Dolby Laboratories | SDU4 | Specifications | Dolby Laboratories SDU4 Specifications

Dolby Laboratories SDU4 Specifications
5.1-Channel
Production
Guidelines
Issue 1
i
S00/12957
5.1-Channel Production Guidelines
Dolby Laboratories Inc
USA
UK
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Los Angeles, CA 90068-1146
Telephone 323-845-1880
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Telephone (44) 1793-842100
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 2000 Dolby Laboratories Inc; all rights reserved.
Dolby, Pro Logic, Surround EX, AC-3 and the double-D symbol are trademarks of Dolby Laboratories.
Issue 1 S00/12957
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5.1-Channel Production Guidelines
Table of Contents
List of Figures
vi
Chapter 1
Introduction
1.1
Historical Perspective
1.2
Dolby Digital and 5.1-Channel Audio
1-1
Chapter 2
Getting Started
2.1
Dolby Digital Encoder and Decoder
2.2
Downmixing
2.2.1 Format Compatibility
2.2.2 Channel Redirection
2.3
Dynamic Range Control (DRC)
2.4
Bass Management
2.5
Compatibility with Existing Dolby Surround Equipment
2-1
2-1
2-2
Production Environment
3.1
Room Layout/Design
3.1.1 Room Size and Shape
3.1.2 Acoustics
3.1.3 Examples/Diagrams
3.2
Monitoring
3.2.1 Front Speakers
3.2.2 Surround Speakers
3-1
3-1
3-2
3-2
3-2
3-6
3-6
3-7
Chapter 3
iii
2-3
2-4
2-6
2-6
5.1-Channel Production Guidelines
3.3
3.4
3.5
3.2.3 Subwoofer(s)
3.2.4 Room Layout
Bass Management
Level Calibration
3.4.1 Playback Levels
3.4.2 Sound Pressure Level Meter
3.4.3 Taking a First Measurement
3.4.4 Bass Redirection
3.4.5 Individual Level Calibration
3.4.6 Subwoofer Calibration
Signal Delay
3.5.1 Surround Delay for Dolby Digital
3.5.2 Center Channel Delay
3.5.3 Compatibility with Dolby Surround Monitoring
Chapter 4
Equipment
4.1
Consoles
4.1.1 Small Format Console
4.1.2 Digital Audio Workstations
4.1.3 Audio Processing Equipment
4.1.4 Routing/Switching
4.2
Recorder/Storage
Chapter 5
Production Techniques
5.1
Microphone Techniques
5.2
Recording
3-8
3-9
3-11
3-14
3-14
3-17
3-17
3-18
3-19
3-19
3-21
3-23
3-24
3-25
4-1
4-1
4-3
4-7
4-9
4-10
4-11
5-1
5-1
5-2
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5.1-Channel Production Guidelines
5.3
Mixing
5.3.1 Center/Front Channels
5.3.2 Surround Channels
5.3.3 LFE Channel
5.3.4 Downmix - Dolby Surround Compatibility
5.3.5 Downmix - Stereo Compatibility
5.3.6 Upmixing
5.3.7 Translation to Consumer Systems
5.3.8 Production Tips
5-2
5-3
5-4
5-5
5-7
5-8
5-9
5-12
5-13
Chapter 6
Preparing the Source Delivery Master
6.1
Channel-to-Track Allocation
6.2
Channel Levels
6.3
Reference Levels
6.4
Time Code
6.5
Documentation
6.5.1 Mix Data Sheet
6.5.2 Mastering Information Sheet
6-1
6-1
6-2
6-3
6-4
6-5
6-6
6-6
Chapter 7
Miscellaneous Information
7.1
Technical Assistance
7.2
Contacting Dolby Laboratories
7.3
General information and Inquiries
7.4
Trademark Usage
7-1
7-1
7-2
7-2
7-3
Appendix A Mix and Mastering Data Sheets
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5.1-Channel Production Guidelines
List of Figures
2-1
2-2
3-1
3-2
3-3
3-4
3-5
3-6
4-1
4-2
4-3
4-4
Dolby Surround Encoder
Dolby Surround Pro Logic Decoder
Typical 5.1-Channel Room Layout
Extended Room Layout
Large Listening Room Layout
ITU-R Recommended Listening Room
Real-Time Analyzer (RTA) Display
Speaker-to-Listener Distances
Interconnect Example
Simple DAW Interconnect
Typical DAW with Multichannel Panner
Typical Digital Multichannel Audio Workstation Interconnect
vi
2-7
2-8
3-3
3-4
3-5
3-10
3-20
3-22
4-6
4-7
4-8
4-9
5.1-Channel Production Guidelines
Chapter 1
Introduction
These guidelines provide starting points for producing 5.1-channel audio content by
explaining terms, highlighting areas where there are alternative courses of action, and
clarifying outcomes that may not be immediately apparent. The multichannel audio
concept originated in the film world; therefore some cinematic terms are used.
1.1
Historical Perspective
5.1-channel audio was first developed for cinema applications. Unlike any other
recording and playback format intended for a consumer audience, film sound is
mixed in the same environment in which it is reproduced. All aspects have been
standardized and calibrated so that what the mixers create on the dubbing stage is
what is heard in the cinema. These aspects include the recording levels on the film
soundtrack and the overall loudness during playback.
To improve the cinema sound years ago, level and calibration standards were
established to ensure uniformity across various playback environments. Even though
the continuous evolution of power amplifier and loudspeaker technologies made it
1-1
5.1-Channel Production Guidelines
Introduction
possible to reproduce a higher quality of sound in the cinema, it was still not easy to
deliver or reproduce strong bass. The best soundtracks of the day (70 mm magnetic)
had reached their maximum recording capability, so it was impossible to increase the
bass without causing overload. Even today, the main screen speakers used in cinemas
do not reproduce below 30 Hz, so if the soundtrack carried more bass to the
amplifiers, it would not necessarily be reproduced.
To increase low frequency playback capabilities, subwoofers were installed in the
cinema. To direct bass signals to the subwoofers, a separate channel was added to the
soundtrack. Known as the LFE channel (for Low Frequency Effects), it handles bass
created specifically for subwoofer boom effects and may also carry low frequency
information from the other channels in order to enrich the overall soundtrack.
A consumer delivery format like a CD is significantly different from a cinema
system. CD loudness is not calibrated—the consumer decides where to set the volume
control. Nor is the CD recording level calibrated—a music producer may add more
bass to a recording by adjusting the overall levels thus ensuring that the additional
bass will not cause overload.
In a similar manner, each channel in the Dolby Digital system can carry bass content.
So why is there an LFE channel in a consumer audio delivery format? Quite simply, it
allows movie soundtracks to be transcribed directly and without alteration to the
home video format. This does not mean the LFE channel should not be used. It
suggests that the LFE channel may not be the only, or the best way to provide loud,
deep bass. This becomes more apparent when one actually mixes multichannel audio
using a properly configured and calibrated studio monitor system.
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5.1-Channel Production Guidelines
1.2
Introduction
Dolby Digital and 5.1-Channel Audio
Dolby Digital (AC-3) is a perceptual audio coding system developed in 1992 to allow
35 mm theatrical film prints to carry multichannel digital audio in addition to the
standard analog optical soundtrack. The system has since been adopted for use with
laser disc, ATSC high definition (HDTV) and DVB/ATSC standard definition
(SDTV) digital television, digital cable television, digital satellite broadcast, DVDVideo, DVD-Audio, DVD-ROM, and Internet audio distribution.
Dolby Digital divides the audio spectrum into narrow frequency bands using
mathematical models derived from the characteristics of the ear, and analyzes each
band to determine the audibility of those signals. To maximize data efficiency, the
greatest number of bits represent the most audible signals; fewer bits represent less
audible signals. In determining the audibility of signals, the system performs what is
known as masking. Masking refers to the phenomenon that the ear cannot detect lowlevel sounds when there are higher level sounds at nearby frequencies. When this
occurs, the high level sound masks the low level one, rendering it inaudible.
Exploiting this phenomenon allows audio to be encoded more efficiently than in other
audio coding systems. This makes Dolby Digital an excellent choice for systems
where high audio quality is desired, but bandwidth or storage space is restricted. This
is especially true for multichannel soundtracks since Dolby Digital’s compact
bitstream allows 5.1-channel audio to occupy less space than a single channel of Red
Book PCM audio.
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5.1-Channel Production Guidelines
Introduction
5.1-channel audio typically consists of five discrete, full range main channels (Left,
Center, Right, Left Surround, and Right Surround) plus an optional band-limited Low
Frequency Effects (LFE) channel for added bass (the .1). Dolby Digital bitstreams
deliver full frequency bandwidth main channels, from 3 Hz to 20 kHz, and a limited
frequency bandwidth LFE channel, from 3 Hz to 120 Hz. Current Dolby Digital
encoders accept word lengths of 16, 18, or 20 bits at sampling rates of 32, 44.1, or
48 kHz. The Dolby Digital algorithm provides 24-bit resolution, and future versions
may extend sampling rates to 96 kHz. All multichannel programs carried within a
Dolby Digital bitstream, can be downmixed (see Section 2.2) for compatibility with
Dolby Surround, stereo, or mono systems.
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5.1-Channel Production Guidelines
Chapter 2
Getting Started
2.1
Dolby Digital Encoder and Decoder
The discrete 5.1-channel mix will encode and decode in a Dolby Digital 5.1-channel
system and remain discrete 5.1. When mixing and monitoring in 5.1, it is important to
have monitors set up and calibrated correctly so the mix will play properly when
decoded by the consumer.
Monitoring through an encoder and decoder is important in regards to downmixing
and Dynamic Range Control (DRC). Using a Dolby Digital encoder and decoder in a
monitor chain will allow quick examination of the variety of ways a consumer may
hear a mix. Dolby Digital offers many features to maintain backward compatibility as
well as to allow consumers the ability to customize their listening environments. For
best results, features such as downmixing, DRC, and bass management need to be
checked during content creation and delivery to see if they meet the intent of the
content provider as well as the needs of the consumer. Encoding with a Dolby
Laboratories Model DP569 Dolby Digital encoder and monitoring with a Model
DP562 Professional Reference Decoder provides monitoring capabilities for these
parameters in addition to being able to simulate almost any listening environment.
