Chapter 32: Multichannel Tracks and

Signal Routing

Surround sessions typically include a combination of mono, stereo, and multichannel audio tracks, Auxiliary Inputs, Master Faders, busses, and inserts.

Once the appropriate I/O Setup has been imported or configured, any audio track can be mixed in multichannel for surround using

Pro Tools mixing features.

Multichannel I/O and signal routing is determined by the paths defined in the I/O Setup dialog.

Multichannel Quick Start

The following is an overview of how to get started mixing in multichannel for surround in

Pro Tools.

To mix in multichannel:

1 Make sure the Surround Mixer plug-in is installed in your Plug-Ins folder. If it is not, it can be installed using your Pro Tools Installer CD-

ROM. For details on installing Pro Tools options from the Pro Tools Installer CD-ROM, see your

Getting Started Guide .

2 Open any stereo Pro Tools session to remix it in surround. (You can also create new, empty

surround sessions. See “New Sessions and I/O

Settings” on page 508.)

3 Configure the I/O Setup dialog with multichannel inputs, outputs, busses, and inserts, as

needed. (See “Configuring Pro Tools for Multichannel Sessions” on page 508.)

4 Do one of the following:

• Create new tracks, and assign track outputs and sends to your multichannel paths.

Configure signal routing as needed for submixing, bussing, processing, and monitoring. For tracks that do not need to be panned in 360°, place them in the mix us-

ing sub-paths and signal routing.(See “Multichannel Signal Routing” on page 516.)

• Use the Import Tracks command to import multichannel tracks.

• Use the Import Session Data command

(Pro Tools 6.x only) to import existing 5.1

tracks, busses, and other data. (See “Importing Tracks and Track Attributes” on page 114.)

5 Pan in surround using the multichannel Track

Output and Send windows. (For information on mixing and panning for surround, see

Chapter 33, “Surround Panning and Mixing.”)

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Multichannel Audio Tracks

Multichannel audio tracks contain an individual channel for each signal in the track (for example, a 5.1 track would have six channels for left, center, right, left surround, right surround, and LFE).

Multichannel audio tracks can be:

• Recorded directly into Pro Tools, using multiple microphones or microphone arrays, or routed to appropriate multichannel Pro Tools

Input paths

• Imported from other Pro Tools sessions

• Edited, processed, and mixed in combination with mono and stereo tracks

5.1 format multichannel audio track

5.1 format audio files and tracks conform to the

Film track layout standard. Regardless of path mapping in the I/O Setup dialog, all 5.1 format audio tracks and meters follow the Film standard track layout:

L C R Ls Rs LFE

Multichannel audio tracks are not required to mix in multichannel formats. Mono, stereo, and all supported track formats can be mixed using

Pro Tools track outputs and sends. See “Multichannel Signal Routing” on page 516.

Placing Audio in Multichannel

Tracks

You can drag audio files and regions from the

Audio Regions List, or from other tracks, to place them in multichannel audio tracks.

To do so, the number of channels being dragged must match the destination track format. For example, you can only drag a stereo pair or two mono regions onto a stereo audio track. Similarly, you can only place audio into an LCR track when you have selected three regions. With 5.1 tracks, you must select six mono files or regions.

When dragged into a multichannel track, audio files are placed from top to bottom in the exact order that they appear in the Regions List or playlist from which they came.

For this reason, you may want to rename audio files before dragging them, so that they are in a preferred order. Rename them so that sorting them By Region Name in the

Regions List results in the preferred order.

(For example, with a 5.1-format track, you can rename the audio tracks, so that the arrangement of the tracks corresponds to L, C,

R, Ls, Rs, and LFE.)

Solo, Mute, and Gain in Multichannel

Tracks and Paths

Stereo and multichannel tracks consist of multiple audio signals, linked together. By default, multichannel tracks are linked and are controlled by a single channel fader, solo and mute switch.

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For discrete control of signals, multichannel tracks can be converted into individual mono tracks. For discrete level and phase adjustment, you can insert and unlink a multi-mono Trim plug-in. Both of these techniques are explained below.

Once converted to mono, multichannel tracks cannot be relinked into their original multichannel format. However, a multichannel track can be reassembled by dragging the corresponding number of mono files into a multichannel track, although some automation data will be lost. As an alternative, record the submix of the mono tracks to disk on a multichannel track.

