claude-noether
514da29a73
Switch the daemon's runtime dlopen targets from Debian-stock soname 61/61/59 (FFmpeg 7.1.3) to the Kwiboo fourier fork's soname 62/62/60 (FFmpeg 8.1) installed at the /opt/fourier prefix. Why --- The substitution arc tracked at daedalus-v4l2#11 needs daedalus- fourier kernel calls woven into libavcodec's H264DSPContext NEON init (replacing ff_h264_idct_add_neon etc. with thunks calling daedalus_recipe_dispatch_h264_*). We do that via patches in the ffmpeg-v4l2-request-fourier package source — which we own, in marfrit-packages, alongside the existing libudev-bypass and nv15-to-p010 patches. But that package builds the Kwiboo fork at soname 62 / /opt/fourier. The daemon currently dlopens soname 61 (Debian-stock + a separately-built +fourier2 patch that isn't in marfrit-packages' source tree), so substitution patches there wouldn't reach the daemon. Switching to soname 62 routes the daemon through the package we control — first step toward landing daedalus-fourier kernel substitution into the production decode path. Compat ------ - /opt/fourier libs are already on every host running the daemon (hard build-dep of ffmpeg-v4l2-request-fourier). Firefox-fourier and mpv-fourier already dlopen them via the same path. - /etc/ld.so.conf.d/fourier.conf entry resolves the new sonames from /opt/fourier/lib via the ld cache; dlopen-by-soname works without LD_LIBRARY_PATH wrappers. - Build-side: daemon's pkg_check_modules picks up libav*.pc from /opt/fourier/lib/pkgconfig when PKG_CONFIG_PATH includes that directory (build-deb.sh follow-up will set it). - API surface unchanged: avcodec_send_packet / receive_frame / AVCodecContext flags / AVFrame fields are all stable between FFmpeg 7.1 and 8.1. Verified clean cross-compile on hertz. Wire protocol unchanged. No kmod bump. Next step (follow-up PRs) ------------------------- 1. ffmpeg-v4l2-request-fourier patch: add 0003-daedalus-fourier- substitute-h264-idct4.patch that replaces ff_h264_idct_add_neon in libavcodec/aarch64/h264dsp_init_aarch64.c with a thunk calling daedalus_recipe_dispatch_h264_idct4. 2. Repeat for IDCT 8×8, deblock luma-v, qpel mc20 (one kernel per PR for reviewability; bench delta + decode_us delta documented per substitution). 3. marfrit-packages bump to pick up the new daemon + the substituted fourier package.
daedalus-v4l2
V4L2 stateless decoder for the Raspberry Pi 5 / CM5, backed by the
daedalus-fourier kernel library (VP9 + AV1 CDEF + H.264 video
decode kernels on VideoCore VII compute + ARM NEON).
Status: scaffold (2026-05-18). Architecture locked per daedalus-fourier session memory; implementation not yet begun.
What this is
Sibling repo to daedalus-fourier (the kernel library; cycles 1-9 closed).
A two-piece userspace + kernel-module stack that exposes a V4L2
stateless decoder interface (/dev/videoNN) so that
libva-v4l2-request-fourier → firefox-fourier /
chromium-fourier can drive it the same way they drive existing
hardware-decode pipelines on Pi 5 / RK3588.
+-----------------------------------------------------------+
| firefox-fourier / chromium-fourier (existing) |
+-----------------------------------------------------------+
| VA-API |
+-----------------------------------------------------------+
| libva-v4l2-request-fourier (existing, sibling project) |
+-----------------------------------------------------------+
| V4L2 stateless ioctl uAPI |
+-----------------------------------------------------------+
| daedalus-v4l2 kernel module (`kernel/`) |
| - registers /dev/videoNN |
| - parses V4L2 stateless ioctls (VP9/AV1/H.264 controls) |
| - forwards bitstream + controls to userspace daemon |
| via chardev or netlink |
+-----------------------------------------------------------+
| daedalus-v4l2 userspace daemon (`daemon/`) |
| - takes bitstream blobs + per-slice controls |
| - drives FFmpeg parsers via dlopen (Option γ) |
| - dispatches per-block ops via daedalus-fourier |
| public API (daedalus_dispatch_*) |
| - posts decoded frames back to kernel module |
+-----------------------------------------------------------+
| daedalus-fourier kernel library (sibling project) |
| - exports include/daedalus.h public API |
| - per-kernel CPU NEON + opportunistic V3D QPU dispatch |
| - 9 closed cycles across VP9, AV1 CDEF, H.264 |
+-----------------------------------------------------------+
| V3D 7.1 (Mesa userspace v3dv) + ARM NEON (BCM2712) |
+-----------------------------------------------------------+
Why this architecture (Option B + γ + sibling)
Locked by user 2026-05-18 from 3 options in
daedalus-fourier/docs/phase8_scoping.md:
- Option B over A (userspace v4l2loopback): real
/dev/videoNN, proper DRM PRIME / dmabuf for browser zero-copy. - Option γ: dlopen FFmpeg as parser at runtime. No vendoring, fastest to v1.
- Sibling repo: per
project_consumer_targetconvention, V4L2-side work lives outside daedalus-fourier so the kernel-library has a clean API boundary.
Status
Initial scaffold only. See docs/architecture.md for the
deeper design and docs/roadmap.md for the
sub-phase breakdown.
Repo layout
kernel/— Linux kernel module (V4L2 device registration + ioctl handling + userspace chardev bridge). Out-of-tree.daemon/— userspace decoder daemon (linkslibdaedalus_core.afrom sibling daedalus-fourier; uses dlopen for FFmpeg parser).include/— shared headers between kernel and daemon.docs/— architecture + roadmap.
License
Kernel module: GPLv2 (required for kernel-tree compatibility). Userspace daemon: BSD-2-Clause (matches daedalus-fourier).