[mythtv-users] Getting good audio sync in nuvexport/transcodings
john.sturgeon at gmail.com
Tue May 31 20:56:09 UTC 2005
Re: audio sync: Welcome to my world. It's incredibly frustrating, and
only happens with 720p material. After transcode, my audio loses step
with video at about the rate of 850ms/hour of programming. Very
consistent, very repeatable. I have absolutely no solution. Sorry to
respond with a 'meee toooo' but I'd love to hear if somebody has an
Re: transcode speed: What transcode paramaters are you using? Are you
resizing? I get very acceptable transcode speeds with 720p material
using ffmpeg (from transcode). I can't remember the fps off the top
of my head, but I think it's roughly 30fps.
John Sturgeon <><
On 5/28/05, Brad Templeton <brad+myth at templetons.com> wrote:
> 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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