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audio: Apply square curve to volume slider

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AudioTrack.setVolume() takes a linear amplitude value, but human hearing
is logarithmic — a linear 0-1 slider sounds like all the volume is
crammed into the bottom quarter of the range. Squaring the slider value
(amplitude = linear²) spreads perceived loudness evenly across the
full slider travel.
This commit is contained in:
Jeena 2026-03-10 02:22:10 +00:00
parent d79fcebc41
commit da3b760f43
1 changed files with 7 additions and 2 deletions
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9
app/src/main/kotlin/net/jeena/pacer/AudioEngine.kt
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@ -22,6 +22,11 @@ class AudioEngine {
companion object { companion object {
private const val BEEP_DURATION_MS = 40 private const val BEEP_DURATION_MS = 40
private const val SILENCE_CHUNK_MS = 10 private const val SILENCE_CHUNK_MS = 10
// Apply a square curve so the slider feels linear to human hearing.
// AudioTrack.setVolume() takes a linear amplitude; our 0-1 slider
// value is perceived as "all the volume at the bottom" without this.
private fun toAmplitude(linear: Float): Float = linear * linear
} }
private val mainHandler = Handler(Looper.getMainLooper()) private val mainHandler = Handler(Looper.getMainLooper())
@ -69,7 +74,7 @@ class AudioEngine {
.setTransferMode(AudioTrack.MODE_STREAM) .setTransferMode(AudioTrack.MODE_STREAM)
.build() .build()
audioTrack?.setVolume(currentVolume) audioTrack?.setVolume(toAmplitude(currentVolume))
audioTrack?.play() audioTrack?.play()
handlerThread = HandlerThread("PacerAudio").also { it.start() } handlerThread = HandlerThread("PacerAudio").also { it.start() }
@ -94,7 +99,7 @@ class AudioEngine {
fun setVolume(volume: Float) { fun setVolume(volume: Float) {
currentVolume = BpmCalculator.clampVolume(volume) currentVolume = BpmCalculator.clampVolume(volume)
audioTrack?.setVolume(currentVolume) audioTrack?.setVolume(toAmplitude(currentVolume))
} }
private fun audioLoop() { private fun audioLoop() {