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speaker-test: Add bandwidth-limited pink noise at -18.5dB AES FS Based

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Closes: https://github.com/alsa-project/alsa-utils/pull/251
Signed-off-by: Rick Sayre <whorfin@gmail.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Rick Sayre 2023-12-30 19:11:48 -08:00 committed by Jaroslav Kysela
parent 6da3737bd4
commit e523020eb8
5 changed files with 272 additions and 19 deletions
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4
speaker-test/Makefile.am
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@ -3,7 +3,7 @@ SUBDIRS= samples
LDADD = $(LIBINTL) -lm LDADD = $(LIBINTL) -lm
bin_PROGRAMS = speaker-test bin_PROGRAMS = speaker-test
speaker_test_SOURCES = speaker-test.c pink.c speaker_test_SOURCES = speaker-test.c pink.c st2095.c
man_MANS = speaker-test.1 man_MANS = speaker-test.1
EXTRA_DIST = readme.txt speaker-test.1 pink.h EXTRA_DIST = readme.txt speaker-test.1 pink.h st2095.h

9
speaker-test/speaker-test.1
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@ -94,11 +94,17 @@ Use number of periods. The default value is 4.
stream of \fIRATE\fP Hz stream of \fIRATE\fP Hz
.TP .TP
\fB\-t\fP | \fB\-\-test\fP \fBpink\fP|\fBsine\fP|\fBwav\fP \fB\-t\fP | \fB\-\-test\fP \fBpink\fP|\fBst2095\fP|\fBsine\fP|\fBwav\fP
\fB\-t pink\fP means use pink noise (default). \fB\-t pink\fP means use pink noise (default).
Pink noise is perceptually uniform noise -- that is, it sounds like every frequency at once. If you can hear any tone it may indicate resonances in your speaker system or room. Pink noise is perceptually uniform noise -- that is, it sounds like every frequency at once. If you can hear any tone it may indicate resonances in your speaker system or room.
\fB\-t st2095\fP means use bandlimited pink noise at -18.5dB AES FS, generated according to SMPTE ST-2095:1-2015.
In addition to speaker localization it may be used for system calibration, for example 85dB for thater drivers, with an extra +10dB for subwoofers.
Per the spec, it is intended "to be used in calibrating the sound pressure level and
electroacoustic response of a cinema B-chain system."
Note that sampling rates less than 48KHz are outside the scope of the spec, and an attempt will be made to construct a reduced rate filter.
\fB\-t sine\fP means to use sine wave. \fB\-t sine\fP means to use sine wave.
\fB\-t wav\fP means to play WAV files, either pre-defined files or given via \fB\-w\fP option. \fB\-t wav\fP means to play WAV files, either pre-defined files or given via \fB\-w\fP option.
@ -180,3 +186,4 @@ Play in the order of front\-right and front-left from the front PCM
The speaker\-test program was written by James Courtier-Dutton. The speaker\-test program was written by James Courtier-Dutton.
Pink noise support was added by Nathan Hurst. Pink noise support was added by Nathan Hurst.
Further extensions by Takashi Iwai. Further extensions by Takashi Iwai.
SMPTE ST-2095:1 band-limited pink noise added by Rick Sayre.

71
speaker-test/speaker-test.c
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@ -25,8 +25,13 @@
* Some cleanup from Daniel Caujolle-Bert <segfault@club-internet.fr> * Some cleanup from Daniel Caujolle-Bert <segfault@club-internet.fr>
* Pink noise option added Nathan Hurst, * Pink noise option added Nathan Hurst,
* based on generator by Phil Burk (pink.c) * based on generator by Phil Burk (pink.c)
* ST-2095 noise option added Rick Sayre,
* based on generator specified by SMPTE ST-2095:1-2015
* Also switched to stable harmonic oscillator for sine
* *
* Changelog: * Changelog:
* 0.0.9 Added support for ST-2095 band-limited pink noise output, switched to harmonic oscillator for sine
* Changelog:
* 0.0.8 Added support for pink noise output. * 0.0.8 Added support for pink noise output.
* Changelog: * Changelog:
* 0.0.7 Added support for more than 6 channels. * 0.0.7 Added support for more than 6 channels.
