[mythtv-users] lossless cut and audio sync drift?
r.d.vaughan at rogers.com
Fri Nov 23 12:37:54 UTC 2012
I have, but rarely, noticed some audio drift. I am fairly sure, as
so many of the other issues are, that mkvmerge finds some problem with
the original recorded mpg file. Here is a reference to mkvmerge
parameters that you can use from the commandline on an out of sync mkv
file post lossless cut.
Some movies start synced correctly but slowly drift out of sync. For
these kind of movies you can specify a delay factor that is applied to
all timestamps -- no data is added or removed. So if you make that
factor too big or too small you'll get bad results. An example is that
an episode I transcoded was 0.2 seconds out of sync at the end of the
movie which was 77340 frames long. At 29.97fps 0.2 seconds correspond to
approx. 6 frames. So I did:
$ mkvmerge -o goodsync.mkv -y 23456:0,77346/77340 outofsync.mkv
I hope this helps.
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