[mythtvnz] Channel change stability issues with MythTV and VDPAU in NZ

[Robert (MythTV)]

Steven Ellis wrote:
> I've finally got a debug dumps from a recent Jean-Yves MythTV build 
> that shows the two issues I'm regularly seeing with VDPAU playback of 
> freeview|HD here in NZ.
>
> 1. MythTV frontend exits during a channel change
> 2. Live TV exits with the message "Error was encountered while 
> displaying video", but the frontend doesn't crash.
I can also confirm this exact same issues on my MythTV Boxes as well. 
(JYA testing repo)
Running 64 bit (not 32 bit)
A). 2Gb RAM, 200Gb system disk, 400Gb dedicated recording disk.
B). 8Gb RAM, 400Gb system disk, 400Gb dedicated recording disk.

Test environments
* Ubuntu 9.04 64 bit (GNOME with Compiz/Composite enabled)
* nVidia VDPAU 185.19
* mythtv - 0.21.0+fixes-svn20649-jya-debug-0ubuntu0
* mythtv - 0.21.0+fixes-20649-openglvdpau-debug-0ubuntu2

RE: 1). Quick channel changes on my Nova-T 500 DVB-T cause the front end 
to crash. This is especially easy to do when changing from DVB-T (i.e. 
TV3) to my Leadtek Winfast 2000XP (analog for Prime). This almost always 
appears to cause the front-end to crash. It is repeatable, but does not 
happen every time though.

Additionally, changing channels on the Winfast can now lead to a full 
system lockup, which did not occur before. i.e. there is no terminal, no 
mouse movement, sound locked in repeated loop - true machine lockup, 
only reset button works. Speed of the channel change in this second case 
is not needed, so this may be (probably is) a different bug.

RE: 2). I can confirm this happening as well. Speed of channel change is 
not an issue for me. I could have been watching a channel (Live TV) for 
a while, then change channel, and it fails. After this is appears that 
the card is still 'in use' and entirely unavailable. Restarting 
mythbackend, mythfrontend, or anything else I've tried does not free up 
the card again. Rebooting the machine (power off) appears to be the only 
solution - which makes me think it could be a firmware loading issue, or 
something in the Nova-T driver itself.

 From a quick cursory look at the crash logs, my box appears to exhibit 
the exact same issues. Not running debug build.

> I have a feeling that both of these issues are down to error handling 
> when the reception picks up a set of bad frames that the H.264 decoder 
> struggles to handle.
In order to eliminate the H264 (software) decoder, I've disabled the 
commercial detection, preview generation, etc. This eliminates the h264 
frame errors in the logs, but the VDPAU ones are still present. No 
difference in stability.

Robert.

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