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-core exactly once, exposed over a stable, versioned C ABI (punktfunk_abi_version(), PunktfunkConfig carries its own struct_size).
• No async on the hot path. The per-frame pipeline uses native threads only; tokio/quinn are gated behind the off-by-default quic feature (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.