Phase 1 of codec negotiation, and the Linux software H.264 encode path it unblocks. **Codec negotiation (core `quic`):** - `Hello.video_codecs` (bitfield: CODEC_H264/HEVC/AV1) — the client advertises what it can decode; appended as a trailing byte (older client → 0 = HEVC-only, back-compat). - `Welcome.codec` — the single codec the host resolved and will emit; trailing byte (older host → HEVC). - `resolve_codec(client, host_capable)` picks the shared codec (precedence HEVC > AV1 > H.264) or `None` → the host refuses honestly rather than sending an undecodable stream. - Roundtrip + back-compat tests; cbindgen exports the CODEC_* constants. **Software encoder (host):** - The openh264 `OpenH264Encoder` (was Windows-only) is now built on Linux too — it's platform-agnostic (consumes CPU RGB `CapturedFrame`s, statically-bundled openh264). `openh264` moved to the shared linux+windows Cargo target. - `PUNKTFUNK_ENCODER=software` selects it: `open_video` gains a `software` branch (H.264 only), and `session_plan::resolve_encoder` / `capture::gpu_encode` resolve `EncoderBackend::Software` → `output_format().gpu = false`, so the portal capturer delivers CPU RGB. Explicit-only (auto never picks it — a box with a dead driver still has /dev/nvidiactl and would mis-resolve NVENC). **Host codec resolution (`punktfunk1`):** - The native path no longer hardcodes HEVC: it resolves the codec from the client's advertised set ∩ the host's capability (`Codec::host_wire_caps`: software→H.264, else HEVC), threads it through `SessionPlan.codec`, and opens the encoder + validates reconfigures at that codec. A software host + HEVC-only client is refused with a clear error. - 4:4:4 is gated on HEVC (it's HEVC-only). **Probe:** advertises H264|HEVC|AV1 and logs the resolved codec. Validated on the GPU-less dev box: negotiation is live end-to-end (probe advertises 0x07 → host resolves H.264 → Welcome reports it → plan = Software/H264), and the openh264 unit test (CPU RGB → AnnexB IDR) now runs on Linux. Full capture→encode still needs a GPU on this box — every compositor screencast path (KWin GL, gamescope VK_EXT_physical_device_drm, wlroots EGL) requires one; software render (llvmpipe/pixman) can't be captured — so this box exercises negotiation + encoder, not live capture. The software path unblocks GPU-less-*encode* boxes that still have a display GPU. Phase 2 (clients advertising real codecs + decoding per Welcome.codec) is a follow-up. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
punktfunk-host
The streaming host — the program you run on the machine whose desktop or games you want to stream. For each client that connects, it spins up a virtual display sized to that device, captures it on the GPU, encodes with hardware NVENC/VAAPI/AMF/QSV, and sends it out over a low-latency transport — no physical monitor, no letterboxing, no rearranging your real screens.
It speaks two protocols from one process:
- GameStream — so any Moonlight / Artemis client works day one.
punktfunk/1— punktfunk's own faster protocol (QUIC control plane, GF(2¹⁶) FEC + AES-GCM data plane) that the native clients use.
Runs on Linux (the primary, most battle-tested path) and Windows (x64). The shared protocol,
FEC, and crypto live in punktfunk-core; this crate is everything
platform-facing around it.
What it does
- Per-client virtual displays at the exact WxH@Hz. Linux uses per-compositor backends — KWin, gamescope, Mutter, and Sway/wlroots; Windows uses its own all-Rust IddCx virtual display, even on the secure desktop (UAC / lock screen).
- GPU zero-copy capture → encode. dmabuf → CUDA/Vulkan → NVENC on Linux; DXGI/WGC → GPU encode on Windows. Encoders auto-select by GPU vendor: NVENC (NVIDIA), VAAPI (Linux AMD/Intel), AMF/QSV (Windows AMD/Intel), or software H.264 as a floor. HDR/10-bit and HEVC 4:4:4 supported.
- Input injection. Mouse/keyboard (libei / gamescope EIS / wlr / Windows SendInput) and virtual gamepads — Xbox 360/One, DualSense, DualShock 4 — with rumble and HID feedback back-channels.
- Audio both ways. Opus audio host→client, plus a virtual microphone the client can talk into.
- Trust & discovery. A persistent host identity, SPAKE2 PIN pairing (default) or TOFU, and mDNS auto-advertisement so clients find the host without typing an IP.
- Management API + web console. A REST API (
mgmt.rs, OpenAPI atapi/openapi.json) drives status, paired devices, and on-demand pairing; the browser UI is inweb/.
Run it
punktfunk-host serve runs inside your desktop session. Bare serve is the secure native-only
default (punktfunk/1 + the management API); add --gamestream on a trusted LAN to also accept
stock Moonlight clients.
# Linux, from the repo root (see the repo README "Running on this box" for the headless recipe):
cargo run -rp punktfunk-host -- serve # native-only (secure default)
cargo run -rp punktfunk-host -- serve --gamestream # + Moonlight compatibility
Then pair from the web console (https://<host-ip>:3000) or the client app.
Most people should install a package rather than run from source — see
packaging/ (apt · rpm/COPR/bootc · Arch/sysext · Windows installer) and
the per-platform guides at docs.punktfunk.unom.io/docs/install.
Subcommands
| Command | Purpose |
|---|---|
serve |
The host (native punktfunk/1 + mgmt API; --gamestream adds Moonlight). |
punktfunk1-host |
Standalone native-protocol listener for testing/measurement (--source virtual, --max-sessions). |
openapi |
Print the management-API OpenAPI spec (regenerates api/openapi.json). |
library |
Inspect the multi-store game library. |
service · driver · web |
Windows: SCM service, driver install, bundled web console. |
*-test / *-selftest / *-probe |
Diagnostics (input, zero-copy, HDR, compositor, gamepads). |
--help lists them all.
Layout
src/
main.rs CLI + subcommand dispatch
config.rs · session_plan.rs · session_tuning.rs · pipeline.rs session setup + the frame pipeline
vdisplay/ per-compositor virtual outputs (kwin · gamescope · mutter · wlroots)
capture/ · capture.rs screen/dmabuf capture (+ Windows DXGI/WGC)
encode/ · encode.rs per-GPU encoders (nvenc · vaapi · ffmpeg_win (AMF/QSV) · sw)
zerocopy/ dmabuf → CUDA → NVENC bridges (EGL/GL tiled, Vulkan LINEAR)
inject/ · inject.rs input backends (libei · wlr · uinput gamepads · UHID DualSense/DS4)
audio/ · audio.rs Opus out + virtual mic (PipeWire / WASAPI)
gamestream/ Moonlight compat: nvhttp · pairing · rtsp · control · stream · gamepad · apps
punktfunk1.rs the native punktfunk/1 host (QUIC control + native-thread UDP data plane)
mgmt.rs · native_pairing.rs · stats_recorder.rs management API, pairing, perf capture
hdr.rs · library.rs HDR metadata; multi-store game library
linux/ · windows/ platform-confined backends
Related
punktfunk-core— the shared protocol · FEC · crypto core- Clients — the apps that connect (Apple · Linux · Windows · Android · probe)
- Packaging & docs — install & operate
design/— architecture rationale and deep-dive plans