[FFmpeg-user] Is mixing of audio channels happening by default in ffmpeg?

[Carl Eugen Hoyos]

Sam Marrocco <smarrocco <at> ringsidecreative.com> writes:

> "ffmpeg-20130507-git-399f6ef-win64-static\bin\ffmpeg.exe" 
> -i "C:\Users\root\Desktop\MultiChannel.mov" -vcodec prores_ks 
> -pix_fmt yuv444p10le -profile:v 3 -acodec copy -t 1 
> -f mov "D:\\MultiChannel\MultiChannel.mov"

> The resulting quicktime appears to contain a single audio 
> track with the contents of original 8 tracks mixed together.

This is very unlikely / no.
(The amerge filter allows to produce the result that you 
describe.)

The default action - since you did not specify a map 
parameter - is to output one audio track.
See the console output:
> Stream mapping:
>   Stream #0:0 -> #0:0 (rawvideo -> prores_ks)
>   Stream #0:1 -> #0:1 (copy)

Input audio track 0:1 is copied into the output file.

Note that if you specify -map 0 (to copy all streams), all 
output audio tracks except the first one will be silent 
(because that is useful for - imo - typical - usecases).
This is probably trivial to fix but I am still searching 
for somebody to help testing.
;-(

Carl Eugen