| /* 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., 51 Franklin St, Fifth Floor, |
| * Boston, MA 02110-1301, USA. |
| */ |
| #ifdef HAVE_CONFIG_H |
| #include "config.h" |
| #endif |
| |
| |
| #include <glib.h> |
| #include <math.h> |
| |
| #include "_kiss_fft_guts_s16.h" |
| #include "kiss_fftr_s16.h" |
| #include "gstfft.h" |
| #include "gstffts16.h" |
| |
| /** |
| * SECTION:gstffts16 |
| * @title: GstFFTS16 |
| * @short_description: FFT functions for signed 16 bit integer samples |
| * |
| * #GstFFTS16 provides a FFT implementation and related functions for |
| * signed 16 bit integer samples. To use this call gst_fft_s16_new() for |
| * allocating a #GstFFTS16 instance with the appropriate parameters and |
| * then call gst_fft_s16_fft() or gst_fft_s16_inverse_fft() to perform the |
| * FFT or inverse FFT on a buffer of samples. |
| * |
| * After use free the #GstFFTS16 instance with gst_fft_s16_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_s16_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_s16_window() can comfortably |
| * be used. |
| * |
| * Be aware, that you can't simply run gst_fft_s16_inverse_fft() on the |
| * resulting frequency data of gst_fft_s16_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. |
| * |
| */ |
| |
| struct _GstFFTS16 |
| { |
| void *cfg; |
| gboolean inverse; |
| gint len; |
| }; |
| |
| /** |
| * gst_fft_s16_new: (skip) |
| * @len: Length of the FFT in the time domain |
| * @inverse: %TRUE if the #GstFFTS16 instance should be used for the inverse FFT |
| * |
| * This returns a new #GstFFTS16 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 #GstFFTS16 instance. |
| */ |
| GstFFTS16 * |
| gst_fft_s16_new (gint len, gboolean inverse) |
| { |
| GstFFTS16 *self; |
| gsize subsize = 0, memneeded; |
| |
| g_return_val_if_fail (len > 0, NULL); |
| g_return_val_if_fail (len % 2 == 0, NULL); |
| |
| kiss_fftr_s16_alloc (len, (inverse) ? 1 : 0, NULL, &subsize); |
| memneeded = ALIGN_STRUCT (sizeof (GstFFTS16)) + subsize; |
| |
| self = (GstFFTS16 *) g_malloc0 (memneeded); |
| |
| self->cfg = (((guint8 *) self) + ALIGN_STRUCT (sizeof (GstFFTS16))); |
| self->cfg = kiss_fftr_s16_alloc (len, (inverse) ? 1 : 0, self->cfg, &subsize); |
| g_assert (self->cfg); |
| |
| self->inverse = inverse; |
| self->len = len; |
| |
| return self; |
| } |
| |
| /** |
| * gst_fft_s16_fft: |
| * @self: #GstFFTS16 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 #GstFFTS16 instance with gst_fft_s16_new(). |
| * |
| * @freqdata must be large enough to hold @len/2 + 1 #GstFFTS16Complex frequency |
| * domain samples. |
| * |
| */ |
| void |
| gst_fft_s16_fft (GstFFTS16 * self, const gint16 * timedata, |
| GstFFTS16Complex * freqdata) |
| { |
| g_return_if_fail (self); |
| g_return_if_fail (!self->inverse); |
| g_return_if_fail (timedata); |
| g_return_if_fail (freqdata); |
| |
| kiss_fftr_s16 (self->cfg, timedata, (kiss_fft_s16_cpx *) freqdata); |
| } |
| |
| /** |
| * gst_fft_s16_inverse_fft: |
| * @self: #GstFFTS16 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 #GstFFTS16 instance with gst_fft_s16_new(). |
| * |
| * @timedata must be large enough to hold @len time domain samples. |
| * |
| */ |
| void |
| gst_fft_s16_inverse_fft (GstFFTS16 * self, const GstFFTS16Complex * freqdata, |
| gint16 * timedata) |
| { |
| g_return_if_fail (self); |
| g_return_if_fail (self->inverse); |
| g_return_if_fail (timedata); |
| g_return_if_fail (freqdata); |
| |
| kiss_fftri_s16 (self->cfg, (kiss_fft_s16_cpx *) freqdata, timedata); |
| } |
| |
| /** |
| * gst_fft_s16_free: |
| * @self: #GstFFTS16 instance for this call |
| * |
| * This frees the memory allocated for @self. |
| * |
| */ |
| void |
| gst_fft_s16_free (GstFFTS16 * self) |
| { |
| g_free (self); |
| } |
| |
| /** |
| * gst_fft_s16_window: |
| * @self: #GstFFTS16 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_s16_window (GstFFTS16 * self, gint16 * 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 * G_PI * i / len)); |
| break; |
| case GST_FFT_WINDOW_HANN: |
| for (i = 0; i < len; i++) |
| timedata[i] *= (0.5 - 0.5 * cos (2.0 * G_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; |
| } |
| } |