Substitutes c->v_loop_filter_chroma_intra and c->h_loop_filter_chroma_intra
with daedalus wrappers in the bit_depth=8 / chroma_format_idc<=1 (4:2:0)
branch. 4:2:2 stays on the in-tree NEON path (the daedalus chroma intra
dispatch is 4:2:0-only).
The fourier dispatches were exposed in PR #11 (DEFINE_INTRA_DISPATCH
macro generates the public daedalus_dispatch_h264_deblock_chroma_*_intra
symbols + recipe wrappers).
Re-architects the chroma init: v_loop_filter_chroma_intra was previously
assigned unconditionally to the NEON variant (which works for both 4:2:0
and 4:2:2). We now assign it INSIDE both branches of the chroma_format_idc
conditional — 4:2:0 picks daedalus, 4:2:2 keeps NEON. No regression for
4:2:2 streams.
Same NEON-to-NEON via recipe shape as 0010 luma intra.
Closes the deblock substitution layer for the 4:2:0 / 8-bit hot path:
- 0005 luma_v non-intra ✓
- 0008 luma_h non-intra ✓
- 0009 chroma_v / chroma_h non-intra ✓
- 0010 luma_v / luma_h intra ✓
- 0013 chroma_v / chroma_h intra ✓
All 8 deblock variants for the common 4:2:0 path now route through
daedalus. 4:2:2 chroma + the chroma422 mbaff variants stay on in-tree
NEON.
Verified the patch applies cleanly on top of 0001-0012 against the
pinned upstream commit b57fbbe5 on hertz.
Closes the H.264 qpel substitution. Extends 0007 (which routed only
mc20 put_) to ALL 15 useful positions in BOTH the put_ and avg_
tables, skipping mc00 (integer copy / pointer-only fast path).
29 substitutions total: 14 new put_ + 15 avg_. Each wraps a single
daedalus_recipe_dispatch_h264_qpel_{avg_,}mcXY call (the dispatches
landed in daedalus-fourier PRs #15-#20). Collapsed via a single
DEFINE_QPEL_WRAPPER macro on the libavcodec shim side so the diff
is uniform.
All recipe-table entries route AUTO to CPU NEON — no QPU shaders
for any qpel position other than mc20 yet. Plumbing-only
NEON-to-NEON via the daedalus recipe layer; bit-exact against
the in-tree ff_*_h264_qpel8_*_neon path (each daedalus dispatch is
already bit-exact-gated by the corresponding fourier PR's test).
16x16 qpel tables ([0][...]) stay on the in-tree NEON. daedalus
only exposes 8x8 today; 16x16 substitution can land once fourier
provides those variants.
Verified the patch applies cleanly on top of 0001-0011 against the
pinned upstream commit b57fbbe5 on hertz.
Substitutes H264DSPContext.chroma_dc_dequant_idct in the 4:2:0 /
bit_depth=8 init path with a wrapper that composes the daedalus
chroma DC Hadamard primitive (daedalus-fourier PR #25) with the
qmul scaling FFmpeg's reference does in one fused function
(h264idct_template.c::ff_h264_chroma_dc_dequant_idct).
Algorithm per H.264 §8.5.11.1 / §8.5.11.2:
1. Extract 4 DCs from the scattered positions in the per-MB
coefficient buffer (stride=32, xStride=16)
2. 2x2 Hadamard transform (daedalus primitive)
3. qmul scale + >> 7, write back to original positions
Bit-exact against ff_h264_chroma_dc_dequant_idct_8_c. The Hadamard
itself is gated by the fourier PR #23 7-case test suite (including
the H·H = 4·I algebraic invariant), and the public-API parity
test added in PR #25 confirms the src/ symbol matches the test ref.
4:2:2 chroma stays on the in-tree ff_h264_chroma422_dc_dequant_idct_c
path — same chroma_format_idc<=1 gating shape as 0009 chroma deblock.
Pin bump: _daedalus_fourier_commit / DAEDALUS_FOURIER_COMMIT bumped
to b9f9ff2a (post-PR #25) so the build picks up the public
daedalus_h264_chroma_dc_hadamard_2x2 symbol.
