[Bug 22007] New: Video playback artefacts when using Xv

[bugzilla-daemon at freedesktop.org]

http://bugs.freedesktop.org/show_bug.cgi?id=22007

           Summary: Video playback artefacts when using Xv
           Product: xorg
           Version: git
          Platform: x86-64 (AMD64)
        OS/Version: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Driver/Radeon
        AssignedTo: xorg-driver-ati at lists.x.org
        ReportedBy: maleadt at gmail.com
         QAContact: xorg-team at lists.x.org


When playing video using the recently Xv acceleration, I experience some minor
artefacts in the image. The artefacts have been occurring for a month or
longer, and might have gotten introduced together with the reworked Xv
acceleration (I'll attempt a git bisect in a few weeks if nothing gets found at
first sight).

When disabling Xv's DMA transfers, the artefacts definitely get worse. It's
also remarkable the artefacts only appear in the lower 30% of the screen, and
tend to appear around heavily moving objects. A single artefact is almost
always a ~360x4 wide rectangle, and if multiple appear they tend to group in
blocks.
Disabling Xv altogether resolves the issue completely.

I'm running -radeon from GIT (Arch Linux AUR build), but the same artefacts
appear on Ubuntu Jaunty with Tormod's PPA enabled (which also provides
up-to-date binaries). Kernel version is 2.6.29, Xorg version is 1.6.1.901. GPU
is an HD4870.

Some images:
Corruption with DMA transfers disabled: http://imgur.com/GYZTc.png (clear band
of corruption in the lower part of the screen)
Same scene with DMA transfers enabled: http://imgur.com/yCXER.png (almost no
corruption, only in the lower right corner)
Another scene with DMA transfers enabled: http://imgur.com/k66ct.png (in this
scene only the hand is actively moving, and the non-moving parts are not
corrupted)


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