@ -55,6 +60,7 @@
#include <sys/time.h> #include <sys/time.h>
#include <math.h> #include <math.h>
#include "pink.h" #include "pink.h"
#include "st2095.h"
#include "gettext.h" #include "gettext.h"
#include "version.h" #include "version.h"
#include "os_compat.h" #include "os_compat.h"
@ -71,6 +77,7 @@ enum {
TEST_PINK_NOISE = 1, TEST_PINK_NOISE = 1,
TEST_SINE, TEST_SINE,
TEST_WAV, TEST_WAV,
TEST_ST2095_NOISE,
TEST_PATTERN, TEST_PATTERN,
}; };
@ -373,16 +380,17 @@ static void do_generate(uint8_t *frames, int channel, int count,
* Sine generator * Sine generator
*/ */
typedef struct { typedef struct {
double phase; double a;
double max_phase; double s;
double step; double c;
} sine_t; } sine_t;
static void init_sine(sine_t *sine) static void init_sine(sine_t *sine)
{ {
sine->phase = 0; // symplectic integration for fast, stable harmonic oscillator
sine->max_phase = 1.0 / freq; sine->a = 2.0*M_PI * freq / rate;
sine->step = 1.0 / (double)rate; sine->c = 1.0;
sine->s = 0.0;
} }
static value_t generate_sine(void *arg) static value_t generate_sine(void *arg)
@ -390,13 +398,13 @@ static value_t generate_sine(void *arg)
sine_t *sine = arg; sine_t *sine = arg;
value_t res; value_t res;
res.f = sin((sine->phase * 2 * M_PI) / sine->max_phase - M_PI); res.f = sine->s * generator_scale;
res.f *= generator_scale;
if (format != SND_PCM_FORMAT_FLOAT_LE) if (format != SND_PCM_FORMAT_FLOAT_LE)
res.i = res.f * INT32_MAX; res.i = res.f * INT32_MAX;
sine->phase += sine->step;
if (sine->phase >= sine->max_phase) // update the oscillator
sine->phase -= sine->max_phase; sine->c -= sine->a * sine->s;
sine->s += sine->a * sine->c;
return res; return res;
} }
@ -414,6 +422,20 @@ static value_t generate_pink_noise(void *arg)
return res; return res;
} }
/* Band-Limited Pink Noise, per SMPTE ST 2095-1
* beyond speaker localization, this can be used for setting loudness to standard
*/
static value_t generate_st2095_noise(void *arg)
{
st2095_noise_t *st2095 = arg;
value_t res;
res.f = generate_st2095_noise_sample(st2095);
if (format != SND_PCM_FORMAT_FLOAT_LE)
res.i = res.f * INT32_MAX;
return res;
}
/* /*
* useful for tests * useful for tests
*/ */
@ -853,10 +875,14 @@ static int write_buffer(snd_pcm_t *handle, uint8_t *ptr, int cptr)
static int pattern; static int pattern;
static sine_t sine; static sine_t sine;
static pink_noise_t pink; static pink_noise_t pink;
static st2095_noise_t st2095;
static void init_loop(void) static void init_loop(void)
{ {
switch (test_type) { switch (test_type) {
case TEST_ST2095_NOISE:
initialize_st2095_noise(&st2095, rate);
break;
case TEST_PINK_NOISE: case TEST_PINK_NOISE:
initialize_pink_noise(&pink, 16); initialize_pink_noise(&pink, 16);
break; break;
@ -901,7 +927,12 @@ static int write_loop(snd_pcm_t *handle, int channel, int periods, uint8_t *fram
do_generate(frames, channel, period_size, generate_pink_noise, &pink); do_generate(frames, channel, period_size, generate_pink_noise, &pink);
else if (test_type == TEST_PATTERN) else if (test_type == TEST_PATTERN)
do_generate(frames, channel, period_size, generate_pattern, &pattern); do_generate(frames, channel, period_size, generate_pattern, &pattern);
else else if (test_type == TEST_ST2095_NOISE) {
reset_st2095_noise_measurement(&st2095);