Verified the patch applies cleanly on top of 0001-0010 against the
pinned upstream commit b57fbbe5 on hertz.
Adds the bS=4 intra-strength variants of the already-substituted
luma_v / luma_h deblock (0005, 0008). Intra MBs and certain
inter-MB edges (4x4 transform boundaries inside an Intra_NxN
neighbour) force boundary strength to 4 per H.264 §8.7.2.1.
H264DSPContext.v_loop_filter_luma_intra →
daedalus_recipe_dispatch_h264_deblock_luma_v_intra
H264DSPContext.h_loop_filter_luma_intra →
daedalus_recipe_dispatch_h264_deblock_luma_h_intra
Both kernels landed in daedalus-fourier PR #11. Recipe → CPU NEON
(no intra QPU shaders yet); plumbing-only NEON-to-NEON via daedalus.
Signature differs from bS<4: no tc0 argument. Wrapper passes
daedalus_h264_deblock_meta with alpha/beta set; tc0[] is ignored by
the intra dispatch (bS=4 hardcodes the strength).
Chroma intra variants are deferred to a follow-up because the chroma
init has a 4:2:0 / 4:2:2 split (chroma_format_idc gating) — the
daedalus dispatch is 4:2:0-only and needs explicit conditional
substitution to avoid running on 4:2:2 chroma.
Verified the patch applies cleanly on top of 0001-0009 against the
pinned upstream commit b57fbbe5 on hertz.
Chroma siblings of 0005 (luma_v) and 0008 (luma_h). Same
NEON-to-NEON pattern via the daedalus recipe layer:
H264DSPContext.v_loop_filter_chroma →
daedalus_recipe_dispatch_h264_deblock_chroma_v
H264DSPContext.h_loop_filter_chroma →
daedalus_recipe_dispatch_h264_deblock_chroma_h
Both kernels landed in daedalus-fourier PR #10. Recipe table routes
AUTO to CPU NEON (no chroma QPU shaders yet), so this is plumbing-
only and stays bit-exact against the in-tree NEON.
Intra chroma (bS=4) loop filters remain on in-tree NEON;
daedalus_h264_deblock_meta covers the non-intra (bS<4) path.
Verified the patch applies cleanly on top of 0001-0008 against the
pinned upstream commit b57fbbe5 on hertz. Wires the new patch into
both arch/PKGBUILD and debian/build-deb.sh.
Adds patch 0008 to the substitution arc, mirroring 0005's V variant
for H.264 non-intra bS<4 horizontal luma deblock.
H264DSPContext.h_loop_filter_luma →
daedalus_recipe_dispatch_h264_deblock_luma_h
The H kernel was added to daedalus-fourier in PR #9 (vendored
ff_h264_h_loop_filter_luma_neon, wired through the same CPU-dispatch
pattern as V). Recipe table routes AUTO to CPU NEON (no QPU shader
for H yet), so this is a NEON-to-NEON substitution via the daedalus
recipe layer — same shape as 0005.
The libavcodec.so ctx remains no-QPU (daedalus_ctx_create_no_qpu),
matching the existing 0003/0004/0005/0007 patches. Higher-cycle
QPU init waits for a feature-flag gating change in a separate PR.
Intra (bS=4) h_loop_filter_luma_intra stays on the in-tree NEON .S
code; daedalus_h264_deblock_meta covers the non-intra path only.
A follow-up can route intra once daedalus-fourier exposes the
intra-h dispatch (the kernel already exists internally per fourier
PR #11).
Wires the new patch into both arch/PKGBUILD and debian/build-deb.sh
sequences. Verified the patch applies cleanly on top of 0001-0007
against the pinned upstream commit b57fbbe5 on hertz.
H264QpelContext.put_h264_qpel_pixels_tab[1][2] (8x8 luma horizontal
half-pel, 6-tap "put" — the canonical representative of the H.264
luma motion-compensation family) now dispatches through
daedalus_recipe_dispatch_h264_qpel_mc20 instead of
ff_put_h264_qpel8_mc20_neon.
