[mythtv-users] nuvexport Video and Audio Sync

[John Sturgeon]

dnk wrote:

>Pardon me if this has been discussed previously; I was not able to find any
>relevant posts.
>
>For a few months, I have been trying to find a way to export ATSC .nuv files
>(from pcHDTV) to any format that would be easily portable for laptop
>viewing.  nuvexport is the obvious tool for the job, and I have tried every
>possible export format.  In every case, the audio and video become
>increasingly out of sync on playback.  For playback, I have tried mplayer
>(linux), xine (linux), Media Player (win32), mplayer (win32), and several
>others, with zero success.  The audio invariably gets ahead of the video.
>Within 30 minutes, the sync error is annoying (~.25-.5 seconds); withing
>45-50 minutes, it is unwatchable (> 1 second).
>
>Is there any way to get a properly synced export of HDTV ATSC .nuv files?
>Can anybody get usable, synchronized .mpg, .asf, Divx, Xvid, or other
>exports to work?
>
>Starting with a .17 base (ATRPMS), I am using CVS versions for the frontend
>and backend and for nuvexport, updated every few days until current.  The
>results never vary.  Frontend running nuvexport is running Fedora Core 3
>with all Fedora updates to kernel 2.6.10-1.770 on an Athlon XP 2500+ CPU.
>
>D. Knisely
>
>  
>
This is a fascinating problem to me.  I have the same exact problem, but 
*only* with 720p.  With 1080i I have no syncing issues at all.  The 
process that I use is to use ProjectX to demux and fix any out of order 
packets, and error correct the video/audio as much as possible, then I 
transcode the video to mpeg4 (ffmpeg) *only* with transcode, then I use 
avimerge to merge the ac3 audio back into the mpeg4 video.  It's a great 
process for keeping my original 5.1 ac3 track, and produces a nicely 
compressed video, but the syncing issue for 720p remains.  As you said, 
the results never vary.  Mine usually measures out at almost exactly 1 
second / hour of video.  I've even gone so far as to map the A/V sync 
buttons to a couple buttons on my remote, then every 7-8 minutes during 
playback, I give the video a little 'bump' of about 100ms.

By the way, this has been happening for me ever since MythTV 0.15 and 
FC1, so I don't think it's  a MythTV issue.

-- 
John Sturgeon <><
http://www.sturgeonfamily.com/mythtv.php