diff options
| -rw-r--r-- | gst/equalizer/gstiirequalizer.c | 118 |
1 files changed, 70 insertions, 48 deletions
diff --git a/gst/equalizer/gstiirequalizer.c b/gst/equalizer/gstiirequalizer.c index dcd27c9f..8c87a664 100644 --- a/gst/equalizer/gstiirequalizer.c +++ b/gst/equalizer/gstiirequalizer.c @@ -83,7 +83,7 @@ enum { ARG_GAIN = 1, ARG_FREQ, - ARG_BAND_WIDTH + ARG_BANDWIDTH }; typedef struct _GstIirEqualizerBandClass GstIirEqualizerBandClass; @@ -110,9 +110,8 @@ struct _GstIirEqualizerBand gdouble width; /* second order iir filter */ - gdouble alpha; /* IIR coefficients for outputs */ - gdouble beta; /* IIR coefficients for inputs */ - gdouble gamma; /* IIR coefficients for inputs */ + gdouble b1, b2; /* IIR coefficients for outputs */ + gdouble a0, a1, a2; /* IIR coefficients for inputs */ }; struct _GstIirEqualizerBandClass @@ -148,7 +147,25 @@ gst_iir_equalizer_band_set_property (GObject * object, guint prop_id, } break; } - case ARG_BAND_WIDTH:{ + case ARG_FREQ:{ + gdouble freq; + + freq = g_value_get_double (value); + GST_DEBUG_OBJECT (band, "freq = %lf -> %lf", band->freq, freq); + if (freq != band->freq) { + GstIirEqualizer *equ = + GST_IIR_EQUALIZER (gst_object_get_parent (GST_OBJECT (band))); + + band->freq = freq; + if (GST_AUDIO_FILTER (equ)->format.rate) { + setup_filter (equ, band); + } + gst_object_unref (equ); + GST_DEBUG_OBJECT (band, "changed freq = %lf ", band->freq); + } + break; + } + case ARG_BANDWIDTH:{ gdouble width; width = g_value_get_double (value); @@ -185,7 +202,7 @@ gst_iir_equalizer_band_get_property (GObject * object, guint prop_id, case ARG_FREQ: g_value_set_double (value, band->freq); break; - case ARG_BAND_WIDTH: + case ARG_BANDWIDTH: g_value_set_double (value, band->width); break; default: @@ -204,18 +221,18 @@ gst_iir_equalizer_band_class_init (GstIirEqualizerBandClass * klass) g_object_class_install_property (gobject_class, ARG_GAIN, g_param_spec_double ("gain", "gain", - "gain for the frequency band ranging from -1.0 to +1.0", - -1.0, 1.0, 0.0, G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE)); + "gain for the frequency band ranging from -24.0 dB to +12.0 dB", + -24.0, 12.0, 0.0, G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE)); g_object_class_install_property (gobject_class, ARG_FREQ, g_param_spec_double ("freq", "freq", "center frequency of the band", - 0.0, 100000.0, 0.0, G_PARAM_READABLE)); + 0.0, 100000.0, 0.0, G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE)); - g_object_class_install_property (gobject_class, ARG_BAND_WIDTH, - g_param_spec_double ("band-width", "band-width", - "band width calculated as distance between bands * this value", 0.1, - 10.0, 1.0, G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE)); + g_object_class_install_property (gobject_class, ARG_BANDWIDTH, + g_param_spec_double ("bandwidth", "bandwidth", + "difference between bandedges in Hz", + 1.0, 100000.0, 1.0, G_PARAM_READWRITE | GST_PARAM_CONTROLLABLE)); } static void @@ -330,53 +347,57 @@ gst_iir_equalizer_finalize (GObject * object) G_OBJECT_CLASS (parent_class)->finalize (object); } -/* - * converts gain values to scale factors. - * - * we map -1 ... 1 to a db range. - * A suitable range would be -12db ... 0 ... + 6db which expressed as - * a factor is about 0.06 ... 1 ... 