[mythtv-users] MythTV Raspberry Pi2 frontend testers

[Lawrence Rust]

On Thu, 2015-12-03 at 09:49 -0500, Peter Bennett (cats22) wrote:
> On 12/01/2015 08:58 AM, Lawrence Rust wrote:
> > I believe Kodi borrowed from omxplayer which uses a single OpenMAX
> > pipeline from decoder to video renderer which shares buffers and avoids
> > copying.  Myth currently requires the separation of the decoder from the
> > renderer and so causes two video buffer copies - one each for the GPU
> > and CPU.  For a 1920x1080 frame this is a significant burden that causes
> > memory contention.
> >
> > I will investigate ways of integrating the decoder and renderer so that
> > they use a single OpenMAX pipeline.  Unfortunately this is not trivial
> > because of the current assumption that ffmpeg is the only provider of
> > hardware accelerated decoding i.e. VDPAU, VAAPI, DXVA2 etc.
> >
> >
> Lawrence
> 
> One thing to bear in mind, in case you are not aware. Kodi has some
> significant audio sync problems when playing the MPG files that mythtv
> produces in my setup. Especially after skipping forward or back, the
> audio sync is sometimes far off. In this regard Mythtv is perfect. So
> maybe that is part of the reason for the mythtv design. I would not want
> to do something that lands up with the audio sync problems of Kodi.
> 
> Note that I tested the Kodi audio sync problem with the mythtv plugin
> and also playing the mythtv MPG files as videos in Kodi. Both ways
> exhibit the problem and the author of the kodi mythtv plugin confirms
> that this is a bug with kodi itself, not the plugin.

Peter,

You might like to know that I've improved the RPi OpenMAX decoder by
reducing the number of frame buffer copies - saving almost 100MB/s on a
1920x1080p at 30Hz stream.  This should (hopefully) allow you to play your
HD streams without jerkiness.  It's not as good as Kodi (yet), but it's
getting closer.

Download the pre-built archives (~100MB) from here:
# For Debian wheezy/0.27:
wget http://www.softsystem.co.uk/download/mythtv/mythtv-v0.27.5-101-g665ee21-RPI2.tar.bz2
# For Debian wheezy/0.28:
wget http://www.softsystem.co.uk/download/mythtv/mythtv-v0.28-pre-3252-g0a0927f-RPI2.tar.bz2
# For Debian jessie/0.28:
wget http://www.softsystem.co.uk/download/mythtv/mythtv-v0.28-pre-3252-g0a0927f-RPI2-jessie.tar.bz2

The jessie build will also run on a Pi Zero.  The Zero can only cope
with small SD material (memory constraints), but at $5 what do you
expect?  I'm working on reducing the memory footprint of the OpenMAX
video renderer and hopefully will have standard SD broadcast TV working
on the Zero.

-- Lawrence Rust