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Can one "overclock" a CRT monitor's video input bandwidth? Need slightly higher refresh rate than m

Discussion in 'Overclocking' started by Ken Moiarty, Apr 19, 2006.

  1. Ken Moiarty

    Jukka Aho Guest

    Nothing was said in the above quoted block about RGB being "encoded", so
    I'm not sure why you're bringing it up. But if you wish to discuss
    "RGB", please specify what kind of application of "RGB" do you mean. RGB
    can exist in both digital and analog forms, it can be full-range RGB or
    not, there can be a "setup" or maybe there isn't, there is 15-bit RGB,
    16-bit RGB and 24-bit RGB, analog RGB signals can be created with
    tv-compatible timings or VGA-compatible timings, sometimes the RGB
    data/signal has gamma on each component, sometimes it is treated as
    linear, etc., etc. Saying something trivial like "RGB is unencoded" is
    simple, but dealing with actual RGB data or analog RGB signals isn't
    always so.

    In any case, common digital video formats use YCbCr - not RGB - as their
    native format for storing pixel data samples. (This is partly because
    these formats are, in one way or the other, derivations of ITU-R BT.601,
    and in big part because color subsampling allows packing video data in a
    tighter space without losing too much of perceived quality.) When
    dealing with digital video, it is usually YCbCr data you're processing.
    RGB is only relevant in the way how it comes into play when that YCbCr
    data is to be displayed on a computer monitor - when you're processing
    the video and trying to monitor what you're doing - and, of course, when
    you're importing computer-generated graphics assets to your video
    project which usually involves an RGB -> YCbCr conversion. As described
    in the previous message, not all video tools are very good at doing
    these YCbCr -> RGB preview conversions in a way that would give you any
    idea of the real colors on a computer monitor, and RGB -> YCbCr is yet
    another kettle of fish.
    As I hopefully managed to explain above, it's not that simple.
    Displaying digital video on a computer screen involves conversions
    between the RGB and YCbCr color spaces, black and white level, gamma,
    etc. Many digital video tools don't even _try_ to do these conversions
    in any way that would begin to faithfully emulate how the image will
    look on a tv screen. (One of the many problems involved with assessing
    digital video quality on a computer screen is that a CRT-based tv screen
    typically has brighter whites than a computer screen - the electron gun
    is driven with a higher voltage, even to the point of getting the
    so-called "blooming effect".)

    In another post you seemed to be questioning whether all this is at all
    relevant to hobbyist-level home video editing. For all the reasons
    discussed in this thread, many people (yours truly included!) prefer to
    edit DV with their camcorder connected simultaneously to the PC (via
    Firewire), and to a 15 kHz video monitor - or, in lower-end setups, to a
    regular tv set - using the analog output terminals on the camcorder
    (preferably s-video.) No tape is involved - the camcorder just acts as a
    realtime DV data stream -> analog video converter.

    This is usually a much better setup than trying to rely on the NLE app's
    "monitor" windows only. Modern DV-aware NLE apps allow previewing and
    scrubbing the timeline directly through the camera, and they even give
    previews of the title and effects editors through DV, so you get to see
    how the colors/gamma, interlacing, and overscan will actually work out
    on a real tv screen, instead of just guessing.
    Even a non-professional, non-calibrated domestic tv set will help in
    judging certain important aspects of the image quality much better than
    a computer monitor would. Fluid interlaced motion, field-related
    problems, at least some rough understanding of the final colors and
    brightness/gamma (including possible color clamping problems the codec
    might have, and which don't necessarily show up on the computer screen
    at all) - etc., etc.

    NLE editing without a 15 kHz video monitor (or tv set) by your side is
    much like editing blind - unless you're working on something that isn't
    ever even _intended_ to be displayed on a regular tv set, such as
    streaming web video.

    * * *

    "Followup-To" header corrected again.
    Jukka Aho, Apr 26, 2006
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  2. Gee, the RADAR guys would really disagree with your definition of

    Service to my country? Been there, Done that, and I've got my DD214 to
    prove it.
    Member of DAV #85.

    Michael A. Terrell
    Central Florida
    Michael A. Terrell, Apr 26, 2006
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