Cycle 9 of the daedalus-v4l2#11 step 2 substitution arc; closes the
4-cycle libavcodec.so substitution sequence:
cycle 6 (PR #76) H.264 IDCT 4x4 done
cycle 7 (PR #85) H.264 IDCT 8x8 done
cycle 8 (PR #86) H.264 luma-v deblock done
cycle 9 (this) H.264 qpel mc20
Bumps daedalus-fourier pin d87239d → 209a421 (PR #2 — public API
gains daedalus_recipe_dispatch_h264_qpel_mc20 +
DAEDALUS_KERNEL_H264_QPEL_MC20).
Verdict per docs/k9_h264qpel_mc20.md: CPU NEON. Per-block 7.6 ns at
131 Mblock/s gives 135× margin over 30 fps 1080p; QPU dispatch floor
at ~250 ns makes any V3D shader strictly worse. Substitution is
plumbing-only — same daedalus_ctx_create_no_qpu pthread_once shape
the cycles 6/7/8 shims already own (kept SEPARATE from the H264DSP
shim's ctx because H264QPEL is its own libavcodec Makefile module
and link order does not guarantee a single .o owns the ctx symbol;
one extra ~µs init per process, paid lazily on first MC call).
Other H.264 luma MC variants (mc02, mc11, mc22 etc.) and the 16x16
size tier stay on the in-tree NEON .S code per the cycle-9 phase-1
rationale (mc20 8x8 is representative; remaining variants would
multiply recipe-lookup overhead without changing the substrate
verdict).
Bit-exact against ff_put_h264_qpel8_mc20_neon (daedalus-fourier
cycle 9 green; 10000/10000 random blocks bit-exact, M3 = 131 Mblock/s).
No SONAME change, no Depends change. PKGREL 9 → 10.
Refs reauktion/daedalus-v4l2#11 — substitution arc step 2 cycle 9.
FFmpeg 8.x dropped the H.264 decoder's low_delay code path —
AV_CODEC_FLAG_LOW_DELAY no longer prevents h264_select_output_frame
from running the display-order DPB output queue. The daedalus-v4l2
daemon's `ctx->flags |= AV_CODEC_FLAG_LOW_DELAY` at
daemon/src/decoder.c:202 has been a silent no-op since the SONAME
61→62 jump landed in reauktion/daedalus-v4l2 PR #16; on Firefox
YouTube this re-introduced the 2-1-4-3 B-frame pair-swap that PR
#12's daemon flag was supposed to prevent.
Fix lives in libavcodec, not the daemon: restore the documented
LOW_DELAY semantics so the daemon (and any other V4L2-stateless-
style consumer) keeps the one-frame-per-send_packet decode-order
output contract it already declares.
## Patch
0006-h264-restore-low-delay.patch touches libavcodec/h264_slice.c:
- h264_select_output_frame: early-exit when LOW_DELAY is set.
Emit the just-decoded picture as next_output_pic, mirror the
corruption / recovery-point tracking the main path performs,
skip delayed_pic[] / POC reorder machinery entirely.
- h264_field_start: suppress the SPS-driven
`has_b_frames = sps->num_reorder_frames` clobber when LOW_DELAY
is set. Without this the per-slice bitstream_restriction_flag
re-pickup would reintroduce a nonzero reorder buffer mid-stream
even after the daemon set has_b_frames=0 at avcodec_open2.
## Why not daemon-side
A daemon SPS-rewrite (`num_reorder_frames=0`) was considered but
rejected: it works only for the daemon's reconstructed SPS NAL,
not for any in-band SPS the daemon dlopens libavformat to parse
in other code paths. Restoring documented FFmpeg flag semantics
is the smaller, more durable change and keeps the daemon
interface stable.
## Packaging
- PKGREL/pkgrel bump to 9.
- No new build-deps, no Depends change.
- Substitution arc cycles 6/7/8 unchanged.
## Refs
- reauktion/daedalus-v4l2#11 / #12 (LOW_DELAY half-measure on
daemon side, originally landed against FFmpeg 7.x).
