enricobuehler
74819b1be8
Two related additions to the native protocol, host-side (the client side of
each is exposed over the C ABI so the platform clients can wire it up).
Bitrate negotiation
- Hello/Welcome carry `bitrate_kbps` (appended trailing-byte field, back-compat:
old peers decode 0 = host default). The client requests a rate; the host
clamps it to [500 kbps, 500 Mbps] (or its 20 Mbps default when 0) and echoes
the resolved value in Welcome. Replaces the hardcoded 20 Mbps NVENC bitrate in
m3.rs — threaded through virtual_stream → build_pipeline → open_video, applied
on the initial mode and every reconfigure rebuild.
- C ABI: punktfunk_connect_ex3(..., bitrate_kbps, ...) (ex2 delegates with 0);
punktfunk_connection_bitrate() reads the resolved value.
Speed test (bandwidth probe)
- New typed control messages ProbeRequest{target_kbps,duration_ms} (0x20) /
ProbeResult{bytes_sent,packets_sent,duration_ms} (0x21), plus a FLAG_PROBE
packet flag. The client asks the host to burst zero-filled, FLAG_PROBE-tagged
access units over the data plane at a target goodput for a duration (clamped
≤ 1 Gbps / ≤ 5 s), pacing by a bytes-allowed budget; video pauses for the
burst. The host reports what it actually sent; the client measures received
bytes + window → goodput and loss. Probe filler is never fed to the decoder
(diverted in the connector pump and the reference client's poll loop).
- The host control task now multiplexes Reconfigure + ProbeRequest (inbound)
and ProbeResult (outbound) over select!; a probe channel reaches the
data-plane thread (both virtual and synthetic sources).
- Connector: NativeClient::request_probe()/probe_result() with an internal
accumulator; C ABI punktfunk_connection_speed_test() +
punktfunk_connection_probe_result() → PunktfunkProbeResult.
- punktfunk-client-rs gains `--bitrate KBPS` and `--speed-test KBPS:MS` (its own
loop measures + logs goodput/loss) for loopback verification.
Validated on loopback (synthetic source): a 20 Mbps / 2 s probe measured
20050 kbps at 0% loss, bitrate negotiated (0→20000 and 50000→50000), and the
interleaved probe AUs were correctly excluded from frame verification
(mismatched=0). Wire codecs + trailing-byte back-compat have unit tests. C
header regenerated.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
punktfunk
A ground-up low-latency desktop streaming stack, built Linux-first, with a shared Rust protocol core and native clients per platform.
punktfunk is a placeholder codename. The bet: ship a Linux virtual-display streaming
host that speaks the existing Moonlight protocol (every Moonlight/Artemis client works
day one), then break the ~1 Gbps FEC wall with a GF(2¹⁶) Leopard-RS transport as a
negotiated extension. See docs/implementation-plan.md.
Status
| Milestone | State |
|---|---|
M1 — punktfunk-core + C ABI |
✅ done & hardened (FEC, packetization, AES-GCM, session, adversarial-review fixes, punktfunk_core.h) |
| M2 — GameStream host → stock Moonlight | ✅ live end-to-end: pairing, RTSP, audio, per-client virtual output at native res, GPU zero-copy NVENC, gamepads |
M3 — punktfunk/1 native protocol |
✅ validated live: QUIC control + GF(2¹⁶) FEC/AES data plane, SPAKE2 PIN pairing, mid-stream mode renegotiation |
| M4 — client decode + present (Apple) | 🟡 macOS first light: AnnexB→VideoToolbox HEVC on glass + input/pairing over punktfunk/1 (clients/apple); iOS + presenter next |
| Web console + management API | ✅ TanStack web console (web/) over the OpenAPI mgmt API: host status, paired devices, on-demand native pairing (arm → show PIN) |
The GameStream host works with a stock Moonlight client — validated live on NVIDIA
(RTX 5070 Ti & RTX 4090, driver 595): trust-on-first-use pairing that persists, an app
catalog, RTSP/ENet/audio, and video at the client's exact resolution and refresh via a
per-session virtual output (KWin, gamescope, Mutter, Sway backends), encoded with GPU
zero-copy (dmabuf → CUDA/Vulkan → NVENC) at up to 5120×1440@240. The native
punktfunk/1 protocol adds a QUIC control plane and a GF(2¹⁶) Leopard-FEC + AES-GCM data
plane (p50 ~0.8 ms capture→reassembled at 720p120), with a SPAKE2 PIN pairing ceremony. Both
run from one process (serve --native), managed through a REST API + web console. Builds
against FFmpeg 7 or 8; deployed live on Bazzite. Full status: CLAUDE.md;
roadmap: docs/roadmap.md.
Layout
crates/
punktfunk-core/ protocol · FEC · pacing · crypto · quic — the C ABI (lib + cdylib + staticlib)
punktfunk-host/ Linux host: vdisplay · capture · encode · inject · gamestream · m3 · mgmt · native_pairing
punktfunk-client-rs/ punktfunk/1 reference client (M3 headless; M4 adds decode+present)
clients/{apple,android}/ native client scaffolds (import punktfunk_core.h); apple = macOS first light
web/ TanStack web console (host status · paired devices · pairing) over the mgmt API
packaging/ Fedora/Bazzite RPM · bootc image · COPR (see packaging/bazzite/README.md)
include/punktfunk_core.h cbindgen-generated C header (checked in)
tools/{latency-probe,loss-harness}/ measurement (plan §10)
docs/{implementation-plan,roadmap,windows-host,dualsense-haptics}.md
Build & test
cargo build --workspace # green on Linux and macOS
cargo test --workspace # unit + loopback + proptest + C ABI harness
cargo clippy --workspace --all-targets
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
The C header regenerates from crates/punktfunk-core/src/abi.rs on every build (cbindgen via
build.rs) into include/punktfunk_core.h.
Design invariants
- One core, linked everywhere. Protocol/FEC/crypto/pacing live in
punktfunk-coreexactly once, exposed over a stable, versioned C ABI (punktfunk_abi_version(),PunktfunkConfigcarries its ownstruct_size). - No async on the hot path. The per-frame pipeline uses native threads only;
tokio/quinnare gated behind the off-by-defaultquicfeature (control plane only). - FEC is the wall-breaker. GF(2⁸) (≤255 shards/block) for Moonlight compat; GF(2¹⁶) (≤65535 shards/block, SIMD, O(n log n)) to push past ~1 Gbps.
License
MIT OR Apache-2.0.