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| GstFFTF32 * | gst_fft_f32_new () |
| void | gst_fft_f32_fft () |
| void | gst_fft_f32_inverse_fft () |
| void | gst_fft_f32_window () |
| void | gst_fft_f32_free () |
GstFFTF32 provides a FFT implementation and related functions for
32 bit float samples. To use this call gst_fft_f32_new() for
allocating a GstFFTF32 instance with the appropriate parameters and
then call gst_fft_f32_fft() or gst_fft_f32_inverse_fft() to perform the
FFT or inverse FFT on a buffer of samples.
After use free the GstFFTF32 instance with gst_fft_f32_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_f32_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_f32_window() can comfortably
be used.
Be aware, that you can't simply run gst_fft_f32_inverse_fft() on the
resulting frequency data of gst_fft_f32_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.
GstFFTF32 * gst_fft_f32_new (gint len,gboolean inverse);
This returns a new GstFFTF32 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().
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void gst_fft_f32_fft (GstFFTF32 *self,const gfloat *timedata,GstFFTF32Complex *freqdata);
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 GstFFTF32 instance with gst_fft_f32_new().
freqdata
must be large enough to hold len
/2 + 1 GstFFTF32Complex frequency
domain samples.
self |
GstFFTF32 instance for this call |
|
timedata |
Buffer of the samples in the time domain |
|
freqdata |
Target buffer for the samples in the frequency domain |
void gst_fft_f32_inverse_fft (GstFFTF32 *self,const GstFFTF32Complex *freqdata,gfloat *timedata);
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 GstFFTF32 instance with gst_fft_f32_new().
timedata
must be large enough to hold len
time domain samples.
self |
GstFFTF32 instance for this call |
|
freqdata |
Buffer of the samples in the frequency domain |
|
timedata |
Target buffer for the samples in the time domain |
void gst_fft_f32_window (GstFFTF32 *self,gfloat *timedata,GstFFTWindow window);
This calls the window function window
on the timedata
sample buffer.
self |
GstFFTF32 instance for this call |
|
timedata |
Time domain samples |
|
window |
Window function to apply |