[mythtv-users] Getting good audio sync in nuvexport/transcodings w/cutlist?

Brad Templeton brad+myth at templetons.com
Sat May 28 18:23:54 UTC 2005

Well, I've seen a number of threads about this but no clear resolution.

Recently I've been trying to transocde a 720p MP2 file to MP4 with
a cutlist.   The file is 4 hours long -- 22 gigabytes, and it has
a whopping 76 minutes of "cuttable material", so use of a cutlist
is pretty important.

However, the result had steadily worsening audio sync, getting over
a second off eventually.   I used divx bucause xvid was so slow
(4fps on a 60fps recording) that it would take at least 33 hours
to transocde even on a fast machine.   That's with ffmpeg, should I
try transcode?  (mencoder does not work yet).

Even dvix took over 8 hours to transcode, but that's a touch more
tolerable.  Worse, while this is 60fps, it's really 24fps underneath,
most frames are duplicates.  Alas the mythtransocde | ffmpeg approach
presumably doesn't allow the encoder access to the knowledge it's just
been handed an exactly duplicate frame and shouldn't waste its time.

To my surprise, also, while I asked for a bitrate of 7200, which should
have generated a file in the range of 9 gigabytes, I got one that
was 4 gigabytes.  It is actually pretty good, video wise, though
with some obvious artifacts in smooth surfaces and a little blurring.
But I felt I was willing to spend more space on it and hopefully be
rid of those.

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