes to a particular scale, from the
common to the esoteric
• Refresh – refresh the view contents
• Preview Notes – toggle whether notes are audible when inputting/editing
in the matrix
• Follow Playhead – enable view scrolling so that the playhead is always
At least one note must be selected for this menu to be active.
• Quantize – quantize the timing or scale of notes
• Transpose – transpose the pitch of, or shift the timing of, a note/notes;
reverse a sequence of notes
• Normalize – normalize the velocity value of notes using a percentage
amount or absolute number
• Randomize – randomize note pitches, times, durations or velocity values
by percentage amounts
• Resize – resize note durations or velocity values
• Rescale – rescale note times, durations or velocity values
• Timeshift – alter the timing of notes on a curve, such that the acceleration
from the beginning note to the ending note is either increased or decreased
See Main Workspace above.
• Shortcuts. . . – list the keyboard key combination equivalents of menu
items and other commands. The content of this menu differs from that of
the main workspace’s shortcuts menu
• About. . . – view information about Qtractor
• About Qt. . . – view information about Qt, the graphics toolkit used for
Qtractor’s user interface
5.3. View / Options
• General – configure global options, such as UI behaviour, session templates, back-ups and transport mode
• Audio – set capture/export format, playback options and metronome
• MIDI – set capture/export format, playback options, control options and
• Display – configure the look-and-feel of the UI, including colours and
fonts, plus enable/disable logging
• Plugins – set plugin paths, toggle plugin editor GUIs, toggle dedicated
audio outputs for tracks and enable/disable various experimental features
Manual - 6 Appendixes
Manual - Table of Contents
6. Appendixes
6.1. References
Qtractor - An Audio/MIDI multi-track sequencer
Qt 4 - C++ class library and tools for cross-platform development and internationalization
JACK Audio Connection Kit
ALSA - Advanced Linux Sound Architecture
libsndfile - C library for reading and writing files containing sampled sound
libvorbis - Ogg Vorbis audio compression
libmad - High-quality MPEG audio decoder
libsamplerate - The secret rabbit code, C library for audio sample rate conversion
LADSPA - Linux Audio Developer’s Simple Plugin API
QjackCtl - JACK Audio Connection Kit - Qt GUI Interface
Cakewalk - Powerful and easy to use products for music creation and recording
SoundTouch - Sound Processing Library
rncbc.org - The personal web presence of Rui Nuno Capela, creator and
developer of Qtractor and other applications or application GUIs such as QjackCtl
(a GUI for jackd), Qsynth (a GUI for fluidsynth), Qsampler, etc.
How To - Contents
How To’s
• How To - Create Individual MIDI and Audio Buses-Ports
• How To - Set the number of channels an audio track records
• How To - Sample MIDI Composition Workflow
How To - Create Individual MIDI and Audio
How To - Contents
You can create individual input, output, or duplex MIDI/audio buses (with
corresponding ports) that can be assigned, after they are created, to individual
tracks in the Track Properties menu for each track.
To do so, from the Main menu go to View > Buses, which opens up the Buses
Illustration 1.1: Buses Menu showing audio & MIDI buses, Properties tab,
Plugins tabs, Create and Update buttons
Select one of the buses of the type of bus that you want to create (MIDI or Audio)
and it’s properties will be shown. Once you change the name, the Update and
Create buttons will be available. You can update the currently selected bus or
create a new one with the name you provided. You can further change other
options that are visible in the menu.
You can now assign them as you like in the Track Properties menu for each
Using individual MIDI buses for each MIDI track enables you to assign the full
range of the 16 MIDI channels through one bus allowing you to avoid having
to select a different channel for each softsynth or external MIDI device as you
would have to do, if you are just using the Master MIDI bus. This also allows
you to use one MIDI bus, connected to one external MIDI port, for different
tracks for each instrument on a multi-instrument synthesizer or sound module.
The same would be true for a multi-voice/instrument softsynth.
For further details, see manual section 4.1.1 Routing General Concepts and
How To - Sample MIDI Composition Workflow
This How To introduces one possible approach to composing with MIDI tracks.
It gives a brief outline of each stage of the process - namely track set-up,
composition, recording, external routing and audio export. It’s aimed mainly
at beginners who aren’t overly familiar with sequencers/DAWs, but some of
the Qtractor-specific information may also be of interest to more experienced
users. Note that a number of the tasks mentioned here are already detailed in
the wiki, so this How To contains several links to it in order to avoid repeating
Different people have different needs in terms of workflow, so this How To is by
no means a definitive guide. However, it should hopefully provide some kind of
direction for people who are uncertain where to start. Finally, it assumes that
you already have Qtractor up and running with JACK etc, so if this is not the
case, please check the set-up information in the wiki before continuing.
- NOTE - This guide was originally written for Qtractor V:0.5.x, when it
was necessary to bounce any MIDI data to audio tracks in order to export it.
