[Libav-user] MPEG-4 Byte alignment problems in libavformat/mov.c

Johann Burkard johann at johannburkard.de
Sat Mar 10 00:26:49 CET 2012


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Hello,

I have a question about MPEG-4 handling in libavformat.

I run an online audio converter called http://media.io that uses
FFMPEG to convert audio files. I have found that I cannot use mplayer
- -identify on MPEG-4 audio files unless these files are aligned to 2048 B.

For example, here is the strace output of a file that was truncated:

read(3,
"\324\n\254\f(H%\"Z\24\2210\0,v\7\237\234!J\376\377\364V`\264D$\313\251z\274"...,
2048) = 1408
...
write(2, "[mov,mp4,m4a,3gp,3g2,mj2 @ 0x211"...,
57[mov,mp4,m4a,3gp,3g2,mj2 @ 0x2115f50]moov atom not found

In other words, as long as a MPEG-4 audio is not completely uploaded,
I cannot call mplayer -identify on it.

Do you know if there's any workaround to this? Is there a
configuration switch that would make libavformat more forgiving of
format errors?

The strace output and the file are of course available.

Thanks.
- -- 
Regards,

Johann Burkard

<http://johannburkard.de>
<http://twitter.com/johannburkard>
<mailto:johann at johannburkard.de>
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