[mythtv] Android mediacodec woes

[Daniel Frey]

Peter,

Have you looked at ExoPlayer. I've had some success with using that in
a branch I've been working on for MythtvPlayer. My hope is that it replaces
all the low-level Android Media APIs.  HLS was pretty flawless in the
latest releases.  I believe there is also a way to get MPEG2 integrated,
but it would be a custom solution.  However, ExoPlayer, is extendable just
for that purpose.

Dan

On Tue, Jun 26, 2018 at 4:12 PM Peter Bennett <pb.mythtv at gmail.com> wrote:

> The double framerate that I am getting from mediacodec is proving to be
> a rather complicated problem to solve. With the situation the way it is
> now, the display of elapsed time is wrong and jumps are very wrong. For
> example after watching for 5 minutes, the OSD shows 10 minutes, and
> doing a forward jump of 1 minute jumps to the real 11 minutes, i.e.
> jumps forward 6 minutes instead of jumping forward 1 minute. Jumping
> back a minute  actually jumps forward 4 minutes.
>
> Detecting the condition is easy enough. Fixing it, not so easy.
>
> I first thought that I could simply double the fps value stored in
> AVFormatDecoder and MythPlayer. That does not work. I found that the
> MpegPreProcess is resetting it back to 29.97 on the next frame. Why do
> we parse the Mpeg input? Maybe that should be eliminated. We could get
> framerate from the decoded timestamps.
>
> I then realized that the whole approach of changing the fps is flawed
> because the code uses framecount all over the place for calculating
> positions in the file. If the frame count from the demultiplexer
> (avformat) is half the frame count from the decoder, all sorts of
> calculations go wrong.
>
> There is a feature in MythPlayer for m_double_framerate for double
> framerate deinterlacers. I am now thinking I should extend that to
> support this new situation of double framerate interlacer that is built
> into the decoder. It will need a number of changes, currently
> m_double_framerate is disabled as soon as it sees a non-deinterlaced
> frame. Currently m_double_framerate indicator causes the same frame to
> be passed to the video output twice, now it will need two consecutive
> frames passed to the video output.
>
> Another option is just drop every second frame. This would be easiest
> but that will surely reduce the quality, which is not what we want.
>
> Peter
>
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