test0r
10114f6781
Fourier's local patch already wired multiplanar plumbing through
src/v4l2.c (helpers v4l2_type_video_{output,capture}() at lines 59-69,
struct v4l2_plane planes[] threading in QUERYBUF/QBUF/DQBUF, per-plane
EXPBUF loop at line 411) and through src/context.c, src/buffer.c,
src/picture.c via the v4l2_type_video_{output,capture}(video_format
->v4l2_mplane) helper calls.
The remaining gap: the NV12 entry in src/video.c was hardcoded to
v4l2_mplane=false, and the bootstrap path in src/surface.c was
hardcoded to singleplanar literals before video_format is populated.
This patch flips the NV12 entry to v4l2_mplane=true and updates the
two singleplanar literals in src/surface.c to their MPLANE variants:
- src/video.c:42 v4l2_mplane=false -> true (NV12 only;
Sunxi-tiled NV12 left at false for cedrus compatibility)
- src/surface.c:84 output_type = v4l2_type_video_output(true)
- src/surface.c:109 v4l2_find_format(..., CAPTURE_MPLANE, NV12)
Empirically, hantro-vpu (RK3568 mainline) advertises NV12 only under
V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE; querying the singleplanar type
returns no match (verified via VIDIOC_ENUM_FMT in Phase 3 GStreamer
strace baseline).
Trade-off accepted: legacy sunxi-cedrus singleplanar NV12 paths are
left unchanged via the SUNXI_TILED_NV12 entry (still mplane=false,
__arm__ only). Pure-NV12 cedrus on aarch64 would regress, but the
known userbase here is RK3566/RK3568 hantro.
Signed-off-by: Markus Fritsche <fritsche.markus@gmail.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.