To convert a multichannel track into discrete mono tracks:

1 Select the multichannel track.

2 Choose File > Split Selected Tracks to Mono.

To have discrete control of gain on individual channels of a multichannel track:

1 Insert a multi-mono Trim plug-in on the multichannel track.

2 Unlink the Trim plug-in by clicking the Link icon so that it is unlit.

3 Use the Channel Selector to display the controls for a channel, and adjust the gain.

See “Linking and Unlinking Controls on

Multi-Mono Plug-Ins” on page 518 for

more information.

Track and Output Formats

When you create new tracks, you specify mono, stereo, or a supported multichannel format for the new tracks.

In the Mix and Edit windows, the track format of a track’s output is always visible by the number of track meters contained in its fader strip

(for example, a single meter for mono tracks, a pair of meters for stereo tracks, and six meters for 5.1 tracks).

Assigning track output determines the format of that output. For example, a mono track always has a single track meter, even when assigned to a stereo output path. If that same mono track is assigned to a 5.1 output path, it's output will be split among those six output channels, depending on the position of its panner.

Changing Format

Changing the output format for a given track has several effects:

• The panner that appears in the track will change to reflect the new output format.

• It may be necessary for one or more pan related automation playlists to be created or deleted.

Because changing the output format has these effects, a warning dialog appears whenever you change the output format of a track to a format of fewer channels. Specifically, this will occur whenever automation playlists will have to be deleted.

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Multiple Output Assignments and Track Format

When a track is assigned to more than one path of differing formats, the main output for that track will match the format of the assigned path with the greatest number of channels.

Multichannel Signal Routing

To mix in a multichannel format, tracks are assigned to multichannel paths.

Multiple Outputs and Automation Playlists

When a track has multiple output assignments,

Pro Tools sorts panning data appropriately for each assigned path. For example, if you assign a mono track to a stereo path and a 5.1 path simultaneously, that track will have a 5.1 panner in the Mix or Edit window. When you pan the track, Pro Tools interprets the 5.1 panning moves into stereo panning moves.

This provides a type of parallel mixing. You can create a variety of mixes of differing formats all at the same time by routing your elements to multiple paths.

Control-Start-click (Windows) or Command-Control-click (Macintosh) any control in an Output window to show its automation playlist in the Edit window and view any pan automation.

This channel’s main output path is mono (“Center music”).

It has a multichannel send providing a multichannel panner

This channel’s output path is multichannel, so the track provides a multichannel panner

Two different ways to configure tracks for multichannel mixing

Tracks can be mixed in surround using the following two methods:

• By setting a track main output to a multichannel path.

• By assigning a multichannel send to route audio to a multichannel path.

See “Multichannel Sends” on page 517 for

more information.

Multichannel Track Outputs

Tracks can be routed to multichannel output or bus paths using the track Output Selector. This

This provides a multichannel panner and meter in the Mix and Edit window I/O View.

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Additional output assignments can be added by

Start-clicking (Windows) or Control-clicking

(Macintosh) the Selector and assigning another path.

Pro Tools bussing and submixing features are available for all channel formats, from mono/stereo through 8-channel. For examples of multichannel monitoring, effects processing, and bussing, see “Mixing with Paths and Sub-

Paths” on page 519. For mono and stereo mix

examples, see Chapter 26, “Basic Mixing.”

Multichannel Sends

All track formats, including mono and stereo, let you assign one or more multichannel sends.

This provides a multichannel panner in the

Sends View. Sends are also useful to bus tracks for multichannel plug-in processing.

Figure 36 shows a mono audio track with a 6-

channel send (Sends View Shows > Send A

View).

Multi-channel send panner

Mono output format

Multichannel Auxiliary Inputs and

Master Faders

A multichannel Auxiliary Input or Master Fader is used as a return for the multichannel bus.

Sends are useful when you need to create an additional, independent mix simultaneously (perhaps of a distinct format), requiring dedicated fader, mute, solo, and automation controls.

You can assign Master Faders to main and subpaths. Main paths must match the format of the

Master Fader, and only one Master Fader can be active and assigned to any single (active) main or sub-path. A Master Fader cannot be assigned to a sub-path if its associated main path is already assigned on another Master Fader. See

“Master Faders” on page 406.

Mono meter

Mono, Multi-Mono and

Multichannel Plug-Ins

Plug-ins can be used in mono, multi-mono, or multichannel formats.

Figure 36. A mono audio track with a mono output format, with a multi-channel send

Plug-in formats

For information about mono, stereo, and mono-

in/stereo-out plug-ins, see Chapter 27, “Plug-In and Hardware Inserts.”

