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punktfunk/clients/android
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fix(client/android): a Bluetooth pad's gyro obeys the same reachability gate as the rest
Follow-up to the G10 merge. The new sensor path was written against main, which does not
carry this branch's G8 work, so it forwarded motion unconditionally — the one thing G8
exists to stop.

`deviceMotion` checked `forwarding` and nothing else. A Bluetooth DualSense in a session
that resolved to an X-Box backend would stream ~200 Hz of samples the host parses and
discards, for the whole session, exactly as the USB capture path did before G8. Not a
regression against shipped behaviour — the path is new — but it would have shipped the
defect back into a client that had just been taught not to have it.

`Slot` now carries `motionReaches`, asked once at open off the kind that pad DECLARED, in
the same shape `ExternalPad` already used. Per pad, not per session: under Automatic the
handshake carries the active pad's kind, so a couch with an X-Box pad on slot 0 and a
DualSense on slot 1 must not have slot 1's working gyro suppressed by slot 0's answer.

The notice moved to where the truth is known. `openSlot` knows only what kind a pad
declared, not whether it physically has a gyro — that is discovered later, when
`PadSensors` finds a gyroscope and calls `setDeviceHasSensorMotion`. Raising it there is
the only placement that both tells a player whose gyro is being dropped and stays silent
for the pads that never had one.

Also unified the last duplicate scale in the module. G10 hoisted the wire units into
`Gamepad` and pointed `DeviceGyro` at them, but `DsDevice` kept its own `20L` / `10000L`
— and `Gamepad`'s new comment claims every sender goes through one place, which was not
yet true. Two copies of a unit constant in one module is precisely the defect this program
opened with (a DualShock 4 blob 40× hot because a second copy had drifted), so the claim
and the code now agree. `val` rather than `const val` only because widening to Long is not
a constant expression; Long is deliberate, since the calibration arithmetic overflows an
Int before it divides.

Proven non-vacuous rather than assumed: changing `Gamepad.MOTION_GYRO_LSB_PER_DEG_S` from
20 to 16 now fails four named cases across three classes —
`DsDeviceTest.calibrationRescalesRawCountsOntoTheWireUnits`,
`.theHostsOwnBlobIsAPassthrough`, `.parseStateAppliesTheCalibration` and
`DeviceGyroTest.wireUnitConstants`. Before this change `DsDevice` would not have noticed.

The gate itself has no test, for the reason the surrounding code already documents:
`GamepadRouter` needs Android plus a live JNI handle, there is no Robolectric in this
module, and a mock would test the mock. It is argued at the call sites instead.

Gate: `:kit:compileDebugKotlin`, `:kit:testDebugUnitTest`, `:app:compileDebugKotlin`,
`:app:testDebugUnitTest` — kit 75 / app 67, 0 failures, counts read out of the JUnit XML.
The merge reconciles: 62 on this branch, plus 6 from main's DeviceGyroTest, plus G10's 7.
2026-08-07 20:18:39 +02:00
..

punktfunk — Android client (phone & TV)

The native Android app for streaming a punktfunk host to your phone, tablet, or Android TV. A Compose app that finds hosts on your network, pairs with a PIN, and streams at the display's own resolution — with hardware HEVC decode, HDR10, and controller support, built for both touch and the couch (D-pad / gamepad focus navigation).

Features

  • Hardware decode — NDK AMediaCodec HEVC → SurfaceView, including HDR10 (Main10 / BT.2020 PQ), with low-latency tuning and a live stats HUD.
  • Audio both ways — Opus + AAudio playback with a jitter ring, plus mic uplink to the host.
  • Controller support — buttons + axes with rumble and HID feedback (lightbar / adaptive triggers); D-pad / gamepad focus navigation for TV and phone.
  • Find hosts automatically — native mDNS discovery; first connect does a one-time SPAKE2 PIN pairing (or TOFU on trusted LANs), then reconnects on a Keystore-wrapped, pinned identity.
  • Compose UI — Connect / Settings / Stream screens with Material You theming.

Built for arm64-v8a + armeabi-v7a + x86_64 — the 32-bit armeabi-v7a slice is what keeps the app installable on the many 32-bit Google TV / Android TV streamers (Walmart onn. 4K, Chromecast with Google TV, budget Amlogic boxes) that otherwise reject a 64-bit-only build as "not compatible".

Get it

Published to Google Play (Internal Testing) — join the beta via the Discord. Per-device setup and pairing: docs.punktfunk.unom.io/docs/install-client.

How it's built — Rust-heavy

Kotlin can't import the cbindgen C header the way Swift can, so a native bridge is unavoidable. We write it in Rust and link punktfunk-core directly — so the Android client reuses the Linux client's orchestration (audio jitter ring, VK keymap inverse, latency/skew math, capture state machine, trust logic) instead of re-porting it into Kotlin.

Side Owns
Rust (native/libpunktfunk_android.so) the JNI seam, NativeClient (QUIC control + UDP data plane), AnnexB → AMediaCodec decode (incl. HDR10), Opus + AAudio audio + mic, controller feedback, latency math, trust/pairing, mdns-sd discovery
Kotlin (app/, kit/) Compose UI, SurfaceView lifecycle, input capture, the Wi-Fi MulticastLock + permission UX, Keystore identity

The single seam is io.unom.punktfunk.kit.NativeBridgeJava_io_unom_punktfunk_kit_NativeBridge_*.

native/           Rust cdylib (workspace member) — links punktfunk-core directly
  src/lib.rs        crate doc · JNI_OnLoad · version probes
  src/session/      session lifecycle: connect/pair + trust, plane start/stop, input shims
  src/decode.rs     AnnexB → AMediaCodec HEVC hardware decode → SurfaceView (incl. HDR10)
  src/audio.rs · src/mic.rs   Opus + AAudio playback / mic uplink
  src/feedback.rs · src/stats.rs   rumble + HID feedback; live video stats
  src/discovery.rs  native mdns-sd browse of the host's _punktfunk._udp advert
app/              :app — Compose UI: Connect / Settings / Stream (phone + TV)
kit/              :kit — NativeBridge · native mDNS discovery · Gamepad · Keymap · Keystore identity

Build & run

Prerequisites: Android SDK + NDK r30 (30.0.14904198), platforms;android-37.0, build-tools;37.0.0, cmake;3.22.1 (builds libopus); JDK 21 (AGP 9.2 runs on JDK 1721, not a newer default); Rust with rustup target add aarch64-linux-android armv7-linux-androideabi x86_64-linux-android and cargo install cargo-ndk. Toolchain is pinned (AGP 9.2 · Gradle 9.4.1 · Kotlin 2.3.21 · Compose BOM 2026.05.01 · compileSdk 37 · minSdk 28).

Android Studio: open clients/android — it uses its bundled JBR 21, and the cargoNdk* task builds the .so as part of the normal build.

CLI (point Gradle at JDK 21 if your machine default is newer):

export JAVA_HOME="$(/usr/libexec/java_home -v 21)"   # or your Temurin 21 path
cd clients/android
./gradlew :app:assembleDebug     # cargo-ndk cross-compiles libpunktfunk_android.so first
./gradlew :app:installDebug      # onto a running emulator/device
# emulators from env setup:  emulator -avd pf_phone   |   emulator -avd pf_tv

The debug APK lands in app/build/outputs/apk/debug/. Launch it, pick a host, pair, and stream.