static void
gst_audio_iir_filter_update_coefficients (GstAudioIIRFilter * self,
GValueArray * va, GValueArray * vb)
{
gdouble *a = NULL, *b = NULL;
guint i;
if (va) {
if (self->a)
g_value_array_free (self->a);
self->a = va;
}
if (vb) {
if (self->b)
g_value_array_free (self->b);
self->b = vb;
}
if (self->a && self->a->n_values > 0) {
a = g_new (gdouble, self->a->n_values);
for (i = 0; i < self->a->n_values; i++) {
GValue *v = g_value_array_get_nth (self->a, i);
a[i] = g_value_get_double (v);
}
}
if (self->b && self->b->n_values > 0) {
b = g_new (gdouble, self->b->n_values);
for (i = 0; i < self->b->n_values; i++) {
GValue *v = g_value_array_get_nth (self->b, i);
b[i] = g_value_get_double (v);
}
}
gst_audio_fx_base_iir_filter_set_coefficients (GST_AUDIO_FX_BASE_IIR_FILTER
(self), a, (self->a) ? self->a->n_values : 0, b,
(self->b) ? self->b->n_values : 0);
}
static void
generate_coefficients (GstAudioChebBand * filter)
{
if (GST_AUDIO_FILTER (filter)->format.rate == 0) {
gdouble *a = g_new0 (gdouble, 1);
a[0] = 1.0;
gst_audio_fx_base_iir_filter_set_coefficients (GST_AUDIO_FX_BASE_IIR_FILTER
(filter), a, 1, NULL, 0);
GST_LOG_OBJECT (filter, "rate was not set yet");
return;
}
if (filter->upper_frequency <= filter->lower_frequency) {
gdouble *a = g_new0 (gdouble, 1);
a[0] = (filter->mode == MODE_BAND_PASS) ? 0.0 : 1.0;
gst_audio_fx_base_iir_filter_set_coefficients (GST_AUDIO_FX_BASE_IIR_FILTER
(filter), a, 1, NULL, 0);
GST_LOG_OBJECT (filter, "frequency band had no or negative dimension");
return;
}
if (filter->upper_frequency > GST_AUDIO_FILTER (filter)->format.rate / 2) {
filter->upper_frequency = GST_AUDIO_FILTER (filter)->format.rate / 2;
GST_LOG_OBJECT (filter, "clipped upper frequency to nyquist frequency");
}
if (filter->lower_frequency < 0.0) {
filter->lower_frequency = 0.0;
GST_LOG_OBJECT (filter, "clipped lower frequency to 0.0");
}
/* Calculate coefficients for the chebyshev filter */
{
gint np = filter->poles;
gdouble *a, *b;
gint i, p;
a = g_new0 (gdouble, np + 5);
b = g_new0 (gdouble, np + 5);
/* Calculate transfer function coefficients */
a[4] = 1.0;
b[4] = 1.0;
for (p = 1; p <= np / 4; p++) {
gdouble a0, a1, a2, a3, a4, b1, b2, b3, b4;
gdouble *ta = g_new0 (gdouble, np + 5);
gdouble *tb = g_new0 (gdouble, np + 5);
generate_biquad_coefficients (filter, p, &a0, &a1, &a2, &a3, &a4, &b1,
&b2, &b3, &b4);
memcpy (ta, a, sizeof (gdouble) * (np + 5));
memcpy (tb, b, sizeof (gdouble) * (np + 5));
/* add the new coefficients for the new two poles
* to the cascade by multiplication of the transfer
* functions */
for (i = 4; i < np + 5; i++) {
a[i] =
a0 * ta[i] + a1 * ta[i - 1] + a2 * ta[i - 2] + a3 * ta[i - 3] +
a4 * ta[i - 4];
b[i] =
tb[i] - b1 * tb[i - 1] - b2 * tb[i - 2] - b3 * tb[i - 3] -
b4 * tb[i - 4];
}
g_free (ta);
g_free (tb);
}
/* Move coefficients to the beginning of the array
