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Remove 4 point fft again completely, its broken

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Ralty
2025-08-02 21:13:02 +07:00
parent 81188b2fd0
commit 0f236b846b
1 changed files with 15 additions and 113 deletions
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source/funkin/backend/utils/AudioAnalyzer.hx
+15 -113
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@@ -99,11 +99,6 @@ final class AudioAnalyzer {
*/
public var fftN(default, set):Int;
/**
* Whether or not should it also use the 4-point butterfly functions for FFT.
*/
public var allow4PointFFT:Bool = false;
/**
* The current buffer from sound.
*/
@@ -149,7 +144,6 @@ final class AudioAnalyzer {
var __twiddleImags:Array<Float> = [];
var __freqReals:Array<Float> = [];
var __freqImags:Array<Float> = [];
var __factors:Array<Int> = [];
// levels
var __frequencies:Array<Float>;
@@ -201,19 +195,6 @@ final class AudioAnalyzer {
__twiddleImags[i] = Math.sin(a);
}
__factors.resize(0);
var n = fftN;
while (n % 4 == 0) {
__factors.push(2);
n >>= 2;
}
while (n % 2 == 0) {
__factors.push(1);
n >>= 1;
}
return fftN;
}
@@ -255,71 +236,6 @@ final class AudioAnalyzer {
* @return Output of frequencies
*/
public function getFrequencies(startPos:Float, ?frequencies:Array<Float>):Array<Float> {
// https://github.com/FunkinCrew/grig.audio/commit/8567c4dad34cfeaf2ff23fe12c3796f5db80685e
inline function butterfly4PointOptimized(i0:Int, i1:Int, i2:Int, i3:Int, t1:Int, t2:Int, t3:Int) {
// Load input values
var x0r = __freqReals[i0];
var x0i = __freqImags[i0];
// Apply twiddle factors to x1, x2, x3
// x1 = workingData[i1] * twiddle1
var x1r_raw = __freqReals[i1];
var x1i_raw = __freqImags[i1];
var tw1r = __twiddleReals[t1];
var tw1i = __twiddleImags[t1];
var x1r = x1r_raw * tw1r - x1i_raw * tw1i;
var x1i = x1r_raw * tw1i + x1i_raw * tw1r;
// x2 = workingData[i2] * twiddle2
var x2r_raw = __freqReals[i2];
var x2i_raw = __freqImags[i2];
var tw2r = __twiddleReals[t2];
var tw2i = __twiddleImags[t2];
var x2r = x2r_raw * tw2r - x2i_raw * tw2i;
var x2i = x2r_raw * tw2i + x2i_raw * tw2r;
// x3 = workingData[i3] * twiddle3
var x3r_raw = __freqReals[i3];
var x3i_raw = __freqImags[i3];
var tw3r = __twiddleReals[t3];
var tw3i = __twiddleImags[t3];
var x3r = x3r_raw * tw3r - x3i_raw * tw3i;
var x3i = x3r_raw * tw3i + x3i_raw * tw3r;
// Compute intermediate values for 4-point DFT
var t0r = x0r + x2r; // (x0 + x2).real
var t0i = x0i + x2i; // (x0 + x2).imag
var t1r = x0r - x2r; // (x0 - x2).real
var t1i = x0i - x2i; // (x0 - x2).imag
var t2r = x1r + x3r; // (x1 + x3).real
var t2i = x1i + x3i; // (x1 + x3).imag
var t3r = x1r - x3r; // (x1 - x3).real
var t3i = x1i - x3i; // (x1 - x3).imag
// Apply j multiplication: j * (a + jb) = -b + ja
var jt3r = -t3i; // j * t3.real = -t3.imag
var jt3i = t3r; // j * t3.imag = t3.real
// Final 4-point DFT butterfly outputs
__freqReals[i0] = t0r + t2r; // X[k]
__freqImags[i0] = t0i + t2i;
__freqReals[i1] = t1r - jt3r; // X[k + N/4]
__freqImags[i1] = t1i - jt3i;
__freqReals[i2] = t0r - t2r; // X[k + N/2]
__freqImags[i2] = t0i - t2i;
__freqReals[i3] = t1r + jt3r; // X[k + 3N/4]
__freqImags[i3] = t1i + jt3i;
}
inline function butterfly2PointOptimized(i0:Int, i1:Int, t:Int) {
var tempr = __freqReals[i1] * __twiddleReals[t] - __freqImags[i1] * __twiddleImags[t];
var tempi = __freqReals[i1] * __twiddleImags[t] + __freqImags[i1] * __twiddleReals[t];
__freqReals[i1] = __freqReals[i0] - tempr;
__freqImags[i1] = __freqImags[i0] - tempi;
__freqReals[i0] += tempr;
__freqImags[i0] += tempi;
}
__freqSamples = getSamples(startPos, fftN, true, __freqSamples);
if (frequencies == null) frequencies = [];
@@ -332,46 +248,32 @@ final class AudioAnalyzer {
__freqImags[i] = 0;
}
var size = 1, n = fftN, half, k, temp;
if (allow4PointFFT) for (factor in __factors) {
half = (size <<= factor) >> factor;
n >>= factor;
var size = 1, n = fftN, half = 1, k, i0, i1, t, tr:Float, ti:Float;
while ((size <<= 1) < fftN) {
n >>= 1;
i = 0;
while (i < fftN) {
k = 0;
while (k < half) {
if (factor == 2)
butterfly4PointOptimized(temp = i + k, temp += half, temp += half, temp += half,
(k * n) % fftN, (2 * k * n) % fftN, (3 * k * n) % fftN);
else
butterfly2PointOptimized(temp = i + k, temp += half, (k * n) % fftN);
i1 = (i0 = i + k) + half;
t = (k * n) % fftN;
tr = __freqReals[i1] * __twiddleReals[t] - __freqImags[i1] * __twiddleImags[t];
ti = __freqReals[i1] * __twiddleImags[t] + __freqImags[i1] * __twiddleReals[t];
__freqReals[i1] = __freqReals[i0] - tr;
__freqImags[i1] = __freqImags[i0] - ti;
__freqReals[i0] += tr;
__freqImags[i0] += ti;
k++;
}
i += size;
}
}
else {
half = 1;
n = fftN;
while ((size <<= 1) < fftN) {
n >>= 1;
i = 0;
while (i < fftN) {
k = 0;
while (k < half) {
butterfly2PointOptimized(temp = i + k, temp += half, (k * n) % fftN);
k++;
}
i += size;
}
half = size;
}
half = size;
}
var inv = 1.0 / fftN;
frequencies[i = 0] = Math.sqrt(__freqReals[0] * __freqReals[0] + __freqImags[0] * __freqImags[0]) * inv;
while (++i < __N2) frequencies[i] = 2 * Math.sqrt(__freqReals[i] * __freqReals[i] + __freqImags[i] * __freqImags[i]) * inv;
frequencies[i = 0] = Math.sqrt(__freqReals[0] * __freqReals[0] + __freqImags[0] * __freqImags[0]) * (tr = 1.0 / fftN);
while (++i < __N2) frequencies[i] = 2 * Math.sqrt(__freqReals[i] * __freqReals[i] + __freqImags[i] * __freqImags[i]) * tr;
return frequencies;
}