Fourier — Hardware-Assisted Video Decoding on the Rockchip Fleet

One umbrella project to bring up working HW video decode on all four Rockchip devices in Markus' fleet. Named 2026-04-24.

Target fleet

Host	SoC	Role	Parent umbrella
fresnel	RK3399	Pinebook Pro fleet laptop	—
ohm	RK3566	PineTab2 tablet	—
boltzmann	RK3588	Rock 5 ITX+ (always on)	Volta
ampere	RK3588	CoolPi GenBook laptop	Coulomb

Current priority: ohm. The other three follow in the order of easiest-win (fresnel, mature mainline) → incremental (ampere, RK3588 landed Feb 2026) → hardest (boltzmann, currently on vendor kernel).

Related Rockchip projects

Fourier touches hardware that already has its own umbrellas. Keep display/boot concerns in those projects; keep video decode in Fourier.

• Coulomb — ampere / CoolPi GenBook stack. Subprojects:
  • Bin — u-boot, display bringup (eDP + keyboard)
  • MegabitChip — DDR init blob matching-decomp / HIL
  • RockHard — mainline kernel (Collabora TF-A, LP5-3200 OC)
• Volta — boltzmann / Rock 5 ITX+ stack. Subprojects:
  • Quark — edk2-rk3588 UEFI firmware
  • Neutron — mainline / vendor kernel, UEFI-booted
• fresnel — Pinebook Pro, custom overclocked kernel package (no umbrella)
• ohm — PineTab2, DanctNIX base, UART capture rig for ampere DDR work

Cross-cutting notes in /home/mfritsche/.claude/projects/-home-mfritsche-claude/memory/ — see MEMORY.md for the index.

Meet His

When Fourier needs infra muscle (wake a sleeping host, reach a VPN peer, bump DHCP on the Fritz, find the right lmcp token, set up distcc for a kernel build), summon His — the Home Infrastructure Specialist.

• As a subagent: Agent(subagent_type: "his", prompt: "...") — takes over a task end-to-end and returns a report.
• As a skill: Skill(skill: "his") — loads the runbook cheatsheet into the current session.

His knows the distcc workers (tesla, CT108, dcc1), the Fritz!DECT plug blast radii (careful with Himbeere + Office), the /opt/herding/ layout on hertz, the lmcp endpoint token map, and the VPN naming (<host>.vpn via shannon's dnsmasq). Canonical runbook: /home/mfritsche/claude/CLAUDE.md on noether.

For Fourier specifically, expect to lean on His for: waking ohm over LAN + VPN, confirming ampere is at .vpn (not the stale .88.x LAN IP), setting up cross-builds of patched ffmpeg via distcc, and nudging kernel packages into the marfrit repo.

Two kernel paths

Rockchip hardware decode has two incompatible kernel driver families. Userspace config diverges accordingly — don't mix flags.

Path A — mainline V4L2 stateless

• Kernel: rkvdec / rkvdec2 stateless V4L2 drivers (mainline or out-of-tree patch series).
• /dev node: V4L2 m2m /dev/videoN with compressed H.264/HEVC/VP9 queues + uncompressed output queue.
• FFmpeg: ffmpeg-v4l2-request-git from AUR (Jernej's patchset). Upstream v2 patchset posted on ffmpeg-devel 2024-08, not yet merged as of 2026-04-24.
• GStreamer: v4l2codecs plugin in gst-plugins-bad. 1.26 added Rockchip buffer formats; 1.28 added the new HEVC UAPI controls.
• mpv: mpv --hwdec=drm --vo=gpu-next (wayland compositor) or --vo=dmabuf-wayland (wlroots).
• Kodi: native V4L2-request API support, independent of FFmpeg.
• VA-API: libva-v4l2-request bridge for Firefox / Chromium paths.

