[mythtv] Feedback on render branch

Peter Bennett pb.mythtv at gmail.com
Wed Apr 3 19:48:37 UTC 2019


Hi Mark

Here are a few observations.

**VAAPI acceleration
OpenGL-HW - no deinterlacer is offered
Resolution change is ok - it would fail on old VAAPI
1080i - ticker jerky due to single frame deinterlace
So it is inferior to the old vaapi in the deinterlace area, superior in 
the changed resolution area.

**VAAPI decode only
the va deinterlacers are not being used - if you select one of them the 
output is still interlaced
video output is corrupt after a change of resolution
1080i - ticker jerky due to interlace
So it is inferior to the old vaapi2 in the deinterlace area and in the 
changed resolution area.

OpenGL Slim (s/w decode)
video output is corrupt after a change of resolution

Screen shot of corrupted video after resolution change
see https://imgur.com/LbACR9c

I have not yet taken much of a look at the code in the render branch 
yet. I thing that tracing through it during playback would help 
understanding.

I did invent my own deinterlace shader and test it with a simple program 
- I am sure it is inferior but I am trying out various things as a 
learning exercise.

I suppose the main complex things that need to be done in shaders is 
deinterlace and conversion from various YUV encodings to RGB for 
display. I plan to look at the code and try to understand how those work.

At some point I hope to try integrating direct NVDEC display.

Let me know if I should look into the issues reported above, and if I 
should make updates to the render branch. I don't want to step on what 
you are doing.

It seems that debugging a shader is not easy - you can't do printf in 
the code or trace through it with gdb to see where something is going wrong.

Peter



More information about the mythtv-dev mailing list