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audiowsincband: Add new windowing functions: gaussian, cos and hann

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This commit is contained in:
Sebastian Dröge 2011-04-13 17:49:22 +02:00
parent 782d6af83d
commit 2575cfc4a6
1 changed files with 53 additions and 14 deletions
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67
gst/audiofx/audiowsincband.c
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@ -26,6 +26,8 @@
* chapter 16
* available at http://www.dspguide.com/
*
* For the window functions see
* http://en.wikipedia.org/wiki/Window_function
*/
/**
@ -104,7 +106,10 @@ gst_gst_audio_wsincband_mode_get_type (void)
enum
{
WINDOW_HAMMING = 0,
WINDOW_BLACKMAN
WINDOW_BLACKMAN,
WINDOW_GAUSSIAN,
WINDOW_COSINE,
WINDOW_HANN
};
#define GST_TYPE_AUDIO_WSINC_BAND_WINDOW (gst_gst_audio_wsincband_window_get_type ())
@ -119,6 +124,12 @@ gst_gst_audio_wsincband_window_get_type (void)
"hamming"},
{WINDOW_BLACKMAN, "Blackman window",
"blackman"},
{WINDOW_GAUSSIAN, "Gaussian window",
"gaussian"},
{WINDOW_COSINE, "Cosine window",
"cosine"},
{WINDOW_HANN, "Hann window",
"hann"},
{0, NULL, NULL}
};
@ -143,6 +154,9 @@ static void gst_audio_wsincband_finalize (GObject * object);
static gboolean gst_audio_wsincband_setup (GstAudioFilter * base,
GstRingBufferSpec * format);
#define POW2(x) (x)*(x)
/* Element class */
static void
gst_audio_wsincband_base_init (gpointer g_class)
@ -263,13 +277,26 @@ gst_audio_wsincband_build_kernel (GstAudioWSincBand * self)
else
kernel_lp[i] = sin (w * (i - len / 2))
/ (i - len / 2);
/* Windowing */
if (self->window == WINDOW_HAMMING)
kernel_lp[i] *= (0.54 - 0.46 * cos (2 * G_PI * i / len));
else
kernel_lp[i] *=
(0.42 - 0.5 * cos (2 * G_PI * i / len) +
0.08 * cos (4 * G_PI * i / len));
/* windowing */
switch (self->window) {
case WINDOW_HAMMING:
kernel_lp[i] *= (0.54 - 0.46 * cos (2 * G_PI * i / (len - 1)));
break;
case WINDOW_BLACKMAN:
kernel_lp[i] *= (0.42 - 0.5 * cos (2 * G_PI * i / (len - 1)) +
0.08 * cos (4 * G_PI * i / (len - 1)));
break;
case WINDOW_GAUSSIAN:
kernel_lp[i] *= exp (-0.5 * POW2 (3.0 / len * (2 * i - (len - 1))));
break;
case WINDOW_COSINE:
kernel_lp[i] *= cos (G_PI * i / (len - 1) - G_PI / 2);
break;
case WINDOW_HANN:
kernel_lp[i] *= 0.5 * (1 - cos (2 * G_PI * i / (len - 1)));
break;
}
}
/* normalize for unity gain at DC */
@ -289,12 +316,24 @@ gst_audio_wsincband_build_kernel (GstAudioWSincBand * self)
kernel_hp[i] = sin (w * (i - len / 2))
/ (i - len / 2);
/* Windowing */
if (self->window == WINDOW_HAMMING)
kernel_hp[i] *= (0.54 - 0.46 * cos (2 * G_PI * i / len));
else
kernel_hp[i] *=
(0.42 - 0.5 * cos (2 * G_PI * i / len) +
0.08 * cos (4 * G_PI * i / len));
switch (self->window) {
case WINDOW_HAMMING:
kernel_hp[i] *= (0.54 - 0.46 * cos (2 * G_PI * i / (len - 1)));
break;
case WINDOW_BLACKMAN:
kernel_hp[i] *= (0.42 - 0.5 * cos (2 * G_PI * i / (len - 1)) +
0.08 * cos (4 * G_PI * i / (len - 1)));
break;
case WINDOW_GAUSSIAN:
kernel_hp[i] *= exp (-0.5 * POW2 (3.0 / len * (2 * i - (len - 1))));
break;
case WINDOW_COSINE:
kernel_hp[i] *= cos (G_PI * i / (len - 1) - G_PI / 2);
break;
case WINDOW_HANN:
kernel_hp[i] *= 0.5 * (1 - cos (2 * G_PI * i / (len - 1)));
break;
}
}
/* normalize for unity gain at DC */