enricobuehler
8f1081719f
Android had two motion sources and both of them are USB claims. DsCapture takes a Sony pad's HID interface away from the kernel; Sc2Capture does the same for a Steam Controller 2. Everything else — a DualSense, a DualShock 4, a Switch Pro, an 8BitDo, paired over Bluetooth — arrives as an ordinary InputDevice. Its buttons worked, its sticks worked, and its gyro was dead, silently, with no log line and nothing in the UI to suggest the pad had a sensor at all. That is not one controller, it is the whole class of controllers people actually pair to a phone. The platform has had the answer since Android 12: InputDevice.getSensorManager hands back a SensorManager scoped to that one controller, carrying its TYPE_GYROSCOPE and TYPE_ACCELEROMETER. PadSensors registers a listener per forwarded pad that has a gyroscope and sends the samples on that pad's wire index. Below API 31 it registers nothing and the pads behave exactly as they did. It is built on DeviceGyro's shape, because the phone mirror had already paid for these lessons. One dedicated HandlerThread, never the main one. Batching off (maxReportLatencyUs = 0) — batching would trade away precisely the latency gyro aim exists to avoid. 200 Hz requested, which is also the ceiling the framework grants an app without HIGH_SAMPLING_RATE_SENSORS, so asking for more would only be capped. And a feed that lets go of a pad still alive parks its rotation at zero first: the host holds motion as state and re-emits it in every virtual-pad report, so an angular velocity left behind is a pad that rotates forever. Two writers on one pad's motion is the failure this program has spent the day unpicking, so the coordination is explicit in three places. A USB capture wins: DsCapture.startUsb already calls releaseDevice at claim time, that closes the slot, and the close now also takes the sensor listeners off — the claim makes the InputDevice vanish anyway, but going through the explicit teardown is what makes the ordering deterministic instead of a race against the platform's own removal callback. The phone-gyro mirror stands down: registering flips a bit the router reports through padHasOwnMotion, which DeviceGyro re-reads on every sample and answers with its own zero park. And a pad with an accelerometer but no gyroscope is deliberately NOT taken — it could only send gravity while pinning rotation at zero, on a pad the mirror is otherwise entitled to speak for, which is the same fight in a quieter costume. The wire units are measured fact (punktfunk_core::input::gamepad: 20 LSB/deg·s, 10000 LSB/g), and they now live in exactly one place on this client: Gamepad.motionGyroWire / motionAccelWire, which DeviceGyro was hand-inlining a second copy of. The gyro program's first finding was a client sending 40x hot because a second copy of a number had drifted, and the merge that followed found a sender nobody remembered to correct. One function, both callers. THE AXIS FRAME ON THIS PATH IS NOT VERIFIED, and the mapping is deliberately straight through rather than guessed at. What is known: the wire is a unit passthrough into a virtual DualSense report, and that report's frame was measured over raw HID on 2026-08-07 as (Right, Up, Backward-toward-the-player) carrying (pitch, yaw, roll), right-handed — which is why the USB path forwards the pad's own order un-remapped and is correct to. Android documents its sensor frame for a handheld device as +x right, +y up, +z out of the face, the same frame once "the face" is read as the one the player looks at. So straight through is what the documentation implies. What nobody has done is put a Bluetooth DualSense in front of the platform sensor framework and compare — those numbers come through a HID driver and InputFlinger's sensor mapper, either of which could permute or negate without saying so. A plausible-looking wrong remap is exactly the bug this program keeps finding, so the code says unverified and names the measurement that settles it, and each feed logs its first converted sample so the cheapest half of that measurement — which slot gravity lands on with the pad flat and still — costs a logcat line. PadSensorsTest pins the scale, the clamp, the rounding and the straight-through order, mutation-checked four ways: 20 to 16 fails gyroScaleFromRadiansPerSecond and straightThroughFrame, reversing the axis order fails straightThroughFrame, truncating instead of rounding fails roundsToNearestNotTowardZero, and negating the accel fails restingPadIsTheHostNeutral. Its frame expectations are written to change together with any remap that lands, not to be edited around one. GamepadRouter needs Android and a live JNI handle and there is no Robolectric here, so its half is argued in comments beside the code, as DsCapture's claim ordering already is. Gates: kit 65 tests (58 before, plus 7), app 67 unchanged, 0 failures, read out of the JUnit XML rather than off a green build.
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
AMediaCodecHEVC →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.NativeBridge ⇄ Java_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 17–21, 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.
Related
- Documentation — quick start, pairing, troubleshooting
- Project README — the host, the other clients, and how it all fits together