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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.
203 lines
6.1 KiB
C
203 lines
6.1 KiB
C
/* GStreamer
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* Copyright (C) <2007> Sebastian Dröge <slomo@circular-chaos.org>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#include <glib.h>
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#include <math.h>
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#include "kiss_fftr_f32.h"
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#include "gstfft.h"
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#include "gstfftf32.h"
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/**
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* SECTION:gstfftf32
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* @short_description: FFT functions for 32 bit float samples
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*
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* #GstFFTF32 provides a FFT implementation and related functions for
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* 32 bit float samples. To use this call gst_fft_f32_new() for
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* allocating a #GstFFTF32 instance with the appropiate parameters and
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* then call gst_fft_f32_fft() or gst_fft_f32_inverse_fft() to perform the
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* FFT or inverse FFT on a buffer of samples.
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*
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* After use free the #GstFFTF32 instance with gst_fft_f32_free().
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*
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* For the best performance use gst_fft_next_fast_length() to get a
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* number that is entirely a product of 2, 3 and 5 and use this as the
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* @len parameter for gst_fft_f32_new().
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*
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* The @len parameter specifies the number of samples in the time domain that
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* will be processed or generated. The number of samples in the frequency domain
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* is @len/2 + 1. To get n samples in the frequency domain use 2*n - 2 as @len.
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*
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* Before performing the FFT on time domain data it usually makes sense
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* to apply a window function to it. For this gst_fft_f32_window() can comfortably
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* be used.
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*
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* Be aware, that you can't simply run gst_fft_f32_inverse_fft() on the
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* resulting frequency data of gst_fft_f32_fft() to get the original data back.
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* The relation between them is iFFT (FFT (x)) = x * nfft where nfft is the
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* length of the FFT. This also has to be taken into account when calculation
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* the magnitude of the frequency data.
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*
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*/
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/**
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* gst_fft_f32_new:
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* @len: Length of the FFT in the time domain
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* @inverse: %TRUE if the #GstFFTF32 instance should be used for the inverse FFT
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*
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* This returns a new #GstFFTF32 instance with the given parameters. It makes
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* sense to keep one instance for several calls for speed reasons.
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*
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* @len must be even and to get the best performance a product of
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* 2, 3 and 5. To get the next number with this characteristics use
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* gst_fft_next_fast_length().
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*
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* Returns: a new #GstFFTF32 instance.
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*/
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GstFFTF32 *
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gst_fft_f32_new (gint len, gboolean inverse)
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{
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GstFFTF32 *self;
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g_return_val_if_fail (len > 0, NULL);
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g_return_val_if_fail (len % 2 == 0, NULL);
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self = g_new (GstFFTF32, 1);
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self->cfg = kiss_fftr_f32_alloc (len, (inverse) ? 1 : 0, NULL, NULL);
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g_assert (self->cfg);
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self->inverse = inverse;
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self->len = len;
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return self;
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}
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/**
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* gst_fft_f32_fft:
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* @self: #GstFFTF32 instance for this call
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* @timedata: Buffer of the samples in the time domain
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* @freqdata: Target buffer for the samples in the frequency domain
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*
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* This performs the FFT on @timedata and puts the result in @freqdata.
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*
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* @timedata must have as many samples as specified with the @len parameter while
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* allocating the #GstFFTF32 instance with gst_fft_f32_new().
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*
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* @freqdata must be large enough to hold @len/2 + 1 #GstFFTF32Complex frequency
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* domain samples.
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*
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*/
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void
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gst_fft_f32_fft (GstFFTF32 * self, const gfloat * timedata,
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GstFFTF32Complex * freqdata)
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{
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g_return_if_fail (self);
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g_return_if_fail (!self->inverse);
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g_return_if_fail (timedata);
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g_return_if_fail (freqdata);
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kiss_fftr_f32 (self->cfg, timedata, (kiss_fft_f32_cpx *) freqdata);
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}
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/**
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* gst_fft_f32_inverse_fft:
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* @self: #GstFFTF32 instance for this call
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* @freqdata: Buffer of the samples in the frequency domain
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* @timedata: Target buffer for the samples in the time domain
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*
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* This performs the inverse FFT on @freqdata and puts the result in @timedata.
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*
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* @freqdata must have @len/2 + 1 samples, where @len is the parameter specified
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* while allocating the #GstFFTF32 instance with gst_fft_f32_new().
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*
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* @timedata must be large enough to hold @len time domain samples.
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*
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*/
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void
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gst_fft_f32_inverse_fft (GstFFTF32 * self, const GstFFTF32Complex * freqdata,
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gfloat * timedata)
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{
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g_return_if_fail (self);
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g_return_if_fail (self->inverse);
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g_return_if_fail (timedata);
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g_return_if_fail (freqdata);
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kiss_fftri_f32 (self->cfg, (kiss_fft_f32_cpx *) freqdata, timedata);
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}
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/**
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* gst_fft_f32_free:
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* @self: #GstFFTF32 instance for this call
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*
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* This frees the memory allocated for @self.
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*
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*/
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void
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gst_fft_f32_free (GstFFTF32 * self)
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{
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kiss_fftr_f32_free (self->cfg);
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g_free (self);
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}
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/**
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* gst_fft_f32_window:
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* @self: #GstFFTF32 instance for this call
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* @timedata: Time domain samples
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* @window: Window function to apply
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*
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* This calls the window function @window on the @timedata sample buffer.
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*
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*/
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void
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gst_fft_f32_window (GstFFTF32 * self, gfloat * timedata, GstFFTWindow window)
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{
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gint i, len;
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g_return_if_fail (self);
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g_return_if_fail (timedata);
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len = self->len;
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switch (window) {
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case GST_FFT_WINDOW_RECTANGULAR:
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/* do nothing */
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break;
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case GST_FFT_WINDOW_HAMMING:
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for (i = 0; i < len; i++)
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timedata[i] *= (0.53836 - 0.46164 * cos (2.0 * M_PI * i / len));
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break;
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case GST_FFT_WINDOW_HANN:
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for (i = 0; i < len; i++)
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timedata[i] *= (0.5 - 0.5 * cos (2.0 * M_PI * i / len));
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break;
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case GST_FFT_WINDOW_BARTLETT:
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for (i = 0; i < len; i++)
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timedata[i] *= (1.0 - fabs ((2.0 * i - len) / len));
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break;
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case GST_FFT_WINDOW_BLACKMAN:
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for (i = 0; i < len; i++)
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timedata[i] *= (0.42 - 0.5 * cos ((2.0 * i) / len) +
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0.08 * cos ((4.0 * i) / len));
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break;
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default:
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g_assert_not_reached ();
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break;
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}
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}
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