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Multi-Mono Plug-Ins Are designed for use on stereo or greater-than-stereo multichannel tracks.

Multi-mono plug-ins are useful, or required, in the following situations:

• When a plug-in does not involve multichannel correlated processing (for example, when applying EQ to select sides of a multichannel signal)

• When you need to adjust signals within the multichannel track independently

• When a plug-in does not support multichannel formats

When a multi-mono plug-in is first inserted on a multichannel track, the plug-in controls are linked. You can unlink them for independent

adjustment. See “Linking and Unlinking Controls on Multi-Mono Plug-Ins” on page 518 for

more information.

Multi-mono plugs-ins can also be inserted on stereo tracks, to apply unlinked plug-ins on the left and right channels.

Multichannel Plug-Ins Are designed for use on stereo and multichannel tracks that require correlated processing, including stereo and multichannel limiting, compression, and similar effects.

Linking and Unlinking Controls on Multi-

Mono Plug-Ins

When a multi-mono plug-in is used on a multichannel track of more than two channels, the controls are normally linked. Adjusting the

Gain control on one channel, for example, will adjust it for all channels.

If necessary, you can unlink plug-in controls on specific channels of a track and edit them independently. You can also selectively link the controls of specific channels.

For example, to apply equal filter cutoffs to the

Ls and Rs (surround) channels in a 5.1 mix, you could link enable just those channels in an unlinked, multi-mono EQ plug-in. Adjusting the controls in the plug-in window for either channel (Ls or Rs) adjusts the other, linked channel as well.

Master Link button

Link Enable buttons

Channel Selector

Channel Selector and Link controls

Channel Selector Accesses a specific channel within a multichannel track for plug-in parameter editing. This menu appears only on multimono plug-ins inserted on tracks with more than two channels.

Master Link Button When enabled, links the controls on all channels of a multi-mono plugin so that they can be adjusted in tandem.

Link Enable Buttons Let you selectively link the controls of specific channels of a multi-mono plug-in. Each square represents a speaker channel. The Master Link button must be disabled to use the Link Enable buttons.

To unlink controls on a multi-mono plug-in:

■

Deselect the Master Link button. It is lit when linked, unlit when unlinked.

To access controls for a specific channel:

■

Select the channel from the Channel Selector.

To open a plug-in window for all channels of a multi-mono plug-in:

■

Alt-click (Windows) or Option-click (Macintosh) the Channel Selector.

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To link the controls of specific channels:

1 Deselect the Master Link button if it is not already deselected.

2 Click the Link Enable buttons for the channels whose controls you want to link.

For information on the Trim plug-in, see the

DigiRack Plug-Ins Guide

.

Paths in Surround Mixes

Because Pro Tools provides a flexible routing and submixing environment, you can maximize your system’s available resources by first identifying the elements that you want to pan dynamically and those that can be placed in certain channels only. (See “Mixing with Paths and

Sub-Paths” on page 519 for an explanation of this concept.)

Once you have identified these elements in your session, you can use a combination of main and sub-path assignments, and multichannel panning.

Mixing with Paths and Sub-Paths

It is rare that every track needs to be “flown” (actively panned in between more than a pair of speakers). In most situations, certain elements are placed in certain speakers and remain there, providing the foundation for a mix.

Figure 37 on page 520 illustrates an example of

how panning and signal routing can be combined in a multichannel mix. The following sections show you how to organize your session and signal routing to maximize the available resources.

See “Extending Stereo Mixing Conventions to Surround Mixing” on page 520 for related information.

When to Assign Multichannel Outputs

■

Assign 5.1 paths only to those tracks that need to be panned to all six channels.

For example, a sound effects track with a jet flyover should be assigned a 5.1 path to be able to fly the sound from front-to-back. In a music mix, fly a solo instrument or make a synth pad swirl around the room as a special effect.

Elements that need to be heard in all speakers simultaneously can also be assigned to the multichannel output, whether or not they need active panning in the sound field.

When to Use Sub-Paths

■

To help simplify large sessions, use sub-paths to route static (or, stationary) elements directly to the output channel or channels.

For example, film dialog is often mixed to the center channel to anchor this essential sound element to the picture. Instead of assigning a sixchannel panner to dialog tracks and panning the tracks to the center speaker only, you can route the dialog track’s main output to a mono

(Center) sub-path.