Path B — Rockchip MPP vendor

• Kernel: mpp_rkvdec / mpp_rkvdec2 from Rockchip BSP (the rkr* kernel series).
• /dev node: /dev/mpp_service chardev, not V4L2.
• FFmpeg: build with --enable-rkmpp against librockchip-mpp.
• GStreamer: Rockchip-specific plugins (rkximagesink, mppvideodec, …).
• Present today on boltzmann (kernel 6.1.75-rkr3).

rkvdec mainline status (2026-04-24)

SoC	Block	Mainline status	Codecs (mainline)
RK3399	Hantro G1/G2	mature	MPEG-2, VP8, H.264, HEVC, VP9
RK3566	rkvdec2 (VDPU346)	not yet (Collabora TODO)	rkvdec1: MPEG-2/VP8/H.264; HEVC/VP9 need out-of-tree
RK3588	VDPU381	merged 2026-02-27	H.264, H.265 (no VP9/AV1 upstream yet)
RK3576	VDPU383	merged 2026-02-27	H.264, H.265

The RK3588 / RK3576 landing was the Feb 2026 Collabora drop. VDPU346 for the RK356x family is on the roadmap but not merged; ohm depends on DanctNIX carrying out-of-tree rkvdec2 patches if we want HEVC/VP9.

ohm — first priority, known recipe

From Martin Chang's blog (clehaxze.tw, 2023, still mirrored by DanctNIX):

sudo pacman -S mpv
yay -S ffmpeg-v4l2-request-git
mpv --hwdec=drm --vo=gpu-next --wayland-disable-vsync=yes input.mp4
# wlroots compositor variant:
mpv --hwdec=drm --vo=dmabuf-wayland input.mp4

2023 coverage: MPEG-2, VP8, H.264. 1080p60 H.264 hit ~80% of one CPU core — decode was on the hardware; the CPU was in the compositor path.

Recon 2026-04-24 (ohm)

• Running kernel: 6.19.10-danctnix1-1-pinetab2.
• Decoder: hantro-vpu on /dev/video1 (DT rockchip,rk3568-vpu at fdea0400); encoder on /dev/video2.
• Exposed stateless formats: S264 (H.264), MG2S (MPEG-2), VP8F (VP8) → NV12. No HEVC, no VP9.
• No rkvdec2 DT node, no rkvdec2 driver, no decoder firmware blob (/lib/firmware/rockchip/ only carries dptx.bin). HEVC/VP9 hardware decode is not available on this image — needs a kernel rebuild with out-of-tree rkvdec2 patches + firmware. Tree-side confirmation (does the danctnix PKGBUILD even attempt to carry rkvdec2?) still pending.
• Userspace: ffmpeg 8.1 (stock, v4l2m2m only — no v4l2request hwaccel, does not drive the stateless decoder), gstreamer 1.28.2 with v4l2codecs exposing v4l2sl{h264,mpeg2,vp8}dec, mpv 0.41.0, libva 2.23.0. No ffmpeg-v4l2-request-git, no libva-v4l2-request, no kodi.
• Noise: bes2600 Wi-Fi OOT driver spams WARN every ~30 s. Unrelated to decode; ignore for this umbrella.

So: 2023 recipe works verbatim for H.264 / MPEG-2 / VP8 once ffmpeg-v4l2-request-git is installed. GStreamer v4l2slh264dec is the shortest path to a first decode proof. HEVC/VP9 park until the kernel side picks up rkvdec2 patches.

Plan (tasks #18–24 in the noether task list)

1. Live recon — kernel, /dev/video*, v4l2-ctl --list-devices, dmesg rkvdec, /lib/firmware/rockchip/, installed ffmpeg/gstreamer/mpv/kodi
2. SW baseline — 1080p H.264 / HEVC / VP9 benchmark with ffmpeg and mpv hwdec=no, record CPU% + fps
3. Driver binding — confirm V4L2 stateless decode node exposed; if not, diagnose kconfig / DT / firmware
4. GStreamer v4l2codecs — cleanest proof; v4l2slh264dec pipeline with fakesink, then with display sink
5. FFmpeg v4l2-request — install ffmpeg-v4l2-request-git (AUR) or verify a DanctNIX-shipped ffmpeg with v4l2-request enabled
6. Kodi + mpv validation — 1080p HEVC at <30% of one core target
7. Document — freeze the final recipe in this README

Status 2026-04-24: ohm reachable; step 1 (live recon) complete; step 3 effectively done for H.264 / MPEG-2 / VP8 (driver bound, node exposed). Open threads: step 2 (SW baseline numbers) and step 5 (ffmpeg-v4l2-request build + install).

Acceptance criterion

1080p @ 30 fps, no dropped frames. Applies to every device and every codec we claim support for. Same bar everywhere — don't grade RK3566 on a curve vs RK3588. Dropped-frame count comes from mpv --msg-level=all=info or ffmpeg -f null -; "no dropped frames" means zero across a 60 s clip.

