S-Video vs. Composite connections

Discussion in 'Archived Threads 2001-2004' started by Blaine Skerry, Oct 24, 2001.

  1. Blaine Skerry

    Blaine Skerry Second Unit

    Joined:
    Aug 15, 2001
    Messages:
    277
    Likes Received:
    0
    Can someone please explain in the simplest terms possible the differences between S-video and composite connectons in terms of filtering or whatever the hell is going on. I am fairly new to the HTF forum so please go easy on me. Thanks
     
  2. Howard Christian

    Joined:
    May 19, 2001
    Messages:
    33
    Likes Received:
    0
    Well look at the cables
    S-video uses 2 cables to transmit the video signals
    composite only uses one cable
    simple enough?
    i think the brightness and something else signals are seperated in s-video
     
  3. Alex Yang

    Alex Yang Stunt Coordinator

    Joined:
    Jan 7, 1999
    Messages:
    188
    Likes Received:
    0
    Blaine,
    Howard is right, the special connector (resembles PS/2 Mouse/keyboard connector) on the Svideo splits a video signal into TWO signals called Chroma - Lumina... Chroma is the COLOR signal
    Lumina is the BRIGHTNESS or CONTRAST signal
    By splitting the signal you get a much sharper picture... I'm sorry I don't know the technical reason WHY it does but hey it works!!!!
    Composite signal combines these two signals... (Standard RCA jack)
    Hope this helps....
    -Alex
     
  4. Blaine Skerry

    Blaine Skerry Second Unit

    Joined:
    Aug 15, 2001
    Messages:
    277
    Likes Received:
    0
    Thank you both for your replies. I was hoping someone could
    explain where the comb filter comes in to play, if it comes in to play at all. I was under the impression that if the S-Video output was used, the originating player's filtering system (once again, I apologise for being vague)not the TV's was used and if the composite output was used, then the TV's comb filter determined picture quality. Anyone out there who can verify this or set me straight?
     
  5. Michael Reuben

    Michael Reuben Studio Mogul

    Joined:
    Feb 12, 1998
    Messages:
    21,763
    Likes Received:
    2
     
  6. NickSo

    NickSo Producer

    Joined:
    Jul 2, 2000
    Messages:
    4,260
    Likes Received:
    0
    Real Name:
    Nick So
    Heres a basic explanation aboutt he three video connections:
    Think about it this way...
    The composite cable, you can see there is like one cable coming from the plug, which basically shows that ALL the video information is passed by one single wire...
    The Svideo cable you can usually see has 2 seperate cables coming from the plug. It carries the video in TWO seperate wires, the video information is split by Color and Brightness (or black and white).
    The Component cables are three seperate cables with three seperate jacks. It carries the video through THREE cables, one for red, one for blue, and one for green. The green also carries the black/white information for brightness/contrast
    The more seperation there is ususally, the better the image as the colors arent 'mixed up' with one another... Its kinda like thinking the video information as clay, or playdough. You have red, green and blue playdough. Squishing it through one composite 'tube' will mix them all up, but you can still tell the difference... But if you passed the three colors of playdough through three seperate component 'tubes', the dough at the end is clearly seperated. This is why RF connections are so poor.. They put both video AND audio into one cable...
    Component is the best among the three types of video connections. Just rephrasing what was said, the larger the TV you have, the more apparent the visual improvement is.
    ------------------
    The So Family Home Theater!
    http://www.multimania.com/sonick182/ht/index.html
    Birthday: November 29 (Sagittarius)
    Horoscope:
    Sagittarius - You are very sexy and women are attracted to you.
    ICQ: Add Me to your Contact List!
     
  7. Blaine Skerry

    Blaine Skerry Second Unit

    Joined:
    Aug 15, 2001
    Messages:
    277
    Likes Received:
    0
    Last question:
    If my TV's (10 month's old) comb filter (a 3D Y/C) is better than my LD player's (9 years old), wouldn't it be better to go composite, or is it always better to go S-Video over composite? I thank one and all for your patience with these pestering queries.
    [Edited last by Blaine Skerry on October 24, 2001 at 06:10 PM]
     
  8. Rich Allen

    Rich Allen Second Unit

    Joined:
    Feb 8, 1999
    Messages:
    382
    Likes Received:
    0
    Location:
    Salisbury MD
    Real Name:
    Rich Allen
    For laserdiscs, it very well may be better to use the composite connection and your TV's comb filter. The only to know for sure though is to try both and compare.
     
  9. Michael Reuben

    Michael Reuben Studio Mogul

    Joined:
    Feb 12, 1998
    Messages:
    21,763
    Likes Received:
    2
    To add to what Rich said: LD is a composite format. So there's no advantage to using an S-Video connection from LD unless the player has a superior comb filter or similar video processing circuitry. Very few players will have anything that beats a good recent model TV.
    M.
     
