Whites blowing out on VHS to DV Conversion

Lightway wrote on 7/26/2003, 2:39 AM

Hi,
I am trying to convert an hour of VHS to DV for eventual transfer to DVD using DVDA. The footage is old (1950's) and would have been converted from film to VHS. The VHS itself seems pretty good and when playing from the VCR into a TV it looks ok. However when I convert it to DV, the quality goes really bad. There are wedding shots and the brides' dresses just blow out the scene saturating the picture in white. In other instance the contrast is all over the place.

I use a panasonic 6head HiFi consumer VCR into a Canon MiniDV cam (for the analogue to DC conversion in realtime vis the firewire port into Vegas (or Vidcap 4 to be precise).

I have tried to capture also using my leadtek cap card on another machine (no compression) and the results are better but nothing like the original.

I would have thought that DV would have reproduced the original with a high degree of fidelity but it seems not so.

Can anyone give me some advice on how I can deal with this problem.

Thanks
Lightway

Comments

RBartlett wrote on 7/26/2003, 3:03 AM

Have you tried sending the captured file (or part thereof) back out as a final render "print to tape"? I guess you've got your display adapter/s set for millions of colors (24bit or higher).

Would you say that there are noticable contours/gradients on shaded areas? Might be the gfx card mode if so. Your analysis is on VGA port, not gfx card TV-out from mediaplayer?

Lightway wrote on 7/26/2003, 7:06 AM

I've actually gone all the way and wrote the DVD in case it was a VGA display type issue. Nope it captures bad and then displays bad. I use a sigma designs Hollywood+ card to output (I don't have a set top DVD player) but the VGA and HW+ output looks very much the same...

BillyBoy wrote on 7/26/2003, 9:51 AM

Read my tutorials. Quickly reading your comments it seems adjusting gamma, gain and levels should help. If not there yet, try color curves.

http://www.wideopenwest.com/%7Ewvg/tutorial-menu.htm

mikkie wrote on 7/26/2003, 10:42 AM

"The VHS itself seems pretty good and when playing from the VCR into a TV it looks ok."

I would guess then that the problem is related to colorspace or perhaps NTSC setup, assuming you've got an NTSC tape, and also assuming that when you say it plays back cool from a VCR, you're talking about the same vcr (and connections) used for capture. It almost sounds like an NTSC tape with 7.5 ire setup included played back in a deck that doesn't remove it, & so raises all the colors up a notch.

In any case, how about the blacks? Are they washed out, too light as well? If so, something like an analog capture to mjpg (or high bitrate all I frame mpg2) might work if you can set the gamma &/or levels prior to capture, darken everything up a bit to get the full lightness range in your footage on disk.

It's possible that the VHS tape is recorded at/with too high white levels that are blended to (clamped) to white by the camcorder or even the DV codec itself. Don't know what control you have over this in the camcorder, but if you can't get the whites to pass through the conversion, again might have to resort to analog capture or other equipment, possibly renting whatever deck or box for the day. As DV can stick to 601 specs with reduced color gamut, might be safer to stick to mjpg or mpg2 for capture as they can use the full PC colorspace, and any 601 complience dealt with later in Vegas - the important thing is to get the white data captured so you can lower any levels as needed.

Lightway wrote on 7/26/2003, 5:34 PM

Thanks for the advice. It's actually PAL though - I should have mentioned that. I wonder whether the same principle applies... I don't seem to have control over th capture parameters, but I'll try some of the suggestions

johnmeyer wrote on 7/26/2003, 7:48 PM

Make sure the "Edit" switch on your VCR is set to the "Edit" position. Sometimes the switch is called "Dub." This will defeat the sharpening circuit (which you want off when copying). This might clip some of the whites.

Use S-Video from your VHS deck to your DV camera if you are not already doing so.

Make sure everything (VHS, DV camcorder, and computer) are plugged into the same mains outlet.

Finally, if you suspect that there is a problem on the computer end of things, you easily determine if that is where the problem lies. Simply copy some of the VHS to the DV deck (onto DV tape), and then play it back on your TV monitor directly from the DV deck. If there is a problem, and the video looks OK going from the S-Video of your VHS deck into your TV, then there is someting amiss with the DV encoding.