[mythtv] VAAPI rewrite

[David Engel]

On Tue, Sep 04, 2018 at 12:38:45PM -0400, Peter Bennett wrote:
> 
> 
> On 09/03/2018 03:08 PM, David Engel wrote:
> > Nice work, Peter.  I've noticed a couple of things others haven't
> > reported yet.
> > 
> > First, all of the VA deinterlacers are enabled in the OSD.  I thought
> > when the post processing was added VAAPI that not all deinterlacers
> > were supported on all hardware.  Maybe things have changed in recent
> > years and I could be wrong.
> I did not see a method for finding out which deinterlacers are supported, so
> I added them all. I suppose if you select one that is not supported you will
> get some sort of failure. The default one, which I labeled "Advanced" is
> documented as finding the best supported, so hopefully that will always
> choose a supported one.

See my later email from last night.  None of the HW-VA choices provide
smooth playback at 1x.

> > Second, I'm seeing strange issues with skip and ff/rew like when the
> > the mediacodec, 2x deinterlacing was first being added.  I think this
> > might be realted to the first issue -- for example, a 2x deinterlacer
> > is requested, but isn't actually being used and the frame timing is
> > getting messed up.  I need to do some more testing to figure out
> > what's going on.
> I also noticed it, but then I switched to a software decode OpenGL profile
> with a 2x interlacer and saw the same thing, so I decided that this may be 
> an existing problem with the drop prediction logic. If you use -v playback
> you can see it gets ahead then behind then ahead in a repeating cycle, so
> something is wrong with that logic. If it is an existing problem I would
> rather fix it in a separate commit later.
> > On the strange observation front, mpeg2 can't time stretch beyond
> > around 1.4x without getting choppy, but h.264 can time stretch at or
> > near 2x.
> Could this be because the h264 is not interlaced or has a lower frame rate?

It's h.264 1080i.  See my later email from last night why I think this
another frame drop/timing issue.

David

> 
> > David
> 

-- 
David Engel
david at istwok.net