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punktfunk/clients/apple
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fix(client/apple): stop dropping rotation, and stop inventing it
G13 — the three capture-fidelity findings from the gyro sweep, two fixed and one
argued.

**The 4 ms floor was a DROP, and it was shedding real rotation.** A sample arriving
3.9 ms after the last one was discarded outright. That is the wrong shape for this
signal: buttons and sticks are absolute state, so a dropped frame costs nothing — the
next one says everything it would have. Angular velocity is a RATE, and a consumer
integrates it into an angle, so a dropped sample is rotation that happened and can never
be recovered. GameController's delivery jitters around the pad's own ~250 Hz, so a floor
set AT that rate does not shed a rare extra sample; it sheds a steady fraction of every
turn. And the error is one-signed, so it accumulates — aim drifting short, which reads
as bad sensitivity rather than as a bug.

Nothing needed the ceiling. GC delivers at the sensor's rate rather than faster, the SDL
client has always forwarded every sample, and the host's idle watchdog is a 100 ms
timeout this cannot outpace. The throttle's two fields went with it: `lastMotionNs` was
left set-but-never-read once the guard was gone, and `motionIntervalNs` had no other
consumer. (Notes elsewhere say `flush` parks motion and reads it — that is PR #88's
branch, not this one. Checked rather than assumed.)

**An X-Box pad was streaming gyro it does not have.** Capture attached to any `GCMotion`,
and an X-Box controller exposes one that reports gravity and NOTHING else. So the client
sent a permanently-zero `rotationRate` to the host as authoritative gyro, under a
declaration saying this pad has one. That is worse than having no motion plane at all: a
game sees a controller being held perfectly still forever, and there is nothing to fall
back to and nothing to notice. Now gated on `hasRotationRate`, which is GameController's
own answer to the question we actually mean.

The settings badge had the same bug from the same cause — `hasMotion` was
`motion != nil`, so an X-Box pad got a gyroscope icon. It now reads `hasRotationRate`
too. One wrong predicate was driving both the UI promise and the wire behaviour, which is
why they were wrong together.

That also simplifies G8's "your gyro can't reach this session" notice, which had to test
`hasRotationRate` itself to avoid nagging about a gyro the pad never had. With the attach
gated on it, the notice is just the else-branch.

**Motion stays on the main queue, and this is the argument for why.** GameController's
`handlerQueue` is a property of the CONTROLLER, not of an element, so moving motion off
main moves buttons, sticks, the touchpad and the escape chord with it. This class is
`@MainActor` throughout — eight `assumeIsolated` sites, the slot table, the gesture
timers — so that is a rewrite of the isolation model rather than a queue assignment, and
it would put the tvOS escape chord (the only controller way out of a stream there) on a
background queue. That is a real risk for a speculative gain. The comment says so at the
call site, and names the measurement to make first if it ever does bite: the host's
per-pad motion inter-arrival histogram already reports exactly this and would say whether
the delay is client-side or on the wire.

Gate: macOS `swift build` + the full suite (215 tests, 5 skipped, 0 failures) and the
iOS-triple typecheck green. No test pins the throttle removal or the capability gate:
both are properties of live `GCMotion` delivery, which this module cannot fake — there is
no injectable seam, and inventing one to assert "we called sendMotion twice" would test
the mock. They are argued at the call sites instead, in the same spirit as the parts of
`DsCapture` that are not unit-testable in their module either. On-glass verification is
owed with the two already outstanding on that rig.
2026-08-07 19:12:02 +02:00
..

punktfunk — Apple client (macOS · iOS · iPadOS · tvOS)

The native Apple app for streaming a punktfunk host to your Mac, iPhone, iPad, or Apple TV. A SwiftUI app that finds hosts on your network, pairs with a PIN, and streams at your display's own resolution and refresh rate — with VideoToolbox hardware decode and full controller support.

