design/latency-reduction-2026-07.md T0.1/T0.2/T1.2/T1.3:
- T1.2 rate-capped front-loaded pacing: the paced overflow's budget is now
min(0.9x slack, overflow wire time at ~3x the live encoder bitrate)
(PUNKTFUNK_PACE_FACTOR, 0 = legacy deadline-only spread). A 300 KB-1 MB
frame's tail leaves in ~2-5 ms instead of smearing across ~15 ms at 60 fps;
GameStream schedule byte-identical (pins unchanged).
- T1.3 data-first wire order: packetize emits every block's data shards before
any parity (per-block parity pools keep all blocks' parity alive for the
second pass), so lossless completion stops waiting behind the parity tail.
EOF = last emitted packet; receiver already order-agnostic.
- T0.1 staged 0xCF: HostTiming gains an append-extensible per-stage tail
(queue/encode/pace us; seal+channel-wait derived as residual) - no cap bit
needed, old peers read the 13-byte prefix. Joined client-side into
Stats::host_{queue,encode,xfer,pace}_ms, the OSD detailed tier, and the
probe's report.
- T0.2 true on-glass present timing: VK_KHR_present_id/present_wait enabled
when supported; a PresentTimer waiter thread resolves each present id to
real visibility, replacing the submit-time display stamp (which undercounts
by up to a refresh and hides a silent-FIFO standing queue).
Validated on .21: core 185 + host 185 tests, pf-presenter 19, clippy
-D warnings across all five touched crates; loss-harness recovery curve
unchanged; C ABI harness round-trips.
Co-Authored-By: Claude Fable 5 <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; on Windows the host pushes frames straight into its own IDD (sealed IDD-push, no screen-scraping) → GPU encode. 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>:47992) 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 IDD-push)
encode/ · encode.rs per-GPU encoders (nvenc · vaapi · ffmpeg_win (AMF/QSV) · sw)
linux/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
native.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
- punktfunk-planning (internal planning repo) — architecture rationale and deep-dive plans