Interlaced MPEG2 at 352x288?

[zedolfblack]

Having recently got my first dvd writer, i'm now looking at making dvds instead of xvcds out of some VHS captures.

Capturing at 352x576 25fps with huffyuv compression.
Getting reasonably good results with picture quality and thinking about converting to half D1 resolution MPEG2 - planning on getting two films on a DVD if the quality's acceptable so a 3000kb/s bitrate two pass VBR encode with TMPGenc is next.
I'm planning on leaving the video interlaced - that's why i captured it at 352x576.
But i'm also considering converting to 352x288...
Would TMPGEnc maintain the complete interlaced picture at 288 lines of resolution?
Would 352x288 give a noticeably better picture with the 3000kb/s bitrate i intend to use? More bits/pixel logically but would i see much difference?

Thanks.

Martin.

[BJ_M]

352x288 wouldn't (shouldn't) be interlaced ...

[FulciLives]

Having recently got my first dvd writer, i'm now looking at making dvds instead of xvcds out of some VHS captures.

Capturing at 352x576 25fps with huffyuv compression.
Getting reasonably good results with picture quality and thinking about converting to half D1 resolution MPEG2 - planning on getting two films on a DVD if the quality's acceptable so a 3000kb/s bitrate two pass VBR encode with TMPGenc is next.
I'm planning on leaving the video interlaced - that's why i captured it at 352x576.
But i'm also considering converting to 352x288...
Would TMPGEnc maintain the complete interlaced picture at 288 lines of resolution?
Would 352x288 give a noticeably better picture with the 3000kb/s bitrate i intend to use? More bits/pixel logically but would i see much difference?

Thanks.

Martin.

352x288 is half 352x576 thus DESTROYING the interlaced picture.

You are doing fine capturing at 352x576 but you don't want to to the 352x288 route. Just TOO much of a quality hit even with a VHS source.

Remember a VHS is around 240 lines of resolution but this is an analog measure. So 352x288 is NOT enough.

Personally I don't like doing Half D1 (352x576) less than 3500kbps even when doing a 2-pass VBR

3000kbps can be a bit low especially with a "noisy" video source such as VHS which tends to need MORE bitrate because of the "junky" signal quality of VHS.

- John "FulciLives" Coleman

[zedolfblack]

Thanks.

As i thought - using 288 lines of resolution isn't the best idea!
I'll keep to my original plan and use 352x576.

Martin.

[SatStorm]

The interlace barrier is 280 lines. PAL use 288.
So, it is possible to have interlace 352 x 288

This is impossible for NTSC users (they have 240 lines, so they are progressive).

In the matter of fact, do you remember sefy's SxVCD? It was exactly that... Interlace mpeg 2 @ 352 x 288.

I have plenty DVDs @ 352 x 288 and the picture is trully VHS like. Of course there are 2 issues to concern:

It is more difficult to keep interlace a 352 x 288 framesize (but possible, with virtualdub/TMPGenc)

Many DVD standalones won't play it correct. I mean, they create something like a tremble in the picture.

If you have a good standalone, then 352 x 288 is the best solution for VHS convertions. Interlace 352 x 288 @ 1150-1800-2520 looks exactly like VHS on TV.
But unfortunatelly, most DVD standalones we use today, expecially those cheap ones (region free / de macrovision), don't do a good digital to analogue picture convertion and the results look weird. Playable of course (after all, it is DVD standard....), but not in a decent way...
In the matter of fact, this also explains why some people believe that 720 x 576 produce the best picture from any source: It doesn't: The DVD standalone they using, simply don't like other framesizes...

[flaninacupboard]

I was just about to hit reply and say "according to satstorm, it's entirely possible" but he beat me to it!!
As ever i'd simply suggest you try it and see if you're happy with the quality. I've found from an analogue source ~6mbps average is best, or from a digital source ~4mbps is good.

[lordsmurf]

It's supported (unofficially, like MP2 audio in NTSC) by the DVD spec. A lot of players play it, including all of mine. Even the stubborn Toshiba if I put it on a CD-R.

SHOULD you do it? Well, that's a different story.

Only do it if you care about space over quality. In all, 352x288 interlace PAL MPEG-2 is MUCH, MUCH better than MPEG-1 352x240 NTSC on DVD.

But both are bottom-barrel. Go higher. 352x480, 352x576

[Xesdeeni]

Remember a VHS is around 240 lines of resolution but this is an analog measure. So 352x288 is NOT enough.

