Some notes on VHS resolution...

[Patrick]

Vikingman, you realize that you've gotten Elie upset now!

[Grigory]

Hi,

As for broadcasting qualty, the standard has only 3 Mhz for "pure" luma bandwidth. Everything else is going inside the chroma subcarrier spectrum. Theoretically, modern filters can separate luma and chroma components to produce correct 400-500 lines of resolution, because the lines of chroma and luma spectral components are not overlapped (especially in NTSC) . However, typical TV receiver treats analog TV signal as simple composite video signal, as it is actually. To separate luma and chroma, simple low-pass filters are used, which limit the luma resolution to 330 lines or so. This is true for my Sony 25' TV. It came to me with a schematic diagramm, so I can see where the filter is, and how it works on supplied waveforms examples.
So, you NEVER get more than 330 lines of luma bandwidth on such TV set with composite (VHS!!!) connection too.

S-video is another story. With S-video connection, chroma and luma component are given different wires. This is the only difference. Chroma components are going on the same subcarrier, and have same bandwidth, so you cannot expect better chroma resolution.
However, luma component has no need for filtering out chroma components, so you can bypass this filter and get full luma resolution.

I have now no RR_G, so I made a test on another device. I captured a text from Notepad as a still image.
First, I made uncompressed avi from still image, with 720x576 size, equal to the original test image.
Then I made two mpeg2 videos, 50 frames each, with bbmpeg encoder. One video had 720x576 frame size, next one was 352x576.
I looked on a mpeg2 video displayed by Hollywood+ decoder on a TV.

720 pixels frames were definitely better in resolution. I could see each character very clear. However, bi-linear resized in bbmpeg frame had still readable characters.

Ok, here we see that 720 pixels are better for composite connection, when viewed on average TV.

Then, I recorded these videos to VHS and tested the image from VHS output on the same TV. I could not distinguish between original 720 pixels movie and 352 movie. Both had blurred characters, still readable, but the blurriness was the same and slightly worse than in the case or 352 pixels original movie.
Conclusion: the mpeg2 decoder that I have, can produce 352 pixel per line video on TV output, that gives NO additional loss of resolution in comparison with 720 pixels per line video, AFTER RECORDING TO VHS TAPE.
Yes, before the tape, the full size movie has better resolution on TV screen. If RR_G and TV output of Gxx card gives you resolution drop AFTER TAPE, the card does not follow Nyquist theory.

Now about resolution itself. I think that the video now is always digital.
Look: in vertical dimension, you always have discrete lines, samples. Do have much to worry about it? When you say about sampling uncertainty, keep in mind that you have not a random sampling, but sampling on a regular intervals. So, if the picture is shifted, ALL digital samples will get different values. It is not the same as an assumption that each pixel has 1/2 pixel uncertainty. Everything is well predictable on entire picture, and this forms a basis of Nyquist theory: regular samples.

Yes, the theory works in practice only if it is implemented as it should be. My experiment with Hollywood+ decoder card shows that this is possible. If you insist that RR_G can reduce the resolution of VHS video if (before recording to VHS) you pass the source through RR_G at 352 pixel per line mode, then RR_G has resolution below the value, typical for correct implementation.

Why the video is digital: it is now produced from CCD devices that have discrete structure both per line and per light sensors along the line. This sampled video can later be used in analog or digital form. But its origination is from discrete samples!

Now, look and another end - TV screen. It is composed from triangles or from vertical lines of light-emitting substance. So, even pure analog video (which does not exist) is displayed by a set of discrete samples.

Some TV screens have well visible structure of elements in OFF mode. I measure the period of SCREEN SAMPLES on 29' TV from Philips - it has about 600 vertical lines on the screen. Can you expect more than 400 lines of resolution on this TV? NO.

Finally, if you see the difference between 704 and 352 pixels editing on VHS tape - use full size captures.

See also: http://www.bealecorner.com/trv900/respat/
Here you can find more at the links presented.

Grigory

[This message has been edited by Grigory (edited 10 November 1999).]

[Patrick]

Grigory, you neglected to mention the most important items in this thread.

Where do the world's most beautiful women reside, and what country produces the best cars?

[Brian Ellis]

Patrick

Women: nowhere I've been, and I've travelled one helluva lot!

