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Updated analyze_fft1024_F32 for windows and more functions

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pull/6/merge
boblark 3 years ago
parent 7f62606877
commit 830cbb136d
2 changed files with 145 additions and 34 deletions
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  1. 5
      analyze_fft1024_F32.cpp
  2. 174
      analyze_fft1024_F32.h

5
analyze_fft1024_F32.cpp
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@ -1,5 +1,5 @@
/* analyze_fft1024_F32.cpp Converted from Teensy I16 Audio Library
* This version uses floating point F32 inputs
* This version uses float F32 inputs. See comments at analyze_fft1024_F32.h
*
* Conversion parts copyright (c) Bob Larkin 2021
*
@ -57,7 +57,6 @@ static void apply_window_to_fft_buffer(void *buffer, const void *window)
void AudioAnalyzeFFT1024_F32::update(void)
{
audio_block_f32_t *block;
block = receiveReadOnly_f32();
if (!block) return;
@ -103,7 +102,7 @@ void AudioAnalyzeFFT1024_F32::update(void)
copy_to_fft_buffer(fft_buffer+0x600, blocklist[6]->data);
copy_to_fft_buffer(fft_buffer+0x700, blocklist[7]->data);
if (window)
if (pWin)
apply_window_to_fft_buffer(fft_buffer, window);
arm_cfft_radix4_f32(&fft_inst, fft_buffer);

