Build 96be740 logs proved the entire software pipeline is healthy:
capture heartbeat: calls=1100 to_write=960 full_drops=0 total_written=1056000
recv heartbeat: decoded_frames=1035 last_written=960 decode_errs=0
recv decoded PCM: range=[-13564..9244] rms=8044 (real audio)
playout WRITE: in_len=960 written=960 rms=2318 (real audio into the ring)
playout heartbeat: calls=1100 nonempty=1099 total_played_real=1055040
1055040 samples / 48000 Hz = 22s — exactly matches wall-clock elapsed,
meaning Oboe IS calling our playout callback at the expected rate and
WE ARE handing it real PCM every 20ms. User still heard nothing. Ergo
Oboe accepted the PCM and routed it to a silent output. Two fixes:
1) MainActivity.kt: switch to MODE_IN_COMMUNICATION + speakerphone ON
right after permissions are granted, and crank STREAM_VOICE_CALL to
max. Without this, an Oboe Usage::VoiceCommunication stream gets
opened, the OS creates a real AAudio pipeline, the callback fires on
schedule — and audio goes to either the earpiece at muted volume or
a "call not active" dead end. Logs the audio mode + volume levels
before and after the switch so we can confirm the state change in
logcat next run.
2) oboe_bridge.cpp: revert Usage::Media → VoiceCommunication (the mode
that matches MODE_IN_COMMUNICATION), pin the audio API to AAudio
explicitly instead of letting Oboe fall back to OpenSLES (which has
its own silent-drop failure modes on some devices), and add getState
+ getXRunCount to the playout heartbeat so we'll see silent stream
disconnects instead of reading zeros forever.
3) engine.rs recv task: dump the first ~10s of post-AGC decoded PCM to
`<app_data_dir>/decoded.pcm` as raw i16 LE so we can adb pull it and
play it back locally:
adb shell run-as com.wzp.desktop cat .wzp/decoded.pcm > decoded.pcm
ffmpeg -f s16le -ar 48000 -ac 1 -i decoded.pcm decoded.wav
This divorces "is our decoder actually producing audible audio" from
"is Android's audio stack playing it". If the recorded WAV sounds
correct when played on a laptop, the decoder is fine and 100% of the
remaining bug surface is AudioManager / Oboe routing.
4) engine.rs: also log when spk_muted=true blocks the write. User
reported the Speaker button in the UI has inconsistent semantics
between desktop and android — adding this log rules out the accidental
"first click muted playback" theory for good.
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