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Bus routing

Main output to sub-paths

Tracks routed to sub-paths Tracks panned in 3D

Auxiliary Input and Master Faders routed to main paths

Main outputs to 5.1 paths for surround panning

Figure 37. Using signal routing and sub-paths to mix in surround

Extending Stereo Mixing Conventions to

Surround Mixing

Stereo mixing sets the precedent for active and static panning, and surround mixing can benefit from the same basic principles.

Panning a sound back-and-forth between the left and right speakers is best used as a special effect. In a typical music mix, the basic tracks are placed in the stereo sound field and remain there.

Surround mixes can become incoherent if too many elements are continuously moving, For special effects, some tracks can be panned dynamically, bouncing between speakers or sweeping from one side to the other.

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Example Paths and Signal

Routing for a Surround Mix

The examples that follow show how Auxiliary

Inputs, Master Faders, and other Pro Tools signal routing features can be used for stem mixes, submixes, and similar project needs.

In these examples, music and effects are being mixed for a trailer, in 5.1 surround. Separate stem mixes (for music and for effects) are to be mastered to 8-track MDM.

Additional stereo output paths, with mono subpaths, have also been defined for the remaining channels.

Example Bus Paths

Figure 39 shows example bus paths.

Example Multichannel Paths

Signal routing is the key element in any

Pro Tools surround session. Signal routing is configured and defined in the I/O Setup dialog.

Example Output Paths

Figure 38 shows output paths defined in the I/O

Setup dialog of an example session that was created on a Pro Tools|HD system with one 192 I/O audio interface.

Figure 39. I/O Setup, example bus paths

Two 5.1 format main paths have been defined

(“Music” and “FX”), each with several subpaths.

Example Sub-Paths

Sub-paths let you route to selective channels within the multichannel surround output. In

Figure 40, the FX bus has several sub-paths that

show this.

Figure 38. I/O Setup, example output paths

Sub-paths have been defined for Mix, Music, and FX main output paths.

Figure 40. I/O Setup, example sub-paths

5.0 Sub-Path The 5.0 FX bus is a 5-channel subpath. Use this type of sub-path routing to conserve mixing resources with tracks you want to keep out of the LFE channel.

LFE Path A custom LFE sub-path has been added to provide a discrete mono path to the LFE channel.

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Signal Routing Examples

The following examples show how main and sub-paths can be used, using an example session consisting of a 5.1 main mix, with music and effects stems (or submixes).

Submix Stem Examples

Figure 41 shows a routing configuration for an effects submix.

Figure 41. FX stem

Some tracks are routed to stereo sub-paths, while others are assigned to mono, LCR, or other subpaths. Two tracks (one stereo, one mono) are assigned to multichannel busses for surround panning.

A 5.1 Auxiliary Input assigned to the FX main bus path serves as a submixer.

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Figure 42 shows a routing configuration for music tracks.

Figure 42. Music stem

Most of the music tracks in this example are routed to the front left/right channels, using a stereo subpath. A 5.1 Auxiliary Input controls the bus and stem output.

Main Stems Example

Figure 43 shows two Auxiliary Input channels assigned to additional 5.1 format paths for a main mix.

Figure 43. Main stems

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Multiple output assignments make it possible to configure a number of multi-format mixes. For example, you can assign an additional stereo output to tracks and create a stereo mix at the same time as a 5.1 mix. For more information,

see “Multiple Output Assignments” on page 412.

Figure 45 shows how a “traditional” LFE track

can be routed to only the LFE channel. This example uses a custom-defined LFE sub-path to the FX main bus path.

LFE Examples

LFE tracks and other audio can contribute to the

LFE output in two ways:

• Using the LFE slider in Output windows. This

LFE signal is post-fader.

– or –

• Using a custom sub-path to route channels discretely.

Figure 44 shows a channel Output window,

sending and metering to the LFE channel.

LFE fader

Figure 45. Discrete LFE routing

For instructions on how to create a sub-path, see

“Custom Multichannel Paths” on page 510.

LFE and Filtering

Pro Tools applies no filtering to LFE signals.

Some delivery requirements may require filter-

ing for the LFE track. See “Mixing Formats and

Surround Formats” on page 497 for more infor-

mation.

LFE faders can follow Mix and Edit Groups.

See “Automation Preferences” on page 456

for more information.

Aux LFE meter

Figure 44. LFE contribution from a stereo output

Using the LFE fader, you can add any amount of any multichannel path to the overall LFE output. In the above example, the track’s Center percentage has been turned off, and the LFE fader has been raised to route it to the LFE channel.

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