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This commit is contained in:
Christopher Herb
2023-07-07 10:07:53 +02:00
commit ad8c3fbe74
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companding/ulaw.h Normal file
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#pragma once
#include <stdlib.h>
#include <cstdint>
#include <cmath>
namespace trnr::lib::companding {
// ulaw compansion based on code by Chris Johnson
class ulaw {
public:
ulaw() {
fpd_l = 1.0; while (fpd_l < 16386) fpd_l = rand()*UINT32_MAX;
fpd_r = 1.0; while (fpd_r < 16386) fpd_r = rand()*UINT32_MAX;
}
void encode_samples(double& input_sample_l, double& input_sample_r) {
// ulaw encoding
static int noisesource_l = 0;
static int noisesource_r = 850010;
int residue;
double applyresidue;
noisesource_l = noisesource_l % 1700021; noisesource_l++;
residue = noisesource_l * noisesource_l;
residue = residue % 170003; residue *= residue;
residue = residue % 17011; residue *= residue;
residue = residue % 1709; residue *= residue;
residue = residue % 173; residue *= residue;
residue = residue % 17;
applyresidue = residue;
applyresidue *= 0.00000001;
applyresidue *= 0.00000001;
input_sample_l += applyresidue;
if (input_sample_l<1.2e-38 && -input_sample_l<1.2e-38) {
input_sample_l -= applyresidue;
}
noisesource_r = noisesource_r % 1700021; noisesource_r++;
residue = noisesource_r * noisesource_r;
residue = residue % 170003; residue *= residue;
residue = residue % 17011; residue *= residue;
residue = residue % 1709; residue *= residue;
residue = residue % 173; residue *= residue;
residue = residue % 17;
applyresidue = residue;
applyresidue *= 0.00000001;
applyresidue *= 0.00000001;
input_sample_r += applyresidue;
if (input_sample_r<1.2e-38 && -input_sample_r<1.2e-38) {
input_sample_r -= applyresidue;
}
if (input_sample_l > 1.0) input_sample_l = 1.0;
if (input_sample_l < -1.0) input_sample_l = -1.0;
if (input_sample_r > 1.0) input_sample_r = 1.0;
if (input_sample_r < -1.0) input_sample_r = -1.0;
if (input_sample_l > 0) input_sample_l = log(1.0+(255*fabs(input_sample_l))) / log(256);
if (input_sample_l < 0) input_sample_l = -log(1.0+(255*fabs(input_sample_l))) / log(256);
if (input_sample_r > 0) input_sample_r = log(1.0+(255*fabs(input_sample_r))) / log(256);
if (input_sample_r < 0) input_sample_r = -log(1.0+(255*fabs(input_sample_r))) / log(256);
}
void decode_samples(double& input_sample_l, double& input_sample_r) {
// ulaw decoding
if (fabs(input_sample_l)<1.18e-23) input_sample_l = fpd_l * 1.18e-17;
if (fabs(input_sample_r)<1.18e-23) input_sample_r = fpd_r * 1.18e-17;
if (input_sample_l > 1.0) input_sample_l = 1.0;
if (input_sample_l < -1.0) input_sample_l = -1.0;
if (input_sample_r > 1.0) input_sample_r = 1.0;
if (input_sample_r < -1.0) input_sample_r = -1.0;
if (input_sample_l > 0) input_sample_l = (pow(256,fabs(input_sample_l))-1.0) / 255;
if (input_sample_l < 0) input_sample_l = -(pow(256,fabs(input_sample_l))-1.0) / 255;
if (input_sample_r > 0) input_sample_r = (pow(256,fabs(input_sample_r))-1.0) / 255;
if (input_sample_r < 0) input_sample_r = -(pow(256,fabs(input_sample_r))-1.0) / 255;
// 64 bit stereo floating point dither
fpd_l ^= fpd_l << 13; fpd_l ^= fpd_l >> 17; fpd_l ^= fpd_l << 5;
fpd_r ^= fpd_r << 13; fpd_r ^= fpd_r >> 17; fpd_r ^= fpd_r << 5;
}
private:
uint32_t fpd_l;
uint32_t fpd_r;
};
}