[FFmpeg-user] Enable all audio channels

MI mi.lists.ffmpeg at alma.ch
Mon Jun 24 11:24:33 CEST 2013

> Do I understand correctly that wherever you want
> to use these files, tracks that contain multi-channel
> audio are simply not accepted? Or is there another
> reason why you don't simply merge channels that
> belong to each other into one track?

I don't know if they could be "accepted", but it would certainly lead to lots of 
grumbling by whoever needs to use the files.

Single mono tracks are the common practice, so that is what the people and the tools 

(It is also what we receive from the sound studio which did the mixes: separate mono 
.wav files. In that case, the file name specifies which channel it is.)

>> The common case I encounter is to have a single
>> language in the .mov, as 8 individual mono tracks
>> of the final audio mixes: Lt, Rt for stereo, and
>> L, R, C, Lfe, Ls, Rs for 5.1 (in that order).
>> A related question would be how to label these
>> single mono tracks?
> Just to avoid confusion:
> For me, "order" and "label" are two completely
> different, partly orthogonal things.
> Is it sufficient if 6 tracks (all being marked
> as "default") in the right order are in the mov
> file or is it necessary that all 6 tracks are
> "labeled" correctly?

It is important to make sure there is no ambiguity for anyone who needs the file.

For 5.1, there are different ordering standards:
L, C, R, Ls, Rs, LFE (ITU 775 for Film),
L, R, C, Lfe, Ls, Rs (for DCP, broadcast, etc.),
and others.

8 mono tracks could also mean 7.1 or it could be 5.1 + Hearing impaired + Visualy 
impared channels, etc.

To specify which is which, QT files have the "channel assignment" field, and also a 
"Name" field. Ideally, both are set correctly to avoid any confusion down the line.

> Or in other words:
> If you search for "first track enabled" in
> libavformat/movenc.c and change the "0x02" in
> that line to "0xf", does it work?

I would have to try that. In the last year, I only used pre-compiled binaries so I 
could easily have the same version on all 3 OSes.


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