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marfrit 5965805d86 Phase 8.7: media controller + multi-frame streaming verification

Two pieces — both shipped:

1. Media controller binding closes the last v4l2-compliance
   failure from 8.6 (DECODER_CMD, which requires has_media on
   stateless decoders) and unlocks the V4L2 request API for
   libva-v4l2-request.

2. Multi-frame streaming test exercises the daemon's
   AVCodecContext state preservation across many REQ_DECODE
   calls — Phase 8.6's tests pushed exactly one keyframe per
   invocation; real content has P-frame references.

Compliance now reaches **49/49 passing.**

Kernel (kernel/daedalus_v4l2_main.{c,h}):
- Added `struct media_device mdev` to daedalus_dev.
- media_device_init(&mdev) BEFORE v4l2_device_register so
  v4l2-core sees v4l2_dev.mdev = &mdev and binds the m2m
  entities into the graph during register.
- After video_register_device:
  v4l2_m2m_register_media_controller(..., MEDIA_ENT_F_PROC_VIDEO_DECODER)
  then media_device_register so userspace sees the complete
  graph in /dev/mediaN with the decoder entity tagged.
- daedalus_remove unwinds in reverse: unregister media,
  unregister mc, unregister video, release m2m, unregister
  v4l2, cleanup mdev.
- Error paths added for both new failure points.

Test harness (tools/test_m2m_stream.c, new):
- Multi-frame V4L2 m2m client: parses IVF → 4-deep buffer
  rings on both queues → per-frame QBUF/DQBUF loop →
  concatenates decoded NV12 to output file. Returns 0 only
  if every input frame decoded without error.
- Same codec vocabulary as test_m2m_decode (vp9 | av1 |
  h264 via 5th arg).

Verification on hertz (Pi 5, 6.12.75+rpt-rpi-2712):

v4l2-compliance: 49 tests, 49 passed, 0 failed, 0 warnings.

  $ v4l2-ctl --list-devices
  daedalus-fourier V3D7+NEON (platform:daedalus_v4l2):
        /dev/video0
        /dev/media3

VP9 320×240 30 frames (1 keyframe + 29 P-frames, 3.46 MB
NV12): byte-for-byte match vs `ffmpeg -i in.ivf -pix_fmt
nv12 -f rawvideo`.

VP9 1920×1080 10 frames (31 MB NV12 through the dmabuf
path): byte-for-byte match vs same reference command.

Daemon log shows cookies 1..30 all completing cleanly in
order; lazily-opened AVCodecContext maintains reference
frames across the chardev round-trips.

Clean SIGTERM + rmmod, no oops/WARN.

Roadmap update (docs/roadmap.md):
- 8.7 marked closed with closure-doc reference.
- 8.8 reshaped: perf profiling, QPU dispatch substitution
  via daedalus-fourier, multi-frame AV1/H.264, HDR (P010M).

Per correctness-before-speed:
- Order-correct media controller lifecycle (init → bind
  v4l2_dev → register video → register mc → register
  media; reverse for teardown).
- 4-deep buffer rings on both queues — the scheduler
  actually pipelines multiple in-flight cookies through
  the chardev (not just one-at-a-time as in 8.5/8.6 tests).
- Bit-exact comparison against ffmpeg, not "looks right."
- All resource paths cleaned on every error branch.

Phase 8.8 next: profile daemon hot loops, dlopen
daedalus-fourier from the daemon, swap FFmpeg per-block
calls for daedalus_dispatch_* where the kernel matches,
target 30fps@1080p from 30fps-floor-is-fine memory.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

2026-05-18 16:21:58 +00:00

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daedalus-v4l2 — roadmap

Sub-phases

Phase 8.1 — kernel module skeleton

Out-of-tree kernel module that:

Registers /dev/videoNN with VFL_TYPE_VIDEO + a no-op V4L2 stateless dispatch table.
Accepts open/close, S_FMT, REQBUFS ioctls without doing anything (yet).
Builds against /lib/modules/$(uname -r)/build.

Deliverable: modprobe daedalus_v4l2 works, v4l2-ctl --list-devices shows the new device.

Phase 8.2 — kernel ↔ daemon chardev bridge

Kernel module creates /dev/daedalus-v4l2 chardev.
Defines a simple req/resp protocol in include/daedalus_v4l2_proto.h.
Daemon connects, exchanges echo requests.