- daemon/src/decoder.c:202 (`ctx->flags |= AV_CODEC_FLAG_LOW_DELAY`
for H.264 only — unchanged, but now actually has effect again).
Cycle 8 of the libavcodec.so substitution arc (reauktion/daedalus-v4l2#11
step 2). H264DSPContext.v_loop_filter_luma — non-intra bS<4 vertical
luma deblock, called per macroblock-row edge from the slice deblock
loop in libavcodec/h264_loopfilter.c — now dispatches through
daedalus_recipe_dispatch_h264_deblock_luma_v instead of
ff_h264_v_loop_filter_luma_neon.
## What
- Add 0005-h264-deblock-luma-v-daedalus-fourier.patch (in both arch/
and debian/ ffmpeg-v4l2-request-fourier/). Extends
libavcodec/aarch64/h264_idct_daedalus.c with
ff_h264_v_loop_filter_luma_daedalus (constructs a
daedalus_h264_deblock_meta from FFmpeg's (alpha, beta, tc0[4]) and
calls daedalus_recipe_dispatch_h264_deblock_luma_v with n_edges=1).
Patches libavcodec/aarch64/h264dsp_init_aarch64.c to wire
c->v_loop_filter_luma to the new shim.
- arch/PKGBUILD + debian/build-deb.sh: append patch + bump pkgrel/PKGREL
to 8.
- No new build-deps, no Depends change, no daedalus-fourier rev — the
d87239d pin already exposes daedalus_recipe_dispatch_h264_deblock_luma_v.
## Why
Cycle 8 is marked "CPU primary; QPU opportunistic" in the daedalus-
fourier API docstring. Per the hybrid substrate philosophy
("if there's a coprocessor, use it") we eventually want the QPU
opportunism active here. But the libavcodec.so context is
process-global and shared with cycles 6/7 via pthread_once, and it
uses daedalus_ctx_create_no_qpu deliberately to avoid implicit
Vulkan init in arbitrary host processes (Firefox content, mpv-fourier,
ffmpeg-fourier CLI, ...). Switching to daedalus_ctx_create here
without a feature flag would be a footgun.
So cycle 8 lands as plumbing-only NEON-by-recipe substitution for
now; opportunistic QPU enablement is a separate follow-up that adds
a DAEDALUS_FOURIER_ENABLE_QPU env var or equivalent.
## Scope NOT covered
- Intra (bS=4) loop filter c->v_loop_filter_luma_intra — daedalus's
daedalus_h264_deblock_meta only covers the non-intra path.
- Horizontal-edge variant c->h_loop_filter_luma — separate kernel
(not yet in daedalus-fourier API).
- Chroma loop filters — separate kernels.
- Bulk batching — single-edge dispatch wastes the kernel's n_edges>1
amortization. Same caveat as cycles 6/7; follow-up.
- QPU opportunism — see "Why" above.
## SONAME
Unchanged. libavcodec.so.62 / libavformat.so.62 / libavutil.so.60.
## Refs
- reauktion/daedalus-v4l2 issue #11: reauktion/daedalus-v4l2#11
- marfrit-packages PR #76 (cycle 6 IDCT 4×4)
- marfrit-packages PR #85 (cycle 7 IDCT 8×8)
- marfrit/daedalus-fourier cycle 8 close (deblock luma-v NEON green)
Cycle 7 of the libavcodec.so substitution arc (reauktion/daedalus-v4l2#11
step 2). H264DSPContext.idct8_add — called per 8×8 block from the
High-profile intra-8×8-DCT decode path in libavcodec/h264_mb.c — now
dispatches through daedalus_recipe_dispatch_h264_idct8 instead of
ff_h264_idct8_add_neon.
## What
- Add 0004-h264-idct8-daedalus-fourier.patch (in both arch/ and debian/
ffmpeg-v4l2-request-fourier/). Extends libavcodec/aarch64/
h264_idct_daedalus.c (introduced by 0003) with ff_h264_idct8_add_daedalus
and a daedalus_recipe_dispatch_h264_idct8 call; patches
libavcodec/aarch64/h264dsp_init_aarch64.c to wire c->idct8_add to
the new shim.
