[mythtv] HD H264 decoding with multiple threads

[John]

Terry Barnaby wrote:
> I have just "updated" my systems to Fedora 12 and MythTv 0.22 (from 
> RpmFusion RPM's). Previously I was using Fedora 11 with MythTv from 
> SVN from around December 2008.
> In order to get smooth HD playback on my Intel G45 frontend (from freesat
> BBC-HD) I had set MythTv to use 2 CPU's in FFMPEG to decode the H264 
> stream.
> With my current setup MythTv only appears to be using 1 CPU for H264 
> decode.
> It does appear to use 2 CPU's for SD MPEG2 decode however.
> Using "mythfrontend -v playback" the log states "Using 2 CPUs for 
> decoding" so
> all looks to be configure Ok.
>
> Any ideas on what is wrong here ?
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>
Its not your Setup, its the BBC :-)

BBC-HD has changed their encoders, dropping the bitrate from 18-20 Mb/s 
o about 14 Mb/s. They have as a consequence changed the way the stream 
is encoded, and the ability of ffmpeg to decode  multi-threaded :-(

However if you turn of the loopfilter, then ffmpeg can decode 
multi-threaded. This is discussed  at

http://svn.mythtv.org/trac/ticket/6986

And patches are  available at my long running plea to have this added to 
svn :-)

http://svn.mythtv.org/trac/ticket/4653

you can either use my full patch (updated by jyavenard)  rather than the 
full patch, which gives the option to disable the loopfilter,

The smaller 28_skiploop_multithread.dpatch which I now use simply 
assumes that if you are watching H.264 and you have set multi-core you 
want to disable the loopfilter.


John