# 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 — VP9 end-to-end via daedalus-fourier

- Wire daemon's per-block walker to `daedalus_dispatch_*` calls.
- Kernel module passes bitstream + controls to daemon over
  chardev.
- Daemon decodes, writes pixels to a shared buffer, returns
  result to kernel.
- Kernel returns via DQBUF.

Deliverable: `v4l2-ctl --stream-from=foo.ivf` produces
decoded frames (output via `--stream-to` PNG dump).

### Phase 8.5 — dmabuf / DRM PRIME

- Kernel module allocates dma-coherent buffers.
- Export via VIDIOC_EXPBUF.
- Daemon writes via mmap into kernel-allocated dmabuf.
- Test: `v4l2-ctl --capture-mmap-dmabuf` works.

Deliverable: dmabuf-fd is exportable; first browser-friendly
frame.

### Phase 8.6 — AV1 + H.264

- Add codec support for AV1 (using CDEF QPU helper) and
  H.264 (using deblock QPU helper for the one cycle 8 path,
  everything else CPU).

Deliverable: real AV1/H.264 clips decode end-to-end.

### Phase 8.7 — performance + 30fps@1080p

- Profile end-to-end pipeline.
- Eliminate copies where possible.
- Hit 30fps@1080p for daily YouTube videos
  (the project's user-facing success criterion per
  `30fps-floor-is-fine` memory).

Deliverable: 30fps stable on real content.

## Effort estimate

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

Could be split across multiple sessions / contributors.