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5.1-Channel Production Guidelines
2.2
Getting Started
Downmixing
Downmixing has two frequently interrelated applications: format compatibility and
channel redirection, as described below.
2.2.1
Format Compatibility
Dolby Surround-compatible, stereo, and mono mixes are often created when
multichannel material is downmixed to fewer channels. It is important to check a
number of aspects of each downmix to confirm that it translates as closely as possible
to the original intent of the mix.
There are many consumers who will listen to Dolby Digital sources such as DVD or
DTV without having a full 5.1-channel Dolby Digital playback system. These
consumers will hear the two-channel analog or PCM outputs of their DVD players or
DTV set-top boxes through existing stereo or Dolby Surround Pro Logic systems. All
DVD-video players and DTV set-top boxes have the ability to create and deliver a
Dolby Surround compatible or stereo downmix from the two-channel analog or PCM
outputs. The DP562 Professional Reference Decoder can simulate what the consumer
will hear while listening in these modes.
Example 1: Using a properly calibrated 5.1-channel monitoring system (incorporating
appropriate bass management) set the DP562 to Dolby Digital and Full. In this
configuration, a 5.1-channel bitstream will reproduce all channels as a consumer with a
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5.1-Channel Production Guidelines
Getting Started
Dolby Digital 5.1-channel system will hear it. Pressing Pro Logic on the DP562
downmixes the five main channels (discarding the LFE channel) to a Dolby Surroundcompatible bitstream. The downmix is then Dolby Surround Pro Logic decoded
resulting in Left, Center, Right, and mono Surround channels at the outputs. Monitoring
in this mode simulates how a consumer will hear the 5.1-channel bitstream when
downmixed and then reproduced through a Dolby Surround Pro Logic system.
Example 2: With Pro Logic still engaged, select Stereo instead of Full in the
Listening Mode section. This mode provides for monitoring the way a consumer will
hear the 5.1-channel bitstream when downmixed and then reproduced through a
stereo system.
Example 3: In addition to Dolby Surround (Lt/Rt) compatible downmixes, Lo/Ro
(Left only/Right only) downmixes can also be checked. Selecting Stereo mode
without Pro Logic engaged will create an Lo/Ro downmix at the outputs.
2.2.2
Channel Redirection
The ability to redirect channel information provides a means to account for the design
and number of speakers in the listening environment.
There will be consumers who may not have or can not use all 5.1 speakers with their
Dolby Digital decoder. Dolby Digital consumer decoders have the ability to redirect
or downmix decoded multichannel information such as a 5.1-channel soundtrack.
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5.1-Channel Production Guidelines
Getting Started
Example 1: Using a properly calibrated 5.1-channel monitoring system
(incorporating appropriate bass management), set the DP562 to Dolby Digital/Full.
In this configuration, a 5.1-channel bitstream will reproduce all channels the way a
consumer with a Dolby Digital 5.1-channel system will hear them. Pressing any of
the other Listening Modes causes the DP562 to redirect audio to the outputs of the
selected speaker configuration.
Example 2: Select 3 Stereo instead of Full in the Listening Mode section and the
Surround channel information is redirected to the Left and Right speakers to simulate
a monitoring system with no Surround speakers.
Example 3: Select Phantom Center and the Center channel information is
appropriately attenuated and redirected to the Left and Right speakers to simulate a
multichannel monitoring system with no Center speaker.
Technical Note: Summing multiple channels of audio, which occurs while
downmixing, has the potential for overloading the decoder outputs. Please refer to
the DP562 operation manual for more information.
2.3
Dynamic Range Control (DRC)
Dolby Digital incorporates both dynamic range compression and protection against
the decoder overload, which can result from downmixing. Some consumer products
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5.1-Channel Production Guidelines
Getting Started
allow the user to choose full or reduced dynamic range when listening to a Dolby
Digital multichannel soundtrack. When downmixing is in use, overload protection is
applied automatically. The DP562 has the capability to monitor the dynamic range
compression information encoded into the Dolby Digital bitstream. For further
information on Dynamic Range Control (DRC), please consult the Dolby Digital
Professional Encoding Manual.
Example: Selecting Line from the Dynamic Compression section implements both
dynamic range compression and Dialog Normalization. This would simulate
consumer listening conditions such as late night viewing of programs with a wide
dynamic range or dynamic range compression required during downmixing. RF
mode implements dynamic range compression, overload protection, and dialog
normalization to simulate the case when the audio signal must follow an RF
remodulation path for playback or for late night listening, when the least amount of
dynamic range (lower signal peaks relative to dialogue level) is desired. Custom
mode offers the same options for monitoring dynamic range compression as Line
along with the ability to defeat Dialog Normalization (consumer products do not offer
this mode). Caution must be used however. Depending upon how Custom mode is
set up, it may not represent either the level balance or dynamic range heard in a
consumer decoder. None is strictly a professional mode that defeats both dynamic
range compression and Dialog Normalization. This mode (None) is used to hear the
full level and dynamics in the program material being encoded. It is never allowed in
a consumer product and may not represent either the level balance or dynamic range
heard in a consumer decoder. Encoding judgments based on this compression mode
should not be made.
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5.1-Channel Production Guidelines
2.4
Getting Started
Bass Management
Bass management allows the user to redirect low-frequency information from any of
the five main speakers to the subwoofer; conversely, if there is no subwoofer, the
LFE information can be redirected to the left and right speakers. This is important as
the vast majority of consumer home theater speaker systems require some degree of
bass management since typically none of the five main speakers is designed to
reproduce frequencies below 80 Hz (i.e., satellite/sub speaker arrangements). The
DP562 provides the same bass management functions as a consumer Dolby Digital
decoder. Even when monitoring with full-range main speakers that require no bass
management, this function is useful for checking how redirected low frequencies
from any of the main channels may interact with the LFE-channel information.
Remember that the consumer will most likely use some form of bass management.
Accordingly, proper bass management is necessary to emulate a consumer home
theater system. See Section 3.3 for more details.
2.5
Compatibility with Existing Dolby Surround
Equipment
In the world of 5.1 digital multichannel audio such as Dolby Digital, it is important to
remember that stereo delivery in the form of broadcast, VHS, and CD will continue to
exist. However, with Dolby Surround, stereo audio formats have delivered
multichannel audio since 1982. Dolby Surround is a passive matrix four-channel (Left,
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5.1-Channel Production Guidelines
Getting Started
Center, Right, Surround: LCRS) to two-channel encoding system that is delivered via
stereo media, Figure 2-1. The stereo-compatible Dolby Surround encoded soundtrack is
referred to as Left total, Right total or Lt/Rt. In both the analog and digital world, Dolby
Surround exists on media, e.g., VHS Hi-Fi, broadcast, CD, laser disc, etc. Dolby Digital
has backward compatibility with Dolby Surround encoded material.
φ
L
_
-3 dB
φ
R
S
BP Filter
Half B NR
-3
-3dB
dB
Rt
φ
C
Lt
Figure 2-1 Dolby Surround Encoder
Every multichannel Dolby Digital decoder, such as an A/V receiver, contains a digital
implementation of a Dolby Surround Pro Logic decoder. Dolby Digital decoders will
allow stereo material encoded with Dolby Surround (Lt/Rt) from digital sources (e.g.,
laser disc, DVD, DBS, digital cable, etc.) to be decoded back to a four-channel output
(LCRS).
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5.1-Channel Production Guidelines
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CENTER MODE
OUTPUT
Lt
INPUT
DECODER
IC
LEVEL
CONTROL
L
C
R
L
C
R
S
Rt
MASTER
LEVEL
CONTROL
LEFT
CENTER
RIGHT
SURROUND
TIME SET
ON/OFF
NOISE
SEQUENCER
ANTI
ALIAS
FILTER
AUDIO
DELAY
7 kHz
LOWPASS
FILTER
MODIFIED
B--TYPE
DECODER
Figure 2-2 Dolby Surround Pro Logic Decoder
In the case of producing a Dolby Surround encoded mix (Lt/Rt) for a Dolby Digital
encoded project, it is important to create the Dolby Surround mix through a Dolby
Surround encoder (SEU4 or DP563) and a Dolby Surround decoder (SDU4) or Dolby
Digital multichannel decoder (DP562).
For further information on the theory of operation of Dolby Surround and how to mix
in Dolby Surround, please refer to the Dolby Surround Mixing Manual (part number
91536) available at www.dolby.com.
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5.1-Channel Production Guidelines
Chapter 3
Production Environment
The advent of 5.1-channel audio production poses unique challenges not only for artists
and audio engineers, but also for the designers and builders of audio facilities.
3.1
Room Layout/Design
Significant, although not necessarily profound, differences exist between stereo and
multichannel production environments. Basic factors to consider when creating any
critical production environment include equipment needs, room size and geometry,
construction methods, wiring, HVAC, lighting, AC power requirements, acoustics, and
ergonomics. The addition and placement of equipment necessary for multichannel
production will often affect room acoustics. Whether designing a new facility or planning
to retrofit a studio, consulting a professional acoustician and architect familiar with
building critical audio monitoring environments is always recommended.
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5.1-Channel Production Guidelines
3.1.1
Production Environment
Room Size and Shape
Depending on the application, room size and shape will vary considerably. In
multichannel audio production for broadcast, limited space in a remote truck often
makes speaker placement difficult. Similarly, in a production facility designed to
accommodate additional listeners such as clients, producers, and staff, increased
furniture and monitoring requirements may become factors.
3.1.2
Acoustics
The advantage of building a new facility is the opportunity to design specifically for
multichannel production. When retrofitting a studio, it is important that additional
equipment needed for multichannel production does not compromise the room
acoustics. Simply relocating this equipment or modifying acoustic treatment can
reduce or even eliminate undesirable acoustic anomalies.
3.1.3
Examples/Diagrams
A variety of room layouts for 5.1-channel audio production exist. All examples
require a space that can allow for placement of five full-range (20 Hz–20 kHz)
speakers around the engineering position with placement of an additional speaker
capable of reproducing the LFE (Low-Frequency Effects) channel (3 Hz–120 Hz) in
the designated space. A typical room layout for producing multichannel audio will
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5.1-Channel Production Guidelines
Production Environment
have Left, Center, and Right speakers placed in front, while two or more surround
speakers are needed behind the engineer,
Figure 3-1 Typical 5.1-Channel Room Layout
Alternative room layouts for multichannel 5.1 production have been suggested by the
International Telecommunication Union, as in Figure 3-4 ITU-R Recommended
Listening Room.