All the networking and protocol work — QUIC control plane, UDP data plane, GF(2¹⁶) FEC, AES-GCM, Opus audio, cert pinning — lives in the shared Rust punktfunk-core (statically linked as PunktfunkCore.xcframework). This package is the Swift shell: decode, present, input, and UI.

Features

  • Hardware decode — VideoToolbox H.264/HEVC (plus AV1 on devices with an AV1 hardware decoder — M3-class Macs, A17 Pro-class iPhones), with a low-latency stage-2 presenter (VTDecompressionSessionCAMetalLayer, presented off a CADisplayLink, ~11 ms p50) as the default and an AVSampleBufferDisplayLayer fallback.
  • HDR & 4:4:4 — PQ passthrough with a correct reference-white anchor, mid-session SDR↔HDR reconfiguration, and hardware-probed 4:4:4 support.
  • Your display's native mode — the host builds a virtual output at exactly your WxH@Hz; mid-stream resize renegotiates without reconnecting.
  • Audio both ways — Opus playback (CoreAudio, no bundled libopus) with a jitter ring, plus mic uplink; speaker/mic selectable in Settings.
  • Full controller support — one selected controller forwarded as pad 0, including DualSense feedback (rumble → CoreHaptics, lightbar, player LEDs, adaptive triggers) and touchpad/motion. The virtual pad type auto-resolves from your physical controller.
  • Mouse & keyboardGCMouse/GCKeyboard capture with click-to-capture and a ⌃⌥⇧Q release (the cross-client Ctrl+Alt+Shift+Q; ⌘⎋ still works as the macOS/iPad toggle), plus iPad pointer lock and touch input.
  • Find hosts automatically — mDNS discovery (NWBrowser over _punktfunk._udp); first connect does a one-time SPAKE2 PIN pairing (or TOFU on trusted LANs), then reconnects on a pinned, Keychain-stored identity.
  • Tune the stream — a fps / Mb·s / latency HUD (skew-corrected across machines), a bitrate control, a per-host network speed test with a recommended bitrate, and a host-compositor picker.

Runs from one shared codebase across macOS, iOS, iPadOS, and tvOS.

Get it

Install from the App Store / TestFlight, or build from source below. Per-device install steps and the pairing walkthrough: docs.punktfunk.unom.io/docs/install-client.

Build / run / test (on a Mac)

Requires Xcode 26.5 / Swift 6.3. First build the Rust core into an xcframework, then build the app:

rustup target add aarch64-apple-darwin x86_64-apple-darwin
bash scripts/build-xcframework.sh            # → clients/apple/PunktfunkCore.xcframework
#   BUILD_IOS=1  also builds the iOS slices  (add the ios rustup targets)
#   BUILD_TVOS=1 also builds tvOS            (tier-3 targets, built from source — see below)

cd clients/apple
open Punktfunk.xcodeproj                      # the real app: ⌘R builds + runs Punktfunk.app
swift run PunktfunkClient                     # or the unbundled dev shell (CLI)
swift build && swift test                     # unit + loopback/remote tests (self-skip w/o a host)

tvOS slices are tier-3 Rust targets, built from source: rustup toolchain install nightly && rustup component add rust-src --toolchain nightly.

Test against a host

# full loopback proof — builds punktfunk-host (synthetic source, runs on macOS) and streams
# byte-verified frames into the Swift client, incl. the PIN pairing ceremony:
bash test-loopback.sh

# against a real Linux host on the LAN (see the repo README "Running on this box"):
PUNKTFUNK_REMOTE_HOST=<box-ip> swift test --filter RemoteFirstLightTests            # headless
PUNKTFUNK_AUTOCONNECT=<box-ip> PUNKTFUNK_MODE=1280x720x60 swift run PunktfunkClient # on glass

