[mythtv-commits] mythtv/master commit: 5e04d57bc by Mark Kendall (mark-kendall)

MythTV noreply at mythtv.org
Mon Apr 11 14:09:09 UTC 2011

      Author:  Mark Kendall <mkendall at mythtv.org>
 Change Date:  2011-04-11T07:08:04-07:00
   Push Date:  2011/04/11 07:08:59 -0700
  Repository:  mythtv
      Branch:  master
New Revision:  5e04d57bc87a6f422ccba79a493bebef50566162
   Changeset:  https://github.com/MythTV/mythtv/commit/5e04d57bc


VDPAU: Dynamically optimise video buffer size.

This builds upon Taylor Ralph's video buffering fix for H.264 streams
with multiple reference frames.

Firstly we make a notional distinction between the number of VDPAU
buffers required to keep the decoder happy (the number of reference
frames) and the number of video buffers required to allow for smooth
video processing and presentation.

For software based decoding, we default to the worst case for the number
of reference frames (16) which, in combination with the default process
queue size of 12, gives a total of 28. This should happily deal with any
H.264 stream and is marginally less than the XVideo/OpenGL equivalent
(which makes sense given the lower expected deinterlacing overhead).

For hardware based decoding, we default to 2 reference frames. When the
decoder is created, and the actual number of reference frames is known
for H.264 streams, additional video buffers are created as needed.

The vdpaubuffersize 'filter' option is retained but now overrides the
number of buffers needed for video processing and presentation.

The default 'processing' size of 12 is based upon extensive testing on a
first generation NVidia Ion system with a range of test clips - the
overwhelming majority of streams are happy with something in the range
of 4-8 but several require 10-12.

The vast majority of VDPAU systems should now play any H.264 stream
without issue with these settings and in most cases with a small memory
saving over the previous code. I expect the only case in which anyone
will want/need to override the buffer size is for systems with lower
video memory (e.g. 256Mb).



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