Please don't get confused. The 240 "lines of resolution" is a HORIZONTAL measurement of analog resolution. The means it is a measure of how many vertical lines can be represented on one horizontal line. It is also specified at the same width as the image is high. In other words, for a square (1:1) image. For a 4:3 image, this value would translate to about 320 analog lines of resolution across the entire image width.

Vertically, a PAL/SECAM image contains over 576 lines of resolution--over 288 per field (576/288 are used because they are the nearest multiple of 8, but analog devices can provide a few more lines of video). That is the case regardless of the format (VHS, S-VHS, Beta, Beta SP, etc.). VCDs are the exception, although the players still have to conform, so they replicate or interpolate to make up the missing lines.

For completeness, I must point out that the analog measure of "lines of resolution" IS NOT equivalent to digital resolution. In the above example, 320 pixels per line WILL NOT reproduce the 320 lines of resolution. The exact ratio required is debatable, but most agree that around the square root of 2 (1.41) is functional.

Xesdeeni

[SatStorm]

In short terms: PAL VHS is ~ 380 x 300 in a ~ 720 x 576 carvas. Others say it is more, others say is less (most users say less).
We CAN'T capture the VHS info only. We can't seperate it from the carvas.
So, we capture all the carvas, which includes the VHS info.

Then, we choose from 2 things:

1 - Try to reconstruct that ~ 380 x 300 VHS resolution. VERY difficult for PAL and impossible for NTSC, because of the interlace barrier.

2 - We encode to mpeg all that Carvas which includes the VHS info. It is an overkill, but it is the easy and fast, with excellent results.

In praxis, we always choose method 2 (which is the only thing you can do with NTSC), and that explains why we encode VHS to 352 x 480/546. It is a neccessary overkill for NTSC and the easiest alternative for PAL.
It is the overall better alternative we have for VHS.

I repait: Encode to 352 x 576/480 from VHS. We don't capture neccessary at this framesize. That depends heavily from the abilities of our capture card / drivers we use. The "safe" mode for capturing IMHO, for all cards, is 704 x 576/480. And that has nothing to do with what is the source...
From the commercial cards of the current market, seems that only the latest ATI and all the nvidia based cards, capture correct on all the framesizes. On the bt8xx(x) cards, it seems that the results are always a product of resizing...

[Xesdeeni]

In short terms: PAL VHS is ~ 380 x 300 in a ~ 720 x 576 carvas. Others say it is more, others say is less (most users say less).
We CAN'T capture the VHS info only. We can't seperate it from the carvas.
So, we capture all the carvas, which includes the VHS info.

I don't understand what you are specifying. Is the 380x300 pixels? If so, then you are losing vertical information.

The discrete sampling of the video signal vertically, even a completely analog one, is already done, when the image was divided into scanlines. Even if the video is filtered prior to being converted to scanlines (by the camera or electronically), there are still precisely 480/576 vertical samples. If you downsample vertically, you will lose information.

Horizontally, I believe most signal analysis experts would say you were a bit low at a 380 pixel per line sample rate. Assuming VHS bandwidth is 240 "lines of resolution" (and I believe this actually applies to NTSC VHS VCRs, while PAL VHS VCRs have a slightly higher bandwidth), that means about 320 analog lines of resolution across the 4:3 screen. A typical value for the Extended Kell Factor (used to estimate that relationship between analog and digital resolutions) is the square root of 2 or about 1.414. That means approximately (320 * 1.414) 452 pixels would be required to represent those 320 analog lines of resolution.

In practice, there are other factors that affect the quality of your source. It is entirely possible that 240 lines of resolution are not reproduced by your equipment (your tape could be old or a copy, your VCR could have a lower bandwidth, your camera could have a lower sensor resolution, you could have used the slower speed of the tape, etc.). So it is entirely possible (and I'd actually say probable) that 352x480/576 is sufficient to reproduce what is on the tape. But if the source maximizes the abilities of the VHS format, you will be losing some horizontal information at that resolution as well.

Xesdeeni

[SatStorm]

I don't specify, I generilize. A total different approach of the subject from you.

You see, you are too technical Xesdeeni, and this forum isn't "doom9" like... Neither my english are good enough to follow you easy.

I didn't try to explain or correct all those correct things you mention about picture loses and the various factors of the analogue to digital convertion.

I tried to answer easy and in a general way, something which I needed 3 years to express it in a simply and understanding by anyone way, with my limited english skills.

Those who need more techical infos, details and the theory behind all this, soon or later gonna move to doom9 forum, as you did (and others).

In other words: You offer a college lesson, to hi school students!

