Rewrites src/mpeg2.c to submit MPEG-2 control payload via the new
split V4L2_CID_STATELESS_MPEG2_{SEQUENCE,PICTURE,QUANTISATION}
controls (mainline kernel <linux/v4l2-controls.h>:1985-2105),
replacing the staging-era V4L2_CID_MPEG_VIDEO_MPEG2_{SLICE_PARAMS,
QUANTIZATION} combined-struct API that the kernel removed.
Per-frame submission: one batched VIDIOC_S_EXT_CTRLS, count=3,
ctrl_class=V4L2_CTRL_CLASS_CODEC_STATELESS (0xf010000), with the
three controls in order:
- id=0xa409dc (SEQUENCE) size=12 bytes
- id=0xa409dd (PICTURE) size=32 bytes
- id=0xa409de (QUANTISATION) size=256 bytes
Matches FFmpeg libavcodec/v4l2_request_mpeg2.c:130-155 reference
implementation. Verified empirically against fresnel-fourier
Phase 0 cross-validator anchor (bit-for-bit byte equivalence on
SEQUENCE first-row + QUANTISATION 256 bytes).
Six structural changes from old to new API:
1. Slice header parsing moved to kernel: bit_size,
data_bit_offset, quantiser_scale_code GONE from new structs.
2. Reference timestamps moved from slice to picture:
forward_ref_ts/backward_ref_ts now in
v4l2_ctrl_mpeg2_picture (offsets 0/8).
3. Boolean fields collapsed into picture.flags bitmask
(TOP_FIELD_FIRST 0x01 .. PROGRESSIVE 0x80, 8 bits total).
4. progressive_sequence collapsed into sequence.flags &
V4L2_MPEG2_SEQ_FLAG_PROGRESSIVE.
5. PICTURE_CODING_TYPE renamed to PIC_CODING_TYPE (values same).
6. Quantisation load_* flags removed; matrices always present;
British spelling — quantiSation not quantiZation.
Behavioral correction (from old code, was a latent bug):
Old src/mpeg2.c:104-118 self-referenced surface_object timestamp
when the VAAPI ref picture was VA_INVALID_ID. New code sets the
ref_ts to 0, matching kernel doc 0-as-sentinel convention
(verified Phase 3 Baseline C: I-frame has both ts == 0; FFmpeg
v4l2_request_mpeg2.c:98-108 same convention).
Quantisation matrix order: zigzag scanning order per kernel doc
v4l2-controls.h:2076. VAAPI VAIQMatrixBufferMPEG2 stores in
zigzag order (per VAAPI spec). Direct memcpy works; no
permutation in libva backend. Kernel hantro_mpeg2.c::
hantro_mpeg2_dec_copy_qtable applies zigzag-to-raster permutation
when copying to the hardware quantisation table.
Default matrices (when iqmatrix_set==false): MPEG-2 spec defaults
per ISO/IEC 13818-2 Table 7-3. The mpeg2_default_intra_matrix
constant was transcribed from fresnel-fourier Phase 3 Baseline C
QUANTISATION verbatim payload bytes 0..63 (256-byte capture from
ffmpeg-v4l2request decode of bbb_720p10s_mpeg2.ts), per
phase5_iter1_review.md S3 amendment that flagged spec-recall as
unreliable. non_intra and chroma_non_intra are 16s per spec
(verified Baseline C bytes 64..127, 192..255). chroma_intra is
copy of intra (Baseline C bytes 128..191, verified identical).
Submission shape: one batched v4l2_set_controls call with all
three v4l2_ext_control entries, matching iter6/7/8 H.264 pattern
at src/h264.c:986. Bound to surface_object->request_fd (the
per-OUTPUT-slot permanent request_fd from iter6 binding).
Behavioral details:
- sequence.vbv_buffer_size = surface_object->source_size, where
source_size is set in picture.c:276 from request_pool slot->size,
which is the V4L2-negotiated sizeimage from VIDIOC_QUERYBUF.
Matches FFmpeg controls->pic.output->size.
- sequence.profile_and_level_indication = 0; not exposed by
VAAPI VAPictureParameterBufferMPEG2.
- sequence.chroma_format = 1 (4:2:0) hardcoded; campaign codec
scope is 4:2:0.
- progressive_frame proxies for progressive_sequence; same bit
for typical streams.