do_generate(frames, channel, period_size, generate_st2095_noise, &st2095);
printf(_("\tSMPTE ST-2095 noise batch was %2.2fdB RMS\n"),
compute_st2095_noise_measurement(&st2095, period_size));
} else
do_generate(frames, channel, period_size, generate_sine, &sine); do_generate(frames, channel, period_size, generate_sine, &sine);
if ((err = write_buffer(handle, frames, period_size)) < 0) if ((err = write_buffer(handle, frames, period_size)) < 0)
@ -953,7 +984,7 @@ static void help(void)
"-b,--buffer ring buffer size in us\n" "-b,--buffer ring buffer size in us\n"
"-p,--period period size in us\n" "-p,--period period size in us\n"
"-P,--nperiods number of periods\n" "-P,--nperiods number of periods\n"
"-t,--test pink=use pink noise, sine=use sine wave, wav=WAV file\n" "-t,--test pink=use pink noise, sine=use sine wave, st2095=use SMPTE ST-2095 noise, wav=WAV file\n"
"-l,--nloops specify number of loops to test, 0 = infinite\n" "-l,--nloops specify number of loops to test, 0 = infinite\n"
"-s,--speaker single speaker test. Values 1=Left, 2=right, etc\n" "-s,--speaker single speaker test. Values 1=Left, 2=right, etc\n"
"-w,--wavfile Use the given WAV file as a test sound\n" "-w,--wavfile Use the given WAV file as a test sound\n"
@ -1082,9 +1113,16 @@ int main(int argc, char *argv[]) {
case 't': case 't':
if (*optarg == 'p') if (*optarg == 'p')
test_type = TEST_PINK_NOISE; test_type = TEST_PINK_NOISE;
else if (*optarg == 's') else if (*optarg == 's') {
if (optarg[1] == 'i')
test_type = TEST_SINE; test_type = TEST_SINE;
else if (*optarg == 'w') else if (optarg[1] == 't')
test_type = TEST_ST2095_NOISE;
else {
fprintf(stderr, _("Invalid test type %s\n"), optarg);
exit(1);
}
} else if (*optarg == 'w')
test_type = TEST_WAV; test_type = TEST_WAV;
else if (*optarg == 't') else if (*optarg == 't')
test_type = TEST_PATTERN; test_type = TEST_PATTERN;
@ -1160,6 +1198,9 @@ int main(int argc, char *argv[]) {
printf(_("Playback device is %s\n"), device); printf(_("Playback device is %s\n"), device);
printf(_("Stream parameters are %iHz, %s, %i channels\n"), rate, snd_pcm_format_name(format), channels); printf(_("Stream parameters are %iHz, %s, %i channels\n"), rate, snd_pcm_format_name(format), channels);
switch (test_type) { switch (test_type) {
case TEST_ST2095_NOISE:
printf(_("Using SMPTE ST-2095 -18.5dB AES FS band-limited pink noise\n"));
break;
case TEST_PINK_NOISE: case TEST_PINK_NOISE:
printf(_("Using 16 octaves of pink noise\n")); printf(_("Using 16 octaves of pink noise\n"));
break; break;

164
speaker-test/st2095.c Normal file
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@ -0,0 +1,164 @@
/*
st2095.c
Generate Bandlimited Pink Noise (-18.5dB AES FS)
Using the SMPTE ST 2095:1-2015 standard
Based on pseudo-code from the above SMPTE standard, which bore the credit
"Revised 2015-01-04 by Calvert Dayton"
Copyleft 2023 Rick Sayre - No rights reserved.
*/
#include "aconfig.h"
#include <stdio.h>
#include <math.h>
#include "st2095.h"
/************************************************************/
void reset_st2095_noise_measurement( st2095_noise_t *st2095 ) {
st2095->accum = 0.;
}
float compute_st2095_noise_measurement( st2095_noise_t *st2095, int period ) {
return(10. * log10f(st2095->accum / (float)period) + 3.01);
}
void initialize_st2095_noise( st2095_noise_t *st2095, int sample_rate) {
