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Scanline sync 720p 144hz

Discussion in 'Rivatuner Statistics Server (RTSS) Forum' started by DoloresGrace, Jan 24, 2019.

  1. DoloresGrace

    DoloresGrace New Member

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    GPU:
    gtx 970
    ryzen 1700 and gtx970 set 144hz benq xl2411p
    i have some weirdo problems with input mouse floating and micro stuttering in quake champions
    put gpu in msi mode and lock fps fix just a half of a problem
    but scanline do a lot better and its with less input lag than natural quake have
    im try some number -50-150
    but rly cant decide whats value better for 720p 1280/720 resolution 144hz gaming with less possible input lag
    idk why but in this broken game 720p feels in 99999 time better than 1080p natural monitor resolution /=
    any help ?
     
    Last edited: Jan 24, 2019
  2. RealNC

    RealNC Ancient Guru

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    The value does not affect input lag. It affects tearing. Technically, the part of the frame after the tear line is the new one, and thus has less input lag, but if you place the tear line at the middle of the screen in order to get the least amount of lag, then you might as well just run without scanline sync. Scanline sync is for getting rid of tearing.
     
  3. mdrejhon

    mdrejhon Member Guru

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    Actually, there's a subtle technicality.

    The value affects lag in a subtle way:
    - Average lag stays the same
    - But lag gradient vertically shifts up/down (with a wraparound effect around bottom through top) when you shift the tearline up/down.

    A screen (and also each frame slice) is a latency gradient.

    This is because of finite-speed screen refresh (high speed videos). Not all pixels on a screen refresh at the same time -- it takes times for pixels to be transmitted over the video cable (the raster scan-out behaviour).

    The input lag right below tearline is:

    Lag of a specific pixel row = (time of one scanline in Horizontal Scan Rate) * (number of scanlines away below the tearline above it)

    If a screen is running at 160KHz horizontal scan rate (view the scanrate in Custom Resolution Utility), then the latency of the pixel row 50 pixel rows below the tearline, is 50/160000sec (about 313 microseconds) laggier than the pixel row immediately underneath the tearline.

    Here's a scanout graph chart of a framerate running at exactly 3x refresh rate (180fps at 60Hz), generating 3 tearlines per refresh cycle:

    [​IMG]

    THEREFORE, moving the tearline affects the input lag of the rest of the screen.

    Shifting the tearline up/down will shift upwards/downwards the latency gradient effect.

    The average input lag remains the same, but the latency gradient shift upwards/downwards.

    To understand the latency gradient of a screen, see high speed video of refresh cycles filmed on the brand-new TestUFO Scanout test.
     
    Last edited: Jan 25, 2019
  4. RealNC

    RealNC Ancient Guru

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    No, it's not wrong. Read again. ;)
     
    Last edited: Jan 25, 2019

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