[Xesdeeni]

Well, I'm not sure I agree that you can give a non-technical answer to a technical question about a technical device. But I understand your point about simplification. The problem I always have is if I give a simple answer, everyone wants an explanation to justify my answer anyway.

So in simple terms, without any explanation:

Capture at the highest resolution your capture card can handle. For VHS, scale down to 352 x 480/576 with highest quality software scaler and encode with CinemaCraft Basic. If the source was from film, inverse the telecine and encode at 23.976/25 progressive fps. Otherwise, leave the video interlaced.

Xesdeeni

[junkmalle]

Xesdeeni is correct in stating that VHS has a horizontal resolution of 240 lines (square) but that is only for the luminance (intensity, black/white) portion of the picture. The chromanance (color information) is half that. That's why colors are smeared much more than the intensity.

VHS tape has as much vertical resolution as the original source. So, if you want to retain that resolution, you should capture at 480 (NTSC) or 576 (PAL) in the vertical dimension.

[SatStorm]

@Xesdeeni:

So:
Someone asks "how windows works". It is a technical question right?
You gonna start telling him the machine code of windows, or you gonna say
"push the red button, click on the "start" tab at the bottom right of your screen and from there choose the program you wish?

You can answer technical questions without be so technical.
IMHO always...

[Xesdeeni]

@Xesdeeni:

So:
Someone asks "how windows works". It is a technical question right?...you gonna say "push the red button, click on the "start" tab at the bottom right of your screen and from there choose the program you wish?

If the question was really "how [does] Windows work?", I would. In answering such a question, I'd consider the level of knowledge of the person making the query, but the answer would absolutely be technical. Your answer is more associated with a question like "How do I work Windows?" The former question is most definitely technical. That latter question is a usage question and is definitely NOT technical.

What was asked in this thread was certainly a technical question...take a look ^^^ up there. It included resolutions, fps, encoding, codecs, bitrates, etc.... all technical details. Without more information on the technical level of the original poster, I opted to provide too much information, rather than not enough. I also consider that other people search these forums and find information just by reading. So while I may have provided too much information for Martin, the info might come in handy for a lurker.

The bottom line is that you disagree with my choice to be verbose. That's your choice. But I don't see why you waste our time complaining.

Xesdeeni

[FulciLives]

Remember a VHS is around 240 lines of resolution but this is an analog measure. So 352x288 is NOT enough.

Please don't get confused. The 240 "lines of resolution" is a HORIZONTAL measurement of analog resolution. The means it is a measure of how many vertical lines can be represented on one horizontal line. It is also specified at the same width as the image is high. In other words, for a square (1:1) image. For a 4:3 image, this value would translate to about 320 analog lines of resolution across the entire image width.

Vertically, a PAL/SECAM image contains over 576 lines of resolution--over 288 per field (576/288 are used because they are the nearest multiple of 8, but analog devices can provide a few more lines of video). That is the case regardless of the format (VHS, S-VHS, Beta, Beta SP, etc.). VCDs are the exception, although the players still have to conform, so they replicate or interpolate to make up the missing lines.

For completeness, I must point out that the analog measure of "lines of resolution" IS NOT equivalent to digital resolution. In the above example, 320 pixels per line WILL NOT reproduce the 320 lines of resolution. The exact ratio required is debatable, but most agree that around the square root of 2 (1.41) is functional.

Xesdeeni

Perhaps I didn't say it very well but I was attempting to point out that VHS at 240 lines of resolution is an analog measure and that 352x288 is a digital measure ... the two don't "match" ... and that 352x288 really is NOT enough to get ALL of the quality that exists on the VHS format.

- John "FulciLives" Coleman

[SatStorm]

Who complains? And who wastes time?

Xesdeeni, I'm long enough around to know you well. Once a year you came here and post the same stuff, with the same order and the same exactly words.
Why you don't post those things as an article? Once and for all?
After all, you copy / paste the same exactly things each year...

So, I tried to speed up the proccess this time, because I have seen the scenary more that once with you.
That's all...

It has nothing to do with your knowledge on those subjects, neither your very advance english skills.

Afterall, we don't argue on something, we expressing the same things on a different way.

If I have a problem with you, is not about your choice to be verbose, but with the fact that most of the non native english speaking users of THIS international forum understands nothing of what you say.

So, be verbose if you like, but with the plain awful english than anyones understand....
We are not all americans you know, neither we speak good english.

[Xesdeeni]

Once a year you came here and post the same stuff, with the same order and the same exactly words.
Why you don't post those things as an article? Once and for all?
After all, you copy / paste the same exactly things each year...

