The host cursor stops riding the video and becomes a real OS cursor on the client (the Parsec/RDP model): pointer feel no longer pays the capture→encode→network→decode→present round trip. Wire (M2a): - Hello grows a client_caps trailing byte (CLIENT_CAP_CURSOR) after the fixed display_hdr block — presence disambiguated by remaining length, which caps the post-HDR tail at 27 bytes (documented); Welcome answers HOST_CAP_CURSOR (capable-and-asked, the 444/clipboard precedent). - CursorShape (0x50, control stream): serial + dims + hotspot + straight RGBA, ≤120px/side so the u16 frame always fits (128² would overshoot); client caches by serial — re-showing a known shape costs 14 bytes, not a bitmap (RDP pointer-cache for free). - CursorState (0xD0 datagram): serial + visible/relative_hint flags + position, sent once per encode-loop tick — latest-wins, self-healing under loss, no refresh timer. relative_hint is reserved for M3. - Client core: two new planes (control-task + datagram-task arms) → next_cursor_shape/next_cursor_state; connect() grows client_caps (C ABI passes 0 until the v11 cursor poll fns exist). Host (M2b, Linux portal only): - handshake::cursor_forward is THE predicate (client asked ∧ Linux ∧ compositor ≠ gamescope) — Welcome bit and session wiring both read it. - SessionPlan.cursor_blend goes false for a forwarding session; the encode loop ticks a CursorForwarder every iteration: shape-serial diff → control-task bridge (mirrors probe_result), state datagram → conn. - CursorOverlay/capture CursorState carry the hotspot through (nearest-neighbor downscale backstop for XL cursors, unit-tested). Presenter: - CursorChannel drains both planes per loop iteration; shapes become SDL color cursors (from_surface + hotspot), applied while the desktop mouse model is engaged; visibility follows the host; capture/released hands back the system cursor. Sessions advertise the cap when they START in desktop mode. Verified on .21: fmt + clippy -D warnings (7 crates) + tests green (core 218 incl. new wire roundtrips, host 245 incl. e2e + forwarder downscale tests). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
punktfunk — probe (reference client)
punktfunk-probe is the headless reference client for the punktfunk/1 protocol — a
command-line tool for testing, latency measurement, and validating host behavior. It's not a
streaming app you'd watch on; it connects, exercises a plane, and reports numbers. If you want to
actually stream, use the Linux, Windows,
Apple, or Android clients.
Because it links the same punktfunk-core as every other client, it's also the canonical
example of driving the protocol end to end: QUIC control plane, UDP data plane, and the side planes
(input, audio, rumble) over QUIC datagrams.
What it does
- Receives a real stream, writes a playable elementary stream (
.h265/.h264/.av1— the extension tracks the negotiated codec; the probe advertises all three and the host picks), and reports per-frame capture→received latency percentiles (the host stamps each frame with its capture clock). - Verification mode against a synthetic host — byte-checks deterministic test frames.
- Exercises every plane with scripted test traffic:
--input-test(mouse/keyboard),--mic-test(a 440 Hz Opus tone up to the host mic),--touch-test(a synthetic finger),--rich-input-test(DualSense touchpad + motion, logging the HID-output feedback that comes back). - Trust —
--pin <64-hex>pins the host fingerprint;--pair <PIN>runs the SPAKE2 pairing ceremony and prints the verified fingerprint to pin from then on. Without a pin it trusts on first use. - Discovery —
--discover [secs]browses the LAN for_punktfunk._udphosts and prints each (name, addr:port, pairing requirement, cert fingerprint), then exits. - Negotiation knobs —
--mode WxHxFPS,--remode(mid-stream mode change),--bitrate,--codec auto|h264|hevc|av1(preference; the host resolves),--audio-channels(stereo / 5.1 / 7.1),--compositor,--gamepad,--launch,--speed-test. Env:PUNKTFUNK_CLIENT_10BIT=1/PUNKTFUNK_CLIENT_444=1advertise the 10-bit / 4:4:4 client caps (for testing a host'sPUNKTFUNK_10BIT/PUNKTFUNK_444).
Usage
# stream 720p120 from a host, save the video, and print latency percentiles:
cargo run -p punktfunk-probe -- --mode 1280x720x120 --connect HOST:PORT --out /tmp/a.h265
# list hosts on the LAN:
cargo run -p punktfunk-probe -- --discover
# pair with a host that requires it (read the PIN off the host), then stream:
cargo run -p punktfunk-probe -- --connect HOST:PORT --pair 1234
cargo run -p punktfunk-probe -- --connect HOST:PORT --pin <64-hex> --input-test
Full flag reference is in the module doc-comment at the top of src/main.rs.
Related
- Project README — the host, the streaming clients, and the protocol
punktfunk-host punktfunk1-host— the persistent native-protocol listener to probe against (see the "Running on this box" section of the repo README /CLAUDE.md)