public WWRadix2Fft(int numPoints)
{
if (!WWUtil.IsPowerOfTwo(numPoints) || numPoints < 2)
{
throw new ArgumentException("numPoints must be power of two integer and larger than 2");
}
mNumPoints = numPoints;
mWn = new WWComplex[mNumPoints];
for (int i = 0; i < mNumPoints; ++i)
{
double angle = -2.0 * Math.PI * i / mNumPoints;
mWn[i] = new WWComplex(Math.Cos(angle), Math.Sin(angle));
}
// mNumStage == log_2(mNumPoints)
int t = mNumPoints;
for (int i = 0; 0 < t; ++i)
{
t >>= 1;
mNumStage = i;
}
mBitReversalTable = new uint[mNumPoints];
for (uint i = 0; i < mNumPoints; ++i)
{
mBitReversalTable[i] = BitReversal(mNumStage, i);
}
}
public override PcmFormat Setup(PcmFormat inputFormat)
{
mPcmFormat = new PcmFormat(inputFormat);
mFftLength = WWUtil.NextPowerOf2(mPcmFormat.SampleRate);
mOverlappedFft = new OverlappedFft(mFftLength);
return(inputFormat);
}
public WWComplex[] ConvolutionContinuousFft(WWComplex[] h, WWComplex[] x)
{
int fftSize = WWUtil.NextPowerOf2(h.Length * 4);
int fragmentSize = fftSize - h.Length + 1;
if (x.Length <= fragmentSize)
{
// 1回のFFTで計算する。
return(ConvolutionFft(h, x));
}
var fft = new WWRadix2Fft(fftSize);
var r = new WWComplex[h.Length + x.Length - 1];
var h2 = new WWComplex[fftSize];
Array.Copy(h, 0, h2, 0, h.Length);
var Hf = fft.ForwardFft(h2);
// x(n)をfragmentSize要素ごとのデータ列に分解し、
// それぞれ長さfftSizeになるように末尾に0を追加してx0(n)、x1(n)を得る。
//Parallel.For(0, x.Length / fragmentSize, i => {
for (int i = 0; i < (x.Length + fragmentSize - 1) / fragmentSize; ++i)
{
var xf = new WWComplex[fftSize];
int count = fragmentSize;
if (x.Length < (i + 1) * fragmentSize)
{
count = x.Length - i * fragmentSize;
}
Array.Copy(x, i * fragmentSize, xf, 0, count);
var Xf = fft.ForwardFft(xf);
var Yf = WWComplex.Mul(Hf, Xf);
var yf = fft.InverseFft(Yf);
for (int j = 0; j < fftSize; ++j)
{
if (r.Length <= i * fragmentSize + j)
{
break;
}
r[i * fragmentSize + j].Add(yf[j]);
}
}
;
return(r);
}
public override double[] FilterDo(double[] inPcm)
{
// この計算で求めるのは、mChannelId==0のとき左耳, mChannelId==1のとき右耳の音。mChannelIdは耳のチャンネル番号。
// 入力データとしてmPcmAllChannelsが使用できる。mPcmAllChannels[0]==左スピーカーの音、mPcmAllChannels[1]==右スピーカーの音。
int fftLength = ((int)mNumSamples < mCoeffs[0].Length) ? mCoeffs[0].Length : (int)mNumSamples;
fftLength = WWUtil.NextPowerOf2(fftLength);
// 左スピーカーの音=mPcmAllChannels[0]
// 左スピーカーと耳chの相互作用のCoeff==mCoeffs[ch]
var leftSpeaker = FFTFir(mPcmAllChannels[0], mCoeffs[mChannelId + 0], fftLength);
// 右スピーカーの音=mPcmAllChannels[1]
// 右スピーカーと耳chの相互作用のCoeff==mCoeffs[ch+2]
var rightSpeaker = FFTFir(mPcmAllChannels[1], mCoeffs[mChannelId + 2], fftLength);
var mixed = Add(leftSpeaker, rightSpeaker);
return(mixed);
}
public WWComplex[] ConvolutionFft(WWComplex[] h, WWComplex[] x)
{
var r = new WWComplex[h.Length + x.Length - 1];
int fftSize = WWUtil.NextPowerOf2(r.Length);
var h2 = new WWComplex[fftSize];
Array.Copy(h, 0, h2, 0, h.Length);
var x2 = new WWComplex[fftSize];
Array.Copy(x, 0, x2, 0, x.Length);
var fft = new WWRadix2Fft(fftSize);
var H = fft.ForwardFft(h2);
var X = fft.ForwardFft(x2);
var Y = WWComplex.Mul(H, X);
var y = fft.InverseFft(Y);
Array.Copy(y, 0, r, 0, r.Length);
return(r);
}
public override string ToSaveText()
{
return(string.Format(CultureInfo.InvariantCulture, "{0}", WWUtil.EscapeString(FilterFilePath)));
}
public override string ToSaveText()
{
return(string.Format(CultureInfo.InvariantCulture, "{0} {1}", TagType, WWUtil.EscapeString(Text)));
}
