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audiotestsrc: add red (brownian) noise generator

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Add another noise generator which produces a quite dark noise color.

Fixes parts of #649969.
This commit is contained in:
Stefan Kost 2011-05-25 23:40:26 +03:00
parent 4c8fd85e8e
commit 1cf831e74e
2 changed files with 62 additions and 5 deletions
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50
gst/audiotestsrc/gstaudiotestsrc.c
View file

@ -130,6 +130,7 @@ gst_audiostestsrc_wave_get_type (void)
{GST_AUDIO_TEST_SRC_WAVE_TICKS, "Periodic Ticks", "ticks"},
{GST_AUDIO_TEST_SRC_WAVE_GAUSSIAN_WHITE_NOISE, "White Gaussian noise",
"gaussian-noise"},
{GST_AUDIO_TEST_SRC_WAVE_RED_NOISE, "Red (brownian) noise", "red-noise"},
{0, NULL, NULL},
};
@ -837,6 +838,49 @@ static const ProcessFunc gaussian_white_noise_funcs[] = {
(ProcessFunc) gst_audio_test_src_create_gaussian_white_noise_double
};
/* Brownian (Red) Noise: noise where the power density decreases by 6 dB per
* octave with increasing frequency
*
* taken from http://vellocet.com/dsp/noise/VRand.html
* by Andrew Simper of Vellocet (andy@vellocet.com)
*/
#define DEFINE_RED_NOISE(type,scale) \
static void \
gst_audio_test_src_create_red_noise_##type (GstAudioTestSrc * src, g##type * samples) \
{ \
gint i, c; \
gdouble amp = (src->volume * scale); \
gdouble state = src->red.state; \
\
for (i = 0; i < src->generate_samples_per_buffer * src->channels; ) { \
for (c = 0; c < src->channels; ++c) { \
while (TRUE) { \
gdouble r = g_rand_double_range (src->gen, -1.0, 1.0); \
state += r; \
if (state<-8.0f || state>8.0f) state -= r; \
else break; \
} \
samples[i++] = (g##type) (amp * state * 0.0625f); /* /16.0 */ \
} \
} \
src->red.state = state; \
}
DEFINE_RED_NOISE (int16, 32767.0);
DEFINE_RED_NOISE (int32, 2147483647.0);
DEFINE_RED_NOISE (float, 1.0);
DEFINE_RED_NOISE (double, 1.0);
static const ProcessFunc red_noise_funcs[] = {
(ProcessFunc) gst_audio_test_src_create_red_noise_int16,
(ProcessFunc) gst_audio_test_src_create_red_noise_int32,
(ProcessFunc) gst_audio_test_src_create_red_noise_float,
(ProcessFunc) gst_audio_test_src_create_red_noise_double
};
/*
* gst_audio_test_src_change_wave:
* Assign function pointer of wave genrator.
@ -889,6 +933,12 @@ gst_audio_test_src_change_wave (GstAudioTestSrc * src)
src->gen = g_rand_new ();
src->process = gaussian_white_noise_funcs[src->format];
break;
case GST_AUDIO_TEST_SRC_WAVE_RED_NOISE:
if (!(src->gen))
src->gen = g_rand_new ();
src->red.state = 0.0;
src->process = red_noise_funcs[src->format];
break;
default:
GST_ERROR ("invalid wave-form");
break;

17
gst/audiotestsrc/gstaudiotestsrc.h
View file

@ -50,6 +50,7 @@ G_BEGIN_DECLS
* @GST_AUDIO_TEST_SRC_WAVE_SINE_TAB: sine wave using a table
* @GST_AUDIO_TEST_SRC_WAVE_TICKS: periodic ticks
* @GST_AUDIO_TEST_SRC_WAVE_GAUSSIAN_WHITE_NOISE: white (zero mean) Gaussian noise; volume sets the standard deviation of the noise in units of the range of values of the sample type, e.g. volume=0.1 produces noise with a standard deviation of 0.1*32767=3277 with 16-bit integer samples, or 0.1*1.0=0.1 with floating-point samples.
* @GST_AUDIO_TEST_SRC_WAVE_RED_NOISE: red (brownian) noise
*
* Different types of supported sound waves.
*/
@ -63,8 +64,9 @@ typedef enum {
GST_AUDIO_TEST_SRC_WAVE_PINK_NOISE,
GST_AUDIO_TEST_SRC_WAVE_SINE_TAB,
GST_AUDIO_TEST_SRC_WAVE_TICKS,
GST_AUDIO_TEST_SRC_WAVE_GAUSSIAN_WHITE_NOISE
} GstAudioTestSrcWave;
GST_AUDIO_TEST_SRC_WAVE_GAUSSIAN_WHITE_NOISE,
GST_AUDIO_TEST_SRC_WAVE_RED_NOISE
} GstAudioTestSrcWave;
#define PINK_MAX_RANDOM_ROWS (30)
#define PINK_RANDOM_BITS (16)
@ -78,6 +80,10 @@ typedef struct {
gdouble scalar; /* Used to scale within range of -1.0 to +1.0 */
} GstPinkNoise;
typedef struct {
gdouble state; /* noise state */
} GstRedNoise;
typedef enum {
GST_AUDIO_TEST_SRC_FORMAT_NONE = -1,
GST_AUDIO_TEST_SRC_FORMAT_S16 = 0,
@ -105,14 +111,14 @@ struct _GstAudioTestSrc {
GstAudioTestSrcWave wave;
gdouble volume;
gdouble freq;
/* audio parameters */
gint channels;
gint samplerate;
gint samples_per_buffer;
gint sample_size;
GstAudioTestSrcFormat format;
/*< private >*/
gboolean tags_pushed; /* send tags just once ? */
GstClockTimeDiff timestamp_offset; /* base offset */
@ -125,11 +131,12 @@ struct _GstAudioTestSrc {
gint generate_samples_per_buffer; /* used to generate a partial buffer */
gboolean can_activate_pull;
gboolean reverse; /* play backwards */
/* waveform specific context data */
GRand *gen; /* random number generator */
gdouble accumulator; /* phase angle */
GstPinkNoise pink;
GstRedNoise red;
gdouble wave_table[1024];
};