1 /* GStreamer

     2  * Copyright (C) <2007> Sebastian Dröge <slomo@circular-chaos.org>

     3  *

     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.

     8  *

     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.

    13  *

    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.

    18  */

    19 

    20 #include <glib.h>

    21 #include <math.h>

    22 

    23 #include "kiss_fftr_s32.h"

    24 #include "gstfft.h"

    25 #include "gstffts32.h"

    26 

    27 /**

    28  * SECTION:gstffts32

    29  * @short_description: FFT functions for signed 32 bit integer samples

    30  *

    31  * #GstFFTS32 provides a FFT implementation and related functions for

    32  * signed 32 bit integer samples. To use this call gst_fft_s32_new() for

    33  * allocating a #GstFFTS32 instance with the appropiate parameters and

    34  * then call gst_fft_s32_fft() or gst_fft_s32_inverse_fft() to perform the

    35  * FFT or inverse FFT on a buffer of samples.

    36  *

    37  * After use free the #GstFFTS32 instance with gst_fft_s32_free().

    38  *

    39  * For the best performance use gst_fft_next_fast_length() to get a

    40  * number that is entirely a product of 2, 3 and 5 and use this as the

    41  * @len parameter for gst_fft_s32_new().

    42  *

    43  * The @len parameter specifies the number of samples in the time domain that

    44  * will be processed or generated. The number of samples in the frequency domain

    45  * is @len/2 + 1. To get n samples in the frequency domain use 2*n - 2 as @len.

    46  *

    47  * Before performing the FFT on time domain data it usually makes sense

    48  * to apply a window function to it. For this gst_fft_s32_window() can comfortably

    49  * be used.

    50  *

    51  * Be aware, that you can't simply run gst_fft_s32_inverse_fft() on the

    52  * resulting frequency data of gst_fft_s32_fft() to get the original data back.

    53  * The relation between them is iFFT (FFT (x)) = x / nfft where nfft is the

    54  * length of the FFT. This also has to be taken into account when calculation

    55  * the magnitude of the frequency data.

    56  */

    57 

    58 /**

    59  * gst_fft_s32_new:

    60  * @len: Length of the FFT in the time domain

    61  * @inverse: %TRUE if the #GstFFTS32 instance should be used for the inverse FFT

    62  *

    63  * This returns a new #GstFFTS32 instance with the given parameters. It makes

    64  * sense to keep one instance for several calls for speed reasons.

    65  *

    66  * @len must be even and to get the best performance a product of

    67  * 2, 3 and 5. To get the next number with this characteristics use

    68  * gst_fft_next_fast_length().

    69  *

    70  * Returns: a new #GstFFTS32 instance.

    71  */

    72 #ifdef __SYMBIAN32__

    73 EXPORT_C

    74 #endif

    75 

    76 GstFFTS32 *

    77 gst_fft_s32_new (gint len, gboolean inverse)

    78 {

    79   GstFFTS32 *self;

    80 

    81   g_return_val_if_fail (len > 0, NULL);

    82   g_return_val_if_fail (len % 2 == 0, NULL);

    83 

    84   self = g_new (GstFFTS32, 1);

    85 

    86   self->cfg = kiss_fftr_s32_alloc (len, (inverse) ? 1 : 0, NULL, NULL);

    87   g_assert (self->cfg);

    88 

    89   self->inverse = inverse;

    90   self->len = len;

    91 

    92   return self;

    93 }

    94 

    95 /**

    96  * gst_fft_s32_fft:

    97  * @self: #GstFFTS32 instance for this call

    98  * @timedata: Buffer of the samples in the time domain

    99  * @freqdata: Target buffer for the samples in the frequency domain

   100  *

   101  * This performs the FFT on @timedata and puts the result in @freqdata.

   102  *

   103  * @timedata must have as many samples as specified with the @len parameter while

   104  * allocating the #GstFFTS32 instance with gst_fft_s32_new().

   105  *

   106  * @freqdata must be large enough to hold @len/2 + 1 #GstFFTS32Complex frequency

   107  * domain samples.

