[Matroska-users] Corrupt .mkv when using PCM audio

Adam Nielsen a.nielsen at optushome.com.au
Thu Dec 25 06:29:11 CET 2003


I've been creating FFMPEG4/Vorbis .mkv files for a while now without problems, 
however I just tried substituting a PCM .wav file instead of an .ogg file, 
but this seriously corrupts the output file.  (I have a script to automate 
the process, and I just replaced "$OUT.ogg" with "$OUT.wav")

The problem was my input audio is out of sync with the video about half way 
through (suddenly the audio loses about 100ms in the middle due to bad 
reception) so I tried inserting 100ms to try to get it back into sync.  Then, 
to save time, instead of encoding it as ogg and then merging it, I just tried 
merging the .wav file in instead (in case I got it wrong and had to alter the 
delay again.)

mkvmerge correctly detected it as PCM, although I didn't get a smooth frame 
count, it went from nothing up to 100% (but took the expected time), and the 
output .mkv file is actually *smaller* with uncompressed PCM that with
Vorbis - so something has definitely gone wrong.

mkvinfo on the corrupt file reports:

| + Muxing application: libebml v0.6.2 + libmatroska v0.6.1
| + Writing application: mkvmerge v0.7.6

Also, it reports the video as 720x576 -> 768x576 instead of 516x570 -> 
760x570, but everything else seems normal.  The input .wav is ~280MB, 
uncompressed 16-bit stereo 48kHz.

Has anything that could be causing this been fixed in the newer releases of 
the Matroska stuff?  I don't really want to go to the trouble of upgrading 
just yet in case it's a new bug and upgrading doesn't make a difference.


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