  10. Guy Kuo

    Guy Kuo Supporting Actor

    Joined:
    Mar 6, 1999
    Messages:
    581
    Likes Received:
    0
    Nick has just about got it right. We probably shouldn't leave the description of component as being red, green, and blue though. Due to a need to conserve bandwidth and storage space, the picture information isn't really stored as red, green, and blue images. Instead a scheme of separating out the black and white and color information is used. The color information is encoded as two "color difference" signals which together specify which and how much color to apply to the black and white picture.
    Component connections simply keep the luma (black and white), and two color difference signals separated on three wires.
    S-video uses two wires and carries luma on one, and combines the two color difference signals together as a single chroma signal. At the TV, the chroma signal is separated into the two color difference signals resulting in the original three. Because of this combining and separating of the two color difference signals, some losses occur in color detail with s-video.
    Composite (almost bottom feeder) combines the luma and chrom signals together onto one wire. The TV must use its color separator (often a comb filter) to separate the luma from the chroma. Then the chroma is separarted just as with s-video into its two color difference signals.
    Coax RF connections take the compsosite signal and modulates it onto an RF carrier. Usually audio is also modulated into the RF signal. The poor TV has to tune i the RF signal, demodulate it. Separate the composite video from the audio signals. Then, comes the usual processing it needs to do with composite. Yuck!
    ----
    One misconception that I've run into is the idea that component signals somehow bypass the color decoder in the TV. That's not really true. I guess you could say that if you only mean the color separator and demodulation of the chroma into the two color difference signals, but there is still the final step of color decoding which must be done. There is where the luma and two color difference signals are dematrixed to produce the final red, green, and blue signals. Dematrixing is where controls such as tint and saturation have their effect. Since component is supposed to already have the correct phase, hue is often not adjustable with component signals. Anyway, this is also the place where red push gets induced. So using the component connection doesn't bypass all the TV's color decoding nor does it eliminate red push.
    ------------------
    Guy Kuo
    www.ovationsw.com
    Ovation Software, the Home of AVIA DVD
     
  11. RyanDinan

    RyanDinan Stunt Coordinator

    Joined:
    Oct 25, 2000
    Messages:
    249
    Likes Received:
    0
    Guy,
    I've noticed that even with RGBHV connections, the HUE/TINT control can still has an effect on the image.
    For example, I have a Sony 53HS10 driven by my HTPC via VGA-5BNC to the RGBHV input on the back.
    When I calibrated the picture with AVIA, I had to adjust the TINT a few clicks to the left (more green or red?) to get the flashing boxes to blend (and it ended up blending EXTREMELY well - Much better than my component DVD player could ever get).
    I was under the impression that an RGB signal DID bypass the color decoder in the TV. Is it just up to the manufacturer to allow this type of control over RGB signals?
    Thanks!
    -Ryan Dinan
    ------------------
    [Edited last by RyanDinan on October 25, 2001 at 11:45 AM]
     
  12. Guy Kuo

    Guy Kuo Supporting Actor

    Joined:
    Mar 6, 1999
    Messages:
    581
    Likes Received:
    0
    The manufacturer can take the RGB signal and transcode it into luma and color difference signals to allow user adjustment of saturation and tint. That gives more flexibility but complicates the processing of otherwise very pristine signals. Another reason for doing this is to force all inputs into a common signal pathway to save cost. Whatever the reason, your set is probably transcoding. It's possible to provide those controls strictly in the RGB color space but unlikely given that it would be considerably more difficult and expensive to do so. I could be wrong about your particular set, but it's a good bet without looking at the schematics.
    ------------------
    Guy Kuo
    www.ovationsw.com
    Ovation Software, the Home of AVIA DVD
    [Edited last by Guy Kuo on October 25, 2001 at 11:01 PM]
     
  13. chester

    chester Auditioning

    Joined:
    Jan 21, 2002
    Messages:
    1
    Likes Received:
    0
    S-Video only requires one video cable which is the same as composite right??? Component on other hand requires 3 video cables for the video signal from the dvd player correct??

    Anyways I compared s-video to composite and found basically no difference at all between the picture quality. Exactly what do I look for when comparing these two video standards???? thanks
     
  14. NickSo

    NickSo Producer

    Joined:
    Jul 2, 2000
    Messages:
    4,260
    Likes Received:
    0
    Real Name:
    Nick So
     
  15. Bob McElfresh

    Bob McElfresh Producer

    Joined:
    May 22, 1999
    Messages:
    5,182
    Likes Received:
    0
    Guy: great description!

    chester: You need to compare composite vs SVideo from a already-seperated source like a DVD. Watching local news on my DSS system which has both composite & SVideo shows little difference.

    Try this: Hook up both Composite & SVideo to your TV so you can toggle back and forth. Load up a DVD with lots of bright colors and straight lines. Something like Toy Story 2 or Austin Powers.

    What to look for:

    - Dot Crawl: Go to the Composite feed. Look at any straight lines where 2 colors intersect (or text & gridlines on a menu display). Even if you pause the image, you can see little dots on the line that appear to "crawl". In one pass, the comb filter says make it color A, but in the next pass, it makes it color B.