That's an interesting comment. It's completely wrong, but it is interesting. If I want to quote a previous post, I link to it. Otherwise I waste my time and this server's storage.

If I have a problem with you, is not about your choice to be verbose, but with the fact that most of the non native english speaking users of THIS international forum understands nothing of what you say.

So, be verbose if you like, but with the plain awful english than anyones understand....
We are not all americans you know, neither we speak good english.

So you are complaining because I use words that are too big!? Do people really go to websites in your native language and ask that it be "dumbed down" so that they can understand? What type of reaction do they receive?

Xesdeeni

[flaninacupboard]

Xesdeeni,

Just drop it.

The original question was wether 352X288 could be interlace, the answer is yes. satstorm then proceeded to offer some information and advice. That's what this forum is for, and we are all free to do so.

I don't believe that satstorm is confused over the issue of optical resolution, and in any case the technicalities are irrelevant. Zedolfblack has his answer, and satstorm even said " Interlace 352 x 288 @ 1150-1800-2520 looks exactly like VHS on TV." He did not say IS identical, just looks identical.

[Xesdeeni]

The original question was wether 352X288 could be interlace, the answer is yes.

How so? It takes 576 lines to make interlaced PAL. 288 will only give you one field.

Interlace 352 x 288 @ 1150-1800-2520 looks exactly like VHS on TV." He did not say IS identical, just looks identical.

That depends on the TV and the viewer. 352x240/288 does not look as good as VHS to me on my TVs. This makes sense, since the VHS VCR has twice as many lines. YMMV.

Xesdeeni

[SatStorm]

Xesdeeni, 352 x 288 can be interlace and this is a fact

How it looks like a VHS? Easy to understand:

You forget the digital to analogue convertion the DVD standalones do inside them, when they play optical discs.

A standalone player with a good digital to analogue convertion circuits, it is possible to sprade the 144 + 144 lines each field has in this case (when the source is 288 interlace vertical lines) to 288 + 288 skylines or whatever.

So, we emulate what VHS do by nature.

VHS transmits 2 fields in an offset position between them and in 4 field pattern, so to fill up the 720 x 576 carvas of the TV screen...

Because TV has the so called "no info value" (personal translation of a Greek word I bet you can't even pronounce correct), you don't see this happen or affect by trembling the picture (because of the phosphor).
But in the digital world, there is no "no info" value.
A capture card see that "no value" as a black line.
So what we do, is to detect those black lines through various steps and reconstruct the original 352 x 288 info.
Then, we get that 352 x 288 info in a unatural (for VHS) order (line after line in a raw without the pattern VHS use) and because we have 288 lines in PAL and we can do interlace, we force an interlace output.
Then we leave the dvd standalone mpeg 2 decoders do the magic convertion to full 720 x 576

That proccess, produce a picture almost like VHS, but not indentical, because VHS isn't 352 x 288. It is more / less depending all those techical factors you mention.
Same way VHS 352 x 576 is an overkill for about the same reasons: We have included in this type of convertion and the "black" skylines in the encoding.

If VHS was 352 x 576/480 as you say, then why SVHS looks much sharper at the same framesize? Just because it has better luminance etc.
NO: Because also includes more video info.
Because there is no 4 field pattern here, just 2 fields per frame direct.

And now, before you ask, I won't link you to read about those things. I don't have to. JVC, the inventor of VHS, determine VHS 352 x 288 for a reason. Search at there knowlegde database if you wish technical infos for that matters.

I already posted all those things, if far better english last year, in your last forum visit. You probably don't remember, 'cause you are not here to read others: You are here to "teach" them in an academic way your point of view.
Well, I have no problem with that but I suggest you to do it in a "Guide" like way.

The reason people ask you for clearifications, is because you confusing them so much with all those technical infos you provide each time you post, they believe they know nothing, even if they are practical masters on the VHS to DVD convertion.

In short terms: Someone with limited enlgish skills, can't follow you

Using plain english doesn't dump anything. It simply make it understandable from us, the adults who had ages outside schools.

And about your previous posts on those subjects, just visit your profile, and hit "find all posts from Xesdeeni"

You know, you are very helpfull and usefull. But just search the word "verbose" you used for example, how many times it is used in 4 years in this forum.
If I have to open the dictionary on each sentence of yours so to understand what you say, then you don't help me at any way.

[Xesdeeni]

Xesdeeni, 352 x 288 can be interlace and this is a fact

Sure, but then it would not be PAL video (http://www.alkenmrs.com/video/standards.html).