- arch/PKGBUILD + debian/build-deb.sh: append the new patch to the
apply list; bump pkgrel/PKGREL to 7.
- No new build-deps, no Depends change, no daedalus-fourier rev — the
d87239d pin already exposes daedalus_recipe_dispatch_h264_idct8.
## Why
The recipe layer picks the substrate; for cycle 7 (H.264 IDCT 8×8)
the recipe is CPU NEON, so this is effectively a NEON-to-NEON
substitution layered on top of cycle 6. Production validation of
cycle 6 on higgs Firefox YouTube: 3040 frames decoded cleanly,
avg_decode_us=3388 (no regression vs the pre-substitution ~4 ms
baseline). Cycle 7 inherits the same shim's pthread_once context.
Bit-exact against ff_h264_idct8_add_neon (daedalus-fourier cycle 7
green; FFmpeg 8×8 block storage block[r + 8*c] matches daedalus
column-major convention).
## Scope NOT covered (deferred)
- Bulk c->idct8_add4 (inter 8×8-DCT macroblocks) stays on the
in-tree NEON .S code; batched substitution with n_blocks>1 lands
later alongside the cycle-6 bulk-paths work.
- High-bit-depth (10-bit) path untouched.
- Cycles 8/9 — separate PRs.
## SONAME
Unchanged. libavcodec.so.62 / libavformat.so.62 / libavutil.so.60.
## Refs
- reauktion/daedalus-v4l2 issue #11 (substitution arc): reauktion/daedalus-v4l2#11
- marfrit-packages PR #76 (cycle 6 IDCT 4×4)
- marfrit-packages PR #78 (libxml2 ABI-skew workaround)
- marfrit/daedalus-fourier cycle 7 close (H.264 IDCT 8×8 NEON green)
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)
The n8.1 pin's hwcontext_v4l2request.c deliberately blanks the
transfer-formats list for AV_PIX_FMT_YUV420P10 sw_format (the mapping
target for V4L2_PIX_FMT_NV15), so `ffmpeg -hwaccel v4l2request
-vf hwdownload,format=p010le` on a Hi10P / Main10 input failed at
filter-init with -22 EINVAL — even though kernel-side decode succeeded.
0002-nv15-to-p010-unpack.patch adds an inline NV15→P010 unpack
(5 bytes per 4 samples, little-endian → high-10-of-16) inside
v4l2request_transfer_data_from, exposes AV_PIX_FMT_P010 in
transfer_get_formats for that sw_format, and rejects non-P010
destinations explicitly with ENOSYS instead of silently corrupting
output via av_frame_copy on NV15-packed bytes.
Verified on fresnel (RK3399, linux-fresnel-fourier 7.0-14):
- 5-frame smoke test from issue #21 → exit 0, 13.8MB output
- 20-frame mid-fixture decode → bit-exact HW==SW
sha256 7d9b66d48d8f17b2281da1881c663ecc31722bb218aba1ae23bf28d07aa66b08
- 8-bit baseline (bbb_60s_720p.h264.mp4) still bit-exact HW==SW (no
regression in the existing NV12 path)
- Cross-device repro of original EINVAL on unpatched ampere (RK3588)
pkgrel=4, confirming the bug is upstream-FFmpeg-side, not RK3399-specific
Patch is upstream-able to Kwiboo's v4l2-request-n8.1 branch.
Closes#21.
PKGBUILD already renamed itself (pkgname=ffmpeg-v4l2-request-fourier,
replaces=(ffmpeg ffmpeg-v4l2-request-git)) but the containing
directory was never moved. This commit completes the rename to align
the path with the package identity and the rest of the -fourier
umbrella (libva, mpv, kwin, qt6-base, chromium, linux-*).
CI workflow path-trigger is wildcard (arch/**), unaffected. Step
names + cp source path updated to the new directory.
claude-noether
marfrit
test0r
claude-noether