Test corpus

Big Buck Bunny is the canonical open test clip (Blender Foundation 2008, CC-BY), ubiquitous in HW-decode testing across a decade of embedded silicon. Various encodes readily available at peach.blender.org and mirrors.

Plan: park a fixed set on doppler under /moviedata/fourier-test/ so Gerbera re-indexes it and every fleet device on LAN + VPN streams identical bits. Canonical encodes:

File	Codec	Res	Notes
bbb_1080p30_h264.mp4	H.264	1080p	covers all four devices
bbb_1080p30_hevc.mp4	HEVC	1080p	ampere/boltzmann full; ohm pending rkvdec2
bbb_1080p30_vp9.webm	VP9	1080p	ohm pending; RK3588 pending upstream
bbb_1080p30_mpeg2.ts	MPEG-2	1080p	Path A fresnel + rkvdec1 baseline
bbb_1080p30_vp8.webm	VP8	1080p	fresnel + RK356x rkvdec1 baseline
bbb_2160p60_hevc.mp4	HEVC	4K60	RK3588 stretch goal (ampere/boltzmann only)

Stretch: add Tears of Steel (2012, also CC-BY) for HDR / high-bitrate HEVC once the stretch goal is viable.

After ohm

• ampere (RK3588) — once RockHard kernel tracks a tree with VDPU381 merged (>= Linux 6.14-ish with the Feb 2026 backport), add v4l2codecs and ffmpeg-v4l2-request packaging to RockHard's output. Should be a small step.
• boltzmann (RK3588) — dual-path decision. Short-term: use Path B with rkmpp (the kernel already exposes it). Long-term: migrate Neutron to a mainline kernel with VDPU381 and move to Path A for symmetry with ampere.
• fresnel (RK3399) — Hantro is mature upstream; likely only needs userspace install + recipe validation. Endeavour OS package names TBD.

Patches upstreamed along the way (v4l2-request to FFmpeg, VDPU346 to linux-media) count double — they benefit the whole fleet.

Known gotchas / watch-for

Sign-posting only — details in linked sources. If you hit one of these, expand the bullet with your specific find.

• IOMMU faults. Collabora's Feb 2026 VDPU381 landing included specific IOMMU fixes. If dmesg shows rockchip-iommu faults during decode, check you're on a kernel that carries the fixes, not just the driver. (Collabora post)
• Firmware blob. rkvdec / rkvdec2 need a firmware file under /lib/firmware/rockchip/ (varies by SoC). Missing blob → driver probe fails silently (no /dev/videoN). Check linux-firmware package currency.
• HEVC UAPI version gating. New explicit RPS controls arrived with the Feb 2026 landing; GStreamer 1.28 + FFmpeg-preliminary honour them. Older userspace on a newer kernel (or vice versa) fails in unintuitive ways. Pin both sides when diagnosing.
• Compositor-bound ≠ decode-bound. The 2023 clehaxze result saw 80% CPU at 1080p60 H.264 — that was the compositor + dmabuf path, not decode. Always attribute CPU with perf top / top -H before calling decode slow. Use mpv --vo=null to isolate the decode path.
• VOP2 cfg_done (RK3588). Decoded frames appear via VP0/VP1/VP2; if the shadow-register latch dance is wrong, frames don't show. See feedback_rk3588_cfg_done.md + project_bin_vp0_theory.md in noether memory. Touches Coulomb / Bin territory — if it gets there, ask.
• Multi-core VDPU381 on RK3588. Silicon has two decoder cores; upstream multi-core support is still landing. Until then, ampere / boltzmann run on one core and under-deliver vs headline specs.

Build infrastructure

Fourier touches two kinds of builds: userspace (FFmpeg + patches, GStreamer, libva-v4l2-request) and kernel (DT + module compiles if we carry out-of-tree rkvdec2 / VDPU346). Both benefit from distcc — CT108 (14-core aarch64 on data, wake via wake-data on hertz) plus always-on tesla on hertz.

Zeroconf is broken in containers — hand-wire DISTCC_HOSTS.

Kernel / DT modules (cross-build from x86 host)

DISTCC_HOSTS="localhost/4 192.168.88.208:3632/14,lzo,cpp tesla.lxd:3632/4,lzo,cpp" \
  pump make -j80 O=build/ ARCH=arm64 \
  CROSS_COMPILE='distcc aarch64-linux-gnu-' HOSTCC='ccache gcc'

Pump mode sometimes misbehaves on aarch64 cross builds — fall back to plain make -j80 without pump if include-server throws.