A standalone player with a good digital to analogue convertion circuits, it is possible to sprade the 144 + 144 lines each field has in this case (when the source is 288 interlace vertical lines) to 288 + 288 skylines or whatever.

I would love to see such a stand-alone player and the name of the format it is playing. Can you give me a link so I can buy one?

VHS transmits 2 fields in an offset position between them and in 4 field pattern, so to fill up the 720 x 576 carvas of the TV screen...

Maybe you are thinking of the 4-field pattern used for color. The luma is a 2-field interlaced pattern. But once you are digital, the color pattern is gone.

Because TV has the so called "no info value" (personal translation of a Greek word I bet you can't even pronounce correct)....

Yes, most of what you are saying is Greek to me.

Same way VHS 352 x 576 is an overkill for about the same reasons: We have included in this type of convertion and the "black" skylines in the encoding.

Do you mean "scanlines?" What do those have to do with digital video?

If VHS was 352 x 576/480 as you say, then why SVHS looks much sharper at the same framesize? Just because it has better luminance etc.
NO: Because also includes more video info.
Because there is no 4 field pattern here, just 2 fields per frame direct.

That is just simply wrong. The difference between VHS and S-VHS is in the horizontal resolution, not the vertical. Just like 720x480/576 looks better than 352x480/576, S-VHS looks better than VHS. The timing of S-VHS is the same as VHS. Take a look at http://www.hut.fi/~iisakkil/videoformats.html under the section "But what about vertical resolution?" It says:

"...the vertical direction of television picture is...always the same as in the video format itself -- 575 visible lines in PAL, 485 in NTSC."

[We round PAL to 576 lines and NTSC to 480 lines because they can be divided by 16.]

And now, before you ask, I won't link you to read about those things. I don't have to. JVC, the inventor of VHS, determine VHS 352 x 288 for a reason. Search at there knowlegde database if you wish technical infos for that matters.

Pixels are digital. A VHS VCR is analog. You will not find any place where JVC says a VHS VCR can record 352 pixels.

288 lines is one field of PAL/SECAM, not two. Yes, VCDs used this resolution. But that was because they were using early MPEG-1 encoders and a low bit rate. But even the very first VCD players had to output the 288 lines twice so that they worked with PAL TVs.

Please take a minute to think about this. VCRs came out in the 1970s. There were not very many digital devices. These were only analog devices. There was no way they could change the signal you got out of the air. They just recorded exactly what they saw on the antenna.

...I suggest you to do it in a "Guide" like way.

Given time, I'm sure I will.

In short terms: Someone with limited enlgish skills, can't follow you...If I have to open the dictionary on each sentence of yours so to understand what you say, then you don't help me at any way.

Just for you, I edited and re-edited this post so I did not use to many big words.

Xesdeeni

[SatStorm]

Xesdeeni, I gonna reply you same way I did 2 years ago...

Point whatever you wish, quote whatever you want....
Put it on any order you wish...

Play that game with the words, quotes, etc with the ones who can play with you. Unfortunatelly, I'm not one of them...

I'm more than certain, that most people around understand me more than you, without having your ass kicking english skills!

And the funny thing is that we don't argue on something really... I just attemping to speed up the proccess for this round.

I also gonna do it next year , at your next visit. I bet we gonna be both around

PS: I am Greek so yes, it is natural that everything sound Greek to you....
Everything you say sounds English for me too....

[lordsmurf]

Xesdeeni, another thing you have to remember is the analog to digital conversion process is not perfect, and analog is not really measurable in precise terms like digital.

The theoretical value of VHS resolution and other (like broadcast) are much higher than what happens in practice. At least with equipment that people like me (and most people on this site) can afford - which is already several grand invested.

What is amusing is the TVL values equate to the approximate resolution seen. People say broadcast is 440x486 to me a lot, with the 336 TVL, but the quality acquired by a card is still lower than 352x480. It's pretty close to about 330x480 in practice. VHS is SOOO much lower than the magic 320x486 given. At that resolution, you'd assume the VHS will look as sharp as 352x480. Well, it doesn't it's much closer to the 200-280 range in there. It's got physical blur that you can't deny. VHS 320x480? I don't think so. TVL has a larger impact earlier in the process than what many theorists want to believe. I'll eventually find the connection, but it's no big deal. I know what works and I publish updates to my site as that info is found.

Theory means nothing. Practice is everything.

352x288 is a PAL resolution for the digital world of video, and interlace is possible. Again, it's not the best, but it can work, and the results are not terrible by any means.