    Now flip to the SVideo feed. The dot-crawl is nearly eliminated. Even though you notice the dots on straight lines, they are present on other intersections.

    - (not shure what to call this) - Solid Colors: Go to the composite feed and look for a scene where two large areas of different colors intersect. Look at the area near the intersection. Now flip to the SVideo feed and look again. The colors stay solid as they near the intersection with SVideo. Flip back to composite to see that it starts to dim/fade a bit.

    Hope this helps.
     
  16. Allan Jayne

    Allan Jayne Cinematographer

    Joined:
    Nov 1, 1998
    Messages:
    2,404
    Likes Received:
    0
    Some minutiae:
    >> S-video requires only one cable...
    The S-video cable typically has an outer covering that looks like a single cable but both the Y and C wires are inside. For component video, the three separate cables may be twisted together still looking like three separate cables.
    Component video is approximately red, white, and blue. Using simple addition (in phase combining), subtraction (out of phase combining), multiplication by constants(amplification) or division by constants (attenuation) the green, and also pure red and blue, can be obtained. Here the traditional NTSC hue (tint) control would not be used but instead there may be an alternate kind of tint control or individual controls for red, green, and blue "gain".
    My set (a Sony) has the color and tint controls inoperative on its RGBHV input.
    A TV can have an excellent comb filter but still have relatively poor color resolution even from S-video. If you have Video Essentials, examine the "Snell & Wilcox zone plate" with the bouncing ball. Near the bottom are some side by side red and blue upright lines: ( ||||||| ) If there is little or no red, or if there are big black gaps between the yellow and blue spots at bottom center, the color resolution (of either the TV or the DVD player's composite or S-video output) is relatively meager and the difference between composite and S-video may be less noticeable.
    Dot crawl occurs because there is chroma (color) information contaminating the luminance information and the frequencies involved correspond to minute light/dark transitions (equal to the size of the crawling dots). The better the comb filter is, the more of this contamination is removed, but no comb filter is perfect
    Video hints:
    http://members.aol.com/ajaynejr./video.htm
     
  17. Robert P. Jones

    Robert P. Jones Second Unit

    Joined:
    Jun 18, 1999
    Messages:
    289
    Likes Received:
    0
    Right, S video, also called Y/C, uses 2 separately shielded wires, even if it looks like one.

    The main difference I see between composite and S is the dot crawl. The pic is also a little brighter sometimes, but the dotcrawl is the dead giveaway. A good comb filter can eliminate the dot crawl, but if your TV doesn't have that good a comb filter, you'll see it as a major difference between the 2.

    Best way to see dot crawl is when 2 pastel colors are side by side, in a straight line, upside each other. The dots look like ball and jacks kind of jacks, like those beachhead thingies on Normandy Beach, in WWII.

    The jacks kind of pattern crawls along in both directions. If you follow it one way, it looks like it goes in that direction. If your eye follows it the opposite way, it goes in the other direction. It can go up and down or side to side, and can absolutely become ferociously busy at corners and intersections...

    Mr Bob
     
  18. Steve Owen

    Steve Owen Second Unit

    Joined:
    Jan 7, 1999
    Messages:
    416
    Likes Received:
    0
    Can anyone confirm that DBS services (specifically DirecTV) deliver a "composite" signal? To be honest, I think the composite on my Sony SAT-T60 looks better than the S-Video, and I believe it's for the same reasons as laserdisc.

    With DVD, it's a no brainer for all the reasons listed here.

    -Steve
     
  19. Robert P. Jones

    Robert P. Jones Second Unit

    Joined:
    Jun 18, 1999
    Messages:
    289
    Likes Received:
    0
    I have Dish regular sattelite, and my S connection to my 65" Panny creates some kind of picket fencing pattern that composite does not. So I have to use composite and not S, against my better judgment.

    On the other hand, and to their credit, I see NO dot crawl on the composite output from the sat. receiver. So I guess it's OK...

    Don't know the answer to your question, but I would find it hard to imagine that the digital signal received by the dish itself arrives in composite. It arrives in highly compressed digital, at the 18" dish antenna itself -

    Mr Bob
     
  20. Bob McElfresh

    Bob McElfresh Producer

    Joined:
    May 22, 1999
    Messages:
    5,182
    Likes Received:
    0
    I posted this same question a year or so ago and was told that the MPEG compression used in both Direct and Dish systems sent the video already seperated.

    So now you are limited by the quality of the camera & production studio equipment.

    For example: The difference between composite & SVideo on a dvd player is very visible.

    But when I got my DishPlayer I compared A/B/C:

    - Local network station on cable

    - Local network station on DishPlayer with Composite video

    - Local network station on DishPlayer with SVideo

    The difference between Composite and SVideo was slight! This was NOT what I expected.

    It turns out, local network feeds are not really high-quality sources. The local station was broadcasting some girl-school slasher movie and it was somewhere .. compromised. I was told that using a movie channel/HBO station should have shown a greater difference.

    So SVideo IS a superior connection, but you have to have a good enough quality source for it to make much difference.
     

Share This Page