295 lines
12 KiB
C#
295 lines
12 KiB
C#
using System;
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namespace NAudio.Dsp
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{
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/****************************************************************************
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*
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* NAME: PitchShift.cs
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* VERSION: 1.0
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* HOME URL: http://www.dspdimension.com
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* KNOWN BUGS: none
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*
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* SYNOPSIS: Routine for doing pitch shifting while maintaining
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* duration using the Short Time Fourier Transform.
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*
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* DESCRIPTION: The routine takes a pitchShift factor value which is between 0.5
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* (one octave down) and 2. (one octave up). A value of exactly 1 does not change
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* the pitch. numSampsToProcess tells the routine how many samples in indata[0...
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* numSampsToProcess-1] should be pitch shifted and moved to outdata[0 ...
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* numSampsToProcess-1]. The two buffers can be identical (ie. it can process the
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* data in-place). fftFrameSize defines the FFT frame size used for the
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* processing. Typical values are 1024, 2048 and 4096. It may be any value <=
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* MAX_FRAME_LENGTH but it MUST be a power of 2. osamp is the STFT
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* oversampling factor which also determines the overlap between adjacent STFT
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* frames. It should at least be 4 for moderate scaling ratios. A value of 32 is
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* recommended for best quality. sampleRate takes the sample rate for the signal
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* in unit Hz, ie. 44100 for 44.1 kHz audio. The data passed to the routine in
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* indata[] should be in the range [-1.0, 1.0), which is also the output range
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* for the data, make sure you scale the data accordingly (for 16bit signed integers
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* you would have to divide (and multiply) by 32768).
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*
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* COPYRIGHT 1999-2006 Stephan M. Bernsee <smb [AT] dspdimension [DOT] com>
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*
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* The Wide Open License (WOL)
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*
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* Permission to use, copy, modify, distribute and sell this software and its
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* documentation for any purpose is hereby granted without fee, provided that
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* the above copyright notice and this license appear in all source copies.
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* THIS SOFTWARE IS PROVIDED "AS IS" WITHOUT EXPRESS OR IMPLIED WARRANTY OF
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* ANY KIND. See http://www.dspguru.com/wol.htm for more information.
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*
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*****************************************************************************/
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/****************************************************************************
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*
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* This code was converted to C# by Michael Knight
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* madmik3 at gmail dot com.
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* http://sites.google.com/site/mikescoderama/
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*
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*****************************************************************************/
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/// <summary>
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/// SMB Pitch Shifter
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/// </summary>
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public class SmbPitchShifter
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{
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private static int MAX_FRAME_LENGTH = 16000;
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private float[] gInFIFO = new float[MAX_FRAME_LENGTH];
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private float[] gOutFIFO = new float[MAX_FRAME_LENGTH];
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private float[] gFFTworksp = new float[2*MAX_FRAME_LENGTH];
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private float[] gLastPhase = new float[MAX_FRAME_LENGTH/2 + 1];
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private float[] gSumPhase = new float[MAX_FRAME_LENGTH/2 + 1];
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private float[] gOutputAccum = new float[2*MAX_FRAME_LENGTH];
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private float[] gAnaFreq = new float[MAX_FRAME_LENGTH];
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private float[] gAnaMagn = new float[MAX_FRAME_LENGTH];
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private float[] gSynFreq = new float[MAX_FRAME_LENGTH];
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private float[] gSynMagn = new float[MAX_FRAME_LENGTH];
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private long gRover;
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/// <summary>
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/// Pitch Shift
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/// </summary>
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public void PitchShift(float pitchShift, long numSampsToProcess,
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float sampleRate, float[] indata)
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{
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PitchShift(pitchShift, numSampsToProcess, 2048L, 10L, sampleRate, indata);
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}
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/// <summary>
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/// Pitch Shift
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/// </summary>
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public void PitchShift(float pitchShift, long numSampsToProcess, long fftFrameSize,
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long osamp, float sampleRate, float[] indata)
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{
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double magn, phase, tmp, window, real, imag;
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double freqPerBin, expct;
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long i, k, qpd, index, inFifoLatency, stepSize, fftFrameSize2;
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float[] outdata = indata;
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/* set up some handy variables */
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fftFrameSize2 = fftFrameSize/2;
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stepSize = fftFrameSize/osamp;
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freqPerBin = sampleRate/(double) fftFrameSize;
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expct = 2.0*Math.PI*(double) stepSize/(double) fftFrameSize;
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inFifoLatency = fftFrameSize - stepSize;
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if (gRover == 0) gRover = inFifoLatency;
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/* main processing loop */
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for (i = 0; i < numSampsToProcess; i++)
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{
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/* As long as we have not yet collected enough data just read in */
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gInFIFO[gRover] = indata[i];
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outdata[i] = gOutFIFO[gRover - inFifoLatency];
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gRover++;
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/* now we have enough data for processing */
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if (gRover >= fftFrameSize)
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{
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gRover = inFifoLatency;
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/* do windowing and re,im interleave */
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for (k = 0; k < fftFrameSize; k++)
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{
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window = -.5*Math.Cos(2.0*Math.PI*(double) k/(double) fftFrameSize) + .5;
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gFFTworksp[2*k] = (float) (gInFIFO[k]*window);
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gFFTworksp[2*k + 1] = 0.0F;
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}
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/* ***************** ANALYSIS ******************* */
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/* do transform */
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ShortTimeFourierTransform(gFFTworksp, fftFrameSize, -1);
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/* this is the analysis step */
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for (k = 0; k <= fftFrameSize2; k++)
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{
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/* de-interlace FFT buffer */
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real = gFFTworksp[2*k];
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imag = gFFTworksp[2*k + 1];
