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lanczos lut

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minjaesong
2023-12-14 02:43:29 +09:00
parent be35d1b4e0
commit 3233e57680
1 changed files with 11 additions and 6 deletions
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17
src/net/torvald/terrarum/audio/AudioProcessBuf.kt
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@@ -32,12 +32,17 @@ class AudioProcessBuf(inputSamplingRate: Int, val audioReadFun: (ByteArray) -> I
private val TAPS = 4 // 2*a tap lanczos intp. Lower = greater artefacts
fun L(x: Double): Double = if (x.absoluteValue < epsilon)
1.0
else if (-TAPS <= x && x < TAPS)
(TAPS * sin(PI * x) * sin(PI * x / TAPS)) / (PI * PI * x * x)
else
0.0
private val Lcache = HashMap<Long, Double>(1048576)
fun L(x: Double): Double {
return Lcache.getOrPut(x.toBits()) { // converting double to longbits allows faster cache lookup?!
if (x.absoluteValue < epsilon)
1.0
else if (-TAPS <= x && x < TAPS)
(TAPS * sin(PI * x) * sin(PI * x / TAPS)) / (PI * PI * x * x)
else
0.0
}
}
private val BS = AUDIO_BUFFER_SIZE
private val MP3_CHUNK_SIZE = 1152 // 1152 for 32k-48k, 576 for 16k-24k, 384 for 8k-12k