[mythtv] [mythtv-commits] Ticket #6130: Experimental VDPAU optimisations

[David Asher]

On Sep 30, 2009, at 12:28 PM, MythTV wrote:

> Secondly, add an option for the user to specify the number of VDPAU  
> video
> buffers to use. It is enabled by adding vdpaubuffersize=X to the  
> filters
> section of the video display profile. Valid values for X are in the  
> range
> 6-50, 6 being the minimum that seems to work with most mpeg2 and h264
> interlaced streams (with 2 reference frames).
>
> The lowest setting can save over 80Mb of video memory for 1080i/p  
> streams
> compared to the default buffer size of 17 frames. This may be enough  
> for
> VDPAU playback on video cards with 256Mb of memory (though certainly  
> no
> guarantee).
>
> Increasing the video buffer size should fix playback for problematic
> streams with more than 2 reference frames. For example, the well known
> 'killa.sampla' h.264 clip needs around 32 video buffers for decent
> playback (16 reference frames) and most broken streams with 4  
> reference
> frames seem to need around 22 buffers.
>
> This a stop gap fix for 0.22 and *should* be replaced by a more
> robust/intelligent/automatic solution for 0.23 - I just haven't  
> worked out
> the magic formula yet...

Is there a rule of thumb based on the memory the video card has?  If  
I've got a 512MB card, what the HIGHEST I could set this to.  It  
sounds like that would make the most videos playable.

Is there a downside to using all video memory available?

Thanks.