claude-noether
7f84bbb50f
buffer-type cases + new VAProbabilityBufferType outer case + per-
frame reset + surface.h params.vp8 union extension
Five sites in picture.c + one site in surface.h wire up the VP8
codec dispatcher introduced by commit B:
1. Include #include "vp8.h" in the codec headers block.
2. codec_set_controls: NEW case VAProfileVP8Version0_3 calling
vp8_set_controls(driver_data, context, surface_object).
Same shape as MPEG-2 + HEVC dispatch.
3. codec_store_buffer VAPictureParameterBufferType: NEW VP8 case
memcpy'ing into surface_object->params.vp8.picture
(sizeof VAPictureParameterBufferVP8).
4. codec_store_buffer VASliceParameterBufferType: NEW VP8 case
memcpy'ing into surface_object->params.vp8.slice (single,
no slices[] array — VP8 is frame-mode, no multi-slice).
5. codec_store_buffer VAIQMatrixBufferType: NEW VP8 case
memcpy'ing into surface_object->params.vp8.iqmatrix +
setting iqmatrix_set true.
6. codec_store_buffer NEW outer case VAProbabilityBufferType
(Phase 5 C3: NOT VAProbabilityDataBufferType — that's the
STRUCT name; the buffer-type enum constant is
VAProbabilityBufferType = 13 per va.h:2058). Inner switch
dispatches by profile, with VP8 case memcpy'ing into
surface_object->params.vp8.probability + setting
probability_set true.
7. RequestBeginPicture: NEW per-frame reset for the two VP8
flags — params.vp8.iqmatrix_set = false +
params.vp8.probability_set = false. Mirrors the existing
iter1 (h264.matrix_set) + iter2 (h265.num_slices) per-frame
resets.
surface.h extension:
8. params union: NEW vp8 struct after h265 — holds the 4 VAAPI
buffer-type structs (VAPictureParameterBufferVP8,
VASliceParameterBufferVP8, VAIQMatrixBufferVP8 + iqmatrix_set,
VAProbabilityDataBufferVP8 + probability_set).
The NEW vp8 union member adds ~5300 bytes (sizeof
VAProbabilityDataBufferVP8 dominated by dct_coeff_probs[4][8][3]
[11] = 1056 + bookkeeping). The h265 member with slices[64] array
remains the largest (~17 KB), so the union size doesn't grow.
After this commit: backend builds clean, links cleanly. mpv-vaapi
VP8 decode should engage end-to-end on hantro env binding. Phase
1 criteria 1 + 2 + 3 expected satisfied; criterion 4 (HW=SW byte-
identical) and criterion 5 (3-codec regression) verified at Phase
6 smoke + Phase 7.
Refs:
../fresnel-fourier/phase4_iter3_plan.md (Commit C site list)
../fresnel-fourier/phase2_iter3_situation.md (B6, B7, B8, B9
bug enumeration)
../fresnel-fourier/phase5_iter3_review.md (C3 VAProbabilityBuffer
Type rename
empirically verified)
Co-Authored-By: Claude Opus 4.7 (1M context) <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.