[FFmpeg-user] demuxing and re-muxing of mxf video files

[Rodney Baker]

On Fri, 22 Apr 2011 16:56:12 Paul Tapper wrote:
> Hi,
> I hope this is the right place to post this question.  Sorry if it isn't.
> I'm trying to use FFmpeg to take an .mxf file and:1. demux the audio out of
> it to a .wav (and then process the .wav myself), then2. mux together the
> video from the original .mxf with the .wav that I have now processed, to
> get back to an .mxf file, as similar as possible to the original .mxf, but
> now with my processed audio, instead of the original audio. I've got step
> 1. working with a very simple:
> ffmpeg.exe -i "test.mxf" "test.mxf.wav"
> but I'm a bit stuck on step 2.
> I've tried the following:
> ffmpeg.exe -an -i "test.mxf" -i "test.mxf.wav" -vcodec copy
> "test.mxf.remux.mxf" but I get an error "[mxf @ 01EF8610] track 0: could
> not find essence container ul, codec not currently supported in container"
> Please could anyone suggest what I should do here?  Is this even a
> sensible thing to attempt with FFmpeg? Thanks
> Paul

First of all, you're telling ffmpeg that you want no audio (the -an) switch, 
then trying to add audio.

You need to specify the 2 input files as you have done, but then map the 
streams from each input file to the output file. If the video in test.mxf is 
stream 0 then you would use -map 0:0 -map 1:0.

You also need the "newaudio" switch.

Your final command would look something like:

ffmpeg -i test.mxf -i test.mxf.wav -acodec copy -vcodec copy -map 0:0 -map 1:0 
output.mxf -newaudio

You might have to play around with the order of the options (order is 
important). Others who have done this before may have better suggestions. 
YMMV.

-- 
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Rodney Baker VK5ZTV
rodney.baker at iinet.net.au
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