vulkan video decoding: anv status

After cleaning up the radv stuff I decided to go back and dig into the anv support for H264.

The current status of this work is in a branch[1]. This work is all against the current EXT decode beta extensions in the spec.

This contains an initial implementation of H264 Intel GPUs that anv supports. I've only tested it on Kabylake equivalents so far. It decodes some of the basic streams I've thrown at it from ffmpeg. Now this isn't as far along as the AMD implementation, but I'm also not sure I'm programming the hardware correctly. The Windows DXVA API has 2 ways to decode H264, short and long. I believe but I'm not 100% sure the current Vulkan API is quite close to "short", but the only Intel implementations I've found source for are for "long". I've bridged this gap by writing a slice header parser in mesa, but I think the hw might be capable of taking over that task, and I could in theory dump a bunch of code. But the programming guides for the hw block are a bit vague on some of the details around how "long" works. Maybe at some point someone in Intel can tell me :-)

Building:

git clone https://gitlab.freedesktop.org/airlied/mesa

git checkout anv-vulkan-video-prelim-decode

mkdir build

meson build -Dvulkan-beta=true -Dvulkan-drivers=intel -Dvideo-codecs=h264dec --prefix=<prefix>

cd build

ninja

ninja install

Running:

export VK_ICD_FILENAMES=<prefix>/share/vulkan/icd.d/intel_icd.x86_64.json

export ANV_VIDEO_DECODE=1

vulkaninfo

This should show support for VK_KHR_video_queue, VK_KHR_video_decode_queue, VK_EXT_video_decode_h264.

[1] https://gitlab.freedesktop.org/airlied/mesa/-/tree/anv-vulkan-video-prelim-decode

Comments

  1. DDD17 December 2022 at 07:50

    Any chance of a quick a VK_AIRLIED_video_decode_av1 extension? :)

    ReplyDelete
  2. Dave Airlie29 December 2022 at 12:26

    we are considering a mesa one

    ReplyDelete

Post a Comment

Popular posts from this blog

tinygrad + rusticl + aco: why not?

I recently came across tinygrad as a small powerful nn framework that had an OpenCL backend target and could run LLaMA model. I've been looking out for rusticl workloads, and this seemed like a good one, and I could jump on the AI train, and run an LLM in my house! I started it going on my Radeon 6700XT with the latest rusticl using radeonsi with the LLVM backend, and I could slowly interrogate a model with a question, and it would respond. I've no idea how performant it is vs ROCm yet which seems to be where tinygrad is more directed, but I may get to that next week. While I was there though I decided to give the Mesa ACO compiler backend a go, it's been tied into radeonsi recently, and I done some hacks before to get compute kernels to run. I reproduced said hacks on the modern code and gave it a run. tinygrad comes with a benchmark script called benchmark_train_efficientnet so I started playing with it to see what low hanging fruit I could find in an LLVM vs ACO shootout
Read more

nvk: the kernel changes needed

The initial NVK (nouveau vulkan) experimental driver has been merged into mesa master[1], and although there's lots of work to be done before it's application ready, the main reason it was merged was because the initial kernel work needed was merged into drm-misc-next[2] and will then go to drm-next for the 6.6 merge window. (This work is separate from the GSP firmware enablement required for reclocking, that is a parallel development, needed to make nvk useable). Faith at Collabora will have a blog post about the Mesa side, this is more about the kernel journey. What was needed in the kernel? The nouveau kernel API was written 10 years or more ago, and was designed around OpenGL at the time. There were two major restrictions in the current uAPI that made it unsuitable for Vulkan. buffer objects (physical memory allocations) were allocated 1:1 with virtual memory allocations for a file descriptor. This meant the kernel managed the virtual address space. For proper Vulkan suppor
Read more

video decode: crossing the streams

I was interested in how much work a vaapi on top of vulkan video proof of concept would be. My main reason for being interested is actually video encoding, there is no good vulkan video encoding demo yet, and I'm not experienced enough in the area to write one, but I can hack stuff. I think it is probably easier to hack a vaapi encode to vulkan video encode than write a demo app myself. With that in mind I decided to see what decode would look like first. I talked to Mike B (most famous zink author) before he left for holidays, then I ignored everything he told me and wrote a super hack. This morning I convinced zink vaapi on top anv with iris GL doing the presents in mpv to show me some useful frames of video. However zink vaapi on anv with zink GL is failing miserably (well green jellyfish). I'm not sure how much more I'll push on the decode side at this stage, I really wanted it to validate the driver side code, and I've found a few bugs in there already. The WIP hac
Read more