10bit(27mhz) vs 10bit(54mhz) whats the difference

Discussion in 'Archived Threads 2001-2004' started by Kevin. W, May 16, 2002.

  1. Kevin. W

    Kevin. W Screenwriter

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    I've seen a spec on regular players that states the video Dac at 10bit(27mhz) vs Progressive 10bit(54mhz). Whats the difference mean? Will it do anything on regular TV's till I got a larger Progressive?

    Kevin
     
  2. Darryl_B

    Darryl_B Stunt Coordinator

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    It doesn't make a difference. It means that the DVD player samples the video on the DVD 2 times before creating an analog signal. 27mhz is the bandwidth required to sample an interlaced signal 2 times. Since progressive is double the bandwidth of an interlaced signal, 54mhz is required to sample it 2 times.

    The only difference you'll notice among the same player between an interlaced signal on a regular TV and progressive-scan signal on a digital set are the inherent benefits of progressive-scan. Not from the video dac - at least not in this case.
     
  3. Phil Nichols

    Phil Nichols Second Unit

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    Matthew D,

    Some new DVD players have 108MHz video DAC's. (i.e. Denon 3800 and 9000 and upcoming Toshiba SD9500).

    This "DAC bandwidth" can be entirely utilized for both progressive and interlaced output using sophisticated engineering to provide high multiples of "over-sampling" to move video noise (naturally created by the DAC conversion process itself) way beyond the frequency that you can see on your screen. Hence, a cleaner, noise free, image than what a player with a lower bandwidth DAC (and hence using lower multiples of over-sampling) can provide.

    For example, the Denon 9000 provides 4X progressive over-sampling and 8X interlaced over-sampling through use of it's 108MHz video DAC's.

    Whether or not you have a HT display system capable of benefitting from DVD player video DAC conversion process noise reduction to these esoteric low levels is the issue, however. Most of us probably don't.
     
  4. BobJ

    BobJ Stunt Coordinator

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  5. Bob McElfresh

    Bob McElfresh Producer

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    When Secrets of Home Theater did their progressive-scan DVD player comparison a few years ago, they noticed that the players with the higher-speed chips eliminated several problems that were common on players with slower chips.
    A few of these problems were visible, the others required some fairly expensive video analysis equipment to detect.
    So I doubt you would see any difference. But when shopping for my next dvd player - the speed will be a factor in my decision.
    Hope this helps.
     
  6. WesleyHester

    WesleyHester Stunt Coordinator

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    Also some Video DACs are 12-bit and even 14-bit. DVD Video will ALWAYS be 10-bit. But for similar reasons that some Video DACs operate at 54mHz and 108mHz, the extra overhead 12- and 14-bit internal processing can provide is just one more additional benefit.

    All of this doesn't dramatically improve the quality of a DVD movie through the use of advanced hardware. What all of this does is allow the movie stored on the DVD to get to your television in all of its glory WITHOUT the hardware getting in the way or becoming a limiting factor.

    What is the difference between a 10-bit/27mHz Video DAC and a 14-bit/108mHz Video DAC? A more faithful DVD image (the SAME image at its original best).

    I say "original" best because I'm sure you all know by now that not all DVDs are created equally - literally. A 14-bit/108mHz can't work miracles. However, a poorly mastered DVD will look its worse on a 10-bit/27mHz Video DAC and not the other way around.
     
  7. Lyle_JP

    Lyle_JP Screenwriter

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