However, it is now (since V:0.6.7) possible to export “internal” MIDI tracks
(i.e. those which use plugin instruments, such as the xsynth example detailed
below) directly as audio, thus avoiding the bounce step. Nevertheless, for
“external” MIDI tracks (those which send data to external instruments driven by
JACK-MIDI or ALSA-MIDI, the output of these instruments then being routed
back into Qtractor), the below workflow still holds true. It follows that a MIDI
session which has both internal and external tracks will necessitate a “hybrid”
workflow, wherein you first bounce the external tracks to Qtractor audio tracks,
then export these together with the internal tracks.
For internal tracks, the workflow described by this How To will have the following
• Section 1: No need to create dedicated audio outputs or audio tracks
• Sections 2, 3, 5: Ignore
• Section 6: Create the Aux Sends in the MIDI tracks (note that they will
still be audio Aux Sends, even though in MIDI tracks)
1. Creating Tracks
To keep things simple, we’ll create just two MIDI tracks - Lead and Bass. Create
a MIDI track, as detailed here, naming it “Lead”. Then, open up the Mixer, by
clicking on its icon.
The Mixer icon
Right-click in the area directly under the “Lead” text, navigate to Audio and
choose Dedicated. This will create an output specifically for this track, which
we’ll later connect up. Note that you can choose to Auto-connect the output –
doing so means that it will automatically be connected to system:playback_1
and 2. Whether you should do this or not will depend on your set-up, but for
the purposes of this How To, we can leave it enabled.
Creating a dedicated output
Then, create another MIDI track, naming it “Bass” and repeat the above.
Next, we’ll create two Audio tracks, to which we’ll later record, or “bounce”,
the output of the MIDI tracks. Using the same Track window as you used for
the MIDI tracks, this time, select Audio, instead of MIDI, under Type and
create a track named “LeadBounce” (there’s no “dedicated output” step here).
Once done, create another Audio track, called “BassBounce”. Qtractor should
then look like this.
MIDI and corresponding Audio tracks
2. Creating Buses
In order to send the output of the MIDI tracks to their Audio tracks, we use
Buses. Buses channel the output from a particular source to a particular
destination. For more detailed information on them and on the concepts of
routing, please see the wiki.
The method of creating a Bus is covered in this How To. Using these instructions,
create an Audio bus, with the Mode set to Input, calling it “LeadBus”. Then,
create another in the same way, calling it “BassBus”. As with the MIDI tracks’
dedicated outputs, you can choose to Auto-connect or not (for the purposes of
this How To, it doesn’t really matter). Your Bus window should then look like
Creating Buses
Note that you can also create mono Buses to record into a mono audio track.
To do this, you would set Channels to 1, as covered in this How To.
3. Connecting everything up
Although we now have MIDI tracks to compose in, Audio tracks to record in
and Buses to route the audio, we won’t be able to use them until we connect
everything up correctly. Double-click on your LeadBounce track in the main
view and, in the Track window which appears, set its Input to LeadBus.
Creating Audio track Inputs
Next, do likewise for BassBounce, connecting its Input to BassBus. Qtractor
should then look like this.
Audio tracks with their Inputs routed from Buses
The Audio tracks are now ready to receive input from their respective Buses,
but we still need physically to connect the flow of audio. We do this via the
Connections window. Click on its icon to open it.
The Connections icon
If you’ve used QjackCtl (also by the author of Qtractor) you’ll be familiar with
the layout. On The Audio tab, connect the Lead and Bass outputs on the left
(which are our MIDI tracks’ dedicated outputs) to their corresponding inputs
on the right (which are our Buses). You can either drag the connections across,
or highlight the source and destination and click Connect. The Connections
window should then look something like this.
Connections window with Dedicated Outputs connected to Buses
Now, the output of the MIDI tracks will be routed to their respective Buses,
which will, in turn, be routed to their respective Audio tracks to be recorded.
4. Compose!
Exactly how you go about composing will depend on your needs, but for the sake
of this How To, we’ll do things simply and use the soft synth, xsynth (though
any other will do). Back in the Mixer window, right-click under the “Lead” text,
as you did previously, but this time, choose Add Plugin. This will bring up the
Plugins window. Here, you can select from among anything you have installed,
of the various plugin types supported (LADSPA, DSSI, VST (Linux native) and
LV2). For more details on these, see the wiki. xsynth is a DSSI plugin, so resides
in the DSSI tab.
The Plugins window
Choose the synth patch you want via xsynth’s GUI and make sure that the
plugin is enabled in Qtractor (green light next to its name in the Mixer). Then,
double-click your MIDI track in the left pane of the main view and, in the Track
window which appears, select “xsynth DSSI plugin” in the MIDI / Instrument
area. The Bank and Program fields should then reflect whatever you chose in
the synth’s GUI and, once you click OK, this information should also appear in
the main view. For DSSI plugins, you should be able to select patches via either
the Track window or the plugin’s GUI, with the other automatically updating,
but this may not be the case with LV2 plugins. Please see the note in the wiki
about this.
