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fix AudioUtils by @itsmeinteger #1895

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Merged
pedroSG94 merged 3 commits into from
Aug 17, 2025
Merged

fix AudioUtils by @itsmeinteger #1895

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42c6eeb
fix mix audio by @itsmeinteger
pedroSG94 Aug 13, 2025
27cfd99
optmize AudioUtils
pedroSG94 Aug 14, 2025
27962be
fix calculateAmplitude by @itsmeinteger
pedroSG94 Aug 15, 2025
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36 changes: 17 additions & 19 deletions encoder/src/main/java/com/pedro/encoder/input/audio/AudioUtils.kt
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Original file line number Diff line number Diff line change
@@ -1,5 +1,7 @@
package com.pedro.encoder.input.audio

import kotlin.math.abs

class AudioUtils {

fun applyVolumeAndMix(
Expand All @@ -8,44 +10,40 @@ class AudioUtils {
dst: ByteArray
) {
if (buffer.size != buffer2.size) return
if (volume == 1f && volume2 == 1f) {
for (i in buffer.indices) {
dst[i] = (buffer[i] + buffer2[i]).toByte()
}
return
}
for (i in buffer.indices step 2) {
val sample = ((buffer[i + 1].toInt() shl 8) or (buffer[i].toInt() and 0xFF))
val adjustedSample = (sample * volume).toInt()
val sample2 = ((buffer2[i + 1].toInt() shl 8) or (buffer2[i].toInt() and 0xFF))
val adjustedSample2 = (sample2 * volume2).toInt()
val sample1 = ((buffer[i + 1].toInt() shl 8) or (buffer[i].toInt() and 0xFF)).toShort().toInt()
val sample2 = ((buffer2[i + 1].toInt() shl 8) or (buffer2[i].toInt() and 0xFF)).toShort().toInt()

dst[i] = (adjustedSample.toByte() + adjustedSample2.toByte()).toByte()
dst[i + 1] = ((adjustedSample shr 8).toByte() + (adjustedSample2 shr 8).toByte()).toByte()
val adjustedSample1 = (sample1 * volume).toInt()
val adjustedSample2 = (sample2 * volume2).toInt()
val mixedSample = (adjustedSample1 + adjustedSample2).coerceIn(Short.MIN_VALUE.toInt(), Short.MAX_VALUE.toInt()) and 0xFFFF
dst[i] = (mixedSample and 0xFF).toByte()
dst[i + 1] = ((mixedSample shr 8) and 0xFF).toByte()
}
}

fun applyVolume(buffer: ByteArray, volume: Float) {
if (volume == 1f) return

for (i in buffer.indices step 2) {
val sample = ((buffer[i + 1].toInt() shl 8) or (buffer[i].toInt() and 0xFF))
val adjustedSample = (sample * volume).toInt()
buffer[i] = adjustedSample.toByte()
buffer[i + 1] = (adjustedSample shr 8).toByte()
val sample = ((buffer[i + 1].toInt() shl 8) or (buffer[i].toInt() and 0xFF)).toShort().toInt()
val adjustedSample = (sample * volume).toInt().coerceIn(Short.MIN_VALUE.toInt(), Short.MAX_VALUE.toInt()) and 0xFFFF
buffer[i] = (adjustedSample and 0xFF).toByte()
buffer[i + 1] = ((adjustedSample shr 8) and 0xFF).toByte()
}
}

/**
* assume always pcm 16bit
* Calculate amplitude peaks. Assume always pcm 16bit
* @return value from 0f to 100f
*/
fun calculateAmplitude(buffer: ByteArray): Float {
if (buffer.size % 2 != 0) return 0f //invalid buffer
var amplitude = 0
for (i in buffer.indices step 2) {
val sample = ((buffer[i + 1].toInt() shl 8) or (buffer[i].toInt() and 0xFF))
if (sample > amplitude) amplitude = sample
val sample = ((buffer[i + 1].toInt() shl 8) or (buffer[i].toInt() and 0xFF)).toShort().toInt()
val sampleAmplitude = abs(sample)
if (sampleAmplitude > amplitude) amplitude = sampleAmplitude
}
return (amplitude / Short.MAX_VALUE.toFloat()) * 100
}
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