For larger listening spaces with secondary listening areas, additional surround speakers
are needed to accommodate the additional space, as show in Figure 3-2 Extended
Room Layout. In this example it is important to optimize the engineer’s listening
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5.1-Channel Production Guidelines
Production Environment
position when compromise between two arrays of surround speakers is required for
area coverage.
Figure 3-2 Extended Room Layout
For larger critical listening environments, such as dubbing stages, several surround
speakers may be used to simulate the playback environment of a movie theatre.
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5.1-Channel Production Guidelines
Production Environment
Figure 3-3 Large Listening Room Layout
All multichannel room design considerations should bear in mind requirements for
producing Dolby Digital 5.1, as well as Dolby Surround. For more information on
Dolby Surround and Dolby-suggested production room layouts, please review the
Dolby Surround Mixing Manual, Part Number 91536, available at www.dolby.com.
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5.1-Channel Production Guidelines
3.2
Production Environment
Monitoring
Some aspects of multichannel studio monitor setup are understood and accepted. The
best approach to others is still open to debate. The following guidelines offer
commonly accepted practices for setting up multichannel audio monitoring systems.
3.2.1
Front Speakers
Multichannel sound systems add a center speaker to the Left/Right pair used in stereo
systems. To promote good imaging, all three should be identical, just as conventional
L and R stereo speakers must be matched. If all three cannot be the same model, the
center speaker may be a smaller model from the same product line.
The front speakers should be equidistant from the listener, with their acoustic centers
in the horizontal plane; that is, on-axis to the ear. The center speaker may need to be
positioned above or below a video monitor forcing the acoustic centers of the three
front speakers out of alignment. If this occurs, attempt to situate the speakers so the
tweeters are in as close to a horizontal straight line as possible. This may require
either an inverted or lateral orientation of the center speaker, as well as rotating the
tweeter (when possible) to maintain the proper dispersion characteristic.
If the center speaker is not equidistant with the L/R pair, signal delay may be used to
obtain coincident arrivals. Please refer to Section 3.4, Level Calibration.
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5.1-Channel Production Guidelines
Production Environment
The front speakers must exhibit the same acoustic polarity. It is highly recommended
that electronic signal polarity be maintained throughout the entire monitoring system.
3.2.2
Surround Speakers
Whenever possible, use the same speakers all around to achieve uniformity. If this is
not feasible, the surround speakers may be smaller than the front speakers but should
maintain the same character; i.e. they might be smaller speakers from the same
manufacturer.
The front and surround speakers should be equidistant from the listener, with their
acoustic centers in the horizontal plane that is on-axis to the ear. Refer to Figure 3-5.
The surround speakers should achieve coincident arrival with the front speakers either
as a result of equal path lengths or through alignment with signal delays. Please refer
to Section 3.4, Level Calibration.
The Surround speakers must exhibit the same acoustic polarity as the front speakers.
It is highly recommended that electronic signal polarity be maintained throughout the
entire monitoring system.
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5.1-Channel Production Guidelines
3.2.3
Production Environment
Subwoofer(s)
The LFE channel requires the use of at least one subwoofer in the monitor system. It
is equally important to include one or more subwoofers and bass management when
some or all of the speakers may not cover the deepest bass in soundtracks or music
recordings. The bass from any channel that is not reproduced in the main speaker for
that channel must be redirected to the subwoofer(s). There are now various products
that handle bass management (crossover filters, bass mixing, and combining with the
LFE channel in the proper mixing ratio) that can help achieve a proper monitor setup
in the studio. It is essential to integrate the subwoofer(s) with the main speakers
correctly to ensure a wide, smooth, and uniform frequency response from all five
main channels. In addition, it is critical to have the LFE channel reproduced in the
proper relation to the other channels.
Positioning the subwoofer(s) can often be an arduous task and the relative location(s)
will not be the same for all rooms. A certain amount of experimentation should be
expected particularly when retrofitting an existing production room. Initially, place
the subwoofer(s) near the listening position. Play program material with significant
low frequency content and listen at likely subwoofer locations in the room. Locations
delivering the smoothest bass response are apt to be the best choice for final
subwoofer placement.
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5.1-Channel Production Guidelines
3.2.4
Production Environment
Room Layout
The ITU-R1 has specifications for a listening room layout designed for the critical
evaluation of multichannel programs. These recommendations are a good starting
point for a mixing room setup as well. Aside from signal alignment, a specific
geometry is described. With the Center speaker directly in front, position the L/R
speakers 30° from center (forming a 60° angle) and the Surround speakers 110° off
center. Please refer to Figure 3-4.
1
The ITU, International Telecommunication Union, headquartered in Geneva, Switzerland, is an international
organization within which governments and the private sector coordinate global telecom networks and services.
ITU-R refers to the Radiocommunication Sector.
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Production Environment
B
C
Reference listening position
L
R
D=B
½B
Worst case listening positions
B: loudspeaker base width
30°
D: listening distance
110°
LS
RS
Figure 3-4 ITU-R Recommended Listening Room
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5.1-Channel Production Guidelines
3.3
Production Environment
Bass Management
Stereo requires the reproduction of signals from 20 Hz to 20 kHz. This is done with
multi-way speaker systems, which utilize a combination of woofers and tweeters to
achieve full range response. These speakers are connected via a crossover network to
route the appropriate frequencies to the various speakers in the system. This may be a
two-way, three-way, four-way, or even-five way system, but in each case, the goal is
to reproduce 20 Hz to 20 kHz evenly.
The introduction of Dolby Surround home theater systems added three speakers to the
stereo system, a full range center speaker and two limited-range surround speakers.
The bandwidth of the surround channel is 100 Hz to 7 kHz. This results in the ability
to use small bookshelf speakers for the surround channel.
Although the center channel is full bandwidth, most consumer applications will not
allow a full-sized center speaker as would be typical for the left and right speakers.
Because of this, a bass management system is included in the Dolby Surround Pro
Logic consumer decoder to cross over the center channel low frequencies below
100 Hz and redirect them to the left and right speakers. The bass signal is now
reproduced by speakers capable of handling the information without overloading the
smaller, center speaker.
Dolby Digital consumer decoders also include a bass management system. Just as
with the stereo and Dolby Surround systems, the goal is to be able to reproduce all
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frequencies within the system. In this case, there are more options, as the five main
channels are full range and an extra LFE channel is added.
Possible combinations of speakers include five full range main speakers and a subwoofer
for the LFE; five small speakers for the main channels and a subwoofer for both the LFE
and all five main channels; and various combinations of the above examples.
As with consumer 5.1 applications, studios must be able to reproduce all reasonable
frequencies from each full bandwidth channel. Crossovers, subwoofers, and main
speakers should work together to give flat response for each of the five main
channels. In addition, larger rooms may dictate the need for more than one subwoofer
to achieve adequate bass response. Many manufacturers of near-field monitors make
complementary subwoofers to complete the system.
When utilizing the LFE channel in a mixing situation, it is important to band-limit the
information for this channel. In the Dolby Digital encoding process, the encoder will
brickwall filter the LFE signal at 120 Hz. To properly hear the LFE content, a sixth or
seventh order 120-Hz low-pass filter must be included in the monitor chain. It is
advisable to include this filter in the console output before the monitor such that both the
recorded information and the heard information are band-limited. Failure to include
this filter will result in hearing substantial bass information above 120 Hz in the mix
that will not be present in the Dolby Digital encoded version. 120 Hz is the proper
crossover frequency for theatrical film applications.
For consumer applications such as DVD and Digital TV, the consumer decoders add
a slight twist to the equation. Consumer decoders take the LFE signal and add any
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channels in need of bass management, as determined either by product design or user
selection. The five main channels are then high-pass filtered at either a fixed
frequency of 80 Hz or a selectable frequency of 80, 100, or 120 Hz. The summation
of the LFE and any other channels is low-pass filtered at the same frequency. If the
crossover frequency is fixed at 80 Hz, as is standard in lower priced decoders,
information in the LFE channel between 80 Hz and 120 Hz will be reproduced at a lower
level than it is recorded at. To replicate what the consumer will hear, a third order 80 Hz
filter in the LFE audio signal path to the recorder is recommended.
While the Dolby Digital Encoder and Decoder together will handle bass management
in decoding, it is not feasible to use it in this way when mixing, due to the delay
through the encoding and decoding process. Because of this, it is necessary to have a
separate crossover system in place to handle the bass management. Many
manufacturers now offer such devices for this purpose. Again, for DVD and other
consumer applications, a crossover frequency of 80 Hz is required.
Once the ability to reproduce all frequencies in each channel has been met, the room
must be calibrated. For each of the five main channels, pink noise is adjusted for
85 dB C-weighted slow. Various EQ curves will come into play, depending on room
size and application. If in doubt, additional information is available in the Dolby
Surround Mixing Manual, Technical Guidelines for Theater Applications and other
publications from Dolby Laboratories.
The LFE channel is calibrated such that each 1/3 octave band between 20 and 120 Hz
is 10 dB higher than the equivalent 1/3 octave bands for any of the full-range
speakers, assuming that the full-range speaker is ideally flat. This level is read from a
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real-time analyzer (RTA), rather than a Sound Pressure Level (SPL) meter. If an RTA
is not available, an SPL meter may be used to approximate the level. When the level
is correct , most meters will read around 90–91 dB SPL C-weighted slow for the LFE
channel. The difference in level is because there is no energy being reproduced for
the frequencies above 120 Hz (80 Hz for consumer applications).
A properly calibrated room will result in mixes that will sound correct when played
back in a consumer environment. An improperly tuned room will result in mixes that
will sound fine in the mixing facility, but will be incorrect in other situations. Using
the guidelines above will result in a properly tuned room. The room alignment has
little to do with the release format. A discrete six-track mix or a Dolby Digital
encoded DVD will reproduce equally well when these guidelines are followed.
