[mythtv] mythtranscode not as good at synchronizing as playback inside MythTV

[Martin Møller]

Well, good news to me and anyone in a similar situation:

mencoder does a really good job with 'copy' as codec once again.

I still have stutter for a while but the sync returns afterwards and thus Episode 215 of 7th Heaven is now secured :)

I did the following:

mencoder -forceidx -ovc copy -oac copy /vol/TV/11_20061106155400.nuv -o I7H-Ep215.avi
mencoder I7H-Ep215.avi -forceidx -oac copy -ovc copy -o My-Ep215.avi

Note: The -forceidx didn't work the first time, probably due to the wrapper format but the second one worked beautifully.

It also worked well with a file that goes waaaaaaay out of sync when mytharchive DVDizes it. No trace of syncproblems anymore.

Yippie!

With a little luck I can use mencoder directly when I want to store DivX files again. Much faster than reencoding the whole shebang...

Hope someone else can use this information as well.

/Martin.

----- Martin Møller <martin at martinm-76.dk> wrote:
> Hi all.
> 
> I have a MPEG-4 recording that has a couple of seconds where the sync
> is troublesome during playback in MythTV but then MythTV recovers.
> When I transcode this recording, the problem arises in the same place,
> but it never goes away again and all the rest of the recording is off
> sync.
> It's OK by me that there's about 10-20 seconds that look weird if only
> the rest of the recording is behaving as normal.
> 
> I have tried mythcommflag --rebuild and tried upgrading to latest SVN,
> but neither of these fixed the problem.
> Updating ffmpeg didn't help either.
> 
> I can make a 5 minute sample available if anyones willing to look into
> it. The problem occurs approximately in the middle of this period.
> The full episode is a bit more than 42 minutes in length.
> 
> If I transcode only the part of the show that is after the problem (a
> few minutes later onwards), there is no problem, but I kinda need the
> whole show :)
> 
> As far as I know --fifosync and --buildindex will not work in my
> situation, but I could be wrong. This is what happens:
> 
> mythtranscode -c 11 -s 2006-11-06T15:54:00 -p autodetect --fifodir
> /tmp/fifo.11365 --honorcutlist &
> nice -n 19 ffmpeg -f s16le -ar 32000 -ac 2 -i /tmp/fifo.11365/audout
> -f rawvideo -s 352x288 -r 25 -i /tmp/fifo.11365/vidout -f avi -vcodec
> xvid -b 900 -g 300 -bf 2 -acodec mp3 -ab 224 "2006-11-06T15:54:00-I
> den syvende himmel - Episode 215.avi"
> 
> I've tried ffmpeg alone on the recording as well and the result seems
> very similar. After loosing sync it never gets back.
> 
> I have looked over the threads I could find in gossamers archive but
> didn't see anything that seems to be related.
> 
> I really hope there's a way to resync after a period like this...
> 
> /Martin.