Mercurial > hg > audiostuff
diff spandsp-0.0.6pre17/tests/noise_tests.c @ 4:26cd8f1ef0b1
import spandsp-0.0.6pre17
author | Peter Meerwald <pmeerw@cosy.sbg.ac.at> |
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date | Fri, 25 Jun 2010 15:50:58 +0200 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/spandsp-0.0.6pre17/tests/noise_tests.c Fri Jun 25 15:50:58 2010 +0200 @@ -0,0 +1,238 @@ +/* + * SpanDSP - a series of DSP components for telephony + * + * noise_tests.c + * + * Written by Steve Underwood <steveu@coppice.org> + * + * Copyright (C) 2005 Steve Underwood + * + * All rights reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2, as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + * + * $Id: noise_tests.c,v 1.18 2009/05/30 15:23:14 steveu Exp $ + */ + +/*! \page noise_tests_page Noise generator tests +\section noise_tests_page_sec_1 What does it do? +*/ + +#if defined(HAVE_CONFIG_H) +#include "config.h" +#endif + +#include <stdlib.h> +#include <stdio.h> +#include <string.h> +#include <sndfile.h> + +//#if defined(WITH_SPANDSP_INTERNALS) +#define SPANDSP_EXPOSE_INTERNAL_STRUCTURES +//#endif + +#include "spandsp.h" +#include "spandsp-sim.h" + +#if !defined(M_PI) +# define M_PI 3.14159265358979323846 /* pi */ +#endif + +#define OUT_FILE_NAME "noise.wav" + +/* Some simple sanity tests for the noise generation routines */ + +int main (int argc, char *argv[]) +{ + int i; + int j; + int level; + int clip_high; + int clip_low; + int quality; + int total_samples; + int seed = 1234567; + int outframes; + int16_t value; + double total; + double x; + double p; + double o; + int bins[65536]; + int16_t amp[1024]; + noise_state_t noise_source; + SNDFILE *outhandle; + + if ((outhandle = sf_open_telephony_write(OUT_FILE_NAME, 1)) == NULL) + { + fprintf(stderr, " Cannot create audio file '%s'\n", OUT_FILE_NAME); + exit(2); + } + + for (quality = 7; quality <= 20; quality += (20 - 7)) + { + /* Generate AWGN at several RMS levels between -50dBOv and 0dBOv. Noise is + generated for a large number of samples (1,000,000), and the RMS value + of the noise is calculated along the way. If the resulting level is + close to the requested RMS level, at least the scaling of the noise + should be Ok. At high levels some clipping may distort the result a + little. */ + printf("Testing AWGN power, with quality %d\n", quality); + for (level = -50; level <= 0; level += 5) + { + clip_high = 0; + clip_low = 0; + total = 0.0; + noise_init_dbov(&noise_source, seed, (float) level, NOISE_CLASS_AWGN, quality); + total_samples = 1000000; + for (i = 0; i < total_samples; i++) + { + value = noise(&noise_source); + if (value == 32767) + clip_high++; + else if (value == -32768) + clip_low++; + total += ((double) value)*((double) value); + } + printf ("RMS = %.3f (expected %d) %.2f%% error [clipped samples %d+%d]\n", + log10(sqrt(total/total_samples)/32768.0)*20.0, + level, + 100.0*(1.0 - sqrt(total/total_samples)/(pow(10.0, level/20.0)*32768.0)), + clip_low, + clip_high); + if (level < -5 && fabs(log10(sqrt(total/total_samples)/32768.0)*20.0 - level) > 0.2) + { + printf("Test failed\n"); + exit(2); + } + } + } + + /* Now look at the statistical spread of the results, by collecting data in + bins from a large number of samples. Use a fairly high noise level, but + low enough to avoid significant clipping. Use the Gaussian model to + predict the real probability, and present the results for graphing. */ + quality = 7; + printf("Testing the statistical spread of AWGN, with quality %d\n", quality); + memset(bins, 0, sizeof(bins)); + clip_high = 0; + clip_low = 0; + level = -15; + noise_init_dbov(&noise_source, seed, (float) level, NOISE_CLASS_AWGN, quality); + total_samples = 10000000; + for (i = 0; i < total_samples; i++) + { + value = noise(&noise_source); + if (value == 32767) + clip_high++; + else if (value == -32768) + clip_low++; + bins[value + 32768]++; + } + /* Find the RMS power level to expect */ + o = pow(10.0, level/20.0)*(32768.0*0.70711); + for (i = 0; i < 65536 - 10; i++) + { + x = i - 32768; + /* Find the real probability for this bin */ + p = (1.0/(o*sqrt(2.0*M_PI)))*exp(-(x*x)/(2.0*o*o)); + /* Now do a little smoothing on the real data to get a reasonably + steady answer */ + x = 0; + for (j = 0; j < 10; j++) + x += bins[i + j]; + x /= 10.0; + x /= total_samples; + /* Now send it out for graphing. */ + if (p > 0.0000001) + printf("%6d %.7f %.7f\n", i - 32768, x, p); + } + + printf("Generating AWGN at -15dBOv to file\n"); + for (j = 0; j < 50; j++) + { + for (i = 0; i < 1024; i++) + amp[i] = noise(&noise_source); + outframes = sf_writef_short(outhandle, amp, 1024); + if (outframes != 1024) + { + fprintf(stderr, " Error writing audio file\n"); + exit(2); + } + } + + /* Generate Hoth noise at several RMS levels between -50dBm and 0dBm. Noise + is generated for a large number of samples (1,000,000), and the RMS value + of the noise is calculated along the way. If the resulting level is + close to the requested RMS level, at least the scaling of the noise + should be Ok. At high levels some clipping may distort the result a + little. */ + quality = 7; + printf("Testing Hoth noise power, with quality %d\n", quality); + for (level = -50; level <= 0; level += 5) + { + clip_high = 0; + clip_low = 0; + total = 0.0; + noise_init_dbov(&noise_source, seed, (float) level, NOISE_CLASS_HOTH, quality); + total_samples = 1000000; + for (i = 0; i < total_samples; i++) + { + value = noise(&noise_source); + if (value == 32767) + clip_high++; + else if (value == -32768) + clip_low++; + total += ((double) value)*((double) value); + } + printf ("RMS = %.3f (expected %d) %.2f%% error [clipped samples %d+%d]\n", + log10(sqrt(total/total_samples)/32768.0)*20.0, + level, + 100.0*(1.0 - sqrt(total/total_samples)/(pow(10.0, level/20.0)*32768.0)), + clip_low, + clip_high); + if (level < -5 && fabs(log10(sqrt(total/total_samples)/32768.0)*20.0 - level) > 0.2) + { + printf("Test failed\n"); + exit(2); + } + } + + quality = 7; + printf("Generating Hoth noise at -15dBOv to file\n"); + level = -15; + noise_init_dbov(&noise_source, seed, (float) level, NOISE_CLASS_HOTH, quality); + for (j = 0; j < 50; j++) + { + for (i = 0; i < 1024; i++) + amp[i] = noise(&noise_source); + outframes = sf_writef_short(outhandle, amp, 1024); + if (outframes != 1024) + { + fprintf(stderr, " Error writing audio file\n"); + exit(2); + } + } + + if (sf_close(outhandle)) + { + fprintf(stderr, " Cannot close audio file '%s'\n", OUT_FILE_NAME); + exit(2); + } + + printf("Tests passed.\n"); + return 0; +} +/*- End of function --------------------------------------------------------*/ +/*- End of file ------------------------------------------------------------*/