[mythtv] Mediacodec problem with avcodec_flush_buffers

[Peter Bennett]

Hi Aman

When doing a skip forward in playback, we use avcodec_flush_buffers and 
then start processing from a different part of the file. We then receive 
a couple of frames from the new location and then one which contains 
part of a frame from before the flush and part of a new frame. There is 
a diagonal jagged line across the middle. Above the jagged line is part 
of an image after the flush. Below the line is part of an image before 
the flush. This produces a noticeable irritating flash on the screen.

In this case the second frame after the flush was corrupted this way. It 
is not consistent, sometimes the third frame, sometimes a later one. I 
tried to compensate by dropping some frames after a flush but it is 
problematic because it is inconsistent.

This link is a photograph of the screen when I stopped it during playback.
https://www.dropbox.com/s/rxub9otpwuop3t9/IMG_20180709_173348703.jpg?dl=0

I have other pictures from before and after the bad one if you need them.

Peter