Audio Sync Problems AIW and MMC 7.5

[cguida]

Using AIW Radeon APG card mmc 7.5
P4 1.6 CPU
512 MB
40Gig drive
I have been experiencing audio out of sync with the tests I have been running with the Digital Record. The longer the capture the further out of sync the aufdio and video is. What is causing the out of sync condition? Is it the dropped frames? What can be done to resolve the problem?

Thanks

[Fastfwd]

I got the same problem but I think it's the playback that is faulty. I try to play a .mpg made from a DVD before I got MMC 7.5 and the sound is out of sync. I play the same file on my laptop with windvd and everything is ok!

[cguida]

I have tested the results on a DVD player and the out of sync is still there. I think it is in the source.

[Macros746]

Well that would definitely be caused by dropping frames. But you have to tell me more. What codec and at what resolution are you capturing to? I would think with a processor at that speed you could do whatever you wanted but remember: the higher the quality and the more compression the more you are asking your CPU to do. I am running 7.5 with no problem...but I wonder if you would have this problem if you went back to MMC 7.1 or 7.2. It is worth considering.

Macros

[VWC]

I ran into the same problem if I had any other programs running while I was capturing. If I ran TMPGEnc and even set it to stop long before my timed capture began, the sync would still be out by close to a second by the end of a half-hour capture. Now I just reboot my system before capturing anything. It's a little extreme, but it gets rid of all the sync and lockup problems I was having.

It may not be relevant to you since when the sync in my captures was really bad, it was running on a PII 400 system with an ATI TV-Wonder card using MMC 1.0 (they used to use different MMC version numbers for the TV-Wonder). I was only capturing for VCD mpeg, though.

If you haven't checked already, here's what ATI has to say about sync problems: http://support.ati.com/infobase/3524.html

[Fastfwd]

If we use another compression format for the capture will it get rid of audi sync problems? Is this problem specific to the mpeg format?

[Sulik]

Try creating a DWORD value DriftLimit=5, under
HKLM\Software\ATI Technologies\Digital VCR

This works with MMC7.2 if your system clock is a bit unstable (it doesn't compensate for dropped frames)
Good values seem to be between 1 and 10.

[next]

Sulik - that's a new one for me and very interesting. Do you have any idea what the dword tag does? I'm not sure myself.

edit - I don't have the tag at that location. Is it there possibly if the box does not meet minimum specs?

<font size=-1>[ This Message was edited by: next on 2001-12-14 19:23:29 ]</font>

[Sulik]

A DWORD is a 32-bit value: in regedit, right-click, select new DWORD value, enter the number.

The DriftLimit adjusts the time of the captured frames to
be within 1%-10% of the value from an ideal clock, so it
removes the jitter in the system clock. The jitter can also
be due to a VCR tape (speed is never perfect on a VCR).
It will also produce more accurate timestamps in the resulting MPEG file.