Re: Building media player for RPI4 : which one to focus on?

[Robert Swindells <rjs%fdy2.co.uk@localhost>]

Mayuresh <mayuresh%acm.org@localhost> wrote:
>I am attempting to build a media player with hardware acceleration for
>RPI4, currently with 64 bit kernel and 32 bit userland, but open to
>alternatives.

What are you hoping to accelerate?

There are two parts of the problem:

  Video decoding, turning the stream into individual images.

  Copying images to the screen fast enough.

There is currently a project to add the RPi3 display drivers from Linux
to the NetBSD kernel. This will provide accelerated X11 with OpenGL in a
system with native xorg. There is one extra driver that would be needed
for the RPi4.

I have no idea whether any RPi GPU can help with video decoding.

There is video decoding hardware built in to Rockchip and Allwinner
ARM chips, Linux has drivers for them which use the Video4Linux2 API
to return a decoded frame to a userland application. Someone could
add equivalent NetBSD drivers and extend our video(4) driver layer
to match the latest Linux changes.

I have run mplayer on a Pinebook using the builtin 1920x1080 display,
it was doing both decode and display in software, I didn't notice
dropped frames, the RPi4 should be faster than this machine.

What problems do you see on the RPi4 when trying to view a video without
any acceleration?

There is a VDPAU driver with an OpenGL backend that may help eventually,
it calls OpenGL to copy a frame to the display, mplayer can be
configured to call different VDPAU drivers, I have a local pkgsrc
package for this but haven't tried using it yet.

Robert Swindells