marfrit e641d679d3 ffmpeg-v4l2-request-fourier: substitute H.264 IDCT 4×4 → daedalus-fourier
First cycle of the libavcodec.so substitution arc (reauktion/daedalus-v4l2#11
step 2).  H264DSPContext.idct_add — called per 4×4 block from the
intra-4×4 decode path in libavcodec/h264_mb.c — now dispatches through
daedalus_recipe_dispatch_h264_idct4 instead of ff_h264_idct_add_neon.

## What

- Add 0003-h264-idct4-daedalus-fourier.patch (in both arch/ and
  debian/ ffmpeg-v4l2-request-fourier/).  Creates
  libavcodec/aarch64/h264_idct_daedalus.c (ff_h264_idct_add_daedalus
  shim + lazy pthread_once context init via
  daedalus_ctx_create_no_qpu), patches
  libavcodec/aarch64/h264dsp_init_aarch64.c to wire c->idct_add to
  the shim, adds the new .o to libavcodec/aarch64/Makefile.
- arch/PKGBUILD + debian/build-deb.sh: fetch + build
  daedalus-fourier (pinned at d87239d — lockstep with the
  daedalus-v4l2 daemon's inline build) with
  -DCMAKE_POSITION_INDEPENDENT_CODE=ON into a per-build temp prefix,
  then pass --extra-cflags=-I.../include --extra-ldflags=-L.../lib
  --extra-libs="-ldaedalus_core -lvulkan -lpthread" to FFmpeg
  configure.  daedalus_core.a is static-linked into libavcodec.so.62.
- debian/control Depends gains libvulkan1 (daedalus_core PUBLIC-links
  Vulkan::Vulkan for the queryable QPU substrate; the no-QPU
  constructor still works at runtime but the loader needs
  libvulkan.so.1 present to dlopen libavcodec.so.62).
- arch/PKGBUILD depends gains vulkan-icd-loader, makedepends gains
  cmake / ninja / vulkan-headers.

## Why

The recipe layer picks the substrate; for cycle 6 (H.264 IDCT 4×4)
the recipe is CPU NEON, so this is effectively a NEON-to-NEON
substitution with one extra dispatch call and recipe-table lookup.
The point of this first cycle isn't perf wins — it's plumbing.  Once
the path is wired and stable, follow-up patches batch through the
bulk paths (idct_add16 / idct_add16intra / idct_add8) and stack
cycles 7/8/9 (IDCT 8×8, luma-v deblock, qpel mc20).

Bit-exact against ff_h264_idct_add_neon (daedalus-fourier cycle 6
green; FFmpeg's 4×4 block storage matches daedalus's column-major
convention).

## Scope NOT covered

- Bulk paths (idct_add16 / idct_add16intra / idct_add8) — most IDCT
  4×4 calls in real H.264 streams go through these, not the per-
  block c->idct_add path; intra-4×4-only macroblocks are a minority.
  Batched substitution lands in a follow-up.
- High-bit-depth (10-bit) path — not touched; 8-bit only.
- Cycles 7/8/9 — separate PRs.

## SONAME

Unchanged.  libavcodec.so.62 / libavformat.so.62 / libavutil.so.60.
No daedalus-v4l2-dkms or daedalus-v4l2 bump required.

## Refs

- reauktion/daedalus-v4l2 issue #11 (substitution arc): reauktion/daedalus-v4l2#11
- marfrit/daedalus-fourier cycle 6 close (H.264 IDCT 4×4 NEON green)
2026-05-21 21:44:35 +02:00

marfrit-packages

Overlay package repository for the reauktion.de infrastructure.

Published at: https://packages.reauktion.de/

Scope

Tree Arches Notes
Arch Linux ARM (ALARM) aarch64 primary target — Pi 5, Rock 5, ampere, KU-1255 test rigs
Arch Linux x86_64 for nuccies / workstations
Debian arm64, amd64 for non-Arch hosts

MIPS is intentionally unsupported. The Fritz!Box is sacred.

Layout (served at packages.reauktion.de)

packages.reauktion.de/
├── arch/
│   ├── aarch64/{marfrit.db,marfrit.files,*.pkg.tar.{xz,zst}{,.sig}}
│   └── x86_64/...
├── debian/
│   ├── dists/
│   │   ├── bookworm/{Release,InRelease,Release.gpg,main/binary-{arm64,amd64}/...}
│   │   └── trixie/...
│   └── pool/main/...
└── marfrit.gpg      # public signing key

Adding the repo (Arch / ALARM)

curl -sO https://packages.reauktion.de/marfrit.gpg
sudo pacman-key --add marfrit.gpg
sudo pacman-key --lsign-key 92D5E96D8F63C75E4116AA1FF5C8C4603D0D250C

# Paste at the end of /etc/pacman.conf:
[marfrit]
Server = https://packages.reauktion.de/arch/$arch
SigLevel = Required DatabaseRequired

sudo pacman -Sy

Adding the repo (Debian)

sudo install -m 755 -d /etc/apt/keyrings
curl -s https://packages.reauktion.de/marfrit.gpg | \
    sudo gpg --dearmor -o /etc/apt/keyrings/marfrit.gpg

echo "deb [signed-by=/etc/apt/keyrings/marfrit.gpg] https://packages.reauktion.de/debian $(lsb_release -cs) main" | \
    sudo tee /etc/apt/sources.list.d/marfrit.list

sudo apt update

Signing key

  • Fingerprint: 92D5E96D8F63C75E4116AA1FF5C8C4603D0D250C
  • UID: Markus Fritsche (marfrit-repo signing) <mfritsche@reauktion.de>
  • Expires: 2030-04-13

Key management procedures (renewal, rotation, revocation) live in DokuWiki at private:reauktion:marfrit_repo_key (admin-only).

Layout in this Git repo

marfrit-packages/
├── README.md
├── arch/
│   └── distcc-avahi/                # ALARM distcc with --with-avahi
├── debian/                          # (future) Debian source packages
└── .gitea/
    └── workflows/
        └── build.yml                # CI pipeline stub

Mail

mfritsche@reauktion.de.

S
Description
ALARM aarch64 + Arch x86_64 + Debian arm64/amd64 overlay repo — published at packages.reauktion.de
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