2 * Copyright (C) <2007> Sebastian Dröge <slomo@circular-chaos.org>
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Library General Public License for more details.
14 * You should have received a copy of the GNU Library General Public
15 * License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 * Boston, MA 02111-1307, USA.
23 #include "_kiss_fft_guts_s32.h"
24 #include "kiss_fftr_s32.h"
26 #include "gstffts32.h"
30 * @short_description: FFT functions for signed 32 bit integer samples
32 * #GstFFTS32 provides a FFT implementation and related functions for
33 * signed 32 bit integer samples. To use this call gst_fft_s32_new() for
34 * allocating a #GstFFTS32 instance with the appropiate parameters and
35 * then call gst_fft_s32_fft() or gst_fft_s32_inverse_fft() to perform the
36 * FFT or inverse FFT on a buffer of samples.
38 * After use free the #GstFFTS32 instance with gst_fft_s32_free().
40 * For the best performance use gst_fft_next_fast_length() to get a
41 * number that is entirely a product of 2, 3 and 5 and use this as the
42 * @len parameter for gst_fft_s32_new().
44 * The @len parameter specifies the number of samples in the time domain that
45 * will be processed or generated. The number of samples in the frequency domain
46 * is @len/2 + 1. To get n samples in the frequency domain use 2*n - 2 as @len.
48 * Before performing the FFT on time domain data it usually makes sense
49 * to apply a window function to it. For this gst_fft_s32_window() can comfortably
52 * Be aware, that you can't simply run gst_fft_s32_inverse_fft() on the
53 * resulting frequency data of gst_fft_s32_fft() to get the original data back.
54 * The relation between them is iFFT (FFT (x)) = x / nfft where nfft is the
55 * length of the FFT. This also has to be taken into account when calculation
56 * the magnitude of the frequency data.
61 * @len: Length of the FFT in the time domain
62 * @inverse: %TRUE if the #GstFFTS32 instance should be used for the inverse FFT
64 * This returns a new #GstFFTS32 instance with the given parameters. It makes
65 * sense to keep one instance for several calls for speed reasons.
67 * @len must be even and to get the best performance a product of
68 * 2, 3 and 5. To get the next number with this characteristics use
69 * gst_fft_next_fast_length().
71 * Returns: a new #GstFFTS32 instance.
74 gst_fft_s32_new (gint len, gboolean inverse)
77 gsize subsize = 0, memneeded;
79 g_return_val_if_fail (len > 0, NULL);
80 g_return_val_if_fail (len % 2 == 0, NULL);
82 kiss_fftr_s32_alloc (len, (inverse) ? 1 : 0, NULL, &subsize);
83 memneeded = ALIGN_STRUCT (sizeof (GstFFTS32)) + subsize;
85 self = (GstFFTS32 *) g_malloc0 (memneeded);
87 self->cfg = (((guint8 *) self) + ALIGN_STRUCT (sizeof (GstFFTS32)));
88 self->cfg = kiss_fftr_s32_alloc (len, (inverse) ? 1 : 0, self->cfg, &subsize);
91 self->inverse = inverse;
99 * @self: #GstFFTS32 instance for this call
100 * @timedata: Buffer of the samples in the time domain
101 * @freqdata: Target buffer for the samples in the frequency domain
103 * This performs the FFT on @timedata and puts the result in @freqdata.
105 * @timedata must have as many samples as specified with the @len parameter while
106 * allocating the #GstFFTS32 instance with gst_fft_s32_new().
108 * @freqdata must be large enough to hold @len/2 + 1 #GstFFTS32Complex frequency
113 gst_fft_s32_fft (GstFFTS32 * self, const gint32 * timedata,
114 GstFFTS32Complex * freqdata)
116 g_return_if_fail (self);
117 g_return_if_fail (!self->inverse);
118 g_return_if_fail (timedata);
119 g_return_if_fail (freqdata);
121 kiss_fftr_s32 (self->cfg, timedata, (kiss_fft_s32_cpx *) freqdata);
125 * gst_fft_s32_inverse_fft:
126 * @self: #GstFFTS32 instance for this call
127 * @freqdata: Buffer of the samples in the frequency domain
128 * @timedata: Target buffer for the samples in the time domain
130 * This performs the inverse FFT on @freqdata and puts the result in @timedata.
132 * @freqdata must have @len/2 + 1 samples, where @len is the parameter specified
133 * while allocating the #GstFFTS32 instance with gst_fft_s32_new().
135 * @timedata must be large enough to hold @len time domain samples.
139 gst_fft_s32_inverse_fft (GstFFTS32 * self, const GstFFTS32Complex * freqdata,
142 g_return_if_fail (self);
143 g_return_if_fail (self->inverse);
144 g_return_if_fail (timedata);
145 g_return_if_fail (freqdata);
147 kiss_fftri_s32 (self->cfg, (kiss_fft_s32_cpx *) freqdata, timedata);
152 * @self: #GstFFTS32 instance for this call
154 * This frees the memory allocated for @self.
158 gst_fft_s32_free (GstFFTS32 * self)
164 * gst_fft_s32_window:
165 * @self: #GstFFTS32 instance for this call
166 * @timedata: Time domain samples
167 * @window: Window function to apply
169 * This calls the window function @window on the @timedata sample buffer.
173 gst_fft_s32_window (GstFFTS32 * self, gint32 * timedata, GstFFTWindow window)
177 g_return_if_fail (self);
178 g_return_if_fail (timedata);
183 case GST_FFT_WINDOW_RECTANGULAR:
186 case GST_FFT_WINDOW_HAMMING:
187 for (i = 0; i < len; i++)
188 timedata[i] *= (0.53836 - 0.46164 * cos (2.0 * M_PI * i / len));
190 case GST_FFT_WINDOW_HANN:
191 for (i = 0; i < len; i++)
192 timedata[i] *= (0.5 - 0.5 * cos (2.0 * M_PI * i / len));
194 case GST_FFT_WINDOW_BARTLETT:
195 for (i = 0; i < len; i++)
196 timedata[i] *= (1.0 - fabs ((2.0 * i - len) / len));
198 case GST_FFT_WINDOW_BLACKMAN:
199 for (i = 0; i < len; i++)
200 timedata[i] *= (0.42 - 0.5 * cos ((2.0 * i) / len) +
201 0.08 * cos ((4.0 * i) / len));
204 g_assert_not_reached ();