[FFmpeg-user] Enable all audio channels in Quicktime

[Rens Dijkshoorn]

Hi, 

this is being discussed before but i could not really find a solution 
or a final conclusion. 

For more PRO oriented use the standard always have been having 
all channels enabled. All quicktime capture cards and applications 
like Softron MovieRecorder or ToolsOnair JustIn behave in this way. 

CMD I in Quicktime 7 or Quicktime X will simply show all 
available tracks in the Quicktime container. The current 
situation with ffmpeg ( 2.1.1) wil only reveal the first audio channel. 

ffmpeg -i PRORES_8CH.MOV -map 0 -map -vf scale=1920:1080 \ 
-pix_fmt yuv420p -c:v libx264 -profile:v high -level 4.0 \ 
-c:a: copy H264_8CH.MOV 

For Quicktime X users there is no way to discover what 
is hiding. 

I can see the use case if you are working with a finished 
movie and properly tagged audio. 

But when working on a movie between various 
stages in the production, the track layout could well be 

1 & 2 Live Recorded Audio 
3 & 4 Music 
5 & 6 Effect sounds 
7 & 8 Narration 

So if you want to create a evaluation copy in H264 
from a 4K prores master with all the audio tracks enabled 
so any casual Quicktime user can hear all the audio still 
in separated tracks this is diffcult to achieve. 

I would be nice t o have an option -enable_all_tracks or 
something similair to adress this issue 

As a first attempt I tried to restore the previous behaviour by 
patching movenc.c but sofar my understanding of the code 
is limited. 


Regards 

Rens Dijkshoorn < rens at online media.nl >