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

Wayne Poll WPoll at nhnz.tv
Tue Jul 30 00:50:31 CEST 2013

Sorry this is so late as a response (I've been away) but the fix is easy Sam; you can exclude the ninth track like this....

./ffmpeg -i input.mxf -map 0 -map -0:9:0 -c copy -c:v prores -profile:v 3 output.mov

The "-map 0 -map -0:9:0" will tell ffmpeg to copy all streams EXCEPT stream 0:9 - which in my case is a metadata track (possibly TC - not sure).

HTH someone...

Wayne Poll | Technical & IT Systems Manager |
NHNZ | 5 Melville Street, Dunedin 9016, New Zealand |
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-----Original Message-----
From: ffmpeg-user-bounces at ffmpeg.org [mailto:ffmpeg-user-bounces at ffmpeg.org] On Behalf Of Sam Marrocco
Sent: Friday, 19 July 2013 3:08
To: FFmpeg user questions
Subject: Re: [FFmpeg-user] Is mixing of audio channels happening by default in ffmpeg?

On 7/18/2013 10:34 AM, Tom Evans wrote:

-map 0 means add every input stream in to the output. You've said what you want done with video, encode to prores_ks, and what to do with audio, copy, you just need to either say don't add all streams (just first video and all audio) or copy all input streams, including metadata, and re-encode the video.

You can do both with -map, eg to not copy the metadata track:  "-map 0:v -map 0:a  -c:a copy -c:v prores_ks"
or to copy everything, but re-encode the video: "-map 0 -c copy -c:v prores_ks"

-c:v is an alias for -vcodec, -c:a for -acodec, in case you were wondering.

Thanks, Tom.
in order to get the video, 8 channels of audio and the ninth track TC (which can't be specified specifically) what you stated might work as:

-map 0:v -map 0:a

If I'm understanding this seems to indicate "copy all video tracks across, using my pre-specified video codec settings" and "copy across all audio tracks, using my pre-specified audio codec settings". The timecode seems to be brought across by default without specifying.

I'll test further, but this seems to do the job.

sam marrocco | chief technical officer

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