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author | steve <steve@b3059339-0415-0410-9bf9-f77b7e298cf2> | 2001-12-14 21:25:49 +0000 |
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committer | steve <steve@b3059339-0415-0410-9bf9-f77b7e298cf2> | 2001-12-14 21:25:49 +0000 |
commit | d6d9a909f05c124098f92e74b2fb2fca31e4e534 (patch) | |
tree | 828fd8f49eea23d7295042363f6aa1de0dd9a6c9 /libao2/firfilter.c | |
parent | 3ea29912ef6367871359b6d2d66f23a1fc4e9c5c (diff) | |
download | mpv-d6d9a909f05c124098f92e74b2fb2fca31e4e534.tar.bz2 mpv-d6d9a909f05c124098f92e74b2fb2fca31e4e534.tar.xz |
tweaked surround lowpass filter, included some new test code
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@3496 b3059339-0415-0410-9bf9-f77b7e298cf2
Diffstat (limited to 'libao2/firfilter.c')
-rw-r--r-- | libao2/firfilter.c | 80 |
1 files changed, 71 insertions, 9 deletions
diff --git a/libao2/firfilter.c b/libao2/firfilter.c index 9a44018a0e..ff4c1d33cd 100644 --- a/libao2/firfilter.c +++ b/libao2/firfilter.c @@ -1,6 +1,8 @@ +#include <math.h> + static double desired_7kHz_lowpass[] = {1.0, 0.0}; -static double weights_7kHz_lowpass[] = {0.1, 0.1}; +static double weights_7kHz_lowpass[] = {0.2, 2.0}; double *calc_coefficients_7kHz_lowpass(int rate) { @@ -18,16 +20,20 @@ double *calc_coefficients_7kHz_lowpass(int rate) #if 0 -int16_t firfilter(int16_t *buf, int pos, int len, int count, double *coefficients) +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 = 0.0; + 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); - // Back 32 samples, maybe wrapping in buffer. - pos = (pos+len-count)%len; - // And do the multiply-accumulate - while (count--) { - result += buf[pos++] * *coefficients++; pos %= len; - } return result; } @@ -57,3 +63,59 @@ int16_t firfilter(int16_t *buf, int pos, int len, int count, double *coefficient 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 |