[Libav-user] MXF muxer generates incomplete file

Alan Moore kahunamoore at gmail.com
Tue Mar 28 23:09:33 EEST 2017


I'm using libavformat to generate an mxf file and for the most part it
seems to be working but some files seem to be unable to import/link into
Avid Media Composer. I've inspected the structure of the file and have seen
two different conditions that appear to be triggering the failed

1) Last frame of video has all the audio channel essences but those
essences are smaller than all the rest.

2) Last frame of video is missing some of the audio channel essences (but
they are the same size as all the rest.)

It seems to happen in various frame rates/formats and only happens
occassionally (timing?) As far as I know I'm writing out all the audio
channel data for each frame. I am buffering the audio in my app (one
second's worth)  and writing the audio out when the cache is full (48K AES
audio) and so each call to av_interleaved_write_frame is given 72k (two

For problem #1 I have written a special case to flush out a full second's
worth of audio even if I have to pad it with silence but this just seems to
force problem #2 and generates a problematic file every time.

Has anyone run across any issues with end-of-file audio issues with ffmpeg
and mxf files?

FYI: I am not using ffmpeg's codec(s) as I have a hardware DNX encoder so
I'm just using libavformat.

Thanks in advance!


*"Whatever you can do, or dream you can do, begin it. Boldness has genius,
power, and magic in it. Begin it now."* - *Goethe*
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