[mythtv] 50fps video playback on 30Hz display (4K on HDMI 1.4 output)

[Peter Bennett]

On 10/30/18 11:42 AM, Andreas Mayer wrote:
> avsync2 works well, but there are a couple of HD channels on Astra 
> 19.2E (720p, ARD, ZDF) where the prebuffer pause does not work anymore 
> when using VAAPI with avsync2 (works with VAAPI2/avsync2 and with 
> VAAPI/without avsync2), video is not able to catch up even if dropping 
> video frames all the time, audio is running with video still picture 
> until I'm pressing pause/unpause, after doing this both audio and 
> video are fine.
> I would like use VAAPI2 with avsync2 for all channels but it looks 
> like VAAPI2 is needing more CPU resources than VAAPI at least for HEVC 
> 2160p (Astra UHD demo channel) decoding, VAAPI is able to keep up 
> without frame drops (at least on a display with 1920x1080 at 60, I think 
> it would not be worse on a 3840x2160 at 30 display).
> I tried to create a video playback profile with VAAPI for HEVC and 
> VAAPI2 for anything else (and avsync2), but it looks like changing 
> between those decoders does not work when switching between channels.
I have added some checkboxes in the video playback advanced settings to 
disable certain pixel types. You can try disabling one or both of those 
to see if the results are any better. These are mainly useful for 
android and low powered systems but they may make a difference.

Please can you supply a sample video to test VAAPI and VAAPI2 issues. I 
will see if there is a way to improve the CPU requirements so that 
vaapi2 and avsync2 give a good result.

Peter