Track window with patch loaded
Once you’ve set up your synth for the “Lead” track as above, repeat the process
for the “Bass” track.
*Note that when working with soundfonts (for example, via the FluidSynth DSSI,
or Calf Fluidsynth LV2, plugins), you can use the View -> Instruments. . .
menu to import their patch names. To do so, click the Import button and select
the desired .sf2/.sf3 file; the patch names will then be imported by Qtractor.
You can also use an external synth, rather than a plugin instrument. If you choose
to go down this route, you would use the Connections window to route the
MIDI track’s output bus (the default is Master) to your synth and, if necessary,
set a specific channel in the Track window described above. Then, again in
Connections, you would route the synth’s audio output to your Qtractor audio
track’s input bus (in the context of this How To, either LeadBus or BassBus).
For more details on using external synths, see the wiki.
Once your synths are set up for both tracks, you can use whatever means you
like to compose. You may choose to use an external MIDI controller to play in
your performance in real-time, or input notes manually via the MIDI Editor.
5. Recording
Once you’re happy with your MIDI composition, it’s time to record it as audio.
Arm the Audio tracks for recording (“R” button on the track, via either the
main view or the Mixer), move the playhead (red vertical line) to somewhere
before your MIDI composition starts, enable the red “Record” icon, then click
the “Play” icon to start the transport rolling (and the “Stop” icon to stop). You
can also use the Punch in/out facility to specify where recording starts and
ends, setting these points with the Edit-head and Edit-tail markers (blue vertical
Qtractor set up to record, with Record and Punch in/out icons highlighted
If you’ve done everything correctly, once you start the transport, the signal
from the MIDI tracks should be routed via the Buses and be recorded in the
corresponding Audio tracks. During the bouncing process there’s always a chance
that x-runs can occur, adversely affecting your audio file, so it’s best to check
for this. The precise positions of x-runs are unfortunately not marked visually
in the track area, but when one occurs a red warning indicator will appear in
the session state information at the bottom-right of the screen. X-runs are also
logged, together with their time of occurrence, in the Messages pane at the
bottom of the screen, so use this as a reference. Once you have your audio safely
recorded, you can adjust gain levels, panning etc via the Mixer.
Session state information showing x-run indicator
When playing back your audio tracks, note that you may, depending on your
set-up, have to mute the MIDI tracks (using the “M” button), to avoid the audio
output doubling up.
6. Effects plugins and Aux Sends
In most cases, you’ll want to add some effects to your tracks. This can be done
very easily via the Add Plugin menu of the Mixer, as covered in 4. Compose!
above. You can also add several plugins to the same mixer strip if desired; they
are processed in order from top to bottom. If you need to change the order of
an already-inserted plugin, you can simply drag and drop it.
You may also want to send several tracks to the same instance of a plugin in
order to share it. This is a reasonably common requirement, particularly for
reverb, and is catered for in Qtractor with Aux Sends. Although we have only
two tracks here, to illustrate the theory, we’ll use Aux Sends to send the two
tracks to another Bus, so that they can share a reverb plugin. First, create a
Duplex Audio Bus via the Bus window we used earlier, calling it “ReverbBus”.
In the Output Plugins tab, right-click in the blank area, choose Add Plugin,
then select the reverb plugin you want to use, making sure it’s active (green
light). You can also do this via the Mixer. If you’re not sure which plugin to
use, the Calf LV2 set is a decent place to start.
Creating a reverb Bus
You’ll probably also need to connect ReverbBus’ outputs to system:playback_1
and 2, via the Connections window we used earlier, so that you can hear the
reverb effect.
Next, in the Mixer, right-click under the Audio track name “LeadBounce” and
choose Inserts -> Audio -> Add Aux Send. In the window which appears,
set the Aux Send to “Active” (top right button), choose ReverbBus in the
Aux Send Bus combo box and choose the amount you want to send via the
Send Gain slider. Then, do the same for “BassBounce”.
The Aux Send window
What value to set Send Gain to depends on exactly what you want to do and
how you have your reverb plugin set up, but the basic theory is to have an
“overall” setting in the reverb plugin itself, then adjust the amount you send
to this plugin via each track’s Send Gain slider. In this way, you can control
the amount of reverb applied, in order, for example, to mimic an instrument’s
placement on the stage. Use a combination of Mixer levels, plugin settings and
Aux Send gain amounts to achieve the effect you want.
