enricobuehler
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`ci.yml` runs `cargo clippy --workspace` on the HOST, where `clients/android/native` and every `#[cfg(target_os = "android")]` module elsewhere compile out, and `android.yml` only ever built. So the Android target was never linted at all — not once. Five lints were sitting in clients/android/native when this was noticed, in code no gate had ever read. The gate is a Gradle task rather than a YAML step because cargo-ndk needs a specific discovery environment (NDK sysroot, SDK cmake 3.22.1 for libopus, `LIBOPUS_STATIC`, Ninja) and duplicating it into the workflow would let the lint drift from the build — a lint that ran against a different toolchain is a lint about a different program. `registerCargoNdkClippy` reuses the build task's environment verbatim via the extracted `cargoNdkEnvironment`, so local and CI runs are the same invocation. It lints BOTH pointer widths, and that is load-bearing rather than thorough: arm64-v8a is 64-bit and armeabi-v7a is 32-bit, so a cast that is redundant on one can be required on the other. Linting only the primary ABI would license "fixes" that break the 32-bit build — the shipping ABI for the many 32-bit Google TV / Android TV boxes this client targets. x86_64 is skipped: it is emulator-only and shares its width with arm64, so it costs lint time for no signal the other two do not already carry. The five resident lints: * `audio.rs` / `mic.rs` `type_complexity` — the open-attempt closures now return named `OpenedPlayback` / `OpenedCapture` aliases. The two tuples are mirror images of each other (playback sends, capture receives), which the aliases now say out loud. * `vsync.rs` ×2 `unnecessary_cast` — **not** taken. `timespec`'s fields are 32-bit on armv7 and 64-bit on arm64, so the casts are REQUIRED on one shipping ABI and redundant on the other; following the suggestion would break the 32-bit build. `i64::from`/`.into()` do not escape it either, they trade `unnecessary_cast` for `useless_conversion` on the 64-bit side. Answered with a documented `#[allow]` at the expression instead of in whichever build breaks first. * `pad_audio.rs` `needless_range_loop` — iterator form, preserving the `channels < 2` no-op the range had. Verified: `:kit:cargoNdkClippy` green on both ABIs, host-lane clippy for the crate still clean, `cargo fmt --all --check` clean. The gate was proven non-vacuous by planting `1i32 as i32` in an android-only module and confirming it fails the task, then reverting.
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