FFmpeg / userspace (native aarch64 host — ohm, ampere, fermi build CT)

export DISTCC_HOSTS="localhost/4 192.168.88.208:3632/14,lzo,cpp tesla.lxd:3632/4,lzo,cpp"
export MAKEFLAGS="-j80"
makepkg -s                    # AUR / marfrit-packages workflow
# or, from raw tree:
./configure && pump make -j80

makepkg honours MAKEFLAGS but not DISTCC_HOSTS for all build hooks — put DISTCC_HOSTS in /etc/makepkg.conf or export before invocation. CC/CXX wrappers: /usr/lib/distcc/ symlinks on native aarch64 (NOT /usr/lib/distcc/bin/).

Remember to re-run wake-data if CT108 is asleep — see his skill or the project_distcc_infra.md memory for the full recipe. When that memory and this README diverge, fix both.

Packaging — marfrit-packages

New fleet hosts should get Fourier userspace via pacman -S / apt install, not per-device AUR rebuilds. Mirror plan in marfrit-packages (layout: arch/<pkg>/PKGBUILD, debian/<pkg>/build-deb.sh + debian/):

Package	Source	CI runner	Target
ffmpeg-v4l2-request-git	fork of AUR (Jernej's patchset on ffmpeg tip)	fermi (Arch ARM aarch64)	Path A: ohm, fresnel, ampere
ffmpeg-v4l2-request	same patches against Debian ffmpeg src	feynman (Debian aarch64)	Path A Debian hosts
gst-plugins-bad-fourier	only if stock distro package is <1.28	fermi / feynman	1.28 HEVC UAPI uplift
libva-v4l2-request	upstream tag	fermi / feynman	VA-API bridge

The Arch package is the priority (ohm + fresnel are Arch-based). Debian package comes second (relevant if a fleet host ever runs Debian — kepler or similar). Both are provides=(ffmpeg) conflicts=(ffmpeg), so install deliberately replaces the distro ffmpeg on a given host.

CI trigger on each push. Artifacts land in packages.reauktion.de (reference_marfrit_repo_bootstrap.md in noether memory has the client bootstrap).

Out of scope: rkmpp-based FFmpeg (Path B). Boltzmann stays on rkr* until Neutron migrates; that host doesn't need a marfrit-packages entry until migration.

Upstreaming policy

Default: upstream-first. Anything generic (FFmpeg v4l2-request polish, GStreamer fixes, linux-media DT nodes for rkvdec2 / VDPU346 on RK356x, kernel compatible-string additions) goes to the relevant maintainer list (ffmpeg-devel, linux-media, linux-rockchip, gstreamer-devel, gitlab.fd.o) — not to marfrit-packages as a downstream carrier.

Fallback: when upstream ideology blocks success, stop fighting the review. Mark the patch # NOT FOR UPSTREAM, carry it in marfrit-packages, and document it in this README under a "fleet-local patches" section. The stance then becomes: Markus has the only devices in the world which are hardware-decoding-capable, and whoever wants to follow should get a Claude plan. Fleet keeps working; replication path is reproducible; no energy burnt arguing with maintainers who won't merge.

The bar for switching: a concrete rejection on ideological grounds (licensing stance, design-religion, NIH), not a normal review cycle. Normal review friction — respin until it lands.

Known RockHard precedent for downstream-only: the GCC_PLUGINS patch (project_linux_rk3588.md). Tag new carrier-only patches the same way for consistency.

Working agreements

Standing rules for how we run this project — inherited from the broader collaboration canon (feedback_* / project_* in noether's memory system), captured here so a cold-start Fourier session doesn't re-learn them.

ReCAP — ReContextualization After Pruning

Claude's context gets compacted when long sessions hit the window limit, and any live-session state not in durable storage vanishes. Our counter:

• Memory files (/home/mfritsche/.claude/projects/-home-mfritsche-claude/memory/, MEMORY.md is the index) are the long-term substrate. Don't keep load-bearing facts only in conversation.
• Project READMEs (this file) carry the research dossier + current plan. Update them when state changes, not later.
• Task list on noether carries active work. Status transitions are cheap — mark in_progress when starting, completed when done.
• After a /compact, re-read relevant memory files + README + recent git log before reasoning. Don't infer from conversation alone.

