CDVDVideoCodecDRMPRIME: software decoding

[lrusak]

This has been in the works for some time but has finally been made possible because of #17688

This allows CDVDVideoCodecDRMPRIME to do sw decoding into dma-bufs. This is equivalent to the functionality that the RPi platform has where it can sw decode directly into mmal buffers.

Currently this only supports AV_PIX_FMT_YUV420 as rendering other formats is more difficult (especially on embedded hardware). Mesa has native support to render this format into EGL (using shaders) so we can allow that easily. Other sw decoded pixel formats such as AV_PIX_FMT_YUV420P10 do not have a mesa EGL equivalent. Typically this is because interleaved formats are much better suited for importing into the GPU such as NV12 or P010.

I've tested this on various hw such as Amd, Intel, Amlogic (odroid-c2). The odroid-c2 is the only platform that supports YUV420 (YU12) int the drm plane so that is the only platform I have tested this with using direct-to-plane rendering and it seems to be fine for 1080P H264.

I also added a setting switch to enable/disable hw decoding methods when using CDVDVideoCodecDRMPRIME so this can be tested easily. This will probably need to be expanded in the future to enable/disable specific codec like we have currently for VAAPI.

Also be aware that this only works with the udmabuf and dma-heap CBufferObject types so if you want to test you will need one of those methods available on your platform.

[jernejsk]

Tested on Allwinner H6 board. Works great. LGTM.

[popcornmix]

Working on Pi too.

[lrusak]

@jernejsk @popcornmix thanks for the review, Can you verify that the setting to disable hw decoding for DRM PRIME actually acts like it should? After that we can shove this in 👍

[jernejsk]

Not sure if "Allow hardware acceleration with DRM PRIME" works correctly. In both cases (that option enabled and disabled) I get "ff-vp9-drm_prime (SW)" when pressing "o".

[popcornmix]

I think (as root):

echo "cma:*" > /sys/kernel/debug/tracing/set_event
# [play video]
cat /sys/kernel/debug/tracing

should show frame sized allocations and frees when software decoding is using dma-heap.
Note: even when not being used I think you see some size=1 allocations.

[jernejsk]

Log: http://ix.io/2mZS So, even if aforementioned option is disabled, DMA buffers are used.

[jernejsk]

Eh, sorry, disregard my comment. I thought settings are the other way around. Yeah, settings work fine. GTG

[popcornmix]

Pretty sure the switch worked as expected when I tested it on Pi.