BTW, another thing I find amusing is the MANY, MANY reasons I've seen concerning x480 and x486 (and even others nearby) and why it is x480 in digital. I could make a page of the reasons alone. I don't believe ANY of them. It all seems like guesswork, and that's not good enough for me.

[FulciLives]

Well ... *cough* ... this thread is getting a tad out-of-control.

Let me say that I respect everyone in this thread. SatStorm, despite English not being his native language, has made many great posts here on this website. Xesdeeni is my hero for figuring out how to do PAL to NTSC long before ayone else did and his methods are still the best and I try to promote that all the time when I see people asking about such conversions. Last not not least LordSmurf has shown himself to also be extremely knowledgable and his website is a great resource.

Having said ALL that though ...

I do think this thread has gotten way out-of-control.

I think it's perhaps best we all just pretend this thread is not here anymore and stop posting before things get ugly 8)

Peace out!

- John "FulciLives" Coleman

P.S.
Edited once to correct spelling errors since English is afterall my native tongue hehehe

[junkmalle]

I think the reason people state that 352x240 is about the same as VHS quality is because, at that frame size, you have better than VHS resolution horizontally, and worse vertically. So the two more or less average out.

I'm going to limit my discussion here to NTSC. But the same is true for PAL, it's just that PAL has a little more vertical resolution, and slower frame rate.

The EXACT horizontal resolution of VHS tape is open to debate but a nominal value is 240 -- lets say dots rather than lines to reduce confusion! But that is measured for a square screen. Real screens are 33 percent wider than tall so lets say the horizontal resolution is 240 * 1.33 = 320.

But that is only for the liminance (intensity) portion of the signal. The chromanance (color) information has even less resolution, about 1/2 of that. Have you ever watched a soccer game and noticed that the guys with red shirts all have red bleeding off to the right? That's because of the low bandwidth of the color signal.

VHS HAS to have a vertical resolution of 480 lines. THis is because the video tape simply records the analog TV signal. It has no choice but to record 480 scan lines because it has to output 480 scan lines to play the video back to the TV. Well, actually, it's 525 scan lines that are recorded but only about 480 of them contain useful picture information. Explained in the next paragraph...

OK there is some debate on just what value to call the vertical resolution. NTSC video is based on a 525 line, 29.97 frame/sec timing standard. But some of those lines are off the top and bottom of the screen, and some of the time is used for vertical retrace (the time it takes for the electron beam to go from the bottom of the screen back to the top to start the next field/frame). High end video (I'm talking TV studio quality) used to have a useful picture output of 486 lines. DVD and general computer usage has reduced that to 480 because that number is evenly divisible by 16. Why divisible by 16? Because MPG video divides the picture up into 16x16 blocks and encodes those blocks. A 480 line picture has 30 of those blocks from top to bottom. Note that the standard horizontal dimensions are all also divisible by 16 (352, 640, 704, and 720) for the same reason. And because it's easier to design the video hardware that way. When a 480 line high file is output to a TV the original 525 line standard is restored to the signal by adding blank lines at the top and bottom, and the extra time for vertical retrace.

Now consider a 352x240 video file. It has slightly more resolution than VHS tape on the horizontal axis, a lot more if you consider color as well as intensity. And it has 1/2 the vertical resolution of VHS tape. Those two factors roughly average out to the same overall picture quality.

Oh, it may be obvious but maybe I should say it just as a matter of completeness: a 240 line video file is converted to a 480 line video signal by displaying each of the 240 lines twice, first over one field then over the next. And of course, the requisite padding for 525 line NTSC timing is restored.

That said though, I can easily see the pixels (jaggies) of a 240 line high picture. The average viewer might not notice at first but point out what to look for and they'll easily see it.

I use 240 scan lines for unimportant things, but always use 480 lines for more critical recordings.

Sorry for the really long post!

[lordsmurf]

See, this is more stuff that makes no sense...

.... For the record junkmalle, I'm not attacking you, just pointing out something I see too much of, so anytime I say "you" it's not to you ... and I'm typing really fast and being brief, so I apologize in advance if I come off sounding like a dick...

The easy reason people confuse VCD with VHS is the number "240" is used in both. However, they measure opposite axes, and in different realities, and this is the problem. As I grow older, I find that most people only half read. Even I am guilty of this when I rush or don't care. This is the reason they see 240 and run with it without thinking.

