diff -r 000000000000 -r 0e761a78d257 gst_plugins_base/gst-libs/gst/fft/gstffts16.c --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/gst_plugins_base/gst-libs/gst/fft/gstffts16.c Thu Dec 17 08:53:32 2009 +0200 @@ -0,0 +1,223 @@ +/* GStreamer + * Copyright (C) <2007> Sebastian Dröge + * + * 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 +#include + +#include "kiss_fftr_s16.h" +#include "gstfft.h" +#include "gstffts16.h" + +/** + * SECTION: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 appropiate 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. + * + */ + +/** + * gst_fft_s16_new: + * @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. + */ +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + +GstFFTS16 * +gst_fft_s16_new (gint len, gboolean inverse) +{ + GstFFTS16 *self; + + g_return_val_if_fail (len > 0, NULL); + g_return_val_if_fail (len % 2 == 0, NULL); + + self = g_new (GstFFTS16, 1); + + self->cfg = kiss_fftr_s16_alloc (len, (inverse) ? 1 : 0, NULL, NULL); + 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. + * + */ +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + +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. + * + */ +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + +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. + * + */ +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + +void +gst_fft_s16_free (GstFFTS16 * self) +{ + kiss_fftr_s16_free (self->cfg); + 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. + * + */ +#ifdef __SYMBIAN32__ +EXPORT_C +#endif + +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 * 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; + } +}