Converting Analog.....

[crazycory23]

Will I get better resolution on the conversion of VHS Tapes to mpeg2 if I use a S-VHS VCR over a standard VCR? I am using the Videoh! PCI by Adaptec as my capture card with movie mill for software and a standard Sony VCR for the output. Is a S-VHS VCR really worth the investment???

Thanks guys.

[Scheif]

Your source material is VHS, and you canont "manufacture" extra quality by playing it on an SVHS VCR. SVHS is only better if the video was originally recorded in SVHS.

[Cornucopia]

That's not exactly true...

SVHS decks will play VHS tapes out the same ports they play SVHS tapes--this means you have the advantage of S-Video output. Plus #1.

Also, SVHS decks are already configured to be able to handle the higher bandwidth of SVHS. This means that the lower bandwidth VHS tapes will be that much more easily reproduced--flatter response, correct comb filtering and all. Plus #2.

And many SVHS decks are the professional or prosumer type which include onboard Noise Reduction and TBC functions. So even your VHS tapes will playback cleaner and more stable. Plus #3.

Having done tens, maybe even hundreds of (S)VHS tape transfers and conversions, I can tell you in all confidence that it does make a difference.

Scott

[Scheif]

I stand by my comment.

1) Simply pushing the video out of an S-Video port does nothing to improve quality.

NTSC color video consists of two signal components -- the luma, or brightness, and the chroma, or color. The luma signal carries a grayscale image, and is the format originally used for black & white broadcasting. The chroma signal adds color information to the picture, and the result is a color image. This is how backward compatibility was maintained when color sets came out.

The longer you can keep the two signals separated, the better the image quality. So, S-VHS VCRs record these signals independently, and S-Video transports them on separate lines. (That's why S-Video cables have four pins.)

Ordinary VHS VCRs accept (and record) only composite video, in which the chroma and luma signals have already been combined.

So, when you play back a VHS original on an S-VHS deck, it must separate these two signals again, and even the best S-VHS VCR will not be able to separate the signals perfectly. You could possibly argue that the S-VHS VCR will be able to perform this separation better than your television (which, of course, it does when you send it composite video), but, in this day and age, I'd bet that S-Video-capable TVs and S-VHS VCRs are equally good at this task.

2) S-VHS VCRs may have a very slightly flatter response when playing back VHS originals, but again, we are talking about very mature technology. I don't think this represents an appreciable benefit.

3) I did not consider time-base-correctors (TBCs) in my original post, and I admit that, in many cases, they will help. As you said, though, these are most commonly found on the higher-end models.

[Cornucopia]

Scheif,
Your arguement is good as far as it goes, but it doesn't go far enough.


You say:

The longer you can keep the two signals separated, the better the image quality.

The corellary to that is that IF they do get combined, the earlier you can re-separate them, the better (cleaner processing, less interference, etc).

You mention ordinary VHS VCR's having only composite inputs, but I know of a number of high-end consumer, and middle-of-the-road industrial VHS decks that have S-Video connections. And most all SVHS decks have composite connections in addition to S-Video. Where am I going with all this? Well, since either type could include either connector--the main difference is in how the signal is put onto tape.

VHS and SVHS tape is recorded as a modulated RF signal.
It has an amplitude plot of the frequency spectrum that looks like this:

|
|
|**********
|*********** *
|************ **
|************ ***
|****************
------------------------------>Freq.
|<---LUMA--->|<-Chroma

The difference between VHS and SVHS being that the valley that separates the Luma from the Chroma is a whole lot wider, in addition to the Luma extending out to a higher freq.
Since SVHS has them more clearly separated by frequency, its much easier for the SVHS electronics to tell what is Luma and what is Chroma and therefore keep each signal type clean and unmixed. VHS has them butted against each other, nearly overlapping, so there is a lot of grunge in both signals unless they are very carefully filtered. In fact, it wasn't until VHS had comb-filtering stock in most of the decks' electronics (c. 1992) that the signal really started to look better. SVHS had comb-filtering incorporated from the start.

I'd say that all these benefits ARE minor, like you say. But 4 or 5 incremental benefits start to add up. And I know what my waveform monitors and scopes show, and what my eyes see. It does look better coming out of an SVHS deck.

Now, does this improvement make a difference with regard to monetary constraints? I don't know. There are probably other things that could be done by the home user, without resorting to buying an SVHS deck, that would help clean up the quality of the capture and subsequent conversion to (S)VCD/DVD.

Scott

[FulciLives]

Hello

This probably does NOT apply to most (probably nearly all) computer capture cards but I have read that if the comb filter on the recording unit (the input on the computer capture card in this case) has a really good comb filter then it is better to feed it composite video over S-Video since the comb filter on the recorder is better at doing the seperation.

One such example is the Panasonic line of stand alone DVD recorders. They have some sort of 3D adaptive Y/C comb filter and I have read many reports that it does SUCH a good job that you should always feed it a composite video signal from a source such as VHS, S-VHS, 8mm and Hi8 and even LaserDisc which WAS the best quality format BEFORE the DVD format.

However, the only computer capture cards I am aware of that have a 3D adaptive Y/C comb filter (similar to that used in the Panny stand alone DVD recorders) are a couple of models made by canopus which are just as much as a stand alone DVD recorder!

- John "FulciLives" Coleman

[Scheif]

Scott,

OK, I'll budge a little and agree with you that you can, in many cases, get a few very minor picture quality benefits by playing back VHS source material in an S-VHS VCR as compared to an ordinary VHS deck. Probably unnoticeable to most, but present nonetheless.

In particular, this argument is strong:

The longer you can keep the two signals separated, the better the image quality.

The corellary to that is that IF they do get combined, the earlier you can re-separate them, the better (cleaner processing, less interference, etc).

This ocurred to me after I posted, and I definitely agree. It is better to separate the signals before sending them out the back of the unit.

[Cornucopia]

See, that's the way international relations should be. I move a little closer to your way of thinking and you move a little closer to my way of thinking!

Scott

[crazycory23]

i guess it makes since that it cant be that much better, cause why are they only made by JVC if they are so great. Thanks for the help guys. Do you know of any software that can clean my vhs conversions to look a little better. Thanks

Cory