// Periodicity in samples must be a power of two, <= 2^31
// Typical values are 524288, 1048576, 2097152 or 4194304
if (sample_rate > 48000) {
// Special case LCG step for 1024K samples @ 88.2K or 96k
st2095->samplesPerPeriod = 1048576;
st2095->randStep = 163841;
} else {
st2095->samplesPerPeriod = 524288;
st2095->randStep = 52737;
}
// set up LCG PRNG
st2095->randMax = st2095->samplesPerPeriod - 1;
st2095->seed = 0;
st2095->scaleFactor = 2.0 / (float)st2095->randMax;
st2095->maxAmp = powf(10.0, ST2095_MAX_PEAK / 20.0);
// Calculate omegaT for matched Z transform highpass filters
st2095->w0t = 2.0 * M_PI * ST2095_HPFC / (float)sample_rate;
// Limit LpFc <= Nyquist (actually lower, based on 48 vs 22.4 KHz spec cutoff)
// The spec says the filter begins at 22.4KHz, if we ask for a Nyquist-impossible
// sampling rate, compute something with the same relationship
st2095->LpFc = ST2095_LPFC;
float rateratio = 48000. / ST2095_LPFC;
if (st2095->LpFc > sample_rate/rateratio)
st2095->LpFc = sample_rate/rateratio;
// Calculate k and k^2 for bilinear transform lowpass filters
st2095->k = tanf(( 2.0 * M_PI * st2095->LpFc / (float)sample_rate ) / 2.0);
st2095->k2 = st2095->k * st2095->k;
// Calculate biquad coefficients for bandpass filter components
st2095->hp1_a1 = -2.0 * expf(-0.3826835 * st2095->w0t) * cosf(0.9238795 * st2095->w0t);
st2095->hp1_a2 = expf(2.0 * -0.3826835 * st2095->w0t);
st2095->hp1_b0 = (1.0 - st2095->hp1_a1 + st2095->hp1_a2) / 4.0;
st2095->hp1_b1 = -2.0 * st2095->hp1_b0;
st2095->hp1_b2 = st2095->hp1_b0;
st2095->hp2_a1 = -2.0 * expf(-0.9238795 * st2095->w0t) * cosf(0.3826835 * st2095->w0t);
st2095->hp2_a2 = expf(2.0 * -0.9238795 * st2095->w0t);
st2095->hp2_b0 = (1.0 - st2095->hp2_a1 + st2095->hp2_a2) / 4.0;
st2095->hp2_b1 = -2.0 * st2095->hp2_b0;
st2095->hp2_b2 = st2095->hp2_b0;
st2095->lp1_a1 = (2.0 * (st2095->k2 - 1.0)) / (st2095->k2 + (st2095->k / 1.306563) + 1.0);
st2095->lp1_a2 = (st2095->k2 - (st2095->k / 1.306563) + 1.0) / (st2095->k2 + (st2095->k / 1.306563) + 1.0);
st2095->lp1_b0 = st2095->k2 / (st2095->k2 + (st2095->k / 1.306563) + 1.0);
st2095->lp1_b1 = 2.0 * st2095->lp1_b0;
st2095->lp1_b2 = st2095->lp1_b0;
st2095->lp2_a1 = (2.0 * (st2095->k2 - 1.0)) / (st2095->k2 + (st2095->k / 0.541196) + 1.0);
st2095->lp2_a2 = (st2095->k2 - (st2095->k / 0.541196) + 1.0) / (st2095->k2 + (st2095->k / 0.541196) + 1.0);
st2095->lp2_b0 = st2095->k2 / (st2095->k2 + (st2095->k / 0.541196) + 1.0);
st2095->lp2_b1 = 2.0 * st2095->lp2_b0;
st2095->lp2_b2 = st2095->lp2_b0;
// initialize delay lines for bandpass filter
st2095->hp1w1 = 0.0;
st2095->hp1w2 = 0.0;
st2095->hp2w1 = 0.0;
st2095->hp2w2 = 0.0;
st2095->lp1w1 = 0.0;
st2095->lp1w2 = 0.0;
st2095->lp2w1 = 0.0;
st2095->lp2w2 = 0.0;
// initialize delay lines for pink filter network
st2095->lp1 = 0.0;
st2095->lp2 = 0.0;
st2095->lp3 = 0.0;
st2095->lp4 = 0.0;
st2095->lp5 = 0.0;
st2095->lp6 = 0.0;
// cycle the generator for one complete time series to populate filter-bank delay lines
for (int i=0; i<st2095->samplesPerPeriod; i++)
generate_st2095_noise_sample(st2095);
st2095->accum = 0.0;
}
float generate_st2095_noise_sample( st2095_noise_t *st2095 ) {
float white, w, pink;
// Generate a pseudorandom integer in the range 0 <= seed <= randMax.
