marfrit
c7d8050cc9
V4L2 stateless decoder for Pi 5, backed by sibling
daedalus-fourier kernel library (VP9 + AV1 CDEF + H.264 video
decode kernels on VideoCore VII compute + ARM NEON).
Architecture locked 2026-05-18 by mfritsche per
daedalus-fourier/docs/phase8_scoping.md:
- Option B: Linux kernel V4L2 shim + userspace daemon (not
v4l2loopback). Real /dev/videoNN; proper DRM PRIME for
browser zero-copy.
- Option γ: dlopen FFmpeg at runtime as parser. No vendoring;
fastest to v1.
- Sibling repo (this repo): V4L2-side work outside of
daedalus-fourier so kernel-library API stays clean.
Components:
kernel/ - Linux out-of-tree kernel module (GPLv2; V4L2
device + chardev bridge to userspace daemon)
daemon/ - userspace decoder daemon (BSD-2-Clause; links
libdaedalus_core.a from sibling; dlopens FFmpeg)
docs/ - architecture + 7-phase roadmap (8.1..8.7)
include/ - shared headers between kernel and daemon
Roadmap (7 sub-phases, ~1 week each):
8.1 kernel skeleton (/dev/videoNN with no-op ioctls)
8.2 chardev bridge (kernel ↔ daemon ping-pong)
8.3 daemon FFmpeg dlopen + parse path
8.4 VP9 end-to-end via daedalus_dispatch_*
8.5 dmabuf / DRM PRIME for zero-copy
8.6 AV1 + H.264 codec support
8.7 performance: hit 30fps@1080p (project floor)
No code yet — only README + design docs + directory structure.
First implementation work starts in Phase 8.1 next session.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
54 lines
1.4 KiB
Markdown
54 lines
1.4 KiB
Markdown
# daemon/ — daedalus-v4l2 userspace decoder daemon
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Userspace daemon that:
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1. Connects to the kernel module's chardev
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2. Receives bitstream + V4L2 control blobs
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3. Parses bitstream via dlopen'd FFmpeg
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4. Dispatches per-block work via `daedalus_dispatch_*`
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from sibling `daedalus-fourier`
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5. Returns decoded frames to kernel
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## Status
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Scaffold only. Phase 8.3 not yet started.
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## Build dependencies (planned)
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- libdaedalus_core.a from sibling daedalus-fourier (static link)
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- FFmpeg dev headers (for AVPacket/AVCodec interface types) +
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runtime FFmpeg .so (loaded via dlopen)
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- libv4l2 (for V4L2 control struct definitions)
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- pthread
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## Build (when implemented)
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```sh
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mkdir build && cd build
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cmake .. -DDAEDALUS_FOURIER_DIR=/path/to/daedalus-fourier
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make
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```
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## Layout (planned)
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- `CMakeLists.txt`
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- `src/main.c` — event loop, chardev connection
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- `src/parser.c` — FFmpeg dlopen wrapper + per-codec dispatch
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- `src/decode_vp9.c`, `src/decode_av1.c`, `src/decode_h264.c` —
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per-codec block walkers
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- `src/frame_io.c` — frame allocation, return to kernel
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## License
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BSD-2-Clause (matches daedalus-fourier sibling).
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## Phase 8.3 starting point
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A standalone program that:
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1. Opens a .ivf or .mp4
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2. Pulls codec packets via dlopen'd avformat
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3. Calls dlopen'd avcodec to parse (without decoding)
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4. Walks the block-level metadata
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5. Validates output structure
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No kernel involvement yet — just confirm the parse path works.
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