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fix: DirectByteBuffer audio path — eliminate JNI array copies
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Adds nativeWriteAudioDirect / nativeReadAudioDirect JNI functions
that accept a DirectByteBuffer instead of ShortArray. The buffer's
native memory is accessed directly by Rust via pointer — no
GetShortArrayRegion / SetShortArrayRegion, no GC-managed array
copies on the audio hot path.

This fixes SIGBUS crashes on Android 16 where ART's concurrent
mark-compact GC crashes when flipping thread roots during JNI
array operations on MAX_PRIORITY audio threads.

Old ShortArray methods kept for backward compatibility.
AudioPipeline switched to use Direct variants.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
Siavash Sameni
2026-04-06 19:29:08 +04:00
parent 5e9718aeb2
commit 9eed94850d
3 changed files with 87 additions and 3 deletions
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17
android/app/src/main/java/com/wzp/audio/AudioPipeline.kt
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@@ -205,6 +205,8 @@ class AudioPipeline(private val context: Context) {
Log.i(TAG, "capture started: ${SAMPLE_RATE}Hz mono, buf=$bufSize, aec=${aec?.enabled}, ns=${ns?.enabled}")
val pcm = ShortArray(FRAME_SAMPLES)
// DirectByteBuffer for zero-copy JNI (avoids ART GC SIGBUS on Android 16)
val directBuf = ByteBuffer.allocateDirect(FRAME_SAMPLES * 2).order(ByteOrder.LITTLE_ENDIAN)
// Debug: PCM file + RMS CSV
var pcmOut: BufferedOutputStream? = null
var rmsCsv: OutputStreamWriter? = null
@@ -224,7 +226,10 @@ class AudioPipeline(private val context: Context) {
val read = recorder.read(pcm, 0, FRAME_SAMPLES)
if (read > 0) {
applyGain(pcm, read, captureGainDb)
engine.writeAudio(pcm)
// Zero-copy write via DirectByteBuffer (no GC array interaction)
directBuf.clear()
directBuf.asShortBuffer().put(pcm, 0, read)
engine.writeAudioDirect(directBuf, read)
// Debug: write raw PCM + RMS
if (pcmOut != null) {
@@ -287,6 +292,8 @@ class AudioPipeline(private val context: Context) {
val pcm = ShortArray(FRAME_SAMPLES)
val silence = ShortArray(FRAME_SAMPLES)
// DirectByteBuffer for zero-copy JNI (avoids ART GC SIGBUS on Android 16)
val directBuf = ByteBuffer.allocateDirect(FRAME_SAMPLES * 2).order(ByteOrder.LITTLE_ENDIAN)
// Debug: PCM file + RMS CSV for playout
var pcmOut: BufferedOutputStream? = null
var rmsCsv: OutputStreamWriter? = null
@@ -303,7 +310,13 @@ class AudioPipeline(private val context: Context) {
}
try {
while (running) {
val read = engine.readAudio(pcm)
// Zero-copy read via DirectByteBuffer
directBuf.clear()
val read = engine.readAudioDirect(directBuf, FRAME_SAMPLES)
if (read > 0) {
directBuf.rewind()
directBuf.asShortBuffer().get(pcm, 0, read)
}
if (read >= FRAME_SAMPLES) {
applyGain(pcm, read, playoutGainDb)
track.write(pcm, 0, read)