[mythtv-users] OpenGL render problems with radeon and 0.24.1

Mark Kendall mark.kendall at gmail.com
Fri Jun 10 01:02:13 UTC 2011


On 9 June 2011 00:44, John King <jmking1 at gmail.com> wrote:
> I'm having problems with myth playback using the OpenGL renderer and
> the radeon Xorg driver.  Basically it looks like the mythtv video
> playback is displaying one frame, but then a stale buffer is displayed
> the next frame.  I uploaded a YouTube video of what's going on:
>
> http://www.youtube.com/watch?v=KM824VcdMDs
>
> Audio is fine, and it appears that the framerate is fine too.
>
> I have the MythTV GUI painter set up to use OpenGL, and it looks like
> a stale GUI background image is being displayed on the alternate (i.e.
> non-video) frames.  And then when the video finishes playing, the GUI
> is messed up too - it seems as though the stale buffer is sometimes
> showing up there.  But the problem still happens even if I switch the
> GUI painter back to Qt.  In that case I get a mostly black stale frame
> with the text "Please Wait..." on it - which is what gets displayed
> just before the video starts.
>
> Is this some sort of OpenGL page flip problem?

Probably:)

In short, this will be fixed shortly in master (and hence for 0.25)
but it is unlikely to be fixed in 0.24 as the code changes are pretty
invasive.

In a little more detail, I've seen the same issue on the integrated
intel graphics on one of my boxes and a similar issue on a macbook
(with OS X). I haven't figured out exactly where the problem is but on
some systems, the driver gets its framebuffer handling confused
between the OpenGL context we use for the main UI and the one we use
for video. The solution is to use one shared OpenGL context. Once I've
resolved a couple of Windows OpenGL issues in master, I'll uncomment
the one line of code that moves us to a single OpenGL context and all
should be good again.

regards

Mark


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