comparison of video links

Discussion in 'Beginners, General Questions' started by Dick Knisely, Oct 25, 2005.

  1. Dick Knisely

    Dick Knisely Second Unit

    Joined:
    Oct 22, 2005
    Messages:
    372
    Likes Received:
    0
    Didn't see this in the FAQ so has anyone here seen a good comparison of the types of possible video links, DVI/HDMI vs. component vs. S-vid, vs composite? (Comparison in terms of signal distortiion and degradation.)

    If so, could you provide a link or summarize?

    Thanks in advance.
     
  2. John S

    John S Producer

    Joined:
    Nov 4, 2003
    Messages:
    5,460
    Likes Received:
    0
    Probably because it is a grey area often having to do with specifics of source and display.

    Examples: Svideo should be best bewteen composite and svideo, but if your display has an excellent 3 line comb filter, you may be better off sending it composite from a Laserdisc player instead of svideo.

    For DVD and HD, any given source or display may exhibit some quirk with DVI/HDMI and therefore Component will end up producing the better results.


    Clear as mud right? [​IMG]
     
  3. ChrisWiggles

    ChrisWiggles Producer

    Joined:
    Aug 19, 2002
    Messages:
    4,791
    Likes Received:
    1
    It is confusing, because your question refers to transmission formats.

    As actual encode formats, the order is like this:

    RGB
    Component video (YCbCr/YPbPr)
    S-video
    composite

    These are signal types/video formats. Transmission methods vary. RGB can be sent in analog RGBhv, or digitally via DVI/HDMI.

    Component video can be sent analog (YPbPr) or digitally via SDI or HDMI (YCbCr).

    S-video and composite formats are almost always analog in anything you'd encounter, but they too can be sent digitally in the professional environment, those transmission standards are defined by SMPTE and I could dig some of them out, but they're not relevant to anything you'd be doing.

    But then the question is for the home, which connection method should you use? Here is more tricky, as mentioned, because the signal type of the source is usually DVD or something else that is encoded digitally in chroma sub-sampled component video YCbCr. Non-subsampled RGB is the preferred encode method, but is hugely wasteful. The limitations are already in the system with chroma sampling. So the difference between RGB and component video transmission is largely moot. So basically in a broad sense, use component or RGB where possible, then S-video, then composite. If you have options between component and RGB, in the home you're usually dealing with SDI, HDMI YCbCr, HDMI RGB, DVI RGB, analog RGB or analog YPbPr component video. Everything is theoretically capable of getting the whole picture to the display perfectly. The differences arise in input and output implementations, which vary from device to device. Sometimes DVI sucks, sometimes analog componet video YPbPR sucks, etc. You really should test your system individually if you have "equivalent" options to see if any are better, though they may well not reveal any differences if all connection methods are implemented well, and the circuitry/processiong through each method is robust.
     
  4. joseph westcott

    joseph westcott Second Unit

    Joined:
    Oct 24, 2005
    Messages:
    355
    Likes Received:
    0
    Very well said Chris Wiggles!

    He is right. It really depends on the analog to digital convesion capabilities of the components used, especially when using HDMI, DVI and component inputsoutputs. Handshaking between components has been a real issue for some mfg's and can really spoil the party.

    So, try them all and see what looks best to you.
     
  5. Dick Knisely

    Dick Knisely Second Unit

    Joined:
    Oct 22, 2005
    Messages:
    372
    Likes Received:
    0
    John & Chris -- gee I'm glad I asked. [​IMG] Seriously tho' I understand the distinction you're making and the fuzziness behind the issue. The question came as a reaction to having read essentially what you said as a hard-and-fast rule about what is "best". i.e.,

    RGB
    Component video (YCbCr/YPbPr)
    S-video
    composite

    Part of me likes nice rules like that but another part of me says -- "Oh, yeah? Who says so and let's see your data to back it up!" Mostly because my experience with all such stuff in the real world has shown that few things turn out to be nearly as simple as we'd like.

    Anyway, so the bottom line is that all other things being equal (i.e., transmission methods constant or of equal quality) above encoding method order should reflect best-to-worst results. In the real world, "your mileage may vary" and it could turn out (for example) that I'd find that composite might actually show better results than S-video between device A and device B.

    Still, I'm sure someone has, for example, tried to prove S-video is measurably better than composite if only to promote it. Maybe some 'net digging would turn up something. Heck, I might learn something even if it didn't. [​IMG]
     

Share This Page