Alright now look. There's a huge problem with this 525/480/486/etc picture......... You say 525 is the complete image, but the 480 we all talk about (or 486 or whatever that's close) is just what is seen on screen.... something about retrace, etc ..... okay, now, this is just off-base. ...... I think the problem is trying to explain the tv in digital terms. The tv does not matter at all. We're not using it for anything. It's unplugged in the corner for all I care. I have a input signal to the computer here............ When we record a signal from broadcast or any other source, we see ALL OF IT, including the magic 481-525 area that theorists always say "doesn't count" or whatever. We DO see the overscan on the PC. In fact, rip all that plastic crap off your tv tube, and a lot of sets will show that area too. The 525 is the beam splattering info on the tube. Whatever hits that tube is the 486 picture size.... I don't care about the beam, or the tv. The source that is given to the beam is what counts. The computer has no such beams, it sees the image as extracted by the digital tuner on the capture card....... I think we need to put the whole 525, scanlines, etc to the sidelines...... the simple fact is that the NTSC signal carries around 480 left-to-right lines (vertically measured or "vertical resolution") of stacked video data that weave (interlace) to show the picture.... and in digital terms, gives off x480 interlaced resolution.... which is somewhat rounded off because of the technology....

So using half resolution x240/x288 tosses out half the data. Period. Deinterlacing creates the jaggies. An interlaced x288 file has no such jaggies, but it does have a software picture from lower resolution.

The horizontally-measured "horizontal resolution" is the top-to-bottom lines standing next to each other, and is the sole factor in picture clarity. This is the important number.

YCrCb are sent at different strengths, but the final MPEG files mocks this too. This is where you hit 4:4:4, 4:2:2, 4:1:1 and 4:2:0. This affects resolution too, but more from a perception moreso than theory and science.

Now we can get all the Kell and TVL and other talks in here, but in the end, much of that has zero effect on the analog source as it applies to digital. It relies too much on the unplugged tv set in the corner. It's too often accepted as canon info and not verified. There is something unsettling about the observations of resolution and the supposed science and theory behind it, as it does not add up. Not visibly at least.

The problem with red shirt soccer players is oversaturation by the tv set, that's not a side-effect of the signal. Again, tv being fluky. Shouldn't even be talked about here. Again, my tv set unplugged in corner, using computer with the signal.

Video is my #1 hobby, but this is the one topic that makes it difficult and not fun.

... and unfortunately, by the time I got done writing this, I forgot where I was headed with it .... so enjoy the random thoughts.

I swear I started to get a headache and get scatter-brained every time I talk about resolution.

[flaninacupboard]

Xesdeeni, 352 x 288 can be interlace and this is a fact

Sure, but then it would not be PAL video (http://www.alkenmrs.com/video/standards.html).

Wow, i am bowled over by the technical info on that website. it's entitled Video Broadcast Standards. we aren't discussing broadcasts here, try to keep up.

A standalone player with a good digital to analogue convertion circuits, it is possible to sprade the 144 + 144 lines each field has in this case (when the source is 288 interlace vertical lines) to 288 + 288 skylines or whatever.

I would love to see such a stand-alone player and the name of the format it is playing. Can you give me a link so I can buy one?

http://www.argos.co.uk/webapp/wcs/stores/servlet/ProductDisplay?storeId=10001&langId=-1&catalogId=1751&productId=94456&Trail=C$cip=12724 >C$cip=12764>C$cip=12765&categoryId=12765


There you go. enjoy. it would be playing a PAL XVCD (have a look in the guides on the left to find out what that means)

That is just simply wrong. The difference between VHS and S-VHS is in the horizontal resolution, not the vertical. Just like 720x480/576 looks better than 352x480/576, S-VHS looks better than VHS. The timing of S-VHS is the same as VHS.

What Satstorm already tried to explain is that while the signal output from a VHS or SVHS player may have 576 lines, only 300 or so contain useful data, which is upsampled to fill the whole 576 lines. (NB i guess when you carvas you mean canvas sat!) To give you an easily reproducible caomparison, find an image that is 352X240 pixels, now resize it to 704x480 pixels and soften it. that's basically what you see on a TV when you watch VHS.

288 lines is one field of PAL/SECAM, not two. Yes, VCDs used this resolution. But that was because they were using early MPEG-1 encoders and a low bit rate. But even the very first VCD players had to output the 288 lines twice so that they worked with PAL TVs.

Well done. so why is it impossible for you to believe a DVD player will take 144 lines from a VCD, resize them to 288 lines and output as Field A and then do the same for the next 144 lines on the disc for Field B?

