[mythtv] [mythtv-users] BBC HD (1080) h.264 / AVC playback

Janne Grunau janne-mythtv at grunau.be
Tue Feb 20 03:00:40 UTC 2007

On Monday 19 February 2007 17:03:20 Mark Kendall wrote:
> On 2/19/07, Tim Small <tim at buttersideup.com> wrote:
> > Steven Adeff wrote:
> > > Have you tried the DirectShow patch in Trac for using CoreAVC?
> > > http://svn.mythtv.org/trac/ticket/3053
> >
> > No, I haven't - as I'm not too keen on non-free software, and I now
> > have a working free software solution on my hardware (albeit not in
> > MythTV yet)...
> I'd be interested to hear how yo get on with BBC HD in mythtv.

I have no experience with BBC's HD stream but I'm testing another high 
bitrate 1080 h264 stream.  

> I spent some time over the weekend trying to find out why playback
> wasn't as good as mplayer (with or without directshow filters). Even
> with coreavc and a Core 2 Duo E660, myth still skips frames even
> though neither core is running more than about 50% (mplayer is fine).
> I have a small test app that just plays back frames as fast as it can
> and that gives me 35-50 fps when using coreavc and if I disable
> sound, playback is absolutely fine.
> There's something strange happening in the a/v sync process but I
> haven't tracked it down yet...

Try playing back without seeking. After seeking the av sync is disturbed 
since the AC3 audio pts gets reseted to 0. I haven't found a reliable 
way to fix this.

The loop filter can be easily disabled by setting the 
avcodeccontext->skiploop to AVDISCARD_ALL in avformatdecoder. I'll 
prepare a proper patch tomorrow.


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