Cars:
(reliable, safe, mass production variety), unquestionably Japan

(unreliable, beautiful, expensive variety),
unquestionably Italy

(cheap but popular crap), unquestionably UK and USA




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Brian (the terrible)

[Patrick]

Brian, that's a sad commentary on the women in the places that you've travelled to.

Maybe you should list off these countries so that the rest of us can avoid going there.

[VIKINGMAN]

Grigory!

I DO NOT agree, whatyou're trying to tell us with your "test" of lines!

You say: Then, I recorded these videos to VHS and tested the image from VHS output on the same TV. I could not distinguish between original 720 pixels movie and 352 movie. Both had blurred characters, still readable, but the blurriness was the same and slightly worse than in the case or 352 pixels original movie.
Conclusion: the mpeg2 decoder that I have, can produce 352 pixel per line video on TV output, that gives NO additional loss of resolution in comparison with 720 pixels per line video, AFTER RECORDING TO VHS TAPE.
Yes, before the tape, the full size movie has better resolution on TV screen. If RR_G and TV output of Gxx card gives you resolution drop AFTER TAPE, the card does not follow Nyquist theory.

Now Grigory! As long as you haven't found the point as to where the sourse has a smaller resolution then the end recorder, you won't be able to tell the difference! It might well be that the VHS-recorder will record a better signal (lines) from the 720 lines than 352. As long as you're not at "the bottom" of the resolution of your VHS, your experiment isn't valid.

What you're stating is, that if I make a copy from video-recoder to video-recorder like this:

SuperVHS-cam to VHS-player
VHS-cam to VHS-player

Then I won't see any difference on either tape! Is this correct!? Nope, there WILL be a difference and anybody with a S-VHS and a regular VHS can confim this. This all in practical fassion, not looking at lines'n'numbers!

And talking S-VHS, there's another issue regarding technical quality. Lenses mean the world! As I've stated before: Sony makes some fine Pro-gear, like studio-cams, but if you look close enough you'll see that the lenses are from Canon! Therefore if you have 2 cams, where the one is a Sony and the other a Canon. They might look exactly the same and they are mechanically, CCD and so on. The Canon will have their own lens, whereas the Sony will have some oem-lens from Sony! It might not be a big difference in pic-quality, but him sure as hell, that it is there!

Brian - Bvahhaahahahahahahahah....never ever again mentione...hahaha....safety....hahaha...in the same sentence as Japaneese cars..hahahaha!

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ASUS P2B-S, PII-350 (o/c to 412MHz), 128MB RAM, Cheetah 9.1 GB, Matrox Mill. G200SG, SB 64AWE, Plextor 32x CD-Rom, Sony CDU-924S CD-R, Canon BJC-7000 InkJet and Canon CanoScan 300 Scanner.

[This_Idiot]

Patrick,

Please can you define "beauty" as in women? Are we talking facial features, bodily stature, personality ?

You can take your pick from Lines of resolution or Parrots as the unit of measurement.

Most desirable car in the world ? Probably an original Cobra 427. Most beautiful woman in the world ? I married her. Both these measured in personal pixel parrots.

[Patrick]

Chris, you're either a very loving, devoted husband, or you're afraid that your wife might see this thread!

I'm not too sure what to make of Grigory's comments. I'm curious what would have happened if Grigory had stayed in Japan for longer than three months.

Regarding what constitutes a beautiful woman, I believe that we, as men, rate women differently as we get older. Initially, as hormone crazed teenagers, we were obsessed by boobs and butts. Facial features were less important (within reason), and personality... well, personality was something that just got in the way. Some men never get beyond this stage, and they usually live an unhappy life messing with one bimbo after another. Facial features seem to become more important as we get a little older. We soon realize that this is the part of a woman that day in and day out we will be looking at and dealing with the most. If their face isn't too pleasing to look at in the beginning, the situation's only going to get worse! I myself, have a weakness for soft eyes. I can overlook a lot of faults if a women has eyes that can turn me into jelly. Finally, as we fully mature, we realize that no matter how physically attractive a women might be, it makes no sense to spend time with her if she has the charm and personality of an alligator. Sure, it's nice to have an attractive babe hanging onto your arm when you make your grand entrance at an important function, but if the tradeoff is a life of misery, forget it.

