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punktfunk/clients/android
enricobuehlerandClaude Fable 5 759aac255b
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feat(phase-lock): controller v3 — grid-locked submits, arrival sensing, antipode damping
Midday on-glass falsified v2's remaining assumptions: a per-frame additive
hold SATURATES the arrival-slaved loop once hold + work >= interval — submits
free-run at their own cadence and the commanded phase dissolves (measured:
+-2 ms hold steps, zero client response) — and the latch statistic hovers at
the target's ANTIPODE, where shortest-way errors sign-flip on noise (the
0<->2<->4 ms offset chatter).

v3, one change per falsified assumption:
- ACTUATOR: submits lock to an absolute grid (epoch + k x period + offset);
  the controller walks only the offset. A periodic grid cannot free-run —
  occupancy is one frame per period whatever the offset — so phase actuation
  is linear BY CONSTRUCTION. Disengaged = no grid sleeps = zero cost; every
  failure path DISENGAGES (never parks: v2's e2e-tax lesson).
- SENSOR: the client reports the circular mean + coherence of the ARRIVAL
  lead (per-AU reassembly stamps vs the panel latch grid) — the phase the
  host actually controls; latch measured downstream of the decoder pipeline,
  which absorbed the actuation. pf.phase logs "arrival lead circ= coh=".
- ANTIPODE DAMPING: errors within 1 ms of +-period/2 take half-steps until
  they commit to a side.

Harness rewritten around plants glass validated: a GRID plant (linear by
construction), the DECOUPLED plant (v2's saturation — must disengage, not
orbit or park), an antipode start (must converge within one period of
travel), incoherence (never engages), a regime change (re-engages after
backoff), and the actuator's own periodicity/offset-linearity. Also fixes
the harness's SIM_TARGET (a mis-derived max asserted 3.5 ms where the
controller's actual target is 2.5 — the controller was right, the ruler
was wrong; the Python cross-check inherited the same constant, a lesson in
replicating the CODE, not the author's belief about it).

Gates: v3 simulations 6/6; host bin suite 345/1 (the documented
environmental qemu UDP test); clippy --all-targets -D warnings clean;
cargo ndk arm64 check clean.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-31 12:20:39 +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.