test0r
385dee1bbf
This is the load-bearing fix that resolves the iter1+iter2+iter3
"frame-11 EINVAL" carryover. Replace the per-surface request_fd cache
+ MEDIA_REQUEST_IOC_REINIT pattern with allocate-fresh-per-frame:
in RequestSyncSurface, after queue + wait_completion succeed, close
the request_fd and reset surface_object->request_fd = -1 so the next
BeginPicture allocates a new one via media_request_alloc.
Diagnostic root cause: per-control VIDIOC_TRY_EXT_CTRLS isolation
showed all four H.264 controls (SPS/PPS/DECODE_PARAMS/SCALING_MATRIX)
fail individually with EINVAL on the *same* request_fd that had been
through queue+wait+reinit. The fd state was bad even though every
ioctl in the previous decode cycle returned success. Allocating fresh
sidesteps any kernel-side request-state-machine subtlety we don't
fully understand.
Empirical verification (iter4 Phase 7, 90s autonomous run on ohm via
firefox-fourier without MOZ_DISABLE_RDD_SANDBOX=1, bbb_1080p30 H.264):
- ENETDOWN count: 0
- S_EXT_CTRLS rejected: 0 (was: fired at frame 11 every iter1-3)
- Unable to set control(s): 0
- Generic EINVAL: 0
- Video stream mTime reached: 49.7 seconds
- Audio stream mTime reached: 51.5 seconds
Cost: ~one extra MEDIA_IOC_REQUEST_ALLOC + close() per decoded frame.
Negligible (cycles below the V4L2 set_controls + queue + wait stack).
Companion fixes that landed earlier in iter4 to get to this point:
74d8dd1 — DPB fields=V4L2_H264_FRAME_REF + skip !used entries
(matches FFmpeg's libavcodec/v4l2_request_h264.c semantics)
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.