3.4
Level Calibration
It is important to have a properly calibrated audio monitoring system to ensure accurate
encoding and decoding. Proper calibration requires the use of an SPL meter and an
RTA to measure relative and specific playback levels (in decibels) of all six channels.
3.4.1
Playback Levels
Use an SPL meter and a Pink Noise Generator to set your system’s playback level to
a particular reference level.
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There are three options to adjust monitor system playback levels:
• Amplifier gain trim controls
• Mixer’s group outputs (one for each of the L, C, R, Ls, Rs, and Sw channels)
• Decoder output level trim controls
The best option is to use your amplifier gain controls to set proper playback levels.
This option allows you to maintain optimum signal-to-noise performance from the
decoder and console. Using either the group outputs from the console or the output
level trim controls on the decoder may sacrifice signal-to-noise ratio.
Pink noise readings depend on the type of meter used to set level (and, strictly
speaking, on the bandwidth of the pink noise signal). In film practice, pink noise level
is read with a true VU meter, or a meter display with a VU characteristic. If reference
level is specified as "0 VU," where "0 VU" corresponds to -20 dBFS for a digital
recording medium, then pink noise should be set to “0 VU” on the console meter or
meter display, and the SPL set accordingly.
Note: Many, if not most, modern consoles have peak-reading meters or meter
displays. Pink noise that reads at reference level using a true VU meter will read
from 8–12 dB higher on a peak reading meter or meter display. If your console has
switchable meter characteristics, be sure to select the "VU" mode when setting pink
noise levels.
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5.1-Channel Production Guidelines
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For film work, pink noise at reference level should produce a sound pressure level
(SPL) of 85 dBC for each of the front channels (left, center, and right). Each surround
channel should produce a sound pressure level of 82 dBC (the lower surround level is
specific to film-style mixing rooms).
For television work, pink noise at reference level is typically set to produce an SPL
ranging from 79 dBC to 82 dBC for each of the main five channels. The lower
reference level for television is due to the lower average listening levels used by the
consumer (typically 70–75 dBC). Since the reference listening level used can
dramatically effect the balance and intelligibility of the mix, it is important to
consider both the level at which a program was mixed, as well as the typical listening
level in the home for the same program.
For music mixing, each speaker channel should be set to the same SPL (the same as
television mixing). There is no standard practice for reference levels for music mixing.
Some engineers prefer to mix louder than others do, but if the levels between channels
are correct, the overall level is not as important. However, as stated previously,
consideration of the typical consumer listening level is always good practice.
When mixing for television or music in small mixing rooms (e.g., remote recording
trucks), the surround channel is generally set 2 dB lower than the front channels (for
example, 80 dB in front and 78 dB in back). This takes into account the short distance
to the surround speakers.
Experience has shown that this setting makes the sound in the home environment
very close to the sound heard by the mixer.
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5.1-Channel Production Guidelines
3.4.2
Production Environment
Sound Pressure Level Meter
To properly calibrate speaker levels, an SPL meter is necessary. A suitable and
relatively inexpensive meter is readily available from Radio Shack ® (Tandy
Electronics outside of North America). Since the relative level between channels is
more important than absolute level, the accuracy of this meter is sufficient for channel
balancing. For greater accuracy, more expensive meters may be used. It is
recommended that an inexpensive meter be left in the control room for quick level
checks. Note that this meter is not generally suitable for calibrating the LFE channel.
Please refer to the subwoofer calibration section.
3.4.3
Taking a First Measurement
1. Before you turn on the Pink Noise Generator, be sure that your playback system
has been set to a moderate listening level. Adjust your amplifiers, self-powered
speakers, or mixer only.
WARNING: BEWARE THAT IF THE PLAYBACK LEVEL IS VERY HIGH,
YOU MAY RISK DAMAGING YOUR SPEAKERS OR POSSIBLY EVEN YOUR
HEARING.
2. An internal test noise generator will typically cycle pink noise automatically
between the Left, Center, Right, Right Surround, and Left Surround channels—
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5.1-Channel Production Guidelines
3.
4.
5.
6.
3.4.4
Production Environment
remaining approximately two seconds at each output before moving on to the
next. If you do not hear pink noise in any of the five main channels as the noise
cycles through that channel, check your system connections and settings.
Ensure that you are sitting in your normal, proper reference listening or mixing
position. Set the SPL meter to “C” weighting and “slow” response.
Facing the front speakers, hold the SPL meter at chest level, with the microphone
facing up at an angle of approximately 45 degrees to the center speaker. Keep the
meter at arm’s length to prevent measuring audio that may reflect from your body.
You should be able to take SPL readings as you look down at the meter.
Keep the SPL meter in this position. Make sure that the meter is aimed at the
center speaker as you take readings for the left and right speakers.
When taking the SPL readings for the left surround or right surround speakers,
keep the meter at the same angle and position as you did for the front speakers.
Turn your body 90 degrees from the center speaker towards the wall closest to the
surround speaker you are measuring. This will minimize “shadowing” or
obscuring the meter with your body.
Bass Redirection
Prior to calibration, decide whether the monitoring system requires bass redirection of
low frequencies. Many decoders are capable of redirecting low-frequency information
below a selected frequency (typically 80, 100, or 120 Hz) to the channels capable of
reproducing them. This is similar to the normal/wide mode for the Center channel in a
consumer decoder with Dolby Surround Pro Logic.
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5.1-Channel Production Guidelines
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For example, if the monitoring system consists of five satellite speakers and a
subwoofer, redirect the low frequencies from the five main channels to the subwoofer
output. If using small Center and Surround speakers, direct the low frequencies from
those channels to the Left, Right, or subwoofer outputs. If no subwoofer is available,
redirect the LFE channel to the Left and Right channel outputs. Bass redirection can
be accomplished in either a Dolby Digital decoder or by using an external dedicated
bass management box.
3.4.5
Individual Level Calibration
There are typically two types of pink noise available for speaker/channel calibration:
pink and filtered. For setting relative levels, filtered noise is recommended, as any
room anomalies will not be factored into the level calibration process. For spectral
balance of each channel, pink noise is used with an RTA to adjust the system for
proper frequency response.
3.4.6
Subwoofer Calibration
Ideally, the test noise used for subwoofer calibration should be band-limited pink noise,
low-pass filtered at 120 Hz. To properly calibrate the subwoofer, an RTA is required. If
an RTA is not available, you can approximate the settings with an SPL meter.
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5.1-Channel Production Guidelines
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When using an RTA, proper calibration requires setting the LFE channel signal sent
to the subwoofer, within its typical bandwidth of 25–120 Hz, 10 dB higher than the
main channels. Refer to Figure 3-5.
+10 dB datum
LFE Channel
+10 dB
0 dB datum
Center channel
25 Hz
120 Hz
2 kHz
Figure 3-5 Real-Time Analyzer (RTA) Display
If an RTA is not available, setting the LFE channel higher (e.g., ~ 90 to 91 dBc for the
subwoofer channel when the Center channel measures 85 dBc), can give an approximate
level with an SPL meter. This level varies with the quality of the meter being used.
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5.1-Channel Production Guidelines
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For future reference, if calibrating the subwoofer with an RTA, measure the level
with an SPL meter and note the meter reading for the proper calibration. Use this
measured value for quick checks of the system calibration in the future.
3.5
Signal Delay
In addition to setting the proper monitoring levels, it is important that the sound from
each speaker arrives at the listening position at the correct time.
In an ideal room setup, the five main speakers would be equidistant from the mixing
position. In this case, the listener would hear common sounds emanating from two or
more speakers at the same time. If the speakers are not and cannot be equidistant,
signal delay will be required to achieve the intended result. The speaker position
furthest from the listener determines which of the remaining speakers will require
signal delay. Relative delay times are derived from the difference in distance between
the furthest speaker and each individual speaker. The required delay time is
approximately 1 ms per foot or 3 ms per meter. With proper compensation, the entire
system should exhibit coincident signal arrival at the primary listening position.
To achieve this, the delay times of the Center and Surround channels may need to be
adjusted. Channel delay is determined by calculating the distances from each speaker
to the listener, as seen in Figure 3-6.
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5.1-Channel Production Guidelines
Production Environment
C
L
R
Dim C
Dim L
Dim R
Dim LS
Dim RS
LS
RS
Dim signifies distance
Figure 3-6 Speaker-to-Listener Distances
Since Dolby Digital is a discrete system, there is no crosstalk between channels.
Although related, the delay times required for Dolby Digital are different from those
required for Dolby Surround.
In decoders, Surround delays may be set up separately for Dolby Surround and Dolby
Digital, with the Center channel delay time being the same for both modes.
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5.1-Channel Production Guidelines
3.5.1
Production Environment
Surround Delay for Dolby Digital
Determining channel delays for Dolby Digital is similar in concept to those for Dolby
Surround Pro Logic, with important additional considerations. Since Dolby Digital
delivers discrete signals for each channel, there is no leakage or crosstalk between
channels. There is, therefore, no need to delay the Surround channels to take advantage
of the Haas effect (precedence effect, which states that if two similar sounds arrive at
our ears at slightly different times, the brain tends to focus on the sound arriving first
and ignore the second). Dolby Surround takes advantage of this effect to reduce the
perceived crosstalk between the front and rear channels. A signal arrival difference of
10–20 ms is adequate to make the Haas effect work. The Surround and front channel
signals should arrive at the listening position at the same time (coincident arrival).
Consequently, the Dolby Digital mode uses approximately 15 ms less delay than the
Dolby Surround Pro Logic mode for the same speaker/seating arrangement.
To calculate the Surround delay for Dolby Digital, measure the distance from the
listening position to each of the three speakers:
•
•
•
Left speaker (L) or Right speaker (R)
Center speaker (C)
Nearest Surround speaker (LS or RS)
All of these measurements must be made in feet. If measuring in meters, multiply the
metric measurements by three to get the approximate equivalent in feet. Once these
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5.1-Channel Production Guidelines
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two measurements have been made, calculate the required delay settings for the room.
Use the following formula to calculate the delays.
(Distance from L) – (Distance from S) = Surround delay for Dolby Digital
L = Left or Right speaker
S = Left Surround or Right Surround speaker
In the example below, the listening position is 15 feet from the Left (or Right)
speaker and 10 feet from the Surround speakers, so the delay setting for the Surround
channels is five milliseconds for Dolby Digital. This is the correct delay in
milliseconds to program into the decoder.
