enricobuehler
55cd58e487
ndk's DataSpace derives Copy/PartialEq/Eq and impls Display (no Debug), so the
{ds:?} in the HDR dataspace log statements wouldn't compile under cargo-ndk.
Host clippy can't catch it — decode.rs is android-gated. Switch to {ds}.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
punktfunk Android client
Native Android client for punktfunk/1, targeting phone + TV (Compose, D-pad + touch).
Architecture — Rust-heavy (like the Linux client, not thin-native like Apple)
Kotlin cannot 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 (clients/android/native → libpunktfunk_android.so) |
the JNI seam, NativeClient (QUIC control + UDP data plane), AnnexB→AMediaCodec decode, Opus+Oboe audio, VK keymap, latency math, trust/pairing |
Kotlin (clients/android) |
Compose UI (host grid / settings / stream), SurfaceView lifecycle, input capture, NsdManager discovery, Keystore identity, permissions |
The single seam is io.unom.punktfunk.kit.NativeBridge ⇄ Java_io_unom_punktfunk_kit_NativeBridge_*.
Layout
clients/android/native/ Rust cdylib (workspace member)
src/lib.rs JNI_OnLoad + abiVersion/coreVersion (native-link proof)
src/session.rs session handle lifecycle (connect/close); plane pumps = TODO
clients/android/ Gradle project (this dir)
settings.gradle.kts · build.gradle.kts · gradle.properties · gradlew
app/ :app — Compose application (MainActivity)
kit/ :kit — Android library: NativeBridge + the cargo-ndk build
build.gradle.kts cargoNdk{Debug,Release} → src/main/jniLibs/<abi>/*.so
Prerequisites (already set up on the dev Mac)
- Android SDK + NDK r30 (
30.0.14904198),platforms;android-37.0,build-tools;37.0.0 - JDK 21 for Gradle/AGP (the machine default JDK 25 is too new for AGP 9.2)
- Rust +
rustup target add aarch64-linux-android x86_64-linux-android+cargo install cargo-ndk
Toolchain pinned: AGP 9.2.0 · Gradle 9.4.1 · Kotlin 2.3.21 · Compose BOM 2026.05.01 · compileSdk 37 · targetSdk 36 · minSdk 31 · ABIs arm64-v8a + x86_64.
Build & run
Android Studio: open clients/android — it uses its bundled JBR 21 automatically. The
cargoNdk* task builds the .so as part of the normal build.
CLI (the machine default is JDK 25, so point Gradle at JDK 21):
export JAVA_HOME="$(brew --prefix openjdk@21)/libexec/openjdk.jdk/Contents/Home"
cd clients/android
./gradlew :app:assembleDebug # cargo-ndk cross-compiles libpunktfunk_android.so first
./gradlew :app:installDebug # onto a running emulator/device
# Emulators (created during env setup): emulator -avd pf_phone | emulator -avd pf_tv
The debug APK lands in app/build/outputs/apk/debug/. The scaffold screen calls
NativeBridge.abiVersion() across JNI — a live ABI version proves the whole native stack is wired.
Status
- Scaffold (done): Gradle modules, cargo-ndk wiring, JNI native-link proof, phone+TV-installable
manifest.
crates/punktfunk-corercgenswitched to theringbackend so the client.sois aws-lc-free. - Next (Android stage 1): video decode (
AMediaCodecasync →SurfaceView), audio (Opus + Oboe + jitter ring), input capture →send_input, pairing/identity (Keystore-wrapped), mDNS discovery, the phone/TV Compose UI. The Rust-side homes are stubbed inclients/android/native/src/session.rswith port pointers toclients/linux.