PC-VCR 2.10 caps NTSC at 30, not 29.97fps?

[mmartins]

Hi, I'm trying to cap some old NTSC tapes with my Marvel G450 eTV card to the 704x576 MPEG-2 format using Vid-Tools 2.10.10 but am having the following problem:

The software only captures at 30 fps, with no option to switch this to 29.97 (the box is greyed out)

This means that, played back at 29.97, the captured video suffers from an A/V desync of about 4 seconds / per hour

Does anyone know of a workaround to force capture at the correct rate?


TIA
Mike

[Kruzin]

Welcome to MURC.
Allow me to direct you to the folks who can best help you.
That's the Desktop Video forum.
This thread will now be moved over there.

[traveller]

Using Vid-Tools is not the best solution for the recording.
I strongly recommend you another tool like AVI_IO

http://www.nct.ch/multimedia/avi_io/

It is small, it is fast and works like a charm.
It is shareware, but if you don't want to buy it, shareware limitations don't hurt you I think
So give it a go and you understand what I mean
Good luck

[junkmalle]

PC-VCR's UI may say 30 fps but I think it actually records 29.97. Several programs I've used (TMPGEnc, AVICODEC, Ulead Media Studio Pro) to examine the frame rate report 29.97.

Your audio sync problems probably have more to do with dropped frames (especially when recording from VHS tapes). AVI_IO does a much better job -- it never loses sync.

[Brian Ellis]

You want 704 x 576 (PAL) with 29.97 (NTSC) ?????????????

[mmartins]

Originally posted by Brian Ellis
You want 704 x 576 (PAL) with 29.97 (NTSC) ?????????????

Nope, my bad - it's 704x480

I'm trying Ulead MediaStudio now, which seems to be working fine

AVI_IO looks fine, but it doesn't seem to have mpeg-2 capture - is there a simple way to use it to create DVDs?



Thanks again for the info
Mike

[traveller]

I suggest to use AVI_IO
As codec go for HUffyuv

http://cultact-server.novi.dk/kpo/huffyuv/huffyuv.html

After capturing you maybe want to edit it-or at least improve the quality, cut noises, cut unwanted scenes
THEN you can code it to any format you want
In such case the best coding tool seems to be TMPGEnc Plus http://www.pegasys-inc.com/e_main.html

[junkmalle]

AVI_IO with HUFFYuv codec gives the best results but the files are huge -- about 30 GB per hour. So you'll need lots of free disk space. You can then convert this to MPG2 for DVD. I recommend you stick with the 704x480 frame size.

Be sure to enable HUFFYuv's "Swap Fields on decompress" option. Matrox's driver captures fields in the wrong order and this option compensates that.

This field order problem is not the same as the usual field order issue (A/B, odd/even, 1/2, top/bottom) that's addressed in Media Stuio Pro's (and many other programs') "Field Order A" vs "Field Order B" setting. To understand this you have to know the following:

30 frame per second video is actually broadcast as 60 fields per second. The camera captures every other scanline, then 1/60 th of a second later it captures the other scanlines to fill in the frame. Most capture devices save the full frame with those scan lines in order:

1
2
3
4
...
479
480

and they set the field order flag to say whether the odd or even scanlines where captured first. The capture order is important because the two sets of scanlines were not captured at the same time, so when they're played back you have to play them in the right order. When you watch this on TV, by the time the second field is displayed, the first field has faded away. So you don't actually see both fields at the same time.

Unfortunately, Matrox's driver saves the scanlines in the wrong order (at least when working in NTSC, I don't know about PAL):

2
1
4
3
...
480
479

Most programs don't know how to deal with this. Even Matrox's own PC-VCR doesn't deal with this correctly! If you record and playback with PC-VCR in YUY2 mode all pairs of scanlines will be displayed reversed.

You might think you can work around this problem by recording with PC-VCR in MPG mode. But this isn't a viable solution if you want high quality video. Not because the realtime MPG compression isn't any good, but because PC-VCR only records one field in MPG mode! It captures one field and then fills in the other field by interpolating between pairs of scanlines from the first. You end up losing half the picture. This is especially problematic with subtitles -- you may end up loosing small horizontal bits like the crossbar in the letters T, E.