gstreamer/gst-libs/gst/fft/gstfftf64.c
Sebastian Dröge edb4a505d7 Remove the magnitude and phase calculation functions as these have very special use cases and can't even be used for ...
Original commit message from CVS:
* docs/libs/gst-plugins-base-libs-sections.txt:
* gst-libs/gst/fft/gstfftf32.c:
* gst-libs/gst/fft/gstfftf32.h:
* gst-libs/gst/fft/gstfftf64.c:
* gst-libs/gst/fft/gstfftf64.h:
* gst-libs/gst/fft/gstffts16.c:
* gst-libs/gst/fft/gstffts16.h:
* gst-libs/gst/fft/gstffts32.c:
* gst-libs/gst/fft/gstffts32.h:
* tests/check/libs/fft.c: (GST_START_TEST):
Remove the magnitude and phase calculation functions as these have
very special use cases and can't even be used for the spectrum
element. Also adjust the docs to mention some properties of the used
FFT implemention, i.e. how the values are scaled. Fixes #492098.
2007-11-06 11:58:59 +00:00

203 lines
6.1 KiB
C

/* 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_fftr_f64.h"
#include "gstfft.h"
#include "gstfftf64.h"
/**
* SECTION:gstfftf64
* @short_description: FFT functions for 64 bit float samples
*
* #GstFFTF64 provides a FFT implementation and related functions for
* 64 bit float samples. To use this call gst_fft_f64_new() for
* allocating a #GstFFTF64 instance with the appropiate parameters and
* then call gst_fft_f64_fft() or gst_fft_f64_inverse_fft() to perform the
* FFT or inverse FFT on a buffer of samples.
*
* After use free the #GstFFTF64 instance with gst_fft_f64_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_f64_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_f64_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_f64_new:
* @len: Length of the FFT in the time domain
* @inverse: %TRUE if the #GstFFTF64 instance should be used for the inverse FFT
*
* This returns a new #GstFFTF64 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 #GstFFTF64 instance.
*/
GstFFTF64 *
gst_fft_f64_new (gint len, gboolean inverse)
{
GstFFTF64 *self;
g_return_val_if_fail (len > 0, NULL);
g_return_val_if_fail (len % 2 == 0, NULL);
self = g_new (GstFFTF64, 1);
self->cfg = kiss_fftr_f64_alloc (len, (inverse) ? 1 : 0, NULL, NULL);
g_assert (self->cfg);
self->inverse = inverse;
self->len = len;
return self;
}
/**
* gst_fft_f64_fft:
* @self: #GstFFTF64 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 #GstFFTF64 instance with gst_fft_f64_new().
*
* @freqdata must be large enough to hold @len/2 + 1 #GstFFTF64Complex frequency
* domain samples.
*
*/
void
gst_fft_f64_fft (GstFFTF64 * self, const gdouble * timedata,
GstFFTF64Complex * freqdata)
{
g_return_if_fail (self);
g_return_if_fail (!self->inverse);
g_return_if_fail (timedata);
g_return_if_fail (freqdata);
kiss_fftr_f64 (self->cfg, timedata, (kiss_fft_f64_cpx *) freqdata);
}
/**
* gst_fft_f64_inverse_fft:
* @self: #GstFFTF64 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 #GstFFTF64 instance with gst_fft_f64_new().
*
* @timedata must be large enough to hold @len time domain samples.
*
*/
void
gst_fft_f64_inverse_fft (GstFFTF64 * self, const GstFFTF64Complex * freqdata,
gdouble * timedata)
{
g_return_if_fail (self);
g_return_if_fail (self->inverse);
g_return_if_fail (timedata);
g_return_if_fail (freqdata);
kiss_fftri_f64 (self->cfg, (kiss_fft_f64_cpx *) freqdata, timedata);
}
/**
* gst_fft_f64_free:
* @self: #GstFFTF64 instance for this call
*
* This frees the memory allocated for @self.
*
*/
void
gst_fft_f64_free (GstFFTF64 * self)
{
kiss_fftr_f64_free (self->cfg);
g_free (self);
}
/**
* gst_fft_f64_window:
* @self: #GstFFTF64 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_f64_window (GstFFTF64 * self, gdouble * 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;
}
}