S-video Cable == What is the maximum resolution?

electrictroy

What is the maximum possible resolution (horizontal) for an S-video cable?

Over 700?

TampaDude

I've gotten 1024 x 768 on my Mitsu with S-video. YMMV.

BobY

There isn't a simple answer. S-Video is an analog signal and the luminance (black&white) portion of the signal can theoretically have bandwidth beyond what you say, but the color portion of the signal won't come anywhere near 700 lines.

If you're dealing with a DVD player or DTV box that has an S-Video output, the output signal is inherently limited to the 720 x 480 pixel resolution of the digital format, although, again, the color resolution is nowhere near that.

Basically S-Video is an improvement over Composite Video as it eliminates the crosstalk between the luminance and color signals, but the color decoding process is the same, slow, imprecise method used for Composite Video. It can't come close to the result using Component Video or DVI/HDMI.

TampaDude-

Sorry, your display may be 1024 x 768, but that's not the signal you're seeing. Digitally-sourced S-Video is inherently limited to 720 x 480 (interlaced). Your display is scaling that up to 1024 x 768. You could feed it a 352 x 240 interlaced Composite Video signal and it would also get scaled to 1024 x 768.

TampaDude

Yup...the computer's video card is at 1024 x 768, but the image on the screen looks like crap. Now I know why. I'm getting a VGA to DVI cable from Monoprice which should allow 1:1 pixel mapping and give a clear image on the TV.

BobY

That's true, but be aware of something with no scaling and 1:1 pixel mapping:

Your display is a widescreen 16:9 aspect ratio and if your video card is for a 4:3 aspect ratio display, everything will look stretched compared to how it looks on your computer (unless your video card has a widescreen mode at 1024 x 768 resolution--this is not normally a widescreen resolution and the pixels will not be square, so some of your computer graphics might look odd since they will probably be generated assuming square pixels).

tipstir

Some Video Cards don't support Sharping, Contrast Max which you'll find on some PCI Express Cards that do a better job in S-Video. You need TV Hardware Decoder, not Software base that would run off you CPU. The max is 1024x768 for S-Video and DVI would be the max of the HDTV or Video Card Res that can be displayed.

electrictroy

Doesn't matter. The human eye can't see hi-resolution color (which is why color resolution is reduced from 720 to ~350 during MPEG2 or MPEG4 compression).

In this case, my source is a 640-pixel wide image from a PS2. I figure there's no need to waste money on component cables, if the S-video can produce just as good an image.

BobY

It can't.

S-Video uses the same 3.57 Mhz color subcarrier/phase encoding that is used for Composite Video. It provides for about 120 lines of color resolution, although typical color decoders in displays can be as bad as 60 lines of color resolution, as they ususally use the same cheap decoder for Composite video and S-Video. Also the phase encoding method takes time to determine the color and during that time the color change is delayed and blurred.

If you think it looks OK, that's fine, but you should compare it with Component Video to see the difference (BTW, you don't have to buy expensive Component Video cables, cheap ones work fine). Also be aware that Composite Video and S-Video do not support progressive scan. I can tell you that on my Toshiba CRT HDTV, the difference between watching a DVD using S-Video and Component Video is huge.

Lee Stewart

S-Video like Composite and RF are all part of the family of NTSC. This was the television standard that was agreed to back in 1953 when Color TV was introduced. NTSC has 2 parts. . . the black and white part and the color part. As stated the B&W is much higher than the Color part.

Back in the 1980's set manufacturers had a "resolution war" which started with Sony claiming one of there set could (and would) resolve 500 lines. It was the 25" Pro something or other and looked like a cube. At the same time ir was stated that within the Video Amp 1 Mhz = 80 lines of resolution so all of a sudden numbers were starting to fly like 550, 600, 700 and even 800. All the set manufacturers were doing was measuring the output of the video amp and listing that spec as the resolution...which was a false spec.

The only system that could resolve 500 lines was Sony's ED-Beta. This was 100 lines greater than Laser Disc at 400 and more than 2X that of the VCR at 240.

Keep in mind (again as stated) that NTSC is an Analog system. Numbers like 640x480 and 720x480 really don't apply because the NTSC system has only 525 Hort. Scanning lines and 25 of them are dedicated to "housekeeping" functions that you will never see.

All the S-Video does is seperate the B&W from the Color signals so some processing can be done to clean up the signal. Both Composite and RF mixed the two together.

