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-   -   Recording Video: Huffyuv and Noisy Video sources? (http://www.digitalfaq.com/archives/capture/1306-recording-video-huffyuv.html)

TKS 10-11-2002 05:07 PM

Recording Video: Huffyuv and Noisy Video sources?
 
Just a quick question:

I was capturing an old VHS tape of mine and it was really noisy, I noticed in Vdub/Huffy/352x480 that i was losing some frames.. Nothing major.. only 12 frames out of like 6000.
But what i was wondering is that if the source is noisy does it cause frames to drop occasionally?

tks

willy_annand 11-23-2002 11:28 AM

it could also be the VCR. Below is a "cut and paste" from another site, in answer to a similar question I asked there.
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This is a very common problem. It is almost certainly due to the fact that you are getting problems with the sync signal recorded on your camcorder's videotape. The reason why you can capture with zero dropped frames direct from broadcast TV is that broadcast TV contains a nice strong perfectly undistroted vertical blanking interval signal. This is the signal that synchronizes the interlaced frames which scan across your TV screen.

VCRs, however, record this sync signal on magnetic tape, and that creates problems. Tape has dropouts. It shrinks and stretches with age. The sync signal degrades. As a result the VBI information can be distorted or missing on some video frames. Since your capture card needs this info to know when one interlaced frame has been captured, corruption of this sync information results in dropped frames due to buffer overrun in your capture card.

The only known way to solve this problem is to use a time base corrector. A TBC will regenerate the corrupted sync signal. Many digital camcorders have built-in TBCs, so recording toa digital camcorder and capturing that way will work. Or you can use a standalone TBC. They tend to be expensive.

The fact that video capture cards cannot reliably capture from many types of videotape playback devices without a TBC inserted in between thecomposite out of the VCR and the composite input of hte capture card is one of the dirty little secrets of video capturing. Nobody talks about it, but it's part of life.

If you own a newer VCR, it may have a TBC built in (my VCR does). If your camcorder is an analog model, it almost certainly does not have a TBC built in. That probably explains why you can capture from your VHS VCR but not from your camcorder.

Try a TBC or a fly in the video from your camcorder into a friends digital camcorder and then capture from the digital camcorder by firewire. Those are your only real options. The fact that you capture fine from your VCR but not your camcorder is the giveaway. It has nothing to do with driver problems. If that were the case, you'd be having dropped frames whatever the source you captured from.
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Hope this helps


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