Please take a minute to think about this. VCRs came out in the 1970s. There were not very many digital devices. These were only analog devices. There was no way they could change the signal you got out of the air. They just recorded exactly what they saw on the antenna.

Well, again, we weren't really talking about broadcast, and anyway, i do hope you're not trying to convince us VHS looks the same as the originally broadcast signal...?

Just for you, I edited and re-edited this post so I did not use to many big words.

You still don't get it. this is an ametuer website. if you use terminology that folks aren't familiar with they won't follow you.

[BJ_M]

i still believe my answer is correct ... "352x288 wouldn't (shouldn't) be interlaced" ...

it CAN be interlaced - but shouldn't


all in all though -- to many people are de-interlacing thier video's .. which is wrong depending on playback .. but most times if source was interlaced and not film based , leave it interlaced ......

our films are shot at 30fps and 48fps and 60fps ... so do you think ntsc or pal dvd's i make should be interlaced or progressive - and at what frame rate? (we shoot at 24fps also for a lot of stuff - one of my jobs is to convert it to 30fps for large screen 70mm film playback, you can't use pulldown for this of course - its film)..

[junkmalle]

Lordsmurf,

The easy reason people confuse VCD with VHS is the number "240" is used in both. However, they measure opposite axes, and in different realities, and this is the problem

You are completely correct. It is an unfortunate coincidence that VCD's vertical resolution roughly matches VHS's horizontal resolution.

When we record a signal from broadcast or any other source, we see ALL OF IT, including the magic 481-525 area that theorists always say "doesn't count"

I did some checking up and you are correct. The 480 (486, whatever) is all the useful picture information. The remainder of the 525 is for vertical retrace, sync pulses etc. Obviously we don't "see" the retrace and sync pulses but the are recorded on the video tape. And not explicitly recorded in the digital computer image.

the simple fact is that the NTSC signal carries around 480 left-to-right lines (vertically measured or "vertical resolution") of stacked video data that weave (interlace) to show the picture.... and in digital terms, gives off x480 interlaced resolution.... which is somewhat rounded off because of the technology...

We agree on this.

I did a little test. I created a 720x480 still image (uncompressed bitmap) of alternating black and white horizontal lines. I recorded this image as a 5 minute movie on DVD. When played back the alternating horizontal black and white lines were clearly visible on the TV screen (and if flickered like you wouldn't believe!). I recorded the DVD to my VCR. Playback on the VCR was also quite clear, alternating black and white lines -- 480 of them (no, I didn't count!). The conclusion, VHS has a vertical resolution of 480 lines.

Just for jollies, I did the same with alternating black and white vertical lines -- to measure horizontal resolution. Except this time I made five different regions of 1, 2, 3, 4, and 5 pixel wide lines. The 1 pixel wide lines represent a resolution of 720 lines (across the entire 4:3 screen), 2 pixel = 360 lines, 3 pixels = 240 lines, 4 pixels = 180 lines, 5 pixels = 144 lines. The astute observer will realize this is just 720/1, 720/2, 720/3, 720/4 and 720/5.

From the DVD all 720 lines were visible on my computer. My TV (component video from DVD player to TV) could not resolve the 720 line region (just looked gray) but the other four regions clearly showed alternating black and white lines.

I recorded the DVD signal to VHS tape (via composite cable -- the TV picture via this same composite cable from the DVD could still resolve all but the 720 line region). The tape could only resolve the the lowest 3 resolutions (240, 180, and 144). So the horizontal resolution of my VCR is somewhere between 240 and 360 lines (over the entire width of a 4:3 image). That corresponds to between 180 and 270 vertical lines over a square (3:3) picture area. So the often quoted horizontal resolution of 240 for VHS is in the right ballpark. At least on my VCR.

The problem with red shirt soccer players is oversaturation by the tv set, that's not a side-effect of the signal.

That may be partly true but...

I created a 720x480 image with a black background and 4 pixel square blocks of red, green, blue, and white. Both at full and half intensity. Again, I made a 1 minute DVD from this file. On the computer screen the DVD showed no "smearing" of the colors, although the edges of the blocks were a little less sharp than the BMP image. On the TV, with component video cables, there was no appreciable smearing. On the TV via composite cables there was a little smearing with red and blue being worse than green and white; the smears were about the same size as the 4 pixel blocks. Recorded and played back from VHS tape the smears were very large -- several times the width of the 4 pixel wide blocks, and again, more on the right than the left, and more on the red and blue. From this it is pretty clear (actually pretty fuzzy!) that the color component of the video signal on VHS tape is recorded with much less resolution than the intensity component.