//# Bitwise AND with randMax zeroes out any unwanted high order bits.
st2095->seed = (1664525 * st2095->seed + st2095->randStep) & st2095->randMax;
// Scale to a real number in the range -1.0 <= white <= 1.0
white = (float)st2095->seed * st2095->scaleFactor - 1.0;
// Run pink filter; a parallel network of first-order LP filters, scaled to
// produce an output signal with target RMS = -21.5 dB FS (-18.5 dB AES FS)
// when bandpass filter cutoff frequencies are 10 Hz and 22.4 kHz.
st2095->lp1 = 0.9994551 * st2095->lp1 + 0.00198166688621989 * white;
st2095->lp2 = 0.9969859 * st2095->lp2 + 0.00263702334184061 * white;
st2095->lp3 = 0.9844470 * st2095->lp3 + 0.00643213710202331 * white;
st2095->lp4 = 0.9161757 * st2095->lp4 + 0.01438952538362820 * white;
st2095->lp5 = 0.6563399 * st2095->lp5 + 0.02698408541064610 * white;
pink = st2095->lp1 + st2095->lp2 + st2095->lp3 +
st2095->lp4 + st2095->lp5 + st2095->lp6 + white * 0.0342675832159306;
st2095->lp6 = white * 0.0088766118009356;
// Run bandpass filter; a series network of 4 biquad filters
// Biquad filters implemented in Direct Form II
w = pink - st2095->hp1_a1 * st2095->hp1w1 - st2095->hp1_a2 * st2095->hp1w2;
pink = st2095->hp1_b0 * w + st2095->hp1_b1 * st2095->hp1w1 + st2095->hp1_b2 * st2095->hp1w2;
st2095->hp1w2 = st2095->hp1w1;
st2095->hp1w1 = w;
w = pink - st2095->hp2_a1 * st2095->hp2w1 - st2095->hp2_a2 * st2095->hp2w2;
pink = st2095->hp2_b0 * w + st2095->hp2_b1 * st2095->hp2w1 + st2095->hp2_b2 * st2095->hp2w2;
st2095->hp2w2 = st2095->hp2w1;
st2095->hp2w1 = w;
w = pink - st2095->lp1_a1 * st2095->lp1w1 - st2095->lp1_a2 * st2095->lp1w2;
pink = st2095->lp1_b0 * w + st2095->lp1_b1 * st2095->lp1w1 + st2095->lp1_b2 * st2095->lp1w2;
st2095->lp1w2 = st2095->lp1w1;
st2095->lp1w1 = w;
w = pink - st2095->lp2_a1 * st2095->lp2w1 - st2095->lp2_a2 * st2095->lp2w2;
pink = st2095->lp2_b0 * w + st2095->lp2_b1 * st2095->lp2w1 + st2095->lp2_b2 * st2095->lp2w2;
st2095->lp2w2 = st2095->lp2w1;
st2095->lp2w1 = w;
// Limit peaks to +/-MaxAmp
if (pink > st2095->maxAmp)
pink = st2095->maxAmp;
else if (pink < -st2095->maxAmp)
pink = -st2095->maxAmp;
// accumulate squared amplitude for RMS computation
st2095->accum += (pink * pink);
return(pink);
}

41
speaker-test/st2095.h Normal file
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@ -0,0 +1,41 @@
#define ST2095_MAX_PEAK -9.5 // dB
#define ST2095_HPFC 10.0 // Highpass filter cutoff in Hz
#define ST2095_LPFC 22400.0 // Lowpass filter cutoff in Hz
typedef struct
{
float maxAmp;
int samplesPerPeriod;
int randStep;
int randMax;
int seed;
float scaleFactor;
float w0t;
float k;
float k2;
float LpFc;
// biquad coefficients
float hp1_a1, hp1_a2;
float hp1_b0, hp1_b1, hp1_b2;
float hp2_a1, hp2_a2;
float hp2_b0, hp2_b1, hp2_b2;
float lp1_a1, lp1_a2;
float lp1_b0, lp1_b1, lp1_b2;
float lp2_a1, lp2_a2;
float lp2_b0, lp2_b1, lp2_b2;
// delay-line variables for bandpass filter
float hp1w1, hp1w2;
float hp2w1, hp2w2;
float lp1w1, lp1w2;
float lp2w1, lp2w2;
// delay-line variables for pink filter network
float lp1, lp2, lp3, lp4, lp5, lp6;
// statistics accumulator
float accum;
} st2095_noise_t;
void initialize_st2095_noise( st2095_noise_t *st2095, int sample_rate );
float generate_st2095_noise_sample( st2095_noise_t *st2095 );
void reset_st2095_noise_measurement( st2095_noise_t *st2095 );
float compute_st2095_noise_measurement( st2095_noise_t *st2095, int period );