Project layout

  • PunktfunkKit (library) — the reusable pieces:
    • PunktfunkConnection — the wrapper over the C ABI (thread-safe close(), per-plane locks, pinning + TOFU).
    • AnnexB / StreamView / VideoDecoder / MetalVideoPresenter — format handling, the stage-1 (AVSampleBufferDisplayLayer) and stage-2 (VTDecompressionSessionCAMetalLayer) presenters.
    • InputCaptureGCMouse/GCKeyboard → host VK/mouse, with fractional-delta accumulation.
    • GamepadManager / GamepadCapture / GamepadFeedback / DualSenseTriggerEffect — controller discovery + selection, capture (buttons/axes/touchpad/motion), and host-feedback rendering.
    • HostDiscoveryNWBrowser over _punktfunk._udp.
  • PunktfunkClient (the app) — hosts grid with an On this network section, add-host sheet, the two trust flows (TOFU prompt + SPAKE2 PairSheet), the stream view with the HUD, a tabbed Settings pane (General / Display / Audio / Controllers / Advanced), and the network speed test. A Scene-level Stream menu carries the cross-client shortcut set: Release Mouse (⌃⌥⇧Q), Disconnect (⌃⌥⇧D) and the HUD toggle (⌃⌥⇧S) — the same Ctrl+Alt+Shift combos the Windows and Linux clients reserve, also shown on a 6-second banner at stream start. On iOS/iPadOS and macOS a connected controller swaps the whole home for the gamepad UI (Home/Gamepad*, Settings/GamepadSettingsView): a console-style host carousel (A connect · Y library · X settings), a controller-navigable settings screen, an add-host flow with an on-screen controller keyboard (no touch required anywhere), and the coverflow library browser — all driven by the shared GamepadMenuInput poller + GamepadCarousel/GamepadMenuList focus machinery, with dual-channel haptics (device Taptic + controller MenuHaptics), over an animated "aurora" backdrop (GamepadScreenBackground — TimelineView-driven drifting color blobs; deliberately pure SwiftUI, since a .metal library only reliably bundles in one of the two build systems these sources compile under). macOS presents the settings/add-host screens as sheets (no fullScreenCover there); PUNKTFUNK_FORCE_GAMEPAD_UI=1 forces the mode without a physical pad (dev/screenshots).
  • Tests (swift test) — Annex-B units, a real-codec VideoToolbox round trip, DualSense trigger-effect and gamepad-wire conversions, loopback integration against real local hosts, and the remote first-light test.

Notes for contributors

  • Xcode project (Punktfunk.xcodeproj) wraps the same sources as the swift run shell (a synchronized folder — no duplication). The macOS target is App-Sandboxed (needs network.server — the raw-UDP plane and quinn both bind()); iOS/tvOS use the shared entitlements file (keep app-sandbox out of it). Verify with codesign -d --entitlements :- <built .app>.
  • Decode flow: the host opens every stream with an IDR carrying VPS/SPS/PPS in-band, and recovery keyframes re-send them — refresh the format description on every IDR; there is no out-of-band extradata, ever.
  • ABI threading: one video pump thread per connection, one optional audio drain thread, and one optional feedback drain thread (rumble + HID-output). send() is enqueue-only and safe alongside all of them. The wrapper's per-plane locks make close() safe from anywhere.
  • DualSense motion scale (GamepadWire) is derived from hid-playstation's math, not yet live-verified — if gyro/accel feel wrong in a game, correct sign/scale there and evtest the host's virtual pad.
  • App Store screenshots are automated — tools/screenshots.sh all renders the real UI at the required pixel sizes via a DEBUG-only shot mode; the apple CI workflow captures the iOS sizes on every main push. See the script header for details. The script's SCENES array is the listing set, in listing order; override it (SCENES="06-gamepad-home 10-edithost" tools/screenshots.sh ios) to capture any of the other scenes in ShotScenes.all. Mock data — hosts, adverts, profiles — is seeded in ShotMock so a capture is byte-for-byte deterministic and never browses the real LAN (a stranger's hostname reached the live listing that way once).
  • Deeper design notes live in the internal planning repo (punktfunk-planning: apple-stage2-presenter.md).