Difference between revisions of "User:Jeff Kelley/Multichannel Audio"

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(Mapping between QuickTime and industry-standard labeling)
m (Producing a multichannel audio movie)
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Once tracks assigned, choose File>Export, Movie to QuickTime Movie, Options, Sound Settings, Channels. Wow!
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[[Image:QT_Audio_Tracks_Export.png]]
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Note that the compression format used will limit the choice of surround formats available. You will most probably prefer AAC over PCM, and the AAC 5.1 format is C L R Ls Rs LFE. However, industry-standard is L C R Ls Rs LFE. Be careful here. Confused? Here is a table to help:
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==== Multichannel Mixing and Surround Formats ====
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{|{{Prettytable}}
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! Format
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! Channels
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! Layout
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|-
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| Mono
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| 1
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| C
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|-
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| Stereo
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| 2
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| L R
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|-
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| Cinema Stereo
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| 3
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| L C R
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|-
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| Quadraphonic
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| 4
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| L R Lr Rr
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|-
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| Dolby ProLogic
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| 4
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| L C R S
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|-
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| Film (Dolby Digital)
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| 6
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| L C R Ls Rs LFE
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|-
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| SMPTE/ITU
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| 6
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| L R C LFE Ls Rs
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|-
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| DTS
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| 6
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| L R Ls Rs C LFE
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|-
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| Dolby Surround EX
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| 7
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| L C R Ls Cs Rs LFE
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|-
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| SDDS
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| 8
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| L Lc C Rc R Ls Rs LFE
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|}
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 +
  
  
 
'''NOTE:''' delete [[:Image:Jef Kelley Images QT Audio Tracks Assign.png]] (stupid one)
 
'''NOTE:''' delete [[:Image:Jef Kelley Images QT Audio Tracks Assign.png]] (stupid one)

Revision as of 00:46, 25 December 2007

   WORK IN PROGRESS

Introduction

Since QuickTime 7, it is possible to deliver multichannel audio. Second Life streamed audio relies on QuickTime and inherits this capability without further work.

Producing a multichannel audio movie

We are using ProTools. Export a multichannel track (ou bounce a multichannel master fader) to multimono files. Here is an example with a 5.1 (L C R Ls Rs Lf) track and the six mono files you get.

PT Multichannel Track.png PT Multimono Files.png

In QuickTime Pro, create a new movie then import the six mono files. You have to open each of the six tracks, select all, "Add to Movie" with playhead at start. Tedious, but we will come with a better solution soon. Now, "Show Movie Properties" then "Audio Settings".

QT Audio Tracks Assign.png

Assign carefully each track. Note that you can see the original filenames in the "Resources" tab.

Mapping between QuickTime and industry-standard labeling

Left L
Right R
Center C
LFE Screen LFE
Left Surround Ls
Right Surround Rs
Left Center Lc
Right Center Rc
Center Surround Cs
Rear Surround Left Lr
Rear Surround Right Rr


Once tracks assigned, choose File>Export, Movie to QuickTime Movie, Options, Sound Settings, Channels. Wow!

QT Audio Tracks Export.png

Note that the compression format used will limit the choice of surround formats available. You will most probably prefer AAC over PCM, and the AAC 5.1 format is C L R Ls Rs LFE. However, industry-standard is L C R Ls Rs LFE. Be careful here. Confused? Here is a table to help:

Multichannel Mixing and Surround Formats

Format Channels Layout
Mono 1 C
Stereo 2 L R
Cinema Stereo 3 L C R
Quadraphonic 4 L R Lr Rr
Dolby ProLogic 4 L C R S
Film (Dolby Digital) 6 L C R Ls Rs LFE
SMPTE/ITU 6 L R C LFE Ls Rs
DTS 6 L R Ls Rs C LFE
Dolby Surround EX 7 L C R Ls Cs Rs LFE
SDDS 8 L Lc C Rc R Ls Rs LFE



NOTE: delete Image:Jef Kelley Images QT Audio Tracks Assign.png (stupid one)