Tell tale signs of Macrovision?

[ember]

I am trying to backup some old VHS tapes using my Win TV capture card. These videos form a series of episodes of an old (first broadcast 1970s) UK tv series. The tapes are in good condition (and original releases) and until the final episode I had no problems capturing to AVI. However, on the final episode of the series, I found that I was losing many frames. I tried capturing to AVI then real time MPEG1 encoding - both dropped frames. Could this be macrovision? What are the tell tale signs? I have Defragmented my drives, and the capturing is good right upto this specific point in the video. Then the frames drop like crazy.

I also tried starting the capture just before this point in the video - and the frames still drop so it is not due to my hard drive.

The videos were relaesed in '92 so I don't know if macrovision was around then.

<font size=-1>[ This Message was edited by: ember on 2001-10-08 08:49:26 ]</font>

[Vejita-sama]

I don't think it's macrovision. Macrovision causes the color and brightness of the video and fade and/out (goes from super bright color to darkest near B&W picture).

[neily]

I'm sure it's not macrovision. I don't think the WinTV is affected at all.

Sounds like a straight bandwidth/CPU problem. If you are capturing not uncompressed, the content of the frames can alter the encoding time, thus lead to dropped frames. Try, space and HD bandwidth permitting, capturing uncompressed. RGB15 and BTYUV are the most efficient, but have marginally worse quality than RGB24 and YUY2.

Alternatively, if you have already captured a lot of stuff to a drive, be aware that transfer rates decrease significantly across the disk. Maybe you have got to a point where the HD can't cope.

I'm sure that either processing power or HD transfer rates are the problem, not macrovision.

[ember]

Thanks everyone : I tried capturing another VHS video and over the 30mins it was fine - few dropped frames. So it must be the tape I am recording - specifically at the point in question. It is obviously not macrovision - judging by your comments.
I lose about 1 frame per minute - based on MS MPEG4 codec V1 at standard bitrate. I use BUTYUV format at 352 x 288 resolution.
I use Virtualdub - 1.4c and 1.4.7
I have:
P2 400MHz
256MB RAM
but my HD are old and rate at best 5MB/s.
I have 1.4GB available on my drive- so I have to capture 30 min episodes as compressed AVI then encode to MPEG1 using TMPGEnc.

[wingnut]

Aha, this could be a problem I encountered. If the vbi - video blanking interval on the tape is noisy you wouldnt see it on screen or in your capture window but the card would be trying to capture a hell of a lot of noise and would drop frames. I got around this using virtualdub to capture with the cropping option set up to crop out everything but the visible picture.

Might be worth a try

Cheers

Ed