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Old 3rd December 2011, 22:16   #4  |  Link
TheSkiller
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Join Date: Dec 2007
Location: Germany
Posts: 632
Quote:
Originally Posted by VirtualDubFan View Post
Why? Well, first I want be efficient, to capture no more than is necessary to get the best possible picture. 352 is something of a standard width, as in VCD for example. I know some say "hey you might be missing some detail" but VHS and analog TV really don't even have the equivalent of 352 columns, it's more like 304 or 310 I've read in reliable-appearing sources.
Yeah, but just because VHS carries only about 250 (at best) lines (samples) in horizontal direction does not mean 250 (or 352) digital pixels are able to hold all those samples!
It may sound weird from a digital point of view but it's true, you cannot represent the full horizontal resolution present in VHS with a horizontal resolution of just 352 digital pixels. You need at about 2 times the amount of pixels to hold all the 250 samples of VHS. So anything below about 500x480 is going to lose samples (of course only if there were such samples to begin with, which means the tape has to be a high fidelity recording, like a commercial one, not a copy of a copy for example and the deck should output a good picture, some like to soften it a lot).
This is also why statements such as "VCD is about the same quality as VHS" which one can find commonly on the internet are very wrong. VCD is inferior to VHS in almost every way.

But there's another "gotcha", most (if not all) capture hardware will always digitize internally with full NTSC/PAL resolution, the resolution you request is then simply downscaled by the driver, probably using an inferior resizer.
The same goes for the color space. Internally the capture hardware uses YUY2, RGB is simply made by the driver from the YUY2 raw data, there is not point in capturing in RGB, you do not gain anything from that. YUY2 is perfectly fine, YV12 should by all means be avoided during capture.

So, in conclusion, if you are not starving on HDD space there is no reason not to capture at the full resolution that your capture hardware supplies, which is in most cases either 704 or 720 (you should test which one is correct, otherwise you just get a scaled version of the other one) and 480 lines, some use all 486.


Edit: Your workflow is very time consuming and outdated. You can do all that easily, faster and with better results in AviSynth.
It would work like this: create a script which loads your raw capture, does inverse telecine and converts to YV12 (very basic script), then open this script in VirtualDub as if it was a video file. Serve to Xvid using VirtualDub's "fast recompress" mode. Done. No need for AVIDemux or SUPER.
You can encode the audio straight to MP3 for example in VirtualDub (just install LameACM). It will be muxed into the AVI output together with the video.
352x480 is fully DVD-compliant, no reencode needed (but it has to be MPEG2 in an authored DVD structure of course, not Xvid). If you aim for "best versatility", then why not go for a standard Video-DVD, Xvid does not play on all hardware players. You also have a full 4.38 GB to play with then.

Last edited by TheSkiller; 3rd December 2011 at 22:53.
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