mirror of
https://github.com/mpv-player/mpv
synced 2024-09-05 02:48:21 +02:00
![alex](/assets/img/avatar_default.png)
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@3849 b3059339-0415-0410-9bf9-f77b7e298cf2
122 lines
3.2 KiB
C
122 lines
3.2 KiB
C
#include <inttypes.h>
|
|
#include <math.h>
|
|
|
|
static double desired_7kHz_lowpass[] = {1.0, 0.0};
|
|
static double weights_7kHz_lowpass[] = {0.2, 2.0};
|
|
|
|
double *calc_coefficients_7kHz_lowpass(int rate)
|
|
{
|
|
double *result = (double *)malloc(32*sizeof(double));
|
|
double bands[4];
|
|
|
|
bands[0] = 0.0; bands[1] = 6800.0/rate;
|
|
bands[2] = 8500.0/rate; bands[3] = 0.5;
|
|
|
|
remez(result, 32, 2, bands,
|
|
desired_7kHz_lowpass, weights_7kHz_lowpass, BANDPASS);
|
|
|
|
return result;
|
|
}
|
|
|
|
#if 0
|
|
|
|
static double desired_125Hz_lowpass[] = {1.0, 0.0};
|
|
static double weights_125Hz_lowpass[] = {0.2, 2.0};
|
|
|
|
double *calc_coefficients_125Hz_lowpass(int rate)
|
|
{
|
|
double *result = (double *)malloc(256*sizeof(double));
|
|
double bands[4];
|
|
|
|
bands[0] = 0.0; bands[1] = 125.0/rate;
|
|
bands[2] = 175.0/rate; bands[3] = 0.5;
|
|
|
|
remez(result, 256, 2, bands,
|
|
desired_125Hz_lowpass, weights_125Hz_lowpass, BANDPASS);
|
|
|
|
return result;
|
|
}
|
|
|
|
#endif
|
|
|
|
int16_t firfilter(int16_t *buf, int pos, int len, int count, double *coefficients)
|
|
{
|
|
double result = 0.0;
|
|
int count1, count2;
|
|
int16_t *ptr;
|
|
|
|
if (pos >= count) {
|
|
pos -= count;
|
|
count1 = count; count2 = 0;
|
|
}
|
|
else {
|
|
count2 = pos;
|
|
count1 = count - pos;
|
|
pos = len - count1;
|
|
}
|
|
//fprintf(stderr, "pos=%d, count1=%d, count2=%d\n", pos, count1, count2);
|
|
|
|
// high part of window
|
|
ptr = &buf[pos];
|
|
while (count1--) result += *ptr++ * *coefficients++;
|
|
// wrapped part of window
|
|
while (count2--) result += *buf++ * *coefficients++;
|
|
return result;
|
|
}
|
|
|
|
void dump_filter_coefficients(double *coefficients)
|
|
{
|
|
int i;
|
|
fprintf(stderr, "pl_surround: Filter coefficients are: \n");
|
|
for (i=0; (i<32); i++) {
|
|
fprintf(stderr, " [%2d]: %23.20f\n", i, coefficients[i]);
|
|
}
|
|
}
|
|
|
|
#ifdef TESTING
|
|
|
|
#define PI 3.1415926536
|
|
|
|
// For testing purposes, fill a buffer with some sine-wave tone
|
|
void sinewave(int16_t *output, int samples, int incr, int freq, double phase, int samplerate)
|
|
{
|
|
double radians_per_sample = 2*PI / ((0.0+samplerate) / freq), r;
|
|
|
|
//fprintf(stderr, "samples=%d tone freq=%d, samplerate=%d, radians/sample=%f\n",
|
|
// samples, freq, samplerate, radians_per_sample);
|
|
r = phase;
|
|
while (samples--) {
|
|
*output = sin(r)*10000; output = &output[incr];
|
|
r += radians_per_sample;
|
|
}
|
|
}
|
|
|
|
// Pass various frequencies through a FIR filter and report amplitudes
|
|
void testfilter(double *coefficients, int count, int samplerate)
|
|
{
|
|
int16_t wavein[8192]; //, waveout[2048];
|
|
int sample, samples, maxsample, minsample, totsample;
|
|
int nyquist=samplerate/2;
|
|
int freq, i;
|
|
|
|
for (freq=25; freq<nyquist; freq+=25) {
|
|
// Make input tone
|
|
sinewave(wavein, 8192, 1, freq, 0.0, samplerate);
|
|
//for (i=0; i<32; i++)
|
|
// fprintf(stderr, "%5d\n", wavein[i]);
|
|
// Filter through the filter, measure results
|
|
maxsample=0; minsample=1000000; totsample=0; samples=0;
|
|
for (i=2048; i<8192; i++) {
|
|
//waveout[i] = wavein[i];
|
|
sample = abs(firfilter(wavein, i, 8192, count, coefficients));
|
|
if (sample > maxsample) maxsample=sample;
|
|
if (sample < minsample) minsample=sample;
|
|
totsample += sample; samples++;
|
|
}
|
|
// Report results
|
|
fprintf(stderr, "%5d %5d %5d %5d %f\n", freq, totsample/samples, maxsample, minsample, 10*log((totsample/samples)/6500.0));
|
|
}
|
|
}
|
|
|
|
#endif
|