Now I realize that judging the beauty of a women is different if we are simply to be admiring from afar, but I've attacked this challenge with the idea of actually having to live with the object of affection.

So to rate these characteristics on a scale of 1 to 10 Parrots (with 10 being more desirable), I'd have to say:

Personality - 10
Facial features - 8
Bodily stature - 7

Please, no nasty emails from militant feminists. We're just a bunch of video/computer geeks having some harmless fun.

[This_Idiot]

Hi Patrick,

Moira doesn't often use the net, and certainly never checks out this site. Fact remains that I am a loving devoted husband (with good reason).

Before embarking upon the next part of my discourse, I'd like to endorse what you said about feminism (I'd hate for swamp monster to come bite my arm off). So the rest of this is totally a-sexist and can be applied as well to either sex.

In an ideal world we would all have a selection of cars for different jobs (given unlimited garage space and funds). So we could have an MR2 for great handling, that ole Cobra for brute force, a diesel Peugot 106 for economy and a Renault Espace for practical family stuff. Oh, and a Cosworth because I love them, and a Lotus Esprit because they look so great. Naturally you have to substitute your own models here.

So given unlimited funds, charisma and living quarters, you might choose Uma Thurman for her face, Xena warrior princess for her ability to guard the family, Judge Judy for her down-to-earthness and Jenna James to wake up to. You could substitute Mel Gibson, Kevin Costner, whoever if you felt that way.

Funny that no-one mentioned Korea earlier in the thread. Voted (by consumers) as the top 2 buys in the UK this year, the Subaru Imprezza and Legacy. Best VFM, lowest problem rate, best service ! I've never been to Korea so I can't comment on the women. Although that begs the question "when will the Phillipines bring out a top car"....

[Grigory]

Women: of course, Russia.
Cars: the most popular here are German cars, starting from Golf and above. Every car here has to resist our:
Roads, full of "imperfections"
Salt
Dust
Gas quality
poor servicing
...


German cars are the best.

As for women, my list of countries includes USA, Canada, Spain, Japan, Italy (north), Austria, Chech republic, Germany, Holland, Belgium, France, ...

Russians (Ukrainian too) are the best.

However, after I have spent 3 months in Japan without my family, I found that my taste began to change... So, it depends.


Grigory

[Patrick]

What, you mean you wouldn't want to wake up to Judge Judy in the morning?

Well, I suppose that would be less upsetting than to wake up and be facing Mel or Kevin...

[Grigory]

Vikingman,

I am sorry to be very busy now to comment you post.

One advice - look how digital video and audio work and see that the bandwidth in digital is VERY different from bandwidth determination in analog.

So, VHS to VHS is definitely worse than SHVS to VHS, even in luma resolution values.

This is not true for the following comparisons:
SVHS-RR@352-VHS is EQUAL to SVHS-VHS
VHS-RR@352-VHS is EQUAL to VHS-VHS

I NEVER said anything more.
To check that I am correct, do the home task.

I am NOT discussing here noise levels, chroma resolution, some distortions introduced by digital compression.

I am sorry, I am very busy to explain everything in details. You can find a lot of explanations in every book on radio electronics.

Patric,

My wife came to me in Japan and made me very happy. So, the experiment was not done up to the measurable result.

Grigory

[Patrick]

Ok Grigory, I get the picture.

[mrpc]

What an interesting thread!

Brian: come to Texas and I'll SHOW you the beautiful women. We raise 'em in special vats and the ugly ones we ship off to Hawaii to make the Sports Illustrated Swimsuit issue.

Richard

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Abit BH6; 300A@450; 128MB
FastTrack66 dual KA 18GB; Marvel 200; MX300

[Elie]

Hi Guys,

Ahrm,

Italian cars RULE!
And I'm not talking Fiats and Seats

VIKINGMAN, What about Alfa Romeo, Lancia, and of coarse MASERATI all are afordable hehe, that's if you buy used especially here in Canada.

I agree Scandinavian women are extremely pretty but Canadian women have to be the best looking right Patrick
Here's why..
In Canada we have such a great mix of cultures from different parts of the world that the end results are simply stunning

Regards,
Elie