Dave Airlie Linux Graphics blog

After hacking the Intel media-driver and ffmpeg I managed to work out how the anv hardware mostly works now for h264 decoding. I've pushed a branch [1] and a MR[2] to mesa. The basics of h264 decoding are working great on gen9 and compatible hardware. I've tested it on my one Lenovo WhiskeyLake laptop. I have ported the code to hasvk as well, and once we get moving on this I'll polish that up and check we can h264 decode on IVB/HSW devices. The one feature I know is missing is status reporting, radv can't support that from what I can work out due to firmware, but anv should be able to so I might dig into that a bit. [1] https://gitlab.freedesktop.org/airlied/mesa/-/tree/anv-vulkan-video-decode [2] https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20782

Needless to say h264/5 weren't my real goals in life for video decoding. Lynne and myself decided to see what we could do to drive AV1 decode forward by creating our own extensions called VK_MESA_video_decode_av1. This is a radv only extension so far, and may expose some peculiarities of AMD hardware/firmware. Lynne's blog entry[1] has all the gory details, so go read that first. (really read it first). Now that you've read and understood all that, I'll just rant here a bit. Figuring out the DPB management and hw frame ref and curr_pic_idx fields was a bit of a nightmare. I spent a few days hacking up a lot of wrong things before landing on the thing we agreed was the least wrong which was having the ffmpeg code allocate a frame index in the same fashion as the vaapi radeon implementation did. I had another hacky solution that involved overloading the slotIndex value to mean something that wasn't DPB slot index, but it wasn't really any better. I think there may...