See project_recap.md in memory for the full protocol.

Commit per experiment

Every experiment that touches the tree — a kconfig change, a DT tweak, a ffmpeg build flag, a test clip benchmark — gets its own commit on a WIP branch, with a short message naming what changed and what was observed.

• Dirty trees are tech debt. If the tree is dirty for >30 min, commit.
• Include benchmark numbers / dmesg excerpts / observation in the commit body, not just the code diff.
• Rebase / squash later if a clean series matters; don't delay the commit waiting for it.

See feedback_commit_cadence.md in memory.

Ask before flash / reboot

This project spans fleet laptops and always-on hosts. We have real blast radius.

• Never flash anything without a verified, tested backup. Fritz!Box 7490 was bricked by flashing with an empty backup on 2026-04-12 — we don't repeat that class of mistake. See feedback_flash_critical.md.
• Shared hardware reboots pause the user's other work. Ask before rebooting data (Proxmox), hertz (home-LAN spine), boltzmann (always-on build host). See feedback_no_bulldoze_reboots.md.
• For kernel / u-boot / firmware changes: simulate first where possible (QEMU, module-style load) before flashing silicon. See feedback_simulate_first.md.
• Never run update-initramfs or equivalent on a remote host that boots from a non-standard root (ZFS, btrfs-with-subvols). See feedback_initramfs.md.

Off-machine backups

Fleet laptops back up to data via backintime (Anacron mode, daily attempts, VPN-guarded, 30-day staleness alert by email). Hertz backs up to data weekly / quarterly via backup-hertz.sh (vitruvius dashboard shows progress). Data itself lives on ZFS RAIDZ2 + snapshots.

• Before any invasive change on a fleet laptop, confirm its last successful backintime snapshot in /opt/herding/var/backintime-status/<host> on hertz.
• New per-device state (kernel patch series, ffmpeg build tree) lives in a Gitea repo + gets backed up with the rest of the working tree — don't leave unique work on a single disk.
• External photos / family data on hertz is mirrored via the hertz backup to data. Restore recipe is in the two-step restore-hertz-step1-sd.sh / restore-hertz-step2-lxd.sh on data.

See also — broader feedback canon

• Test the observer first (feedback_observer_first.md) — before drawing decode-performance conclusions, confirm the rig (v4l2-ctl reports sensible caps? ffmpeg actually routing through v4l2request?).
• Three strikes then verify (feedback_three_strikes.md) — after two failed fixes, stop guessing; verify the binary / wire / protocol.
• TRM or nothing (feedback_trm_or_nothing.md) — register writes need documentation backing. Relevant for any DT or driver patches we ship.
• Trust Markus' eyes (feedback_trust_user_eyes.md) — if he reports "it plays smoothly", that's primary evidence. Don't over-qualify.
• No budget framing (feedback_no_budget_framing.md) — don't pre-shrink scope citing "session cost"; Markus sets pace.

References

Mainline kernel state

• Rockchip RK3588 / RK3576 H.264 and H.265 video decoders gain mainline Linux support (CNX Software, 2026-02-27)
• RK3588 and RK3576 video decoders support merged in the upstream Linux Kernel (Collabora)
• Upstream support for Rockchip's RK3588: Progress and future plans (Collabora)
• media: rkvdec: Add support for VDPU381 and VDPU383 (LWN)
• RKVDEC2 Driver Posted For Accelerated Video Decoding On Newer Rockchip SoCs (Phoronix)

FFmpeg V4L2 request API

• PATCH v2 0/8 Add V4L2 Request API hwaccels for MPEG2, H.264 and HEVC (ffmpeg-devel, 2024-08)
• Miouyouyou/FFmpeg-V4L2-Request (build script)
• ffmpeg v4l2 requests 4.4.3 patchset (artemis.sh, 2023-03)

GStreamer v4l2codecs

• GStreamer v4l2codecs plugin docs
• Adding VP9 and MPEG2 stateless support in v4l2codecs for GStreamer (Collabora, 2021)
• GStreamer 1.26 — improved hardware efficiency (Collabora)

PineTab2 specific

• Hardware accelerated playback on PineTab 2 (clehaxze.tw, 2023-09)
• PINE64 Mainline Hardware Decoding wiki
• dreemurrs-embedded/linux-pinetab2 releases (6.15.2-danctnix2 latest)