Q on VHS to DVD thru MiniDV Camcorder

[casperg]

Hi All,

I am trying to make a DVD of an old home video in VHS (NTSC). I do not have a capture card, hence I used my Sony MiniDV as a pass-thru device to convert the movie into an AVI on the PC.

VCR -->(analog)--->Sony MiniDV--->(Firewire Digital)--->PC

The problem :confused: - The captured avi has a resolution of 720x480 (which matches the DVD specs), but when I play the avi on my PC the image seems stretched horizontally (or compressed vertically?...)

I will be watching the DVD both on a NTSC TV as well as my PC. I have the Canopus DV decoder and I am going to use AVISynth to frameserve the AVI to TMPEGenc to make my MPEG2 files.

Should I ignore the distorted picture and just encode it directly to MPEG2 and make my DVD? Or do I have to resize the AVI before encoding? I just want the movie to display properly on the TV. I read all the discussion about aspect ratios on this forum, but it only left me more confused.

Any answers/comments will be much appreciated.

Thanks.

[ulfschack]

Almost certain that it'll be fine as long as you do the mepeg encoding with the proper AR flag set. I e 4:3 in your case as I doubt that your VCR recording is 16:9. I said almost, cause I'm from a PAL country myself.

In any case, why not just make a short test clip and see for yourself?

cheers

[Xesdeeni]

PC pixels and TV "pixels" are not the same shape. PC pixels are almost all square (1280x1024 is one exception). But TV "pixels" are generally based on the ITU-R BT 601 (formerly CCIR-601) specification, which specifies a 13.5MHz sample rate. On a 4:3 NTSC TV, this (720x480) translates to rectangular pixels that are taller than they are wide. On a 4:3 PAL TV, this (720x576) translates to rectangular pixels that are wider than they are tall.

But most PC players show each video pixel as a PC pixel. So if you take the tall, thin NTSC pixels and show them as square, the image appears short and fat. And if you take the short fat PAL pixels and show them square, the image appears tall and thin.

Some players correct for this, such as the Elecard player, so the image looks correct.

Note that anamorphic videos also use 720x480/576, but at a 16:9 aspect ratio. So in both NTSC and PAL, the pixels are wider than they are tall, although they aren't exactly the same rectangle.

Xesdeeni

[saptecai]

When I convert old VHS -->> DV (using composite conectors), the bottom of the picture on the DV tape has the bottom 3-4 lines completely out of alignment with the rest of the image.

Has anybody noticed something similar ?? Anyway to repair that? Probably not... :(

I am thinking about cropping those and then resize back to 720x576 for the final DVD.

Recently I bought a DVD ("The Point!" (http://www.harrynilsson.com/article1510.html)) which I suspect it was a low budget "VHS -> DV -> DVD" conversion because it has the same screwed 3-4 bottom lines. How careless!

[Xesdeeni]

VCRs use a circular, spinning head for playback and recording of the video. The tape wraps around the video head as it spins (http://static.howstuffworks.com/gif/vcr-path.gif). But note in the image that, the head doesn't touch the tape for part of the rotation. It is in this small region, where the head leaves the tape, that the video gets screwed up. This is sometimes called "head switching."

However, remember that TV was designed to be overscanned. So this garbage is cut off on your TV. When viewing on a PC, you may see this effect at the bottom.

If you insist on removing it, just blank out the lines, and don't scale the image. You will screw up the aspect ratio so that everything will appear taller than it should be, and if you are keeping the results interlaced, you'll have issues scaling the fields.

Xesdeeni

[FredThompson]

yup, crop out the junk and letterbox to create the necessary blank lines.

Also, since your source is NTSC DV, I highly suggest you use Xesdeeni's 411 Helper if using VirtualDub, trbarry's Reinterpolate411 if using AviSynth. Tech discussion is at http://forum.doom9.org/showthread.php?s=&threadid=57112