15 (number of feet from L) – 10 (number of feet from S) = 5 (Surround delay for
Dolby Digital, in milliseconds)
3.5.2
Center Channel Delay
The concept of coincident arrival can also be applied to the adjustment of the Center
channel in Dolby Digital. No delay is required if the Center speaker can be placed at
the same distance from the listener as the Left and Right speakers (in an arc). Thus,
distance C = distance L or R. If the Center speaker is placed closer to or farther from
the listening position than the Left and Right speakers, delay can be added to the
Center channel signal to bring it into acoustic alignment with the Left and Right
speakers. This will electronically move the speaker to its proper position in the room.
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For example, if distance C is two feet less than distance L or R, Center delay is set to
2 ms. If distance C is two feet more than distance L or R, Center delay is set to -2 ms.
To make the Center delay negative, the decoder actually sets C delay to zero and adds
delay to the Left, Right, Left Surround, and Right Surround outputs of up to 3 ms. This
ensures coincident arrival of the Surround and front channel signals.
3.5.3
Compatibility with Dolby Surround Monitoring
When monitoring Dolby Surround signals, a decoder adds additional delay (typically
15 ms) to the Surround channel output. When using a Dolby SDU4 or Dolby DP562
for Dolby Surround decoding, the minimum delay setting for these units will allow
them to be used with 5.1-channel monitoring systems.
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Chapter 4
Equipment
Much of the equipment used for stereo and Dolby Surround production can also be
used for 5.1-channel production. There are, however, some needs specific to 5.1channel production.
4.1
Consoles
When deciding on a console, it is wise to consider both current project demands and
future 5.1-channel production needs. The requirements of 5.1-channel mixing
consoles differ significantly from those of two-channel stereo. Fortunately, with the
increasing flexibility of analog and digital consoles there are now many options for
surround mixing. Film-style four-bus (Left, Right, Center, and Surround) consoles
have been in production for many years. The fundamental requirement, however, of a
5.1-channel mixing console is a minimum of six discrete output buses (Left, Center,
Right, Left Surround, Right Surround, and LFE) per input/output channel. As with
four-channel production, the six-bus console must also provide a means of panning
audio. A console with film-style panning between the five main channels (Left,
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5.1-Channel Production Guidelines
Equipment
Center, Right, Left Surround, and Right Surround) and routing to an LFE channel will
offer the greatest flexibility of sound placement in the surround field. While most
manufacturers provide channel bus and pan features within the console, third-party
developers have created add-on outboard devices with mixing controls to properly
route multichannel audio for 5.1-channel mixes. In addition, whether onboard or
third-party, console parameter automation is an asset when completing complex
multichannel mixes.
Analog mixing consoles with six bus outputs and automation can offer a capable
solution for multichannel mixing. However, since 5.1-channel audio is delivered in
the digital domain, using an analog mixing console requires an additional analog-todigital conversion stage.
In contrast, digital mixing consoles offer a direct path to today’s multichannel
delivery systems. Many digital consoles provide format conversion and internal
signal processing. This all-in-one design delivers greater efficiency and flexibility
during production. Be aware though, that unwanted signal delays created by linking
and chaining digital effects in digital audio consoles can cause timing errors between
output channels. For instance, Left and Right audio channels may be configured to
pass with relatively little processing along their signal paths. If the Center channel
signal were to undergo processing using digital EQ, dynamic compression, etc., a
measurable output signal delay would occur between the Center and Left/Right
channels. Acknowledging this, digital console designers and manufacturers have
created a variety of solutions to these timing problems.
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5.1-Channel Production Guidelines
4.1.1
Equipment
Small Format Console
There has been an explosion of small professional consoles with enough buses to
handle 5.1 mixing. While the implementation of multi-bus panning may be different,
the functionality and setup of analog consoles and the newer consumer digital
consoles are basically the same. Instead of panning in stereo, consoles with four or
more auxiliary sends (in addition to the stereo bus prefader) can be used to place
sounds anywhere in the 5.1-channel soundfield.
The semi-professional eight-bus analog consoles on the market today do not include
surround panners or built-in master surround panners. Panning between buses on
these consoles usually entails using auxiliary sends. There are also excellent
retrofitting solutions available such as PicMix from Otari, (www.otari.com) and the
OPS-1 Surround Sound Panner from Omnisound (www.omnisound.com). These
panning systems include all the features of a large format surround sound console
using external rack-mounted systems and joystick panners.
Currently, there are several excellent small digital consoles on the market from
Tascam, Yamaha, Ramsa, Mackie, and others. These consoles handle five-channel
panning in different ways, with different features on the various models. Key features
of some of these consoles include:
Yamaha (Current models are 02R and 03D)
1. Center mix level–allows adjustable panning through the center channel.
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5.1-Channel Production Guidelines
Equipment
2. Surround pattern editor–allows the path of the surround pan to be changed. Select
the size and shape of a circle, arc, or line.
3. Jog wheel speed manipulation–allows use of the wheel to change the speed of a pan.
4. Multiple surround formats: 2+2, 3+1, 3+2+1.
5. Master fader can be made into six-channel ganged fader.
6. Software editing available.
Tascam (Current models TMD8000 and TMD4000)
1. Divergence control on L/R and F/S–use these controls to focus or spread the
sound by controlling the bleed to adjacent channels during a pan.
2. Surround Bus Assignment–in 5.1 mode, set this to Type 4 to comply with current
L, R, C, LFE, LS, RS assignments.
3. LFE level–controls the amount of signal going into the LFE channel. This also
may be set to Off.
Mackie (Current Model D8B)
1. Surround Bus Isolation–Surround buses 1–8 are automatically solo-isolated so
that they are not muted when any (surround-pan enabled) channel is in solo mode.
2. Software control includes morph function that can interpolate between an a and b
point (currently a straight line).
3. On-screen editing of surround panning with Mackie OS2 Ramsa (Panasonic)
(Current Model WR-DA7).
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5.1-Channel Production Guidelines
Equipment
4. Surround pattern editor–allows the path of the surround pan to be changed. Select
the size and shape of a circle, arc, or line.
5. Copy control of surround pans between channels.
6. Jog wheel speed manipulation–allows use of the wheel to change the speed of a pan.
7. Software editing available.
Each of these console types puts the surround mix through either the output bus path, or,
in some cases, through auxiliary bus paths without separate multichannel monitoring
paths. This means that to have constant levels to the multitrack recorder as well as
adjustable monitoring volume, it is necessary to bring the outputs of the multitrack back
onto six grouped faders on the console and out a separate path to the amps and speakers.
For the monitor outputs, use either use auxiliary sends, or a separate I/O card.
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5.1-Channel Production Guidelines
Equipment
Line Inputs
Mixing
Console
Surround Section
Bus Outs
(Digital if Available)
Digital
Multitrack
Auxiliary
Bus Outs
Amps &
Speakers
Figure 4-1 Interconnect Example
In Figure 4-1, arrows refer to six-channel buses, and should be connected using the
following channel assignments, if possible: (1) Left, (2) Right, (3) Center, (4) LFE,
(5) Left Surround, and (6) Right Surround. Choice of mix outputs (Bus, Aux,
Monitor, etc.) will depend on the console.
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5.1-Channel Production Guidelines
4.1.2
Equipment
Digital Audio Workstations
Digital audio workstations (DAWs) can be employed to great effect for non-linear
editing and mixing of multichannel audio. Though the vast majority of systems
currently available are designed with stereo in mind, it is possible to use these
workstations for multichannel applications with the help of some simple workarounds.
The minimum requirement for mixing 5.1-channel audio is a stereo bus with four or
more auxiliary sends that can be used for discrete placement of audio elements.
Digital
Audio
Workstation
Stereo
Outs
Digital
Multitrack
Recorder
Aux
Outs
To Amps
/Speakers
Figure 4-2 Simple DAW Interconnect
Currently, there are numerous DAWs on the market from a wide range of manufacturers,
including Digidesign, Solid State Logic, Sonic Solutions, SaDie, Digital Audio Labs,
and Fairlight.
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5.1-Channel Production Guidelines
Equipment
Figure 4-3 Typical DAW with Multichannel Panner
Each of these workstations positions the surround mix through either the output bus
path or the auxiliary buses. These outputs are typically routed to a multichannel
digital mastering deck (e.g., ADAT or DA-88, etc.). However, in order to have
consistent levels feeding the multitrack recorder that do not affect your overall
monitoring/listening levels, it may be desirable to route the outputs of the multitrack
recorder back through another set of grouped input faders on the console and route
them to a separate set of output buses to your monitoring system. See Figure 4-4.
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5.1-Channel Production Guidelines
Equipment
Digital
Audio
Workstation
Console
Digital
Multitrack
Recorder
To Amps/
Speakers
Figure 4-4 Typical Digital Multichannel Audio Workstation Interconnect
4.1.3
Audio Processing Equipment
Audio processors can supplement fundamental sound design and enhance image
placement in 5.1-channel productions. Processors are available for every phase of
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production, from conception and recording to mastering and duplication. Factors to
consider when purchasing audio processors for multichannel production include
specifications and multichannel functionality.
Multichannel processors are being developed to accommodate the production
demands of film, music, and broadcast. Products that offer true multichannel
processing and feature sets (e.g., signal alignment and channel linking options) will
become increasingly important as multichannel production grows.
4.1.4
Routing/Switching
Routing and switching multichannel material builds on the techniques used in mono
and stereo productions. The majority of audio signal routing during production will
be done to mono sources through the bus assignment functions of the audio console.
Stereo sources can also be routed via the bus assignments, either as grouped stereo or
split mono signals depending on the particular console. Switching multichannel
programs requires multichannel group functionality. To provide the adequate
resources for additional channels of material in both the production and mastering
stages of audio creation, both routing and switching capabilities will need to be
expanded from existing mono or stereo configurations.
For additional information on multichannel routing and switching as it applies to
broadcast production and delivery, please refer to the Dolby Digital Broadcast
Implementations Guidelines available on the Dolby website, www.dolby.com.