Phase 6 smoke test (post Commit A + Commit B):
- vainfo enumerates VAProfileMPEG2Simple + VAProfileMPEG2Main
on hantro bind. (Phase 1 criterion 1)
- libva trace: vaCreateConfig(VAProfileMPEG2Main) =
VA_STATUS_SUCCESS. (Phase 1 criterion 2)
- ffmpeg -hwaccel vaapi exits 0 with no Failed-to-create-
decode-configuration. (Phase 1 criterion 3 adjusted)
- mpv --hwdec=vaapi --vo=image at +02s seek: 2 distinct
frames with hashes byte-identical to SW reference:
HW frame 1: 6e7873030dbf0403c67f35dd106ebef3c7909a0fd12433b82ad758e7fee9f092
SW frame 1: 6e7873030dbf0403c67f35dd106ebef3c7909a0fd12433b82ad758e7fee9f092
HW frame 2: ccc7ce08810d4a96e9ba7a19f4f95bbf6cc861bda9337604b5c668ad52bef7de
SW frame 2: ccc7ce08810d4a96e9ba7a19f4f95bbf6cc861bda9337604b5c668ad52bef7de
(Phase 1 criterion 4 — DMA-BUF GL import path; cache-coherency-safe)
- T4 H.264 reference hashes still match (criterion 5; verified
Phase 3 Baseline D earlier).
Cache-stale class observation (out-of-scope iter1 work item):
ffmpeg -hwaccel vaapi -hwaccel_output_format vaapi + hwdownload
pipeline produces all-zero NV12 for MPEG-2 (same iter1 patch-0011
cache-coherency bug class observed for H.264 in fresnel-fourier
T4). Kernel + HW decode is correct (verified via ffmpeg
-hwaccel v4l2request -hwaccel_output_format drm_prime + hwdownload
which produces correct non-zero pixels matching SW reference).
Bug is in libva backend vaDeriveImage path; Phase 4 cross-
cutting work to add VIDIOC_EXPBUF + DMA_BUF_IOCTL_SYNC support.
Not blocking iter1 — DMA-BUF GL import path (mpv --vo=image) is
cache-coherency-safe and gives bit-exact pixels.
Auxiliary EINVAL noise (out-of-scope iter1 work item):
src/context.c:142-155 unconditionally sets H.264 device-wide
controls (V4L2_CID_STATELESS_H264_DECODE_MODE,
_START_CODE) on every CreateContext, regardless of profile.
EINVALs on hantro-vpu-dec (no H.264 controls there). Intentional
best-effort behavior — return value cast to (void) and discarded
at line 153. The error message "Unable to set control(s):
Invalid argument" is logged from src/v4l2.c:484 but doesn't
propagate as a backend error. Stays as documented auxiliary
noise.
Drop #include <mpeg2-ctrls.h> from src/config.c:37 and src/mpeg2.c
(formerly line 38). The kernel UAPI for MPEG-2 stateless control
IDs comes from <linux/v4l2-controls.h>, pulled transitively via
<linux/videodev2.h> (and explicitly from src/mpeg2.c after this
rewrite). The fork local include/mpeg2-ctrls.h header is deleted
in commit C; this commit removes the last includes of it.
src/config.c:38 still includes <hevc-ctrls.h> — left untouched per
phase5_iter1_review.md Nit 6 (lower-risk path; HEVC iteration
deletes its header).
Refs:
../fresnel-fourier/phase4_iter1_plan.md (contract clauses 1-6,
File 2 patch shape)
../fresnel-fourier/phase5_iter1_review.md (S3, Q4, Q5 amendments)
../fresnel-fourier/phase0_evidence/2026-05-07/iter1_phase3/
baseline_C_xvalidator/ffmpeg.stdout (cross-validator anchor)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Reference frames are now identified using their timestamp:
set the timestamp when queuing the output buffer and use it to identify
the frame later on.
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
This adds support for MPEG2 quantization matrices, which are optional
given that fallback default matrices are used (on the kernel side) when
no such matrix is provided.
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
The cedrus_data structure carries the old name. In order to migrate to the
new name, let's rename it to request_data.
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
The sunxi_cedrus.h header contains a bunch of defines prefixed with
SUNXI_CEDRUS.
As part as the ongoing migration to a more generic name, change that prefix
for V4L2_REQUEST, and the header file to request.h
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Some functions setting the controls will need the context in the future.
Make sure that we provide it as an argument.
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
The coding style has been a bit erratic. Enforce the linux kernel coding
style by reusing their .clang-format file, running clang-format on the
source, and ignoring the few shortcomings that clang-format has at the
moment (especially on aligning the define values).
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
This long structure name makes it quite difficult to fit within the 80
characters limit. Shorten it.
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
The MPEG2 header doesn't need any header, since it's only using pointers.
Remove them, and add them to the mpeg2 file when needed.
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
This patch introduces the support of MPEG2 video decoding. It basically
just copies data from VA's frame/slice headers data structures to v4l's
MPEG2 frame header extended controls data structures.
claude-noether
Paul Kocialkowski