Video refresh question

Discussion in 'Displays' started by Wayde_R, Nov 17, 2005.

  1. Wayde_R

    Wayde_R Stunt Coordinator

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    I understand that video TV refreshes at a rate of 60Hz, it's been that way since late Roman times.

    Is this correct? The interlaced 480i TV refreshes at 60Hz.

    Now my question is what about new HDTVs that are progressive scan and alternate display technologies to the CRT?

    For instance does a 720P LCD TV refresh at a rate of 60Hz? What about Plasma?

    I believe it does but want to know if any of the video gurus out there can verify this is a correct assumption.
     
  2. ChrisWiggles

    ChrisWiggles Producer

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    standard TVs refresh at 60hz (more precisely 59.97hz) interlaced. Multi-scan monitors can refresh at basically whatever they want. Standard TVs are used only for video at 60hz, so that's all they were designed for usually. Now, it's far more common for TVs to support different kinds of refresh rates and resolutions similar to a multi-scan monitor (like a computer monitor).

    So it really depends on the design of the actual display and what refresh rates and resolutions it will support. Most anything sold as a TV will do the standard video rate, a lot now will also do multiples of the film rate of 24, so it may also do 48hz especially with digitals. 48hz is generally too flickery for CRT displays even progressive, and not many consumer displays have the electronic capabilities to do 72hz progressive at high resolutions, but pro-grade displays often do.
     
  3. Wayde_R

    Wayde_R Stunt Coordinator

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    Thanks Chris, very informative. It's one of those things I was never sure about.

    Not to get into a long 1080P debate, that's not what I'm looking for. I hear 1080P talks quickly turn into ... 1080P/60. Is there a reason that 1080P/60 is considered the holy grail? Just because 60 is good enough not to flicker and looks a heck of a lot better than 30Hz or something closer to 24?

    If you say 48Hz shows flicker, that would mean to me you'd want any display to do at least 60Hz.
     
  4. ChrisWiggles

    ChrisWiggles Producer

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    That's with CRT displays, you can run digitals at lower refresh rates because it's kind of changing the panel each time, and it stays the same until it gets new information. A CRT needs to be constantly scanned if you scan too slowly the phosphors decay once the beam passes by and you get flickering. You can run a DLP or LCD at 48hz and there won't be any flicker, you could also run at plain 24hz too.

    1080p60 takes up a ton of data space and a lot of electronic capabilities to handle that. I am guessing that 1080p60 content won't be around for a long time. We'll be looking at 24p and 30p stuff pretty much maxed out, or 1080i60 which is similar to 1080p30 in terms of bandwidth/data space etc.
     
  5. Wayde_R

    Wayde_R Stunt Coordinator

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    Thanks for the chat Chris, I am digesting your Setting Source Options guide. I think they should make it a sticky[​IMG] j/k

    Thanks Again
    Wayde
     

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