The last step was the introduction of Component which took this seperation to the last degree though some say they can't see the difference between S-Video and Component.

For those of us that went Front Projection, ANY improvement was a help as blowing an image up to 100" or greater from a system that was designed to be viewed on a 27" or smaller screen...the smallest increase was easily seen. A small sparkle on a 27" tube became the size of a baseball on my 144" screen.

Then came DVD which is really a hybrid of the NTSC system. It is a digital format and unlike all other mediums before it was recorded as a progressive signal as opposed to an interlace signal which is how the NTSC system works. Your PC outputs a Progressive signal meaning all scanning line are shown at one as opposed to odd and even.

The first DVD players took that Progressive signal and down converted it to Interlace so your TV would recoginize the input. When Digital TV's became popular they simply removed this circuit and outputed the Progressive signal...that is why Prog Scan DVD players are so cheap. They didnt add anything...they removed something.

So, in answer to the question the maximum resolution of S-Video is 500 lines.

Lee

TampaDude

Yeah, that's fine. The 1024 x 768 image will be 4:3 and won't fill the screen, and I'm okay with that. This is just an HP laptop with VGA out. I would have to get a video card with DVI-D out to take advantage of the full resolution of my TV.

BobY

Lee-

Conventional DVD's are stored in interlaced form, although movies are sourced from progressive frames. This was done as all displays at the time were interlaced and it helped reduce the processing overhead (at the time, the video decoders were hard-pressed just to do the MPEG2 decompression in real-time). Progressive scan players actually do additional processing to de-interlace the content.

TampaDude-

If your display is 1024 x 768 native resolution, then 1:1 pixel mapping won't give you a 4:3 window with the rest of the screen unfilled, it will stretch the image and fill the screen. Each of the 1024 x 768 pixels of the video card will map directly onto one of the the 1024 x 768 pixels of the display panel.

Lee Stewart

BoBy,

I beg to differ with you. I remember Joe Kane (remember him) describing the benefits of DVD when it first cane out and he pointed to 3 distinct benefits:

#1 Signal was stored as a progressive signal - the player interlaced it for the display. ( he felt that some companies might grab the output before it went to the interlacer and send that signal to the display avoiding the purchase of a line doubler (remember those) This was a huge improvement over LD the top performer at the time which was an Analog interlaced format.

#2 Anamorphic Widescreen - increased the vertical resolution by using more scanning lines to create the image

#3 Greater Color resolution - it was double of what LD was (240 lines) which again improved the image

Lee

electrictroy

False. "[1.40] - There's enormous confusion about whether DVD video is progressive or interlaced. Here's the one true answer: Progressive-source video (such as from film) is encoded on DVD as interlaced field pairs that can be reinterleaved." - DVD FAQ http://dvddemystified.com/dvdfaq.html#1.4

The DVD data is stored in an interlaced format:
- First the even field
- Then the odd field
- Then the even field
- et cetera. It was designed to be compatible with 1995 technology (interlaced NTSC or PAL). The idea of progressive scan did not arrive until many years later.


That is self-evident. A letterboxed video that only uses 320 lines won't have as much detail as a "distorted" anamorphic video that fills all 480 lines. (BTW there are anamorphic laserdiscs.)


Source? As I understand it, both LD and DVD have 480 lines. (Actually LD, being analog, has 486 visible/525 total.)

electrictroy

(1) Are you sure? Doesn't 3.5 megahertz bandwidth translate to ~400 lines across? (shrug)

(2) What kind of color encoding does the YCbCr Component use? And how much resolution across?

(3) After I bought my S-video cable, I stared at the screen. I could see the individual pixels, and I thought the PS2 games looked as clear as if I were viewing a VGA monitor. ----- That's why I felt another upgrade to component cable was not necessary. Perhaps I should rethink that.

Well I think my S-video connection looks *beautiful* on my 27 inch. I've never seen a picture look so crystal-clear. It's hard to imagine them being better.

electrictroy

P.S. I just read an interesting article:
http://members.aol.com/ajaynejr/compon.htm

It says that Component Difference Video has HALF the chromo width (270). And S-video has one-quarter (135 across). Interesting stuff!!! I had no idea that the color signal was so "squashed". I thought that Component Difference Video represented a lossless format...... and the S-video was just slightly less.