There are a couple of things to be aware of with regard to the way Qtractor
routes audio when using Aux Sends:
• Pre/post-fader placement: All plugins in Qtractor are pre-fader - there
is no facility to place them post-fader. This can cause issues in cases such
as the above when you want to send an audio track to a reverb bus, as
you would generally (though, again, it depends on what you want to do)
place the send post-fader: the reason for this is that with the send in the
post-fader position, the dry/wet (non-reverb/reverb) ratio is maintained
even if the fader is adjusted. This limitation can be mitigated to an extent
by inserting any kind of plugin which controls gain before the Aux Send
and using that, rather than the Mixer’s gain fader, to control the track’s
• Panning: If you manipulate the Mixer’s pan setting with an Aux Send
enabled, you’ll only be panning the original signal; the “sent” signal will
enter its destination Bus panned to the centre. This means that you’ll
hear the original signal wherever you’ve panned it, but the Bus’ copy in
the centre (unless you’ve panned it again there). If you want to pan both
the signals in tandem, add a plugin which controls panning before the Aux
Send and use this, rather than the Mixer’s pan setting, to pan the track
7. External routing using Inserts
In Qtractor, Aux Sends are used for routing audio internally, as described
above. Inserts are similar, but are used to route audio externally. Once you
have your mix set up, you may want to route it to an external source, such as
JAMin. The details of how to use JAMin are outside the scope of this How To,
but we will cover one way of connecting it up to Qtractor. The manual features
some information on how to use the program if you’re unfamiliar with it.
With JAMin running, in Qtractor’s Mixer, right-click below the name of the
Master Out Bus (right hand side) and choose Inserts -> Audio -> Add
Insert. In the window which appears, set the Insert to “Active” (top right
button). Leave Send Gain at 1.000, Dry Gain at 0.000 and Wet Gain at
1.000, unless you have some other set-up in mind.
The Insert window
Next, use the Sends button to connect the Insert to JAMin and the Returns
button to connect JAMin back to the Insert. These buttons open up the same
Connections window we used earlier, so this process should be straightforward.
Once you’ve connected everything up, repeat the above process for ReverbBus,
but connect only the Sends (leave Returns unconnected). ReverbBus will now
have two entries in its Mixer strip – the reverb plugin above and the Insert below.
This means that the reverb plugin will be processed first, followed by the Insert,
which is the order we want.
The audio from both your Buses should now be routed into JAMin - where
you can use its many features to fine tune your mix - then back into Qtractor’s
Master Out. In this way, the Master Out strip of the Mixer, at the point
below the JAMin Insert, will have a “complete” stereo signal, containing the
output of both buses. Beyond (that is, below) this point, you can perform any
processing/analysis relevant to the mix as a whole, such as goniometer and mono
Note that upon connecting JAMin up, you may find that it is also sending its
output directly to system:playback_1* and 2, which will cause some unpleasant
doubling up of audio. To fix this, disable the outputs in JAMin, via* Ports ->
Out -> out_L & out_R.
There’s an important point to be aware of when working with Inserts and other
external connections: Qtractor will only restore such connections if they are
present when the session is saved. For example, if you proceed as above, save,
then close and restart both Qtractor and JAMin, the connection will be correctly
restored. However, if you close JAMin first, make a change in Qtractor and
save (i.e. with Qtractor/JAMin in a “non-connected” state), upon restarting
Qtractor/JAMin, the connection will be lost and you’ll need to make it again.
This behaviour can be avoided by always ensuring that you have your external
connections in order before closing Qtractor (easier said than done when using
many external applications). It can also be mitigated somewhat by using
QjackCtl’s Patchbay feature to make the connections persistent; however, this
too is rather unwieldy as it means adding each item manually to the Patchbay.
A third approach would be to use a session manager, such as QJackCtl’s Session
feature (which employs “JACK session”), or NSM.
8. Exporting
We’ve now covered how to set up MIDI tracks, bounce their audio to Audio tracks,
add plugins and route the mix to JAMin. The only thing that remains is to
export the result into a single audio file. This can be done by right-clicking within
the left pane of the main view and choosing Export Tracks -> Audio. . . .
For details on the options available, please see the wiki. In the context of this
How To, we’d highlight both Master and ReverbBus in order to export them
2018/02/01; Qtractor 0.8.6
How To - Set the number of channels an audio
track records
How To - Contents
The number of channels that an audio track will record is determined by the
channel count of its input bus. If you use the Master In bus (with its default
setting of 2 channels) as the input bus for a track, the track will record two
channels of audio data. If you’re recording from a single channel source, such
as a typical microphone or electric guitar pre-amp, you should create an input
bus with a single channel, making sure it’s connected to the external source you
want to record, and then select it as the input bus in the track properties. This
will result in a single-channel track which can be panned normally for mixdown
to a stereo bus (such as Master Out), and avoids wasting disk space on empty
or duplicate audio tracks.
For further details, see manual section 4.1. Routing–Connections, Ports, Tracks
and Buses.
Download PDF