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5.1-Channel Production Guidelines
4.2
Equipment
Recorder/Storage
The evolution of non-linear multitrack digital audio recording and editing have made
multichannel production for 5.1 commercial releases attainable by a large community
of audio production engineers. While conceptualizing a multichannel project of
whatever media type (digital audio workstations or modular digital audio recorders),
in both recording and mixing a multichannel audio project it is important to budget
the appropriate amount of audio tracks. An audio track may not be limited to fixed
audio tape tracks, but rather may be in reference to hard disk space or RAM. For a
5.1-channel audio mixdown, a good starting point is allocating six to eight tracks of
audio (or corresponding disk space and/or RAM) for the final delivery tracks at the
appropriate bit resolution and sampling rate. For work pertaining to DVD video, it is
important to remember the 48-kHz sampling rate for the relationship to video. When
audio is used with a visual application such as laser disc, time code is also required.
Please review Section 6.4, Time Code for more information on time code as it applies
to production.
Common audio formats currently being used include those of digital audio
workstations such as Digidesign’s ProTools, Studio Audio’s SaDie, Digital Audio
Labs V8 with Minnetonka’s MX51, as well as modular digital audio recorders such as
Tascam’s DA88/DA98, Alesis’ ADAT, and Fairlight’s Digital Audio Dubber. While
new media formats continue to be introduced into the market, the most common
current delivery is on eight-track modular digital multitrack tape such as the Tascam
DA88 format. Frequently, times-two mixes will exist on the same delivery medium to
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Equipment
support both a discrete 5.1-channel mix, as well as a matrix-encoded Dolby Surround
(Lt, Rt) on the remaining two tracks of the eight-track media.
For more information on documentation for mixing and mastering, please review the
material in Chapter 6.
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Chapter 5
Production Techniques
Many traditional two-channel techniques are applicable to 5.1-channel production.
Nonetheless, there is an opportunity to create more convincing and engaging listening
experiences.
5.1
Microphone Techniques
Prior to beginning a 5.1-channel production, consider the type and size of the
environment to be created. A variety of close, distant, coincident, and spaced
microphone techniques can be used to produce a natural-sounding environment.
Processing such as artificial delay and reverb may also be used to enhance the
listening experience or compensate for compromises made during the recording.
Sources can be recorded individually, with or without spatial information, for
placement at any point in the 5.1-channel soundfield during mixing. Carefully
combining microphone technique, processing, and mixing allows one to place the
listener almost anywhere in the desired setting. Although the listener’s perspective
will most often be the same as that of an audience member, numerous possibilities
exist for both realistic and unrealistic environments.
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5.1-Channel Production Guidelines
5.2
Production Techniques
Recording
Multitrack audio recording technology has undergone great advancements in recent
decades. Today, audio professionals have an increasing number of options for
recording, editing, and delivering content. The specific allocation of tracks for a 5.1channel production depends on the project and the mix. If the final product will have
no panning movement, such as documenting an acoustic performance, one might
simply allot separate tracks for stereo surround ambience. If directional surround
placement of prominent elements is desired, more preproduction and additional tracks
may be necessary.
It is important to remember that in 5.1-channel audio, the multichannel source
delivery master requires three times the amount of data storage as required in stereo
production. Regardless of the type of multichannel project, reserve adequate hard
drive space or linear tracks for additional channel content.
Refer to Chapter 6 for information on correct formatting and track layout.
5.3
Mixing
With the addition of the Center, Surround, and LFE channels, 5.1-channel mixing
presents both interesting choices and unique challenges not present with traditional
stereo.
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5.1-Channel Production Guidelines
5.3.1
Production Techniques
Center/Front Channels
In a stereo program there is only one way to obtain a centrally placed sound image: mix
the signal equally to the L/R channels. In a multichannel system, there are three ways:
• Create a phantom center just as with stereo.
• Use the center channel alone.
• Use all three front channels equally or in varied proportion.
Each approach offers advantages and drawbacks. In use since stereo began, the
phantom center is well understood. The primary disadvantage of this technique is that
the listener must be equidistant from the L/R speakers to achieve proper center
imaging. This is rarely the case in the home, and is nearly impossible in a car.
Another disadvantage is that due to cross-cancellation effects, the timbre is not the
same as from a direct speaker source.
Using the center speaker alone creates a stable center image for every listener no
matter where they sit. To prevent the image from sounding too focused or narrow,
reverb from the center channel can be spread to the L/R channels.
Distributing the center image amongst the three front speakers allows control of the
range of spatial depth and width. A phantom center can be reinforced by some
additional signal in the center channel, or a center channel signal can be enhanced
with some additional signal spread into the L/R pair. The more channels that are used
to carry the same signal, however, the more likely it is that side effects may occur.
5-3
5.1-Channel Production Guidelines
Production Techniques
Signals might interact with each other causing the phantom image to conflict with the
true center image. In systems using dissimilar speakers, or in cases where the listeners
are seated off the central axis, the sound arrivals from all three speakers may not
blend well. Differences in arrival time can cause a comb-filtering effect, shifts in
tonal color, or a smearing of the image. Consider all of these effects when placing the
exact same signal in all three front channels. To counteract these effects, process the
additional signals first to change their spatial character, timbre, or prominence
relative to the main center signal.
5.3.2
Surround Channels
Whereas center-image signals were always part of mixing for stereo, surround
channels offer a completely new sonic dimension to consider. Using stereo surrounds
is already well established in the film industry; however there is still room for
experimentation in the music, multimedia, and broadcast industries. It can certainly
be said that the use of surround channels can enhance the sense of depth and space
over conventional stereo.
For example, the ambience and room reflections of a concert hall delivered from the
surround speakers can drastically change the listener's perspective. Imagine the
difference between peering through a window and sitting in a concert hall. Popular
music can often benefit as well from a creative use of the surrounds, whether with
background singers, instruments, or effects. But as with any new tool or effect, it can
be overdone and become tiresome if used to excess. The principle that has served the
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5.1-Channel Production Guidelines
Production Techniques
film industry so well also applies to multichannel mixing: Use the surround channels
to enhance rather than distract from the overall experience.
5.3.3
LFE Channel
What is the difference between the LFE channel and the subwoofer signal? The LFE
channel is a separate, limited frequency bandwidth signal created by the mixing
engineer and delivered alongside the main channels in the mix.
The subwoofer signal is created in the decoder as needed for the particular speaker
complement in use, using crossover filters. This signal is created using bass
management, and all Dolby Digital decoders perform this function. Through bass
management, a subwoofer signal may comprise bass from any channel or
combination of channelstypically bass frequencies from channels being replayed
on small speakers are directed to the subwoofer speaker. If no subwoofer is present,
the bass (including the LFE channel, if it exists) is redirected to the speaker(s) best
able to reproduce it, usually the main stereo pair.
Even though an eighth-order, 120-Hz brickwall filter can be applied to the LFE
channel by a Dolby Digital encoder, a low-pass filter must be inserted into the LFE
signal path during the mix process to ensure proper monitoring. Furthermore, the
filter must be applied to the signal being recorded so that the results will be
consistent, whether delivered by Dolby Digital or Linear PCM. A maximum cutoff of
80 Hz is suggested when using a typical filter with a gradual slope as compared to the
steep, low-pass filter in a Dolby Digital encoder.
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5.1-Channel Production Guidelines
Production Techniques
In theatres, the LFE channel is used in conjunction with subwoofers to supplement
the capabilities of the screen speakers. In most music productions, it is unlikely there
will be a technical need to use the LFE channel. Since the overall program level may
be adjusted to render any proportion of bass perfectly, the LFE channel might be an
advantage only in situations similar to the famous cannon shots in Tchaikovsky’s
1812 Overture. In such a case, the overall program level might have to be reduced
several dB just so the last few minutes can make the desired impact without overload.
By using the LFE channel, the orchestra can be recorded at a normal level, with some
of the loudest, deepest bass of the cannons carried in the LFE channel. Of course, the
main channels will still carry the cannon shots so that they will be heard from the
appropriate locations and in a downmix.
Another benefit to using the LFE channel when carrying explosive bass signals is that
smaller stereo systems may not be able to handle such high levels of deep bass without
significant stress. Since the Dolby Digital downmix process discards the LFE signal,
these low-frequency signals will not present any difficulty for these smaller systems.
The remaining portions of the bass frequencies delivered by the main channels will
convey the essential aspects of the performance when listening to the downmix.
While it may be of no particular consequence for effects, filters like those used in
generating the LFE signal may interfere with the ability to seamlessly blend the LFE
channel with the other channels. The best way to ensure a cohesive audio signal across
the entire audible spectrum is to maintain its integrity in the main channel(s).
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5.1-Channel Production Guidelines
5.3.4
Production Techniques
Downmix - Dolby Surround Compatibility
Always check the downmix for Dolby Surround compatibility. Dolby Surround is
comprised of mono surround information; therefore stereo surround information in
the 5.1-channel mix will be summed and reduced in level to become compatible in
the Dolby Surround downmix. While the LFE channel is used primarily for
supplemental high impact effects (e.g., explosions, crashes, storms, aerial fly-overs,
etc.), delivering crucial low-frequency material exclusively in the LFE channel will
produce a Dolby Surround downmix lacking in low-frequency content.
When the 5.1-channel mix is completed, it is often compared with the Dolby
Surround mix, if one exists. Several audible differences may be noticed.
• The panning and location of elements within the mix may have changed. Because
the 5.1-channel mix is discrete, positioning of elements is easier than through the
Dolby Surround matrix.
• Center channel buildup will not be present in the 5.1-channel mix. Mono sounds
in the Left and Right channels will stay there, and not appear in the center.
• The 5.1-channel mix increases the potential acoustical dynamic range since there
are now five full-range channels instead of two.
• In the 5.1-channel mix the frequency bandwidth of the Surround channel is now
full-range, not limited as with Dolby Surround. Also, there are now two Surround
channels, not one (stereo, not mono).
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5.1-Channel Production Guidelines
Production Techniques
If the possibility of delivering the original Lt/Rt exists, this is the preferred method. If
it is not possible, then mix compromises may be necessary to compensate for
unwanted artifacts caused by the downmix process.
5.3.5
Downmix-Stereo Compatibility
Even with the popularity of Dolby Digital and Dolby Surround systems, there will
always be a need to address stereo reproduction. There are three basic ways to
accomplish this.
