[FFmpeg-user] converting 1080 to 720 mpeg2

Andy Sheen sheen.andy at googlemail.com
Fri Mar 2 22:08:51 CET 2012

Carl Eugen Hoyos wrote on Fri 02 Mar at 20:53 UK time
> Andy Sheen <sheen.andy <at> googlemail.com> writes:
>> The only problem was the new ffmpeg introduced a 100ms delay 
>> in the audio but you can work around that too ;).
> I don't think this is a known problem for any developer
> (and please understand that unknown problems usually get not fixed 
> while known regressions should be fixed fast).

I do a lot of reencoding from UK broadcast .ts files to .mkv files. I do
a 2 pass reencode of video to a lower bitrate .x264, mux out the audio
and then remux with mkvmerge. I currently use mkvmerge to mux to .mkv.
The version I use is:

mkvmerge v4.7.0 ('Just Like You Imagined') built on Apr 21 2011 01:13:14

For me, simply upgrading from:

FFmpeg version SVN-r26400, Copyright (c) 2000-2011 the FFmpeg developers
  built on Jan 18 2011 04:07:05 with gcc 4.4.2


ffmpeg version N-32611-gd55b06b, Copyright (c) 2000-2011 the FFmpeg
built on Sep 15 2011 00:26:45 with gcc 4.6.1

caused me to have to change my mkvmerge command line from:

mkvmerge -o file.mkv file.h264 --language 0:eng file.ac3


mkvmerge -o file.mkv file.h264 --language 0:eng --sync 0:100 file.ac3

It may well be some sort of bug in mkvmerge, but the only thing changed
was ffmpeg and this applies across all channels and all re-encodes...

> Carl Eugen


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