174
analyze_fft1024_F32.h
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@ -26,9 +26,42 @@
* THE SOFTWARE.
*/
/* Moved directly I16 to F32. Bob Larkin 16 Feb 2021
* Only Hann window for now.
*/
/* Moved directly I16 to F32. Bob Larkin 16 Feb 2021
* Does real input FFT of 1024 points. Output is not audio, and is magnitude
* only. Multiple output formats of RMS (same as I16 version, and default),
* Power or dBFS (full scale). Output can be bin by bin or a pointer to
* the output array is available. Several window functions are provided by
* in-class design, or a custom window can be provided from the INO.
*
* Functions (See comments below and #defines above:
* bool available()
* float read(unsigned int binNumber)
* float read(unsigned int binFirst, unsigned int binLast)
* int windowFunction(int wNum)
* int windowFunction(int wNum, float _kdb) // Kaiser only
* float* getData(void)
* float* getWindow(void)
* void putWindow(float *pwin)
* void setOutputType(int _type)
*
* Timing, max is longest update() time:
* T3.6 Windowed, RMS out, 1016 uSec max
* T3.6 Windowed, Power Out, 975 uSec max
* T3.6 Windowed, dBFS out, 1591 uSec max
* No Window saves 60 uSec on T3.6 for any output.
* T4.0 Windowed, RMS Out, 149 uSec
*
* Scaling:
* Full scale for floating point DSP is a nebulous concept. Normally the
* full scale is -1.0 to +1.0. This is an unscaled FFT and for a sine
* wave centered in frequency on a bin and of FS amplitude, the power
* at that center bin will grow by 1024^2/4 = 262144 without windowing.
* Windowing loss cuts this down. The RMS level can grow to sqrt(262144)
* or 512. The dBFS has been scaled to make this max value 0 dBFS by
* removing 54.2 dB. With floating point, the dynamic range is maintained
* no matter how it is scaled, but this factor needs to be considered
* when building the INO.
*/
#ifndef analyze_fft1024_F32_h_
#define analyze_fft1024_F32_h_
@ -36,24 +69,17 @@
#include "Arduino.h"
#include "AudioStream_F32.h"
#include "arm_math.h"
#include "mathDSP_F32.h"
#define FFT_RMS 0
#define FFT_POWER 1
#define FFT_DBFS 2
/* // windows.c
extern "C" {
extern const int16_t AudioWindowHanning1024[];
extern const int16_t AudioWindowBartlett1024[];
extern const int16_t AudioWindowBlackman1024[];
extern const int16_t AudioWindowFlattop1024[];
extern const int16_t AudioWindowBlackmanHarris1024[];
extern const int16_t AudioWindowNuttall1024[];
extern const int16_t AudioWindowBlackmanNuttall1024[];
extern const int16_t AudioWindowWelch1024[];
extern const int16_t AudioWindowHamming1024[];
extern const int16_t AudioWindowCosine1024[];
extern const int16_t AudioWindowTukey1024[]; )
*/
#define NO_WINDOW 0
#define AudioWindowNone 0
#define AudioWindowHanning1024 1
#define AudioWindowKaiser1024 2
#define AudioWindowBlackmanHarris1024 3
class AudioAnalyzeFFT1024_F32 : public AudioStream_F32 {
//GUI: inputs:1, outputs:0 //this line used for automatic generation of GUI node
@ -63,6 +89,7 @@ public:
arm_cfft_radix4_init_f32(&fft_inst, 1024, 0, 1);
useHanningWindow(); // Revisit this for more flexibility <<<<<
}
bool available() {
if (outputflag == true) {
outputflag = false;
@ -70,10 +97,14 @@ public:
}
return false;
}
float read(unsigned int binNumber) {
if (binNumber>511 || binNumber<0) return 0.0;
return output[binNumber];
}
// Return sum of several bins. Normally use with power output.
// This produces the equivalent of bigger bins.
float read(unsigned int binFirst, unsigned int binLast) {
if (binFirst > binLast) {
unsigned int tmp = binLast;
@ -89,34 +120,115 @@ public:
return (float)sum * (1.0 / 16384.0);
}
void useHanningWindow(void) {
for (int i=0; i < 1024; i++) {
// 2*PI/1023 = 0.006141921
window[i] = 0.5*(1.0 - cosf(0.006141921f*(float)i));
}
int windowFunction(int wNum) {
if(wNum == AudioWindowKaiser1024)
return -1; // Kaiser needs the kdb
windowFunction(wNum, 0.0f);
return 0;
}
// void windowFunction(const float *w) {
// window = w;
// }
int windowFunction(int wNum, float _kdb) {
float kd;
pWin = window;
if(wNum == NO_WINDOW)
pWin = NULL;
else if (wNum == AudioWindowKaiser1024) {
if(_kdb<20.0f)
kd = 20.0f;
else
kd = _kdb;
useKaiserWindow(kd);
}
else if (wNum == AudioWindowBlackmanHarris1024)
useBHWindow();
else
useHanningWindow(); // Default
return 0;
}
// Fast pointer transfer. Be aware that the data will go away
// after the next 512 data points occur.
float* getData(void) {
return output;
}
// You can use this to design windows
float* getWindow(void) {
return window;
}
// Bring custom window from the INO
void putWindow(float *pwin) {
float *p = window;
for(int i=0; i<1024; i++)
*p++ = *pwin++;
}
// Output RMS (default) Power or dBFS
void setOutputType(int _type) {
outputType = _type;
}
virtual void update(void);
private:
float output[512];
private:
// void init(void);
float window[1024]; int doPrint = 0;
float window[1024];
float *pWin = window;
audio_block_f32_t *blocklist[8];
float fft_buffer[2048];
uint8_t state = 0;
bool outputflag = false;
audio_block_f32_t *inputQueueArray[1];
arm_cfft_radix4_instance_f32 fft_inst;
int outputType = FFT_RMS; //Same type as I16 version has
};
int outputType = FFT_RMS; //Same type as I16 version init
// The Hann window is a good all-around window
void useHanningWindow(void) {
for (int i=0; i < 1024; i++) {
// 2*PI/1023 = 0.006141921
window[i] = 0.5*(1.0 - cosf(0.006141921f*(float)i));
}
}
// Blackman-Harris produces a first sidelobe more than 90 dB down.
// The price is a bandwidth of about 2 bins. Very useful at times.
void useBHWindow(void) {
for (int i=0; i < 1024; i++) {
float kx = 0.006141921; // 2*PI/1023
int ix = (float) i;
window[i] = 0.35875 -
0.48829*cosf( kx*ix) +
0.14128*cosf(2.0f*kx*ix) -
0.01168*cosf(3.0f*kx*ix);
}
}
/* The windowing function here is that of James Kaiser. This has a number
* of desirable features. The sidelobes drop off as the frequency away from a transition.
* Also, the tradeoff of sidelobe level versus cutoff rate is variable.
* Here we specify it in terms of kdb, the highest sidelobe, in dB, next to a sharp cutoff. For
* calculating the windowing vector, we need a parameter beta, found as follows:
*/
void useKaiserWindow(float kdb) {
float32_t beta, kbes, xn2;
mathDSP_F32 mathEqualizer; // For Bessel function
if (kdb < 20.0f)
beta = 0.0;
else
beta = -2.17+0.17153*kdb-0.0002841*kdb*kdb; // Within a dB or so
// Note: i0f is the fp zero'th order modified Bessel function (see mathDSP_F32.h)
kbes = 1.0f / mathEqualizer.i0f(beta); // An additional derived parameter used in loop
for (int n=0; n<512; n++) {
xn2 = 0.5f+(float32_t)n;
// 4/(1023^2)=0.00000382215877f
xn2 = 0.00000382215877f*xn2*xn2;
window[511 - n]=kbes*(mathEqualizer.i0f(beta*sqrtf(1.0-xn2)));
window[512 + n] = window[511 - n];
}
}
};
#endif

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