4.0 - * - * We need to subtract one so that gain is centered around zero - * - * visualize via gnuplot: - * set xrange [-1:1] - * plot 10.0 ** (12*x/10.0) - */ -static gdouble +static inline gdouble arg_to_scale (gdouble arg) { - return (pow (10.0, (6.0 * fabs (arg)) / 10.0) - 1.0); + return (pow (10.0, arg / 20.0)); } +/* Filter taken from + * + * The Equivalence of Various Methods of Computing + * Biquad Coefficients for Audio Parametric Equalizers + * + * by Robert Bristow-Johnson + * + * http://www.aes.org/e-lib/browse.cfm?elib=6326 + * http://www.musicdsp.org/files/EQ-Coefficients.pdf + * + * The bandwidth method that we use here is the preferred + * one from this article transformed from octaves to frequency + * in Hz. + */ static void setup_filter (GstIirEqualizer * equ, GstIirEqualizerBand * band) { g_return_if_fail (GST_AUDIO_FILTER (equ)->format.rate); /* FIXME: we need better filters - * - the band-width control is not good * - we need shelf-filter for 1st and last band */ { gdouble gain = arg_to_scale (band->gain); gdouble frequency = band->freq / GST_AUDIO_FILTER (equ)->format.rate; - gdouble q = pow (HIGHEST_FREQ / LOWEST_FREQ, - 1.0 / (equ->freq_band_count - 1)) * band->width; + gdouble omega = 2.0 * M_PI * frequency; + gdouble bw = + 2.0 * M_PI * (band->width / GST_AUDIO_FILTER (equ)->format.rate); - gdouble theta = frequency * 2 * M_PI; + gdouble edge_gain = sqrt (gain); + gdouble gamma = tan (bw / 2.0); - band->beta = (q - theta / 2) / (2 * q + theta); - band->gamma = (0.5 + band->beta) * cos (theta); - band->alpha = (0.5 - band->beta) / 2; + gdouble alpha = gamma * edge_gain; + gdouble beta = gamma / edge_gain; - band->beta *= 2.0; - band->alpha *= 2.0 * gain; - band->gamma *= 2.0; + band->a0 = (1.0 + alpha) / (1.0 + beta); + band->a1 = (-2.0 * cos (omega)) / (1.0 + beta); + band->a2 = (1.0 - alpha) / (1.0 + beta); + band->b1 = (2.0 * cos (omega)) / (1.0 + beta); + band->b2 = -(1.0 - beta) / (1.0 + beta); GST_INFO - ("gain = %7.5g, frequency = %7.5g, alpha = %7.5g, beta = %7.5g, gamma=%7.5g", - gain, frequency, band->alpha, band->beta, band->gamma); + ("gain = %7.5g, , bandwidth= %7.5g, frequency = %7.5g, a0 = %7.5g, a1 = %7.5g, a2=%7.5g b1 = %7.5g, b2 = %7.5g", + gain, band->width, frequency, band->a0, band->a1, band->a2, band->b1, + band->b2); } } @@ -425,11 +446,13 @@ gst_iir_equalizer_compute_frequencies (GstIirEqualizer * equ, guint new_count) * FIXME: arg! we can't change the name of parented objects :( * application should read band->freq to get the name */ + step = pow (HIGHEST_FREQ / LOWEST_FREQ, 1.0 / new_count); freq0 = LOWEST_FREQ; for (i = 0; i < new_count; i++) { freq1 = freq0 * step; equ->bands[i]->freq = freq0 + ((freq1 - freq0) / 2.0); + equ->bands[i]->width = freq1 - freq0; GST_DEBUG ("band[%2d] = '%lf'", i, equ->bands[i]->freq); /* if(equ->bands[i]->freq<10000.0) @@ -442,6 +465,7 @@ gst_iir_equalizer_compute_frequencies (GstIirEqualizer * equ, guint new_count) freq0 = freq1; } + if (GST_AUDIO_FILTER (equ)->format.rate) { for (i = 0; i < new_count; i++) { setup_filter (equ, equ->bands[i]); @@ -462,16 +486,16 @@ one_step_ ## TYPE (GstIirEqualizerBand *filter, \ SecondOrderHistory ## TYPE *history, TYPE input) \ { \ /* calculate output */ \ - TYPE output = filter->alpha * (input - history->x2) + \ - filter->gamma * history->y1 - filter->beta * history->y2; \ + TYPE output = filter->a0 * input + filter->a1 * history->x1 + \ + filter->a2 * history->x2 + filter->b1 * history->y1 + \ + filter->b2 * history->y2; \ /* update history */ \ history->y2 = history->y1; \ history->y1 = output; \ history->x2 = history->x1; \ history->x1 = input; \ \ - /* for negative gains we subtract */ \ - return (filter->gain>0.0) ? output : -output; \ + return output; \ } \ \ static const guint \ @@ -484,17 +508,15 @@ guint size, guint channels) \ guint frames = size / channels / sizeof (TYPE); \ guint i, c, f; \ BIG_TYPE cur; \ - TYPE val; \ \ for (i = 0; i < frames; i++) { \ for (c = 0; c < channels; c++) { \ SecondOrderHistory ## TYPE *history = equ->history; \ - val = *((TYPE *) data); \ - cur = 0.25 * val; /* FIXME: should be without factor*/ \ + cur = *((TYPE *) data); \ for (f = 0; f < equ->freq_band_count; f++) { \ GstIirEqualizerBand *filter = equ->bands[f]; \ \ - cur += one_step_ ## TYPE (filter, history, val); \ + cur = one_step_ ## TYPE (filter, history, cur); \ history++; \ } \ cur = CLAMP (cur, MIN_VAL, MAX_VAL); \ |