[mythtv] Playback next steps

David Engel david at istwok.net
Sun Dec 2 03:06:41 UTC 2018

On Sat, Dec 01, 2018 at 04:58:16PM -0500, Peter Bennett wrote:
> I have added support in MythTV playback for VAAPI2 (VAAPI plus deinterlace
> plus ability to handle format changes) and Mediacodec. I plan to do the same
> However these new methods are passing images through main memory on their
> way to the output and using the existing OpenGL code for rendering, We need
> to pass images directly from decoder to graphics output to improve
> efficiency and to support 4K video at 50 fps. The next task will be to
> support this. I am not sure how this will work. The existing OpenGL code in
> MythTV does a lot of processing of each image and in order to achieve the
> required performance, some of this may have to be avoided. It may entail a
> new type of lightweight opengl that leaves out the extensive opengl
> processing of images currently undertaken, or may require new types of video
> rendering.
> My knowledge / experience with OpenGL is very little and I have found the
> existing OpenGL code rather difficult to understand.
> If anybody has information/ideas about how to proceed with this please let
> me know.

Aman probably has some helpful tips for mediacodec.  Is there a reason
you didn't copy him?

Also regarding mediacodec, I still believe surface rendering of video
is the preferred method on Android.  We've already been told that will
fix the multifreme corruption problem on interlaced video.  I believe
OpenGL can/should still be used to render the OSD in such cases.  I
hope that means only a small amount of new code needs to be added to
scale and shift the video.

David Engel
david at istwok.net

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