/
Quantizer.cpp
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/
Quantizer.cpp
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/* Audio Library for Teensy 3.X
* Copyright (c) 2019, Paul Stoffregen, paul@pjrc.com
*
* Development of this audio library was funded by PJRC.COM, LLC by sales of
* Teensy and Audio Adaptor boards. Please support PJRC's efforts to develop
* open source software by purchasing Teensy or other PJRC products.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice, development funding notice, and this permission
* notice shall be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
/*
by Alexander Walch
*/
#include "Quantizer.h"
#define SAMPLEINVALID(sample) (!isfinite(sample) || abs(sample) >= 1.2f) //use only for floating point samples (\in [-1.,1.])
Quantizer::Quantizer(float audio_sample_rate){
#ifdef DEBUG_QUANTIZER
while(!Serial);
#endif
randomSeed(1);
if(audio_sample_rate==44100.f){
_noiseSFilter[0]=-0.06935825f;
_noiseSFilter[1]=0.52540845f;
_noiseSFilter[2]= -1.20537028f;
_noiseSFilter[3]= 2.09422811f;
_noiseSFilter[4]= -3.2177438f;
_noiseSFilter[5]= 4.04852027f;
_noiseSFilter[6]= -3.83872701f;
_noiseSFilter[7]= 3.30584589f;
_noiseSFilter[8]= -2.38682527f;
// all coefficients in correct order:
// {1. , -2.38682527, 3.30584589, -3.83872701, 4.04852027,
// -3.2177438 , 2.09422811, -1.20537028, 0.52540845, -0.06935825};
} else if(audio_sample_rate==48000.f){
_noiseSFilter[0]=0.1967454f;
_noiseSFilter[1]=-0.30086406f;
_noiseSFilter[2]= 0.09575588f;
_noiseSFilter[3]= 0.58209648f;
_noiseSFilter[4]= -1.88579617f;
_noiseSFilter[5]= 3.37325788f;
_noiseSFilter[6]= -3.88076402f;
_noiseSFilter[7]= 3.58558504f;
_noiseSFilter[8]= -2.54334066f;
// all coefficients in correct order:
// {1. , -2.54334066, 3.58558504, -3.88076402, 3.37325788,
// -1.88579617, 0.58209648, 0.09575588, -0.30086406, 0.1967454};
// }
}
else {
_noiseSFilter[0]=0.f;
_noiseSFilter[1]=0.f;
_noiseSFilter[2]=0.f;
_noiseSFilter[3]=0.f;
_noiseSFilter[4]=0.f;
_noiseSFilter[5]=0.f;
_noiseSFilter[6]=0.f;
_noiseSFilter[7]=0.f;
_noiseSFilter[8]=0.f;
}
_bufferEnd0=&_buffer0[NOISE_SHAPE_F_LENGTH];
reset();
}
void Quantizer::configure(bool noiseShaping, bool dither, float factor){
_noiseShaping=noiseShaping;
_dither=dither;
_factor=factor;
if (_dither){
_factor-=1.f;
}
if (_noiseShaping){
// the maximum rounding error is 0.5
// Assuming the rounding errors of the last NOISE_SHAPE_F_LENGTH samples was 0.5 at the positive noise-shaping-coefficients and -0.5 at the negative coefficients,
// the maximum added value can be computed as follows:
float* f=_noiseSFilter;
float maxAddedVal=0.f;
for (uint16_t j =0; j< NOISE_SHAPE_F_LENGTH; j++){
maxAddedVal+=abs(*f++);
}
maxAddedVal/=2.f;
_factor-=maxAddedVal;
}
reset();
}
void Quantizer::reset(){
_bPtr0=_buffer0;
_bPtr1=_buffer1;
_fOutputLastIt0=0.;
_fOutputLastIt1=0.;
memset(_buffer0, 0, NOISE_SHAPE_F_LENGTH*sizeof(float));
