"Audio Drift"... is there a driver solution?

[homerpez]

I think I already know the answer, but...

I noticed since moving from an ATI card (run through a Sound Blaster PCI 128) to a Gainward Geforce 4 (with VIVO) and the same audio card, I am now getting a greater degree of "audio drift"...

That's where the audio rate fluctuates enough that V-Dub will drop frames to compensate...

It used to be I would randomly drop a frame here and there, but now it's fairly predictable. Especially after 5 minutes or so, the rate is off by enough that it will start dropping frames.

Overall, it's still not too bad, but it's also not "zero".

So, my question, has anyone made any "custom" audio drivers to specifically help the drift problem? I already have the latest "official" drivers.

I know I'm fishing here, but I have to at least ask... unfortunately it's probably hardware-related only...

[homerpez]

Is it the way I write, or just personal?

Anyway, I may have found one solution... maybe...

When the "news" post changed today, one program mentioned was "Virtual VCR"... looks like someone made a "simple" capture program which is free, and looks a lot like V-Dub....

They are trying to use a different method to control this problem. While V-Dub drops video frames to compensate, and other programs drop audio samples (I think ATI MMC does this), Virtual VCR has a resampler, which hopes to solve this problem by resampling the audio on-the-fly, so the audio will always match video frame duration, even if a few samples are missed here and there...

I haven't tried it, but here's the page on it:

http://www.digtv.ws/html/virtualvcr/sync.php

If anyone has tried this, how does it work for you? I imagine it's got to use some extra CPU power...

I'll run some tests myself when I get home today...

[patrickm]

try two things

-first, remove the ATI cinemaster MPEG-2 playback codec. i removed most sync issues by only installing ATI capture and file player, and using my copy of windvd for the MPEG-2 codec (the ati player and ms media player will use it). the problem is usually decode and edit related.

-if that doesn't work, add the DriftLimit registry key. i dont' have it in now, so i can't say for sure where it goes, but it's a way to let it go shorter or longer w/o dropping when it starts losing sync.
search the forums for more info

[patrickm]

to fully get rid of ATI MPEG-2 decoder, uninstall ATI DVD, remove registry references to Ravisent (sp?), Cinemaster, and go into device manager, show hidden devices, non-plug-and-play, and uninstall the Cinemaster engine device driver.

[Sulik]

Actually, an easier way is to just use "regsvr32 /u dscinemaudiodecoder.ax" (It will switch to other audio decoders).

The cinemaster audio decoder is reponsible for most A/V sync issues on playback (after seek operations). I never had a captured file that was out of sync with MMC 7.7, but the ravisent audio decoder always messes the a/v sync on playback since 7.6

[homerpez]

I guess I wasn't too clear on this, I'm using the Geforce card now, not the ATI, I completely removed that #@*&^$ software.

I'd forgotten about this thread! But I remember now, I ran a test with VirtualVCR... well, I couldn't get that to work. It resampled the audio, but it was out of synch to the video anyway, so I was back to square one.

And my desynch isn't on PLAYBACK... it's on CAPTURE. It's the synch difference between the video capture frames, and the audio capture rate (starts out at 41,000k but goes up and down).

I have found that, so far, letting V-Dub drop video frames to compensate for sound chip desynchs seems to work out best. I guess that's my answer, even though it looks a little scary when I watch the numbers...

[patrickm]

And my desynch isn't on PLAYBACK... it's on CAPTURE. It's the synch difference between the video capture frames, and the audio capture rate (starts out at 41,000k but goes up and down).

I have found that, so far, letting V-Dub drop video frames to compensate for sound chip desynchs seems to work out best. I guess that's my answer, even though it looks a little scary when I watch the numbers...

then get a real sound card with a stable clock that isn't a creative PCI bus hog

[homerpez]

Curious...

I nearly forgot that my MSI motherboard has on-board sound on it... I've been wary about using it since I always thought they were inferior, and probably they are... but maybe I'll just try that...