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/* GStreamer
* Copyright (C) <2007> Sebastian Dröge <slomo@circular-chaos.org>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include <glib.h>
#include <math.h>
#include "_kiss_fft_guts_f32.h"
#include "kiss_fftr_f32.h"
#include "gstfft.h"
#include "gstfftf32.h"
/**
* SECTION:gstfftf32
* @short_description: FFT functions for 32 bit float samples
*
* #GstFFTF32 provides a FFT implementation and related functions for
* 32 bit float samples. To use this call gst_fft_f32_new() for
* allocating a #GstFFTF32 instance with the appropiate parameters and
* then call gst_fft_f32_fft() or gst_fft_f32_inverse_fft() to perform the
* FFT or inverse FFT on a buffer of samples.
*
* After use free the #GstFFTF32 instance with gst_fft_f32_free().
*
* For the best performance use gst_fft_next_fast_length() to get a
* number that is entirely a product of 2, 3 and 5 and use this as the
* @len parameter for gst_fft_f32_new().
*
* The @len parameter specifies the number of samples in the time domain that
* will be processed or generated. The number of samples in the frequency domain
* is @len/2 + 1. To get n samples in the frequency domain use 2*n - 2 as @len.
*
* Before performing the FFT on time domain data it usually makes sense
* to apply a window function to it. For this gst_fft_f32_window() can comfortably
* be used.
*
* Be aware, that you can't simply run gst_fft_f32_inverse_fft() on the
* resulting frequency data of gst_fft_f32_fft() to get the original data back.
* The relation between them is iFFT (FFT (x)) = x * nfft where nfft is the
* length of the FFT. This also has to be taken into account when calculation
* the magnitude of the frequency data.
*
*/
/**
* gst_fft_f32_new:
* @len: Length of the FFT in the time domain
* @inverse: %TRUE if the #GstFFTF32 instance should be used for the inverse FFT
*
* This returns a new #GstFFTF32 instance with the given parameters. It makes
* sense to keep one instance for several calls for speed reasons.
*
* @len must be even and to get the best performance a product of
* 2, 3 and 5. To get the next number with this characteristics use
* gst_fft_next_fast_length().
*
* Returns: a new #GstFFTF32 instance.
*/
GstFFTF32 *
gst_fft_f32_new (gint len, gboolean inverse)
{
GstFFTF32 *self;
gsize subsize = 0, memneeded;
g_return_val_if_fail (len > 0, NULL);
g_return_val_if_fail (len % 2 == 0, NULL);
kiss_fftr_f32_alloc (len, (inverse) ? 1 : 0, NULL, &subsize);
memneeded = ALIGN_STRUCT (sizeof (GstFFTF32)) + subsize;
self = (GstFFTF32 *) g_malloc0 (memneeded);
self->cfg = (((guint8 *) self) + ALIGN_STRUCT (sizeof (GstFFTF32)));
self->cfg = kiss_fftr_f32_alloc (len, (inverse) ? 1 : 0, self->cfg, &subsize);
g_assert (self->cfg);
self->inverse = inverse;
self->len = len;
return self;
}
/**
* gst_fft_f32_fft:
* @self: #GstFFTF32 instance for this call
* @timedata: Buffer of the samples in the time domain
* @freqdata: Target buffer for the samples in the frequency domain
*
* This performs the FFT on @timedata and puts the result in @freqdata.
*
* @timedata must have as many samples as specified with the @len parameter while
* allocating the #GstFFTF32 instance with gst_fft_f32_new().
*
* @freqdata must be large enough to hold @len/2 + 1 #GstFFTF32Complex frequency
* domain samples.
*
*/
void
gst_fft_f32_fft (GstFFTF32 * self, const gfloat * timedata,
GstFFTF32Complex * freqdata)
{
g_return_if_fail (self);
g_return_if_fail (!self->inverse);
g_return_if_fail (timedata);
g_return_if_fail (freqdata);
kiss_fftr_f32 (self->cfg, timedata, (kiss_fft_f32_cpx *) freqdata);
}
/**
* gst_fft_f32_inverse_fft:
* @self: #GstFFTF32 instance for this call
* @freqdata: Buffer of the samples in the frequency domain
* @timedata: Target buffer for the samples in the time domain
*
* This performs the inverse FFT on @freqdata and puts the result in @timedata.
*
* @freqdata must have @len/2 + 1 samples, where @len is the parameter specified
* while allocating the #GstFFTF32 instance with gst_fft_f32_new().
*
* @timedata must be large enough to hold @len time domain samples.
*
*/
void
gst_fft_f32_inverse_fft (GstFFTF32 * self, const GstFFTF32Complex * freqdata,
gfloat * timedata)
{
g_return_if_fail (self);
g_return_if_fail (self->inverse);
g_return_if_fail (timedata);
g_return_if_fail (freqdata);
kiss_fftri_f32 (self->cfg, (kiss_fft_f32_cpx *) freqdata, timedata);
}
/**
* gst_fft_f32_free:
* @self: #GstFFTF32 instance for this call
*
* This frees the memory allocated for @self.
*
*/
void
gst_fft_f32_free (GstFFTF32 * self)
{
g_free (self);
}
/**
* gst_fft_f32_window:
* @self: #GstFFTF32 instance for this call
* @timedata: Time domain samples
* @window: Window function to apply
*
* This calls the window function @window on the @timedata sample buffer.
*
*/
void
gst_fft_f32_window (GstFFTF32 * self, gfloat * timedata, GstFFTWindow window)
{
gint i, len;
g_return_if_fail (self);
g_return_if_fail (timedata);
len = self->len;
switch (window) {
case GST_FFT_WINDOW_RECTANGULAR:
/* do nothing */
break;
case GST_FFT_WINDOW_HAMMING:
for (i = 0; i < len; i++)
timedata[i] *= (0.53836 - 0.46164 * cos (2.0 * M_PI * i / len));
break;
case GST_FFT_WINDOW_HANN:
for (i = 0; i < len; i++)
timedata[i] *= (0.5 - 0.5 * cos (2.0 * M_PI * i / len));
break;
case GST_FFT_WINDOW_BARTLETT:
for (i = 0; i < len; i++)
timedata[i] *= (1.0 - fabs ((2.0 * i - len) / len));
break;
case GST_FFT_WINDOW_BLACKMAN:
for (i = 0; i < len; i++)
timedata[i] *= (0.42 - 0.5 * cos ((2.0 * i) / len) +
0.08 * cos ((4.0 * i) / len));
break;
default:
g_assert_not_reached ();
break;
}
}
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