enricobuehler
09a5957c6d
One stat model everywhere (design/stats-unification.md): four measurement points (capture/received/decoded/displayed), three stages that tile the interval exactly, and a HUD that shows the addition explicitly — end-to-end 14.2 ms p50 · 19.8 p95 · capture→on-glass = host+network 9.8 + decode 2.1 + display 2.3 replacing each client's ad-hoc mix of overlapping absolutes (the Apple HUD's three arrow lines that looked sequential but weren't), mean-vs-median decode times (Windows/Linux), missing same-host-clock flags (Windows/Linux), and three different names for the same capture→received measurement (probe's "reassembled", Apple/Android's "client", Windows/Linux's post-decode "lat"). Per client: Apple threads receivedNs through the VT decode via the frame refcon bit pattern so the decode stage exists at all (stage-1 fallback honestly degrades to a capture→received headline); Windows carries FrameTimes through the existing frame channel to the render thread and adds e2e p50/p95 post-Present; Linux stamps received at AU pop and rides decoded_ns on DecodedFrame to the paintable-set site; Android pairs receipt stamps with MediaCodec output buffers via the codec's pts round-trip (JNI stats array 14→16 doubles, indexes 0-13 unchanged). fps now uniformly counts received AUs; lost/(received+lost) per window, hidden at zero. docs-site gains "Understanding the Stats Overlay": what each line means, why the equation only approximately sums (percentiles), and a line-by-line Moonlight/Sunshine matrix — including that Moonlight has no end-to-end number and its "network latency" is an ENet control RTT, so punktfunk's headline must not be compared against any single Moonlight line. Verified here: linux client + probe + core check/clippy/fmt green, android native cargo-ndk arm64 check green. Pending: Windows CI + on-glass, swift test on the mac, on-device Android. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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) — thepunktfunk/1data plane over raw UDP: packetization, reassembly (with attacker-bounded limits), pacing, and socket tuning. - FEC (
fec/) — the wall-breaker. Two codes:- GF(2⁸) classic Reed–Solomon with the Cauchy generator matrix — byte-identical to the
nanorslibrary 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/1negotiates this one.
- GF(2⁸) classic Reed–Solomon with the Cauchy generator matrix — byte-identical to the
- Crypto (
crypto.rs) — AES-128-GCM session encryption with per-direction nonce salts and sequence-as-AAD; SPAKE2 PIN pairing lives behind thequicfeature. - QUIC control plane (
quic.rs,client.rs, featurequic) — the Hello/Welcome/Start handshake, cert pinning/TOFU, reverse audio, and the embeddableNativeClientconnector. This is the only placetokio/quinnare allowed; the feature is off by default so the core stays runtime-free. - C ABI (
abi.rs) — the versioned surface (punktfunk_abi_version(),PunktfunkConfigcarrying its ownstruct_size) that generatesinclude/punktfunk_core.hvia 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.
Related
punktfunk-host— the streaming host built on this core- Clients — the apps that link this core over the C ABI (or directly, in Rust)
design/implementation-plan.md— why GF(2¹⁶) FEC, the latency budget, and the architecture thesis