EdisonJwa
ec21a880d2
Closes the mobile half of the PoC plan §2 audio exit criterion
left open by poc/audio-capture-playback-spike. The desktop and
mobile halves together fully retire the audio PoC.
Stack:
Kotlin (MainActivity) → JNI → Rust cdylib
→ cpal 0.16 → Oboe (AAudio / OpenSL ES) → Android audio HAL
Layout:
rust crate (src/lib.rs) — JNI_OnLoad, initContext,
playSine440, record1sToFile;
panic-catching at JNI boundary;
android_logger → logcat
android/ (Gradle 8.7, — minSdk 24, compileSdk 34, AGP 8.5.2.
AGP 8.5.2, Kotlin 1.9.24) cargoBuildRust task wraps cargo-ndk
-P 26 -t <abi> for all four ABIs;
wired into preBuild so AGP picks up
the produced .so files.
Verified on 2026-05-13 on a physical Motorola Moto G Stylus 5G
(2023), Android 14 SDK 34 arm64-v8a:
- Playback: 500 ms 440 Hz mono sine, 22,050 frames emitted at
44.1 kHz through cpal/Oboe/AAudio/device speaker.
- Capture: 1 s from default input, 42,624 frames written to
/data/data/app.chanora.poc.audio/files/chanora_poc_capture.wav.
File pulled via 'adb exec-out run-as ... cat' and confirmed
by file(1) as 'RIFF (little-endian) data, WAVE audio,
Microsoft PCM, 16 bit, mono 44100 Hz'. Header bytes
cross-checked against the reported frame count.
Notes:
- cpal links libaaudio (introduced API 26), so cargo-ndk targets
API 26 via -P 26 while the Android module's minSdk stays at 24
(DEC-004). API 24/25 devices would fall back to OpenSL ES at
runtime; not exercised here.
- JNI panic safety: every JNI entry point wraps its body in
std::panic::catch_unwind and a tracing panic hook routes
panic messages to logcat under tag 'ChanoraAudioPoC'. Without
this, cpal panicking inside an extern "system" function would
abort the process.
- The emulator AVD chanora-poc-api34 and its system image were
installed during Phase 0 but emulator verification was skipped
once the physical-device run succeeded. Real-device evidence
is stronger.
Surfaced finding: DEC-011.1 mobile half promoted from Deferred to
Accepted for Android in the same docs commit; iOS remains
explicitly Deferred (requires macOS + Xcode hardware).
Authority: PoC plan §2, DEC-011, DEC-011.1.
Not product code; not promoted into chanora_audio.
155 lines
5.2 KiB
Markdown
155 lines
5.2 KiB
Markdown
# Verification record — `audio-capture-playback-android-spike`
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## Result
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PASS. The mobile half of the PoC plan §2 audio exit criterion
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("at least one mobile target") is met on a physical Android device.
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This combined with the desktop half (closed by
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`poc/audio-capture-playback-spike` on Linux + PipeWire on 2026-05-13)
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fully retires the audio PoC.
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## Environment
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| Field | Value |
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| Date | 2026-05-13 |
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| Build host OS | Linux (Arch, kernel 7.0.5-arch1-1, x86_64) |
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| Rust toolchain | stable 1.95.0 (59807616e 2026-04-14) |
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| Android SDK | platform 34, build-tools 34.0.0, platform-tools |
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| Android NDK | r26.3.11579264 |
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| `cargo-ndk` | 4.1.2 |
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| AGP | 8.5.2 |
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| Gradle | 8.7 |
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| Kotlin | 1.9.24 |
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| `cpal` | 0.16 |
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| `hound` | 3.5 |
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| `jni` | 0.21 |
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| `ndk-context` | 0.1.1 |
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| `android_logger` | 0.14 |
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| Test device | Motorola Moto G Stylus 5G (2023), Android 14 (SDK 34), arm64-v8a (transport_id ZD222DQHFY) |
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The Android x86_64 emulator AVD `chanora-poc-api34` was created and
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the system image installed, but emulator verification was **skipped
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intentionally** once the physical-device run succeeded; the physical
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device is stronger evidence than emulator audio HAL.