• Prepare a new stereo mix from the original multitrack elements.
• Prepare a studio-adjusted downmix from the multichannel mix.
• Let the decoder derive a stereo downmix.
Created from Multitrack Elements
This option is no different from today's conventional stereo mixing sessions. The stereo
mix is carried as PCM or as a separate two-channel Dolby Digital bitstream.
Created from a Multichannel Mix
The second option takes advantage of all the work that has gone into the mixing of
the 5.1-channel version, and allows the mixing engineer to quickly derive a stereo
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5.1-Channel Production Guidelines
Production Techniques
version while retaining flexibility in the exact proportions of each channel
represented in the final stereo mix.
Created by Decoder
This option does not create a separate mix. In this case, the decoder derives a stereo
downmix based on preset formulas. When applicable, consumer decoders will apply
dynamic range reduction during the downmix process to prevent overload. All
downmix and dynamic range control options can be previewed in the production
studio. A range of adjustments is possible and the resultant effect can be checked in
advance. For additional information on the downmix process in the decoder, please
refer to the Dolby Digital Professional Encoding Manual.
5.3.6
Upmixing
Upmixing describes the process where additional new channels of audio information
are created from an original soundtrack, for example making a 5.1-channel version
from a stereo master.
The term “5.1” has strong appeal to many people. Consumers and professionals alike
can sometimes be drawn by the idea that a soundtrack available in 5.1 is somehow
better than a stereo or mono soundtrack. However, there are many instances where
this may not be true. For example, an old black-and-white movie may sound
incongruous with a 5.1 soundtrack, and mono may be the better format in this case.
Conversely, there are instances where there is a legitimate need for a multichannel
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5.1-Channel Production Guidelines
Production Techniques
version when the master is not available in the 5.1 format. The question is how to deal
with this latter situation.
The most obvious and best solution is the remix. If original elements such as a multitrack
source tape or individual stems have been archived, then this could provide the source
material to create a new 5.1 version. Of course the original mix should be given due
consideration, preferably by enlisting the help of the original artist or producer.
A difficulty arises when these elements do not exist and the only source material is
the final release master. There is much debate about how best to upmix to create extra
channels from a given source. Most approaches rely on the use of phase relationships
or timing between signals, based on the simple idea that in-phase material should go
to the center channel and out-of-phase material should go to surrounds. See below for
a discussion of some of the benefits and consequences of upmixing using this method.
Two-Track Master
It is usually best to transmit two-channel material, be it matrix-encoded or
conventional stereo, to the consumer in its existing two-channel format, rather than
decoding it in the studio to derive an artificial discrete multichannel mix. The results
of upmixing will vary from the intent of the original producer/director, especially in
the case where extra processing has been added on top of surround decoding in the
studio, perhaps to generate an LFE channel or stereo surrounds. Consequently, the
sound may fail to meet listener expectations for true 5.1-channel material. Upmixing
in this way can never create a truly discrete mix and the effects of the upmixing
system will always be audible.
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5.1-Channel Production Guidelines
Production Techniques
In addition, many consumers do not yet have a full 5.1-channel Dolby Digital
playback system, and instead connect their DTV set-top boxes' and DVD players'
two-channel outputs to a stereo or Dolby Surround Pro Logic system. Under these
conditions, the multichannel soundtracks will be downmixed to mono, stereo, or
Dolby Surround matrix-encoded stereo. If the multichannel soundtrack was derived
by phase decoding and upmixing a two-track master, there may be downmix quality
problems due to signal addition and cancellation as the various channels are
combined in the downmixing process. Decoding the downmixed 5.1 content with
Dolby Surround Pro Logic will make these problems even more obvious. In nearly
every case, the original stereo or Dolby Surround mix will give the best results. If
upmixing is absolutely necessary, it is best to use a decoding system without matrix
steering or even a simple Hafler matrix. Any steering logic, including that used by
Dolby Pro Logic, adds some degree of image instability that is unwelcome,
particularly for pure music applications. When using a decoder to upmix, it is
important to turn off any surround channel time delays as they can introduce
problems when the sound track is downmixed.
Sometimes additional processing is used on top of the surround decoding in the
studio, perhaps to generate an LFE channel or stereo surrounds. When this is done,
the sound may fail to meet the listener’s expectations for true 5.1-channel material;
upmixing in this way can never create a truly discrete mix and the effects of the
upmixing system will always be audible.
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5.1-Channel Production Guidelines
Production Techniques
Other Formats
Dolby analog, or Dolby Stereo matrix-encoded film soundtracks were originally
produced from discrete four-track master tapes. While the four tracks on these
masters corresponded to L, C, R, and S, during the matrix-encoding process the
results were monitored through a matrix decoder (4:2:4 monitoring) to anticipate
what would actually be heard in the cinema. The final sound heard in the cinema,
therefore, can be quite different from that of the four channels played discretely, due
to the matrix encoding and decoding. It is therefore a good idea to compare the
discrete four-track mix to the decoded Lt/Rt mix, and adjust accordingly.
Alternatively, you may simply use a Dolby Surround matrix encoder to create a
surround-encoded two-channel mix for DTV or DVD from the four-channel master,
and flag the bitstream as matrix surround-encoded.
A few films were released in a six-track format based on magnetic tracks recorded on
70 mm film. These masters require special consideration; for example, there were two
different channel configurations available to filmmakers. They first used the
conventional LCRS channels and added both Left-Extra and Right-Extra channels to
convey extra low-frequency information. The other format had a channel
identification similar to the 5.1 seen today.
5.3.7
Translation to Consumer Systems
One of the most important considerations when dealing with multichannel audio is
the translation to the final listening environment. Everyone is familiar with the
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5.1-Channel Production Guidelines
Production Techniques
requirements for mono compatibility in stereo mixes; taking this one stage further,
thought must be given to how our track will sound in stereo, mono and Dolby Pro
Logic, as well as 5.1. Specific attention must also be paid to the available options in
dynamic range settings accessible to listeners. The key tool in the checking process
will be the professional decoder, as it can mimic all of the possible listening
configurations quickly and easily. All of the methods used today to check the mix in a
variety of situations are as relevant with Dolby Digital as they are with conventional
stereo work. Taking a copy home, listening in the car, or on a small speaker to mimic
the sound of radio receivers is crucial. It may also be worth considering the
installation of a small consumer-style surround system in the mixing room for quick
and easy compatibility checks.
5.3.8
Production Tips
1. More discrete sources available for the mix will result in more control of the
soundfield creation. Record as many discrete sources as possible.
2. Echo and reverb effects may need to be rethought for 5.1 mixes. In particular,
elements present in the center channel which have echo or reverb effects added
will usually require some of the effect to be present in the center channel for a
more natural sound. Failure to include the effects for a vocal track in the center
channel will usually produce a naked sounding vocal. There is much debate over
this matter and probably will be for some time.
3. Remember that some listeners will hear a downmix of the 5.1-channel mix. It may
be decoded with a Dolby Surround Pro Logic decoder or heard in stereo. It is
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5.1-Channel Production Guidelines
Production Techniques
important to check the downmixes and to listen for center channel buildup or
unwanted surround information from the Pro Logic decoding process. Some effects
that work well to create a 5.1 mix do not work with Pro Logic decoding. The 5.1channel system is discrete, i.e., where a sound is put is where it will stay.
4. Never decode a Dolby Surround track to make it discrete. The resulting track will
not properly downmix for the consumer. Use the Dolby Digital 2/0 mode with the
surround flag set to ON instead.
5. Remember that listeners prefer natural soundfields. Sometimes effects that sound
exciting at first can become distracting or tedious with repeated listening.
6. Be sure to document calibration levels, mixing levels, and other small, but
important, information for later reference. The 3-dB difference in surround level
between film-style rooms and video-style rooms will have a big impact on the
mix when set wrong during the encoding process (see 6.2 for more information).
Several projects have gone into production with improper surround levels,
resulting in questionable mixes and element balances.
5-14
5.1-Channel Production Guidelines
Chapter 6
Preparing the Source Delivery Master
When preparing the source delivery master, adhere to accepted standards and
practices to ensure proper Dolby Digital encoding.
One of the most common source delivery formats for Dolby Digital encoding is the
Hi-8 mm tape used in many popular Modular Digital Multitracks (MDMs). Digital
Audio Workstations (DAWs), open reel digital multitracks, and other formats are also
used for this application, although infrequently.
6.1
Channel-to-Track Allocation
Whenever possible, Dolby encourages the adoption of channel-to-track allocation
described in the forthcoming ITU-R recommendation, Parameters for Multichannel
Sound Recording. Track layouts depend on channel complement, although tracks 1, 2,
and 3 are always channels Left (L), Right (R), and Center (C) respectively. Table 6-1
shows one possible configuration. Since inclusion of the LFE channel is optional and
the listener determines its reproduction from a decoder, essential low frequency
information should not be mixed exclusively to the LFE channel. When the LFE
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5.1-Channel Production Guidelines
Preparing the Source Delivery Master
channel is not used, track 4 may contain a mono Surround (S) signal. Alternative
practices exist within various industries, so it is imperative to check the source and
accompanying documentation.
Table 6-1 Channel-to-Track Layout Example
Channel
Track
6.2
L
1
R
2
C
3
LFE
4
LS
5
RS
6
Lt
7
Rt
8
Channel Levels
Relative channel levels should assume each speaker delivers identical acoustic sound
pressure levels to the listener, excluding the LFE channel which is intended for
reproduction at +10 dB SPL (with respect to the main channels within the same 3–
120 Hz passband). Assuming that a Surround (S) signal is delivered to a single
speaker and two Surround signals (LS, RS) are each delivered to individual speakers,
Surround levels should be identical to the front channels.
In film sound practice, stereo Surround channel levels are typically recorded +3 dB
relative to the front channels. This is done to compensate for the -3 dB Surround
levels (relative to the front channels) encountered in cinema monitor systems. In such
cases, select the 3 dB Attenuation option for the LS and RS channels in the Dolby
Digital encoder.
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5.1-Channel Production Guidelines
Preparing the Source Delivery Master
When the Surround channel is mono, allocate it to both tracks 5 and 6 with 3 dB
attenuation applied to each signal. Use the following formula:
Track 5 = Track 6 = 0.707 * S
Follow this recommendation even when track 4 also contains the S signal, which
should always be at normal level on this track. Indicate on the tape label clearly that
tracks 5 and 6 each contain the S signal at -3 dB relative to their normal levels.
