[Ffmpeg-devel] matroska to vob frame skipping issue.

[Aurelien Jacobs]

On Sun, 7 Jan 2007 02:28:23 +0100
Aurelien Jacobs <aurel at gnuage.org> wrote:

> On Fri, 5 Jan 2007 00:54:13 -0000
> "Chris" <chris at garveycocker.com> wrote:
> 
> > 
> > > > Thanks for the sample.
> > > > This issue is now fixed.
> > > >
> > > > Aurel
> > > 
> > > 
> > > Aurel,
> > > 
> > > Excellent job. Works perfectly on all my samples now. Many thanks.
> > > 
> > > There is another issue (now?) with that planet earth sample (and others).
> > > If
> > > you pass-through the audio the file size is constantly at 76KB throughout
> > > the encoding process. Then at the end there are loads of "buffer
> > > underflows", the resultant mpg does not play:
> > > 
> > > ffmpeg.exe -y -i planet.earth.mkv -target dvd -acodec copy
> > > planet.earth.mpg
> > > FFmpeg version SVN-r7159, Copyright (c) 2000-2006 Fabrice Bellard, et al.
> > >   configuration:  --enable-a52 --enable-gpl --enable-memalign-hack
> > > --disable-debug
> > >   libavutil version: 49.1.0
> > >   libavcodec version: 51.25.0
> > >   libavformat version: 51.6.0
> > >   built on Nov 29 2006 10:08:22, gcc: 3.4.4 (mingw special)
> > > [matroska @ 00709434]Ignoring seekhead entry for ID=0x1549a966
> > > [matroska @ 00709434]Ignoring seekhead entry for ID=0x1654ae6b
> > > [matroska @ 00709434]Ignoring seekhead entry for ID=0x114d9b74
> > > [matroska @ 00709434]Unknown entry 0x73a4 in info header
> > > [matroska @ 00709434]Unknown track header entry 0x55aa - ignoring
> > > [matroska @ 00709434]Unknown track header entry 0x23314f - ignoring
> > > [matroska @ 00709434]Unknown track header entry 0x55ee - ignoring
> > > [matroska @ 00709434]Unknown track header entry 0xaa - ignoring
> > > [matroska @ 00709434]Unknown track header entry 0x55aa - ignoring
> > > [matroska @ 00709434]Unknown track header entry 0x23314f - ignoring
> > > [matroska @ 00709434]Unknown track header entry 0x55ee - ignoring
> > > [matroska @ 00709434]Unknown track header entry 0xaa - ignoring
> > > Input #0, matroska, from 'planet.earth.mkv':
> > >   Duration: 00:01:02.3, bitrate: N/A
> > >   Stream #0.0: Audio: ac3, 48000 Hz, 5:1
> > >   Stream #0.1: Video: h264, yuv420p, 1280x720, 25.00 fps(r)
> > > Assuming PAL for target.
> > > Output #0, dvd, to 'planet.earth.mpg':
> > >   Stream #0.0: Video: mpeg2video, yuv420p, 720x576, q=2-31, 6000 kb/s,
> > > 25.00
> > > fps(c)
> > >   Stream #0.1: Audio: ac3, 48000 Hz, 5:1
> > > Stream mapping:
> > >   Stream #0.1 -> #0.0
> > >   Stream #0.0 -> #0.1
> > > Press [q] to stop encoding
> > > [dvd @ 00709434]buffer underflowB time=61.5 bitrate=  10.1kbits/s
> > > [dvd @ 00709434]buffer underflow
> > > [dvd @ 00709434]buffer underflow
> > > 
> > > [...]
> > > 
> > > [dvd @ 00709434]buffer underflow
> > > [dvd @ 00709434]buffer underflow
> > > [dvd @ 00709434]buffer underflow
> > > [dvd @ 00709434]buffer underflow
> > > frame= 1541 q=2.0 Lsize=   38154kB time=61.6 bitrate=5074.0kbits/s
> > > video:34731kB audio:2919kB global headers:0kB muxing overhead 1.338196%
> > > 
> > > 
> > > I am not sure whether this was an issue before or is a result of the
> > > recent
> > > update.
> > > 
> > > Regards,
> > > 
> > > Chris
> > > 
> > 
> > 
> > Aurel,
> > 
> > Any thoughts on this?
> 
> Well, I already verified that there is indeed an issue, but I didn't
> had much time to work on it.
> I will try to fix it at some point...

It took me quite some time before looking at this issue.
But finally I've done a bunch of improvements in our matroska demuxer.
So now transcoding planet.earth.mkv with -acodec copy works perfectly
fine.

Aurel