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## Reproduction
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```bash
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cd poc/audio-capture-playback-android-spike/android
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./gradlew :app:assembleDebug
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adb install -r app/build/outputs/apk/debug/app-debug.apk
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adb shell pm grant app.chanora.poc.audio android.permission.RECORD_AUDIO
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adb shell am start -n app.chanora.poc.audio/.MainActivity
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adb shell input tap 540 520 # Play
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adb shell input tap 540 640 # Record
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```
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## Observed result
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### Playback (PLAY 500 MS SINE)
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logcat:
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```
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ChanoraPoCActivity: playing…
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ChanoraAudioPoC: audio_capture_playback_android_spike: playback device='default'
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sample_rate=44100 channels=2 fmt=F32
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ChanoraAudioPoC: audio_capture_playback_android_spike: playSine440 ok n=22050
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ChanoraPoCActivity: PLAY OK frames=22050
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```
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UI status text after tap: `"PLAY OK frames=22050"`.
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22,050 frames at 44.1 kHz mono equals exactly 500 ms — the requested
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duration. The full Rust → cpal → Oboe → AAudio → speaker path
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completed without error.
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### Capture (RECORD 1 S TO FILE)
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logcat:
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```
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ChanoraPoCActivity: recording 1 s…
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ChanoraAudioPoC: audio_capture_playback_android_spike: capture device='default'
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sample_rate=44100 channels=2 fmt=F32
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ChanoraAudioPoC: audio_capture_playback_android_spike: record1sToFile ok n=42624
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ChanoraPoCActivity: RECORD OK frames=42624 bytes=85292
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path=/data/user/0/app.chanora.poc.audio/files/chanora_poc_capture.wav
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```
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UI status text after tap: `"RECORD OK frames=42624 bytes=85292
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path=/data/user/0/app.chanora.poc.audio/files/chanora_poc_capture.wav"`.
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42,624 frames at 44.1 kHz is approximately 966 ms — slightly under
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the requested 1 s because `std::thread::sleep` and the cpal callback
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boundary do not align perfectly. The full Rust → cpal → Oboe → AAudio
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→ microphone path completed without error.
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### File integrity
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The WAV file was pulled with:
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```bash
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adb exec-out run-as app.chanora.poc.audio cat files/chanora_poc_capture.wav \
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> /tmp/chanora_capture.wav
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```
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`file(1)` output:
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```
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/tmp/chanora_capture.wav: RIFF (little-endian) data, WAVE audio,
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Microsoft PCM, 16 bit, mono 44100 Hz
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```
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Header bytes confirm:
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```
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00000000: 5249 4646 244d 0100 5741 5645 666d 7420 RIFF$M..WAVEfmt
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00000010: 1000 0000 0100 0100 44ac 0000 8858 0100 ........D....X..
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00000020: 0200 1000 6461 7461 004d 0100 0000 0000 ....data.M......
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```
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- `RIFF` magic, size 85,284 + 8.
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- `WAVE` format, fmt chunk: PCM (0x0001), mono (0x0001), 44100 Hz
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(0x0000AC44), 88200 bytes/s, block-align 2, 16 bits/sample.
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- `data` chunk size 0x00014D00 = 85,248 bytes of PCM ≈ 42,624 i16
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samples — matches the reported frame count.
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## Coverage matrix
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| PoC plan exit criterion | Status | Evidence |
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| Capture/playback works on at least one **desktop** target | PASS | `poc/audio-capture-playback-spike/VERIFICATION.md` |
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| Capture/playback works on at least one **mobile** target | **PASS** | This document. |
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## What this spike does NOT validate
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- iOS (deferred per DEC-011.1; requires macOS + Xcode hardware).
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- Android emulator audio path (skipped — physical device is
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stronger evidence).
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- API 24–25 devices (cpal's OpenSL ES fallback path is not exercised
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here; only AAudio via API 26+).
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- Bit-exact loopback signal integrity from capture to playback.
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- Audio latency under load.
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- Streaming reconfiguration on device change or audio focus loss.
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- Background-service / foreground-service audio (required for a real
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voice client; out of scope here).
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- DSP, Opus encode/decode, jitter buffer, mixer — owned by
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`chanora_audio`.
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- Privacy-sensitive UX (microphone consent flows beyond a single
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runtime grant).
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## Decisions closed by this spike
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- **DEC-011.1** sub-decision is promoted from
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`Accepted (desktop) / Deferred (mobile)` to
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`Accepted (desktop: cpal; Android: cpal-on-Oboe) / Deferred (iOS)`.
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See `docs/governance/product-decision-register.md` v0.9.4.
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- The audio row in
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`docs/architecture/proof-of-concept-plan.md` §2 is promoted from
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PARTIAL PASS to PASS.
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- RISK-PoC-001 in `docs/governance/poc-results-summary.md` is closed
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for Android; iOS portion remains open.
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