Files
punktfunk/crates/punktfunk-core
enricobuehler 5c05246098 feat: M10 — FFmpeg is gone from the client
cargo tree -p punktfunk-client-session finds no ffmpeg. The host still does,
which is the whole point: pf-encode keeps libavcodec unconditionally and no
host workflow, packaging script or licence file was touched.

Deleted: crates/pf-ffvk, video_vulkan.rs, video_vaapi.rs, video_libav.rs, the
libavcodec half of video_d3d11.rs, the av_log machinery, ffmpeg::codec::Id as
the decoder's vocabulary (the quic CODEC_* wire constants now serve, which is
why the evidence table was keyed on them), DecodedImage::VkFrame and ::Dmabuf,
the presenter's AVVkFrame lane, and the ffmpeg-fallback feature with
everything behind it. DrmFrameGuard collapses from an enum to a newtype, which
removes an unsafe impl Send. Roughly 25,000 lines.

Then the CI, packaging, licensing and docs work the plan's §6 lists: the
Windows workflows lose FFMPEG_DIR, PF_FFVK_VULKAN_INCLUDE and their PATH
prepend; the MSIX loses its DLL wildcard; the client .deb stops emitting libav
sonames on its own because depends come from dpkg-shlibdeps; arch, flatpak and
nix drop the dependency; and the README's "FFmpeg 7 or 8" contract narrows to
the host.

Three defects reached users' machines in the first cut, and none was in the
deletion itself.

All three desktop Settings UIs offer vulkan, vaapi and d3d11va as stored
decoder values, so those strings sit in shipped settings files today. Refusing
them by name — which is the correct rule for a stale pin — would have bricked
every upgraded client whose owner ever touched that dropdown. They now migrate
onto the native rung for the same hardware family, at decoder construction AND
at each dialog's lookup, because a legacy value that matches no preset
displays as "Automatic" and silently rewrites the user's preference on the
next save.

M9's evidence filter was deleted on the argument that with no libavcodec twin
below, barring an unproven rung removes hardware decode rather than moving
down one rung. That is true on Windows and false on Linux for Intel and every
unknown vendor id, where prefer_vulkan_first is false and the order is
native-vaapi → native-vk: a rung that has decoded nothing anywhere sitting
above one that is 250/250 on three drivers. Every Intel Linux desktop would
have moved from libavcodec VAAPI, shipping for years, onto pf-vaadec by
default — and a rung that constructs and then produces wrong pixels leaves
only by the error-streak demotion, which this codebase already documents as
not tripping on the B580's strobing. The filter is restored as a narrow, pure,
testable rule: an unproven rung yields to a proven one, and to nothing else.
Windows deliberately passes no rung below, because that vendor family is the
one with a measured wrong-pixel report against Vulkan decode, and trading no
evidence for evidence of corruption is the wrong direction.

And the notices still said FFmpeg was bundled. The root file is what both
desktop clients include_str! and what the MSIX ships, three lines under the
new card saying no FFmpeg is bundled; Apple's Acknowledgements said it too, on
iOS, tvOS and macOS. The generator now emits four per-client files scoped by
transitive closure — 0 FFmpeg mentions in each, verified — while the root file
keeps it for the host. That also ends the standing false attribution of
ffmpeg-next, GTK4, windows-rs and the NVENC SDK to an iPhone.

Windows has no reachable box, so it was compiled instead: a cross clippy at
-D warnings on x86_64 and aarch64-pc-windows-msvc with the C toolchain stubbed
so build scripts run without linking. That gate immediately caught an
include_str! path one directory too deep, which nothing else could have.

Gates: container clippy -D warnings, 160 tests, workspace check, both Windows
targets clean, client ffmpeg count 0 and host 2. The four decode crates are
untouched, so the hardware rungs' 250/250 stands.

⚠ Owed and unrun: no GPU has executed any of this milestone. M8's on-glass
software check, M7's D3D11 and VAAPI AV1 hardware legs, and M9's field bake
all still want hardware, and the bake window and criteria remain the user's.
2026-08-07 08:58:47 +02:00
..

punktfunk-core

The shared protocol core — the one place where punktfunk's transport, forward error correction, and crypto live. It's linked into the host and every native client, so there's exactly one implementation of the wire format everywhere.

Written in Rust with no async on the per-frame path (native threads only). It exposes both a normal Rust API and a stable, versioned C ABI, so the Swift and Kotlin clients — and any C embedder — link the same code as the Rust ones.

What's in here

  • Transport & session (session.rs, transport/, packet.rs) — the punktfunk/1 data plane over raw UDP: packetization, reassembly (with attacker-bounded limits), pacing, and socket tuning.
  • FEC (fec/) — the wall-breaker. Two codes:
    • GF(2⁸) classic ReedSolomon with the Cauchy generator matrix — byte-identical to the nanors library Moonlight uses, so our parity is decodable by a stock Moonlight client.
    • GF(2¹⁶) Leopard-RS (SIMD, O(n log n)) — up to 65535 shards/block, which removes the ~1 Gbps FEC ceiling. punktfunk/1 negotiates this one.
  • Crypto (crypto.rs) — AES-128-GCM session encryption with per-direction nonce salts and sequence-as-AAD; SPAKE2 PIN pairing lives behind the quic feature.
  • QUIC control plane (quic.rs, client.rs, feature quic) — the Hello/Welcome/Start handshake, cert pinning/TOFU, reverse audio, and the embeddable NativeClient connector. This is the only place tokio/quinn are allowed; the feature is off by default so the core stays runtime-free.
  • C ABI (abi.rs) — the versioned surface (punktfunk_abi_version(), PunktfunkConfig carrying its own struct_size) that generates include/punktfunk_core.h via cbindgen at build time.

Build outputs

The crate builds three ways at once (crate-type = ["lib", "cdylib", "staticlib"]):

Output Used by
lib (rlib) the host, probe, and tools link it as a normal Rust crate
cdylib (.so/.dylib) the Swift / Kotlin clients via the C ABI
staticlib (.a) the C test harness and static embedding

Test

cargo test -p punktfunk-core                 # unit + proptest + loopback
cargo run  -p loss-harness                   # FEC loss-resilience sweep (no network needed)
bash crates/punktfunk-core/tests/c/run.sh    # standalone C-ABI link + round-trip proof

Design invariants (do not regress)

  • One core, linked everywhere — protocol/FEC/crypto live only here, behind the stable C ABI.
  • No async on the hot path — the per-frame pipeline is native threads only; quic (tokio/quinn) is control-plane only, feature-gated, off by default.
  • Security hardening stays intact — the reassembler bounds attacker-controlled fields before allocating; AES-GCM keeps per-direction nonce salts + seq-as-AAD; the ABI checks struct_size. Regression tests exist — keep them green.
  • punktfunk-host — the streaming host built on this core
  • Clients — the apps that link this core over the C ABI (or directly, in Rust)
  • punktfunk-planning: implementation-plan.md (internal planning repo) — why GF(2¹⁶) FEC, the latency budget, and the architecture thesis