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fix(android): read volume samples in native byte order #466

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fix(android): read volume samples in native byte order #466

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5 changes: 5 additions & 0 deletions .changeset/android-volume-byte-order.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
'@livekit/react-native': patch
---

android: Fix useTrackVolume reading audio samples in the wrong byte order
15 changes: 9 additions & 6 deletions android/src/main/java/com/livekit/reactnative/audio/processing/VolumeProcessor.kt
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Expand Up @@ -6,6 +6,7 @@ import com.facebook.react.modules.core.DeviceEventManagerModule
import com.livekit.reactnative.audio.events.Events
import livekit.org.webrtc.AudioTrackSink
import java.nio.ByteBuffer
import java.nio.ByteOrder
import kotlin.math.round
import kotlin.math.sqrt

Expand Down Expand Up @@ -34,17 +35,20 @@ abstract class BaseVolumeProcessor : AudioTrackSink {
numberOfFrames: Int,
absoluteCaptureTimestampMs: Long
) {
audioData.mark()
audioData.position(0)
// WebRTC hands us a JNI direct buffer, which Java defaults to big-endian,
// while the PCM samples are native (little-endian). Read through a view
// in native order so the sink's buffer is left untouched.
val samples = audioData.duplicate().order(ByteOrder.nativeOrder())
samples.position(0)
var average = 0L
val bytesPerSample = bitsPerSample / 8

// RMS average calculation
for (i in 0 until numberOfFrames) {
val value = when (bytesPerSample) {
1 -> audioData.get().toLong()
2 -> audioData.getShort().toLong()
4 -> audioData.getInt().toLong()
1 -> samples.get().toLong()
2 -> samples.getShort().toLong()

@devin-ai-integration devin-ai-integration Bot Sep 28, 2026

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🟡 Quiet audio leaves track volume stale

When corrected samples produce zero, onVolumeCalculated emits a reading that useTrackVolume ignores. The track keeps its previous nonzero volume during near-silent frames.

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The processor emits normalized volume values for each audio buffer. The useTrackVolume listener updates state only when event.volume is truthy, so it discards zero. Correct native-order decoding can turn a low-level frame that previously decoded as nonzero into a zero RMS reading. The listener then preserves an earlier, louder reading.

Example: A 480-frame buffer containing one PCM16 sample of value 1 and otherwise zeros produces a zero RMS after native-order decoding. Before this change, swapping that sample to 256 produced a nonzero reading. If the last displayed volume was 0.5, the new zero event leaves it at 0.5.

Recommended fix: In useTrackVolume, check the event ID and tag independently of the numeric volume; accept zero as a valid reading. Add a transition test from nonzero to zero.

Devin Review

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4 -> samples.getInt().toLong()
else -> throw IllegalArgumentException()
}

Expand All @@ -60,7 +64,6 @@ abstract class BaseVolumeProcessor : AudioTrackSink {
4 -> volume / Int.MAX_VALUE
else -> throw IllegalArgumentException()
}
audioData.reset()

onVolumeCalculated(volumeNormalized)
}
Expand Down
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