claude-noether
6bc12fe7e4
Per Phase 7 close + user-directed Option B trigger (web research /
rockchip-mpp showed Hi10P is effectively impossible on the current
stack). Cross-test on ampere RK3588 confirmed the SAME failure mode
as fresnel RK3399 — both produce all-zero output via libva; kdirect
fails with EINVAL on both. The blocker is in ffmpeg-v4l2-request
userspace plumbing for the new uAPI controls Karlman's kernel patches
introduced, NOT in our backend or the kernel.
Sources confirming kernel + HW capable but userspace pending:
- lwn.net/Articles/950434: "to fully runtime test... you may need
upstream DRM commits, FFmpeg patches"
- patchwork.kernel.org Karlman v6 → v10 series on linux-media
- Rockchip RK3399 + RK3588 datasheets list 10-bit H.264 support
Stop enumerating Hi10P + Main10 so VAAPI consumers don't try the
broken path. The backend infrastructure (codec.c profile cases,
context.c NV15 CAPTURE + synthetic SPS bit_depth=2 + video_format
invalidation, image.c P010 reporting + NV15→P010 unpack, surface.c
RT_FORMAT_YUV420_10 guard + NV15 PRIME fourcc, nv15.c + nv15.h
unpack primitive, request.h is_10bit flag) is RETAINED — just
re-add the two profiles[index++] lines and bump the H264 guard
back to (-6) when upstream ffmpeg-vaapi V4L2 hwaccel learns 10-bit.
Memory: feedback_rk3399_h264_hi10p_advertised_not_functional.md
captures the empirical evidence for future iterations.
vainfo after this commit: 10 profiles (was 12), matches the iter38
baseline. iter38 5/5 PASS preserved (no other codec touched).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
v4l2-request libVA Backend
About
This libVA backend is designed to work with the Linux Video4Linux2 Request API that is used by a number of video codecs drivers, including the Video Engine found in most Allwinner SoCs.
Status
The v4l2-request libVA backend currently supports the following formats:
- MPEG2 (Simple and Main profiles)
- H264 (Baseline, Main and High profiles)
- H265 (Main profile)
Instructions
In order to use this libVA backend, the v4l2_request driver has to
be specified through the LIBVA_DRIVER_NAME environment variable, as
such:
export LIBVA_DRIVER_NAME=v4l2_request
A media player that supports VAAPI (such as VLC) can then be used to decode a video in a supported format:
vlc path/to/video.mpg
Sample media files can be obtained from:
http://samplemedia.linaro.org/MPEG2/
http://samplemedia.linaro.org/MPEG4/SVT/
Technical Notes
Surface
A Surface is an internal data structure never handled by the VA's user containing the output of a rendering. Usualy, a bunch of surfaces are created at the begining of decoding and they are then used alternatively. When created, a surface is assigned a corresponding v4l capture buffer and it is kept until the end of decoding. Syncing a surface waits for the v4l buffer to be available and then dequeue it.
Note: since a Surface is kept private from the VA's user, it can ask to directly render a Surface on screen in an X Drawable. Some kind of implementation is available in PutSurface but this is only for development purpose.
Context
A Context is a global data structure used for rendering a video of a certain format. When a context is created, input buffers are created and v4l's output (which is the compressed data input queue, since capture is the real output) format is set.
Picture
A Picture is an encoded input frame made of several buffers. A single input can contain slice data, headers and IQ matrix. Each Picture is assigned a request ID when created and each corresponding buffer might be turned into a v4l buffers or extended control when rendered. Finally they are submitted to kernel space when reaching EndPicture.
The real rendering is done in EndPicture instead of RenderPicture because the v4l2 driver expects to have the full corresponding extended control when a buffer is queued and we don't know in which order the different RenderPicture will be called.
Image
An Image is a standard data structure containing rendered frames in a usable pixel format. Here we only use NV12 buffers which are converted from sunxi's proprietary tiled pixel format with tiled_yuv when deriving an Image from a Surface.