Mpeg Codecs = Cause of Audio De-Sync ??

[REiREi]

OK, we've all had enuf sync problems, especially (like me) with ATI AIW Radeon and MMC 7.x. After battling for months, i found some very interesting factors, and now my TV caps are pretty much in sync, even after i edit the mpeg2s.
Since i have not seen a lot of post regarding this, i'll write here.

I saw a post on Rage3d forum talking about mpeg codecs:

http://www.rage3d.com/board/showthread.php?s=&threadid=33583552.

I can't access the link at the moment, so i'll write here roughly what the guy said:

[Begin quote]

" The graph (as shown in graph edit) uses the built in mpeg2 splitter provided with windows, the cine master video decoder and a mpeg audio decoder. These are then passed on to an audio renderer and a video render. The playback fine with no problems with audio sync.
This codec only works if the overlay is not being used by another app (the tv or another movie).

I install ulead video studio 4. This installs the ligos playback codec.
Specifically this includes the ligos mpeg splitter, the ligos video decoder.
If these codecs get set as the default ones to use for mpeg2 then the ati software uses them.

If another video is open then windows will uses these to render the mpeg file to a non overlay renderer. If a graph is made with these codecs, i get severe audio desync.

Specifically, a 20 minute video was off sync (recorded with NO dropped frames). I was getting frustrated as to why after installing some software (be it the ulead product or something else) i would get audio desync. This is because the app makes this ligos coded the default.

Since the ligos codec produces audio desync (and i beleive the demuxer is part of the problem) i would not use this codec for anything.

There is also another mpeg2 codec avaialbe from www.elecard.com.
This codec also has its own splitter and video decoder and also suffers from severe audio problems. It also cannot be used.

The mpeg2 played back properly with the powerdvd decoder as well.
It also used the same mpeg2 splitter. The ravenset (something like that) one also worked.
I am willing to be the windvd one also works though i have not tried it. "

[end of quote]


After I saw this, i started playing around with the mpeg codecs installed, playing a captured mpeg2 files in media player 6.4 and checking what codecs it uses and checking the sync.

In deed, with ligos and elecard, i get massive audio desync.
So i uninstalled them.
(I use M2-edit to edit mpegs, and it uses elecard codecs, so i unregister them as well. M2-edit will complain it cannot find codec to, but it will use windows codecs if you uncheck the mpeg2 option in preference).

I installed powerDVD, the sync is better, but i still get some editing issues (desync after edited by M2-Edit). So I unregistered the cyberlink filters, and now my mpegs just played with the default Ravisent codecs. The edited mpegs are now in sync, just like unedited.


So in my case, some of these sync problems are due to the codecs, not due to my hardware config - hell, i have P4 1.5, and i capture at Half-D1, so it should be quite capable.

Also, one thing i noticed: seems like this codec de-sync problems happen more with PAL. In the old days when still using the ligos codecs, i get much more desync with PAL mpegs than NTSC ones.

I cannot say this is the definite answer/solution to sync problems, so that's why i am posting here to see what the experts say about this.


REi

[Sulik]

PAL transfers more data per frame than NTSC, although less frequently, so it may make the sync issues worse if it is due to the sound card not getting enough bus bandwidth (because of video transfers).

See my other posts. If you capture with MMC you're much better off with MMC 7.5 (no more audio sync problems).

[REiREi]

Yes, i do cap in MMC 7.5 now and sync is much better,
but still (for editing out adverts), it's only so if i don't install other mpeg codecs.

[Fred©]

ReiRei,

I have some audio sync problems after installing lots of trial version softwares... I have Ulead DVD Moviefactory, m2-edit, Ulead Video Studio 4.0, Panasonic MPEG-1 encoder, windows media player 7.1, windDVD 2.6, etc... all using ATI AIW 128 pro as source for capturing...

Now I want to stay only with the default codecs that comes with ATI and windows 98... How do I do to unregister those codecs?

Thanks,