Deliverable: ping-pong test passes.

Phase 8.3 — daemon FFmpeg dlopen + parse

Daemon links libdaedalus_core.a from sibling.
Daemon dlopens FFmpeg.
Test program: feed a VP9 IVF file to FFmpeg parsers, extract block-level metadata, validate against expected.

Deliverable: daemon can parse a VP9 frame and walk the block-level info.

Phase 8.4 — daemon ↔ kernel decode round-trip (closed 2026-05-18)

Shipped as a debugfs-triggered chardev round-trip rather than the original V4L2-ioctl plan (which moved to Phase 8.5).

REQ_DECODE / RESP_FRAME wire protocol
Daemon decodes VP9 via FFmpeg dlopen, returns FNV-1a digest
Verified content-dependent + deterministic; structured error handling for bad bitstreams

See docs/phase_8_4_closure.md.

Phase 8.5 — full V4L2 m2m driver (closed 2026-05-18)

Real V4L2 m2m driver — userspace clients drive S_FMT/REQBUFS/QBUF/DQBUF the standard way. Bitstream flows kernel→daemon as inline REQ_DECODE payload; decoded NV12 pixels flow daemon→kernel as inline RESP_FRAME payload. Works end-to-end for small frames (≤ ~64 KiB NV12).

Deliverable hit: kernel m2m driver passes most v4l2-compliance checks; tools/test_m2m_decode produces a NV12 frame that's byte-for-byte identical to ffmpeg -pix_fmt nv12 reference.

See docs/phase_8_5_closure.md.

Phase 8.6 — dmabuf + AV1 + H.264 + stateless controls (closed 2026-05-18)

CAPTURE (and OUTPUT) on vb2_dma_contig_memops.
New DAEDALUS_IOC_GET_DMABUF chardev ioctl — daemon mmaps the in-flight CAPTURE buffer, decodes pixels in place, sends RESP_FRAME metadata-only.
64 KiB frame-size cap removed. 1080p VP9 + 128×96 AV1
- 128×96 H.264 all byte-exact against reference FFmpeg decode.
V4L2 stateless controls registered for VP9 / AV1 / H.264 (11 controls visible to userspace).
Colorspace round-trip fix (TRY_FMT preserve, S_FMT OUTPUT→CAPTURE propagation).
Cookie unified across V4L2 + debugfs paths.
v4l2-compliance: 47/48 (only DECODER_CMD remains, needs media controller — moved to 8.7).

See docs/phase_8_6_closure.md.

Phase 8.7 — media controller + multi-frame streaming (closed 2026-05-18)

Media controller bound via v4l2_m2m_register_media_controller + media_device_register; /dev/mediaN published.
tools/test_m2m_stream parses IVF and pushes frames sequentially through a 4-deep buffer ring; daemon AVCodecContext preserves reference frames across calls.
30-frame VP9 320×240 stream byte-exact (3.46 MB across 1 keyframe + 29 P-frames).
10-frame VP9 1080p stream byte-exact (31 MB across 10 frames at full HD).
v4l2-compliance: 49/49 passing (was 47/48 in 8.6; media controller added a 49th test and closed DECODER_CMD).

See docs/phase_8_7_closure.md.

Phase 8.8 — perf, QPU dispatch, AV1/H.264 streams, HDR

Profile daemon end-to-end on hertz; identify FFmpeg hot functions per codec.
dlopen daedalus-fourier's per-kernel entry points from the daemon; substitute daedalus_dispatch_* for FFmpeg's matching per-block calls (IDCT 4×4 / 8×8, MC, deblock, qpel — from cycles 1, 2, 4, 9).
Validate bit-exactness after each substitution.
Hit 30fps@1080p stable on VP9 — the 30fps-floor-is-fine memory's user-facing criterion.
Multi-frame AV1 + H.264 round-trips (extend stream tests).
HDR / 10-bit (P010M CAPTURE, depth-aware pack_nv12_to_planes).

Deliverable: 30fps stable on real content across all three codecs.

Effort estimate

Each phase: ~1 week of focused work (~40 hours). Total: 7 weeks for v1.

Could be split across multiple sessions / contributors.

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