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/* compute magnitude and phase */
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magn = 2.0*Math.Sqrt(real*real + imag*imag);
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phase = Math.Atan2(imag, real);
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/* compute phase difference */
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tmp = phase - gLastPhase[k];
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gLastPhase[k] = (float) phase;
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/* subtract expected phase difference */
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tmp -= (double) k*expct;
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/* map delta phase into +/- Pi interval */
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qpd = (long) (tmp/Math.PI);
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if (qpd >= 0) qpd += qpd & 1;
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else qpd -= qpd & 1;
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tmp -= Math.PI*(double) qpd;
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/* get deviation from bin frequency from the +/- Pi interval */
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tmp = osamp*tmp/(2.0*Math.PI);
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/* compute the k-th partials' true frequency */
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tmp = (double) k*freqPerBin + tmp*freqPerBin;
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/* store magnitude and true frequency in analysis arrays */
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gAnaMagn[k] = (float) magn;
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gAnaFreq[k] = (float) tmp;
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}
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/* ***************** PROCESSING ******************* */
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/* this does the actual pitch shifting */
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for (int zero = 0; zero < fftFrameSize; zero++)
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{
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gSynMagn[zero] = 0;
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gSynFreq[zero] = 0;
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}
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for (k = 0; k <= fftFrameSize2; k++)
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{
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index = (long) (k*pitchShift);
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if (index <= fftFrameSize2)
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{
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gSynMagn[index] += gAnaMagn[k];
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gSynFreq[index] = gAnaFreq[k]*pitchShift;
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}
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}
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/* ***************** SYNTHESIS ******************* */
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/* this is the synthesis step */
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for (k = 0; k <= fftFrameSize2; k++)
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{
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/* get magnitude and true frequency from synthesis arrays */
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magn = gSynMagn[k];
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tmp = gSynFreq[k];
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/* subtract bin mid frequency */
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tmp -= (double) k*freqPerBin;
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/* get bin deviation from freq deviation */
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tmp /= freqPerBin;
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/* take osamp into account */
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tmp = 2.0*Math.PI*tmp/osamp;
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/* add the overlap phase advance back in */
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tmp += (double) k*expct;
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/* accumulate delta phase to get bin phase */
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gSumPhase[k] += (float) tmp;
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phase = gSumPhase[k];
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/* get real and imag part and re-interleave */
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gFFTworksp[2*k] = (float) (magn*Math.Cos(phase));
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gFFTworksp[2*k + 1] = (float) (magn*Math.Sin(phase));
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}
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/* zero negative frequencies */
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for (k = fftFrameSize + 2; k < 2*fftFrameSize; k++) gFFTworksp[k] = 0.0F;
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/* do inverse transform */
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ShortTimeFourierTransform(gFFTworksp, fftFrameSize, 1);
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/* do windowing and add to output accumulator */
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for (k = 0; k < fftFrameSize; k++)
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{
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window = -.5*Math.Cos(2.0*Math.PI*(double) k/(double) fftFrameSize) + .5;
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gOutputAccum[k] += (float) (2.0*window*gFFTworksp[2*k]/(fftFrameSize2*osamp));
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}
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for (k = 0; k < stepSize; k++) gOutFIFO[k] = gOutputAccum[k];
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/* shift accumulator */
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//memmove(gOutputAccum, gOutputAccum + stepSize, fftFrameSize * sizeof(float));
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for (k = 0; k < fftFrameSize; k++)
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{
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gOutputAccum[k] = gOutputAccum[k + stepSize];
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}
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/* move input FIFO */
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for (k = 0; k < inFifoLatency; k++) gInFIFO[k] = gInFIFO[k + stepSize];
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}
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}
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}
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/// <summary>
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/// Short Time Fourier Transform
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/// </summary>
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public void ShortTimeFourierTransform(float[] fftBuffer, long fftFrameSize, long sign)
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{
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float wr, wi, arg, temp;
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float tr, ti, ur, ui;
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long i, bitm, j, le, le2, k;
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for (i = 2; i < 2*fftFrameSize - 2; i += 2)
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{
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for (bitm = 2, j = 0; bitm < 2*fftFrameSize; bitm <<= 1)
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{
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if ((i & bitm) != 0) j++;
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j <<= 1;
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}
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if (i < j)
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{
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temp = fftBuffer[i];
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fftBuffer[i] = fftBuffer[j];
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fftBuffer[j] = temp;
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temp = fftBuffer[i + 1];
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fftBuffer[i + 1] = fftBuffer[j + 1];
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fftBuffer[j + 1] = temp;
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}
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}
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long max = (long) (Math.Log(fftFrameSize)/Math.Log(2.0) + .5);
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for (k = 0, le = 2; k < max; k++)
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{
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le <<= 1;
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le2 = le >> 1;
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ur = 1.0F;
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ui = 0.0F;
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arg = (float) Math.PI/(le2 >> 1);
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wr = (float) Math.Cos(arg);
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wi = (float) (sign*Math.Sin(arg));
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for (j = 0; j < le2; j += 2)
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{
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for (i = j; i < 2*fftFrameSize; i += le)
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{
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tr = fftBuffer[i + le2]*ur - fftBuffer[i + le2 + 1]*ui;
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ti = fftBuffer[i + le2]*ui + fftBuffer[i + le2 + 1]*ur;
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fftBuffer[i + le2] = fftBuffer[i] - tr;
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fftBuffer[i + le2 + 1] = fftBuffer[i + 1] - ti;
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fftBuffer[i] += tr;
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fftBuffer[i + 1] += ti;
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}
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tr = ur*wr - ui*wi;
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ui = ur*wi + ui*wr;
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ur = tr;
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}
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}
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}
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}
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} |