[FFmpeg-trac] #2153(avcodec:new): aac 7.1 channel layout

FFmpeg trac at avcodec.org
Mon Jan 21 04:23:49 CET 2013


#2153: aac 7.1 channel layout
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             Reporter:  Crayden     |                    Owner:
                 Type:  defect      |                   Status:  new
             Priority:  normal      |                Component:  avcodec
              Version:  git-master  |               Resolution:
             Keywords:  7.1 aac     |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
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Changes (by cehoyos):

 * keywords:  7.1 aac channel layout => 7.1 aac


Comment:

 The sample that you provided has a channel configuration (as defined in
 the AAC specification) of "7" and this corresponds to the channel layout
 "7.1 wide": FL FR C LFE BL BR FLC FRC (in a specific order but the order
 is not what this ticket is about afaict).
 To the best of my knowledge, this is defined in the AAC specification and
 FFmpeg decodes the given sample in accordance with the specification (and
 its output matches QuickTime output which may not be a strong argument,
 see below).
 Afaiu, the patch would change this behaviour from conforming to the
 specification to non-conforming.

 I attached a sample with channel configuration "0" which means the channel
 layout is defined through PCE (program configuration element as in the
 specification), the sample is correctly identified as 7.1 (non-wide) and
 is decoded correctly afaict. (QuickTime apparently fails to decode the
 attached sample correctly, it seems to assume all 8 channel aac samples as
 7.1 wide.)

 Perhaps Hendrik can comment further?

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2153#comment:2>
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