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binaural panning filter

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minjaesong
2023-11-23 18:38:28 +09:00
parent 99bc57acdf
commit 4676ceb522
1 changed files with 60 additions and 1 deletions
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61
src/net/torvald/terrarum/audio/TerrarumAudioFilter.kt
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@@ -1,8 +1,11 @@
package net.torvald.terrarum.audio
import com.jme3.math.FastMath
import com.jme3.math.FastMath.sin
import net.torvald.terrarum.audio.TerrarumAudioMixerTrack.Companion.BUFFER_SIZE
import net.torvald.terrarum.audio.TerrarumAudioMixerTrack.Companion.SAMPLING_RATEF
import kotlin.math.absoluteValue
import kotlin.math.roundToInt
import kotlin.math.tanh
abstract class TerrarumAudioFilter {
@@ -175,4 +178,60 @@ object Buffer : TerrarumAudioFilter() {
override fun thru(inbuf0: List<FloatArray>, inbuf1: List<FloatArray>, outbuf0: List<FloatArray>, outbuf1: List<FloatArray>) {
bypass = true
}
}
}
/**
* The input audio must be monaural
*
* @param pan -1 for far-left, 0 for centre, 1 for far-right
* @param soundSpeed speed of the sound in meters per seconds
* @param earDist distance between ears in meters
*/
class BinoPan(var pan: Float, var soundSpeed: Float = 340f, var earDist: Float = 0.18f): TerrarumAudioFilter() {
private val PANNING_CONST = 3.0 // 3dB panning rule
private fun getFrom(index: Float, buf0: FloatArray, buf1: FloatArray): Float {
val index = index.toInt() // TODO resampling
return if (index >= 0) buf1[index]
else buf0[buf0.size + index]
}
private val delays = arrayOf(0f, 0f)
private val mults = arrayOf(1f, 1f)
override fun thru(inbuf0: List<FloatArray>, inbuf1: List<FloatArray>, outbuf0: List<FloatArray>, outbuf1: List<FloatArray>
) {
val angle = pan * 1.5707963f
val timeDiffMax = earDist / soundSpeed * SAMPLING_RATEF
val delayInSamples = (timeDiffMax * sin(angle)).absoluteValue
val volMultDbThis = PANNING_CONST * pan.absoluteValue
val volMultFsThis = decibelsToFullscale(volMultDbThis).toFloat()
val volMultDbOther = -(PANNING_CONST * pan.absoluteValue)
val volMUltFsOther = decibelsToFullscale(volMultDbOther).toFloat()
if (pan >= 0) {
delays[0] = delayInSamples
delays[1] = 0f
}
else {
delays[0] = 0f
delays[1] = delayInSamples
}
if (pan >= 0) {
mults[0] = volMUltFsOther
mults[1] = volMultFsThis
}
else {
mults[0] = volMultFsThis
mults[1] = volMUltFsOther
}
for (ch in 0..1) {
for (i in 0 until BUFFER_SIZE / 4) {
outbuf1[ch][i] = getFrom(i - delays[ch], inbuf0[0], inbuf1[0]) * mults[ch]
}
}
}
}