6.3
Reference Levels
The standard reference level is -20 dBFS for digital recorders (0 VU for analog
recorders). This level is typically +4 dBu from professional consoles and -10 dBV
from semi-professional consoles. When transferring from 35 mm magnetic film
(analog), attenuation and/or peak limiting may be needed to avoid digital clipping. If
used, these processes will affect what value is selected for the Dolby Digital Dialog
Normalization parameter setting during encoding and will require complementary
gain recovery in the reproduction chain.
A 30-second, 1-kHz alignment signal at -20 dBFS should appear on all channels at
the beginning of the source delivery master prior to program start. The finished
master should contain at least 30 seconds of digital black after the alignment signal
and before each subsequent program. Each title should begin with at least two
seconds of encoded digital black.
6-3
5.1-Channel Production Guidelines
6.4
Preparing the Source Delivery Master
Time Code
Time code plays two important roles in preparing mixes for Dolby Digital encoding.
First, it is common to use some form of SMPTE or MIDI time code for synchronizing
recording machines (DA88, ADAT) and digital editors (Pro Tools or MIDI
sequencing program) while recording and mixing material. It is important to be aware
at the beginning of a project what the final time code delivery format will be.
Working in that format will save time later and prevent possible errors in frame rate
and synchronization. This is especially true when working with video. Even with the
introduction of high-definition video formats worldwide, varying frame rates and
time code modes (including drop-frame) will be around for some time to come.
Second, if the material is going to be encoded using Dolby Digital for either DVD or
Digital Television, it might be necessary to add a time code stamp to the Dolby
Digital bitstream at the time of encoding. This is done by sending the time code from
the source material into the Dolby Digital encoder Time Code input and selecting
Enable Time Stamp from the setup section of the Dolby Digital encoder. Dolby
Digital has the ability to add a time code stamp to the associated Dolby Digital frame.
This stamp can be used to align the Dolby Digital audio file with a compressed video
file containing a corresponding time code stamp. This process can be done with either
a DVD-authoring station or DTV encoder.
Having the correct time code that matches the picture is essential to proper audio and
video synchronization. In addition, it is also very important that the time code source
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5.1-Channel Production Guidelines
Preparing the Source Delivery Master
feeding the Dolby Digital encoder be stable and uninterrupted. Always use the time code
generated from a digital source such as a DA88 or digital VTR. If unsure of the time code
source, it is best to generate clean time code from a synchronizer or use a quality time
code regenerator before routing the time code into the Dolby Digital encoder.
6.5
Documentation
Complete, clear, and accurate documentation should always accompany the source
delivery master used for Dolby Digital encoding. This information is important not
only when the master is in use but also as a reference, once it is archived. Dolby has
created Mix Data and Mastering Information Sheets to facilitate proper documentation
or to use as a guide for creating similar documents. These sheets are available in
Appendix A of this document and on the Dolby website under the Technical
Information heading at www.dolby.com. The Mix Data Sheet provides concise
information about the source media to all the engineers on a project. Typically, it will
include information on sampling frequency, bit resolution, time code, track assignment,
titles, and program start and stop times. The Mastering Information Sheet provides
documentation relevant to the mastering engineer or authoring facility on source media,
timing, and encoder settings, as well as general notes.
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5.1-Channel Production Guidelines
6.5.1
Preparing the Source Delivery Master
Mix Data Sheet
The purpose of a Mix Data Sheet, Appendix A is to provide all production engineers
with thorough and concise media layout information.
The information contained in the Mix Data Sheet should be distributed for technical
parameters prior to encoding for final delivery, i.e., in production or postproduction
PRIOR to the output distribution (DVD or Digital Broadcast). An important point to
note is that all mix data information should be duplicated and should be placed on the
master media as well. While size of the recording and production media may be on a
smaller scale, accurate labeling of the media with Mix Data Sheet information will
provide additional engineers with the proper insight of origin.
6.5.2
Mastering Information Sheet
The purpose of a Mastering Information Sheet, Appendix A, is to provide the
mastering engineer or the digital authoring specialist technical information with
respect to media layout, timing information, and encoder-specific information.
This information is created during authoring/creation of the final delivery medium,
e.g., Dolby Digital encoding of an AC-3 stream for a movie on DVD.
Additional documentation such as production notes will be invaluable in completing a
project. The purpose of Notes is to provide engineers with any explanation for key
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5.1-Channel Production Guidelines
Preparing the Source Delivery Master
actions with relationship to time, level, error, or artistic consideration. In addition to
hard copy, all documentation should be duplicated and affixed to the delivery media.
6-7
5.1-Channel Production Guidelines
Chapter 7
Miscellaneous Information
7.1
Technical Assistance
Dolby Laboratories provides technical support to content creators and encoder users
in a variety of ways. Many technical documents are available for viewing or
downloading on the Dolby website at www.dolby.com. Printed copies of documents
may also be obtained by sending an email request to info@dolby.com with a
description of the desired documents, and a complete mailing address.
Dolby has a staff of engineers who can assist with soundtrack production, encoding,
and trademark usage questions. Dolby engineers are also available to provide on-site
assistance with room configuration and calibration, soundtrack production, and
encoding. Telephone support is available free of charge, and local on-site support can
often be provided without cost. However, in situations where extensive on-site
support or long distance travel is required, standard engineering rates may apply.
For technical support, please contact the nearest Dolby office at any of the locations
listed on page ii of this document.
7-1
5.1-Channel Production Guidelines
7.2
Miscellaneous Information
Contacting Dolby Laboratories
In addition to its headquarters in San Francisco, Dolby has several other offices around
the world. All offices can provide information on soundtrack production and encoding.
Contact Dolby from anywhere in the world via the following e-mail addresses:
Address
Use to --
apply for a Dolby trademark agreement (TSA).
ask questions on HDTV audio production, encoding, and
hdtv@dolby.com
implementation issues.
ask questions about TV broadcast audio technologies,
tvaudio@dolby.com
equipment, and implementation.
ask questions on audio encoding for DVD.
dvd@dolby.com
multimedia@dolby.com ask questions on multimedia applications.
request general information and make inquiries.
info@dolby.com
tsa@dolby.com
7.3
General information and Inquiries
A wide variety of technical and trademark information can be found on Dolby’s
website at www.dolby.com.
Please contact the nearest office, as listed in this document, for direct assistance.
7-2
5.1-Channel Production Guidelines
7.4
Miscellaneous Information
Trademark Usage
Dolby Laboratories encourages use of the Dolby Digital trademark to identify
soundtracks that are encoded in Dolby Digital. This is an effective way to inform
listeners of the soundtrack format, and the use of a standard logo promotes easy
recognition in the marketplace. As with any trademark, the Dolby Digital logo may
not be used without permission. Dolby Laboratories provides a royalty-free
Trademark and Standardization Agreement (TSA) for companies who wish to use
Dolby trademarks. The company that owns the program material being produced
must sign this agreement. Recording studios or production facilities that provide
audio production, encoding, or manufacturing services for outside clients generally do
not require a trademark license. However, we do ask that these facilities refer their
clients to us for trademark licensing information.
To use the Dolby Digital logo, apply for a Dolby Trademark and Standardization
Agreement (TSA) by sending email to tsa@dolby.com or by contacting Dolby
Laboratories at any of the locations given in this document. When sending written
requests, please indicate whether you would like a Dolby Digital or Dolby Surround
trademark license, or both; also include your name, company name, mailing address,
and the type of media your soundtracks, music recording, etc., will be distributed on
(such as DVD, DVD-ROM, DTV broadcast, etc.).
For detailed information on Dolby trademark licensing, please refer to the document
Use of Dolby Trademarks on Audio and Video Media, available on the Dolby website
at www.dolby.com. A licensing application form is also available through our website.
7-3
5.1-Channel Production Guidelines
Miscellaneous Information
If you are already a Dolby licensee and would like more information on trademark
usage, please contact Dolby Laboratories. We are always happy to review artwork
and assist with the proper use of our trademarks.
7-4
5.1-Channel Production Guidelines
Appendix A
Mix and Mastering Data Sheets
A-5
Mix Data Sheet
/
Date
Project
Client
Studio
/
Project #
Producer
Engineer
Sampling Frequency
32 kHz
44.1 kHz
48 kHz
96 kHz
Bit Resolution
16-bit
18-bit
20-bit
24-bit
Time Code Format
25 fps
29.97 NDF
Tape Format
Surround Level SPL
Calibration
ADAT
DA-88
½" Digital
Data Cartridge (JAZ)
Equal to Front
-3 dB to Front
CH1
CH2
CH3
CH4
CH5
Time Code
:
:
:
:
;
;
:
:
:
:
;
;
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
:
;
;
;
;
;
;
;
;
;
;
;
;
;
CH6
Program
Notes:
A-3
CH7
CH8
Mastering Data Sheet
/
Date
Project
Client
Studio
/
Project #
Producer
Engineer
Sampling Frequency
32 kHz
44.1 kHz
48 kHz
96 kHz
Bit Resolution
16-bit
18-bit
20-bit
24-bit
Time Code Format
25 fps
29.97 NDF
Tape Format
ADAT
DA-88
½" Digital
Data Cartridge (JAZ)
Dolby Digital Encoding Information
Bitstream Information
Processing
Audio Service Configuration
Default
Digital De-Emphasis
LFE Filter
Copyright Bit
DC High-Pass Filter
ON
OFF
Dial Norm Setting:
Center Mix Level:
Bandwidth Low-Pass
Mix Level:
Surround Mix Level:
LFE Low-Pass Filter
Data Rate:
Surround Channel Processing
Dynamic Range Compression
90-Degree Phase Shift
None
Speech
Film:
3 dB Attenuation
Mode
:
:
:
:
:
:
:
:
:
:
:
:
:
CH1
CH2
CH3
CH4
Time Code
:
;
:
;
:
;
:
;
:
;
:
;
:
;
:
;
:
;
:
;
:
;
:
;
:
;
CH5
A-4
Std.
Std.
Light
Light
CH6
Program
Music:
CH7
CH8
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