* and multiply the b coefficients with -1 to move from
* the transfer function's coefficients to the difference
* equation's coefficients */
b[4] = 0.0;
for (i = 0; i <= np; i++) {
a[i] = a[i + 4];
b[i] = -b[i + 4];
}
/* Normalize to unity gain at frequency 0 and frequency
* 0.5 for bandreject and unity gain at band center frequency
* for bandpass */
if (filter->mode == MODE_BAND_REJECT) {
/* gain is sqrt(H(0)*H(0.5)) */
gdouble gain1 =
gst_audio_fx_base_iir_filter_calculate_gain (a, np + 1, b, np + 1,
1.0, 0.0);
gdouble gain2 =
gst_audio_fx_base_iir_filter_calculate_gain (a, np + 1, b, np + 1,
-1.0, 0.0);
gain1 = sqrt (gain1 * gain2);
for (i = 0; i <= np; i++) {
a[i] /= gain1;
}
} else {
/* gain is H(wc), wc = center frequency */
gdouble w1 =
2.0 * G_PI * (filter->lower_frequency /
GST_AUDIO_FILTER (filter)->format.rate);
gdouble w2 =
2.0 * G_PI * (filter->upper_frequency /
GST_AUDIO_FILTER (filter)->format.rate);
gdouble w0 = (w2 + w1) / 2.0;
gdouble zr = cos (w0), zi = sin (w0);
gdouble gain =
gst_audio_fx_base_iir_filter_calculate_gain (a, np + 1, b, np + 1, zr,
zi);
for (i = 0; i <= np; i++) {
a[i] /= gain;
}
}
gst_audio_fx_base_iir_filter_set_coefficients (GST_AUDIO_FX_BASE_IIR_FILTER
(filter), a, np + 1, b, np + 1);
GST_LOG_OBJECT (filter,
"Generated IIR coefficients for the Chebyshev filter");
GST_LOG_OBJECT (filter,
"mode: %s, type: %d, poles: %d, lower-frequency: %.2f Hz, upper-frequency: %.2f Hz, ripple: %.2f dB",
(filter->mode == MODE_BAND_PASS) ? "band-pass" : "band-reject",
filter->type, filter->poles, filter->lower_frequency,
filter->upper_frequency, filter->ripple);
GST_LOG_OBJECT (filter, "%.2f dB gain @ 0Hz",
20.0 * log10 (gst_audio_fx_base_iir_filter_calculate_gain (a, np + 1, b,
np + 1, 1.0, 0.0)));
{
gdouble w1 =
2.0 * G_PI * (filter->lower_frequency /
GST_AUDIO_FILTER (filter)->format.rate);
gdouble w2 =
2.0 * G_PI * (filter->upper_frequency /
GST_AUDIO_FILTER (filter)->format.rate);
gdouble w0 = (w2 + w1) / 2.0;
gdouble zr, zi;
zr = cos (w1);
zi = sin (w1);
GST_LOG_OBJECT (filter, "%.2f dB gain @ %dHz",
20.0 * log10 (gst_audio_fx_base_iir_filter_calculate_gain (a, np + 1,
b, np + 1, zr, zi)), (int) filter->lower_frequency);
zr = cos (w0);
zi = sin (w0);
GST_LOG_OBJECT (filter, "%.2f dB gain @ %dHz",
20.0 * log10 (gst_audio_fx_base_iir_filter_calculate_gain (a, np + 1,
b, np + 1, zr, zi)),
(int) ((filter->lower_frequency + filter->upper_frequency) / 2.0));
zr = cos (w2);
zi = sin (w2);
GST_LOG_OBJECT (filter, "%.2f dB gain @ %dHz",
20.0 * log10 (gst_audio_fx_base_iir_filter_calculate_gain (a, np + 1,
b, np + 1, zr, zi)), (int) filter->upper_frequency);
}
GST_LOG_OBJECT (filter, "%.2f dB gain @ %dHz",
20.0 * log10 (gst_audio_fx_base_iir_filter_calculate_gain (a, np + 1, b,
np + 1, -1.0, 0.0)),
GST_AUDIO_FILTER (filter)->format.rate / 2);
}
}
