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Thread: Image Quality Leak in Accelerated 1080p Video Playback

  1. #1
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    Apr 2010
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    Default Image Quality Leak in Accelerated 1080p Video Playback

    I am wondering why one is experiencing this very noticeable breakdown in terms of image quality when using accelerated playback of non-scaled HD 1080p videos in e.g. mplayer. We see pixel macro-blocks as if the video resolution were ~4 times lower. At the same time unaccelerated (-vo x11) playback gives the clear and sharp result we expect from the HD material (while x11 is unfortunately not an option due to the well known tearing artifacts). As input size equals output size no scaling filters are involved, and x264 pre/post-processing is independent from the output graphic driver. The effect is the same on any other software player (vlc, whatsoever), in a non-compiz environment.

    I can't see any restriction on textured video size in the manpage, and no other options than EXA for "AccelMethod" are set in xorg.conf, so any comment, workaround, solution is very appreciated.

  2. #2
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    Please open a bug report (https://bugs.freedesktop.org) and attach your xorg log, config, dmesg, and a picture of the problem.

  3. #3
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    On a closer look to the manpage it would have turned out that the "ScalerWidth" parameter has to be set manually. Mea culpa, mea maxima culpa.

  4. #4
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    Quote Originally Posted by dwarsch View Post
    On a closer look to the manpage it would have turned out that the "ScalerWidth" parameter has to be set manually. Mea culpa, mea maxima culpa.
    what card do you have (pci ids)? It would be nice to set the scalerwidth properly by default for your card. Textured video should also work and doesn't have the same limitations as the overlay.

  5. #5
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    01:00.0 VGA compatible controller: ATI Technologies Inc Radeon Mobility X700 (PCIE) (prog-if 00 [VGA controller])
    Subsystem: Hewlett-Packard Company HP Compaq NW8240 Mobile Workstation
    Flags: bus master, fast devsel, latency 0, IRQ 16
    Memory at c0000000 (32-bit, prefetchable) [size=128M]
    I/O ports at 2000 [size=256]
    Memory at c8800000 (32-bit, non-prefetchable) [size=64K]
    [virtual] Expansion ROM at c8820000 [disabled] [size=128K]
    Capabilities: [50] Power Management version 2
    Capabilities: [58] Express Endpoint, MSI 00
    Capabilities: [80] MSI: Enable- Count=1/1 Maskable- 64bit+
    Capabilities: [100] Advanced Error Reporting


    where chipid is identified by the driver as

    (--) RADEON(0): Chipset: "ATI Mobility Radeon X700 (M26) (PCIE)" (ChipID = 0x5653)

    The maximum resolution for the external VGA port is 2048x1536, so ScalerWidth 2048 might be a reasonable choice (for that i can confirm it's working properly).

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