   108  *

   109  */

   110 #ifdef __SYMBIAN32__

   111 EXPORT_C

   112 #endif

   113 

   114 void

   115 gst_fft_s32_fft (GstFFTS32 * self, const gint32 * timedata,

   116     GstFFTS32Complex * freqdata)

   117 {

   118   g_return_if_fail (self);

   119   g_return_if_fail (!self->inverse);

   120   g_return_if_fail (timedata);

   121   g_return_if_fail (freqdata);

   122 

   123   kiss_fftr_s32 (self->cfg, timedata, (kiss_fft_s32_cpx *) freqdata);

   124 }

   125 

   126 /**

   127  * gst_fft_s32_inverse_fft:

   128  * @self: #GstFFTS32 instance for this call

   129  * @freqdata: Buffer of the samples in the frequency domain

   130  * @timedata: Target buffer for the samples in the time domain

   131  *

   132  * This performs the inverse FFT on @freqdata and puts the result in @timedata.

   133  *

   134  * @freqdata must have @len/2 + 1 samples, where @len is the parameter specified

   135  * while allocating the #GstFFTS32 instance with gst_fft_s32_new().

   136  *

   137  * @timedata must be large enough to hold @len time domain samples.

   138  *

   139  */

   140 #ifdef __SYMBIAN32__

   141 EXPORT_C

   142 #endif

   143 

   144 void

   145 gst_fft_s32_inverse_fft (GstFFTS32 * self, const GstFFTS32Complex * freqdata,

   146     gint32 * timedata)

   147 {

   148   g_return_if_fail (self);

   149   g_return_if_fail (self->inverse);

   150   g_return_if_fail (timedata);

   151   g_return_if_fail (freqdata);

   152 

   153   kiss_fftri_s32 (self->cfg, (kiss_fft_s32_cpx *) freqdata, timedata);

   154 }

   155 

   156 /**

   157  * gst_fft_s32_free:

   158  * @self: #GstFFTS32 instance for this call

   159  *

   160  * This frees the memory allocated for @self.

   161  *

   162  */

   163 #ifdef __SYMBIAN32__

   164 EXPORT_C

   165 #endif

   166 

   167 void

   168 gst_fft_s32_free (GstFFTS32 * self)

   169 {

   170   kiss_fftr_s32_free (self->cfg);

   171   g_free (self);

   172 }

   173 

   174 /**

   175  * gst_fft_s32_window:

   176  * @self: #GstFFTS32 instance for this call

   177  * @timedata: Time domain samples

   178  * @window: Window function to apply

   179  *

   180  * This calls the window function @window on the @timedata sample buffer.

   181  *

   182  */

   183 #ifdef __SYMBIAN32__

   184 EXPORT_C

   185 #endif

   186 

   187 void

   188 gst_fft_s32_window (GstFFTS32 * self, gint32 * timedata, GstFFTWindow window)

   189 {

   190   gint i, len;

   191 

   192   g_return_if_fail (self);

   193   g_return_if_fail (timedata);

   194 

   195   len = self->len;

   196 

   197   switch (window) {

   198     case GST_FFT_WINDOW_RECTANGULAR:

   199       /* do nothing */

   200       break;

   201     case GST_FFT_WINDOW_HAMMING:

   202       for (i = 0; i < len; i++)

   203         timedata[i] *= (0.53836 - 0.46164 * cos (2.0 * M_PI * i / len));

   204       break;

   205     case GST_FFT_WINDOW_HANN:

   206       for (i = 0; i < len; i++)

   207         timedata[i] *= (0.5 - 0.5 * cos (2.0 * M_PI * i / len));

   208       break;

   209     case GST_FFT_WINDOW_BARTLETT:

   210       for (i = 0; i < len; i++)

   211         timedata[i] *= (1.0 - fabs ((2.0 * i - len) / len));

   212       break;

   213     case GST_FFT_WINDOW_BLACKMAN:

   214       for (i = 0; i < len; i++)

   215         timedata[i] *= (0.42 - 0.5 * cos ((2.0 * i) / len) +

   216             0.08 * cos ((4.0 * i) / len));

   217       break;

   218     default:

   219       g_assert_not_reached ();

   220       break;

   221   }

   222 }