Why does my Capture card run faster than 29.97?

[mpiper]

I have the avermedia capture card on my home PC.

No matter what capture program I use (IUvcr, VirtualVCR, etc.) when I set the frame rate to 29.97, I end up with 29.9765891 or so.

This causes dropped frames, about 1 per minute, since the capture is not times to match the signal.

Does anyone know why this happens? And how to fix it?

By the way, I have set my PCI bus to various speeds (30 - 47) and nothing changed the framerate, so that is not the issue.

Thanks!
Mike

[Blazey]

Taken from Doom9:

NTSC: Due to a minor bug in VirtualDub the native NTSC framerate of 29.97 cannot be set. The capture will then be at a framerate of 29.971 fps, a framerate that AVI2SVCD will reject rendering the file rather useless. Therefore the fps MUST be set to 29.9697 to work with AVI2SVCD. (The option "Lock video stream to audio" only works for "Compatibility capture mode", so it doesn't do anything here.)

My system gives the same FPS as yours so I'll assume the bug is there in your software as well as Vdub. I have made hundreds of successful caps without lost frames. I don't think this is your problem. Try running End It All before starting VDub and see if you still drop frames. If not, it's something in your system.

[mpiper]

Where do I find End It All?

I am in agreement with you on this. Any video I capture plays back fine, and the audio seems to stay in sync, I just don't like the frame rate not being the ideal setting. Maybe End It All will resolve the issues.

Thanks for the help!!
Mike

[Blazey]

End it all: http://www.docsdownloads.com/Tier1/enditall.htm

Read the Help menu and be sure you understand what this is doing before you "end it all"!

I just looked at your PC setup in profile and there is NO WAY you should be dropping more than 1 or 2 frames at the start/finish of each capture. Also, try Virtual Dub Sync - it may work out better for you. Use the Huffy codec or no codec at all if possible as well.

[mpiper]

I am actually not sure if all the frames are really being dropped. When I play back the vid captures, I don't see any stuttering, or jumping.

It may be just the program and how it determines dropped frames, or a result of the cumulative framerate offset.

If the video source is at 29.97 FPS, and the capture card is at 29.97691, then 60 seconds of video sends 1798.2 frames. But the capture card is trying to capture 1798.61 frames. this means for every minute of capture, I am trying to capture .41 of a frame that does not exist. This would mathematically result in a frame total being off by 1 frame compared to expected for every minute or so of video.

I can tell when I drop real frames (background processes) because they always drop in groups of 2 or more at a time. The 1 per minute is the irritation, since I feel like it is something that should not be happening.

Thanks for the link to "End It All" This should solve the "true" dropped frames, and maybe even the "ghost" dropped frames as well, if they really exist. lol.

Mike