memset(_buffer1, 0, NOISE_SHAPE_F_LENGTH*sizeof(float));
}
void Quantizer::quantize(float* input, int16_t* output, uint16_t length){
float xn, xnD, error;
const float f2 = 1.f/1000000.f;
#ifdef DEBUG_QUANTIZER
float debugFF=1024.f;
const float factor=(powf(2.f, 15.f)-1.f)/debugFF;
#endif
for (uint16_t i =0; i< length; i++){
xn= SAMPLEINVALID(*input) ? 0.f : *input*_factor; //-_fOutputLastIt0 according to paper
++input;
if (_noiseShaping){
xn+=_fOutputLastIt0;
}
if(_dither){
const uint32_t r0=random(1000000);
const uint32_t r1=random(1000000);
xnD=xn + (r0 + r1)*f2-1.f;
}
else {
xnD=xn;
}
float xnDR=round(xnD);
if (_noiseShaping){
//compute quatization error:
error=xnDR- xn;
*_bPtr0++=error;
if (_bPtr0==_bufferEnd0){
_bPtr0=_buffer0;
}
float* f=_noiseSFilter;
_fOutputLastIt0=(*_bPtr0++ * *f++);
if (_bPtr0==_bufferEnd0){
_bPtr0=_buffer0;
}
for (uint16_t j =1; j< NOISE_SHAPE_F_LENGTH; j++){
_fOutputLastIt0+=(*_bPtr0++ * *f++);
if (_bPtr0==_bufferEnd0){
_bPtr0=_buffer0;
}
}
}
#ifdef DEBUG_QUANTIZER
xnDR*=debugFF;
#endif
if (xnDR > _factor){
*output=(int16_t)_factor;
}
else if (xnDR < -_factor){
*output=-(int16_t)_factor;
}
else {
*output=(int16_t)xnDR;
}
++output;
}
}
void Quantizer::quantize(float* input0, float* input1, int32_t* outputInterleaved, uint16_t length){
float xn0, xnD0, error0,xnDR0, xn1, xnD1, error1,xnDR1;
const float f2 = 1.f/1000000.f;
#ifdef DEBUG_QUANTIZER
float debugFF=1024.f;
const float factor=(powf(2.f, 15.f)-1.f)/debugFF;
#endif
for (uint16_t i =0; i< length; i++){
xn0= SAMPLEINVALID(*input0) ? 0.f : *input0*_factor; //-_fOutputLastIt0 according to paper
++input0;
xn1= SAMPLEINVALID(*input1) ? 0.f : *input1*_factor; //-_fOutputLastIt0 according to paper
++input1;
if (_noiseShaping){
xn0+=_fOutputLastIt0;
xn1+=_fOutputLastIt1;
}
if(_dither){
uint32_t r0=random(1000000);
uint32_t r1=random(1000000);
xnD0=xn0 + (r0 + r1)*f2-1.f;
r0=random(1000000);
r1=random(1000000);
xnD1=xn1 + (r0 + r1)*f2-1.f;
}
else {
xnD0=xn0;
xnD1=xn1;
}
xnDR0=round(xnD0);
xnDR1=round(xnD1);
if (_noiseShaping){
//compute quatization error0:
error0=xnDR0- xn0;
error1=xnDR1- xn1;
*_bPtr0++=error0;
*_bPtr1++=error1;
if (_bPtr0==_bufferEnd0){
_bPtr0=_buffer0;
_bPtr1=_buffer1;
}
float* f=_noiseSFilter;
_fOutputLastIt0=(*_bPtr0++ * *f);
_fOutputLastIt1=(*_bPtr1++ * *f++);
if (_bPtr0==_bufferEnd0){
_bPtr0=_buffer0;
_bPtr1=_buffer1;
}
for (uint16_t j =1 ; j< NOISE_SHAPE_F_LENGTH; j++){
_fOutputLastIt0+=(*_bPtr0++ * *f);
_fOutputLastIt1+=(*_bPtr1++ * *f++);
if (_bPtr0==_bufferEnd0){
_bPtr0=_buffer0;
_bPtr1=_buffer1;
}
}
}
#ifdef DEBUG_QUANTIZER
xnDR0*=debugFF;
#endif
if (xnDR0 > _factor){
*outputInterleaved++=(int32_t)_factor;
}
else if (xnDR0 < -_factor){
*outputInterleaved++=-(int32_t)_factor;
}
else {
*outputInterleaved++=(int32_t)xnDR0;
}
if (xnDR1 > _factor){
*outputInterleaved++=(int32_t)_factor;
}
else if (xnDR1 < -_factor){
*outputInterleaved++=-(int32_t)_factor;
}
else {
*outputInterleaved++=(int32_t)xnDR1;
}
}
}