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<h2><span class="refentrytitle"><a name="gst-plugins-base-libs-gstfftf32.top_of_page"></a>gstfftf32</span></h2>
<p>gstfftf32 — FFT functions for 32 bit float samples</p>
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<div class="refsynopsisdiv">
<a name="gst-plugins-base-libs-gstfftf32.synopsis"></a><h2>Synopsis</h2>
<pre class="synopsis">
#include <gst/fft/gstfftf32.h>
<a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32">GstFFTF32</a>;
struct <a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32Complex" title="struct GstFFTF32Complex">GstFFTF32Complex</a>;
<a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="returnvalue">GstFFTF32</span></a> * <a class="link" href="gst-plugins-base-libs-gstfftf32.html#gst-fft-f32-new" title="gst_fft_f32_new ()">gst_fft_f32_new</a> (<em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint"><span class="type">gint</span></a> len</code></em>,
<em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> inverse</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gst-plugins-base-libs-gstfftf32.html#gst-fft-f32-fft" title="gst_fft_f32_fft ()">gst_fft_f32_fft</a> (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> *self</code></em>,
<em class="parameter"><code>const <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gfloat"><span class="type">gfloat</span></a> *timedata</code></em>,
<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32Complex" title="struct GstFFTF32Complex"><span class="type">GstFFTF32Complex</span></a> *freqdata</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gst-plugins-base-libs-gstfftf32.html#gst-fft-f32-inverse-fft" title="gst_fft_f32_inverse_fft ()">gst_fft_f32_inverse_fft</a> (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> *self</code></em>,
<em class="parameter"><code>const <a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32Complex" title="struct GstFFTF32Complex"><span class="type">GstFFTF32Complex</span></a> *freqdata</code></em>,
<em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gfloat"><span class="type">gfloat</span></a> *timedata</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gst-plugins-base-libs-gstfftf32.html#gst-fft-f32-window" title="gst_fft_f32_window ()">gst_fft_f32_window</a> (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> *self</code></em>,
<em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gfloat"><span class="type">gfloat</span></a> *timedata</code></em>,
<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstfft.html#GstFFTWindow" title="enum GstFFTWindow"><span class="type">GstFFTWindow</span></a> window</code></em>);
<span class="returnvalue">void</span> <a class="link" href="gst-plugins-base-libs-gstfftf32.html#gst-fft-f32-free" title="gst_fft_f32_free ()">gst_fft_f32_free</a> (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> *self</code></em>);
</pre>
</div>
<div class="refsect1">
<a name="gst-plugins-base-libs-gstfftf32.description"></a><h2>Description</h2>
<p>
<a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> provides a FFT implementation and related functions for
32 bit float samples. To use this call <a class="link" href="gst-plugins-base-libs-gstfftf32.html#gst-fft-f32-new" title="gst_fft_f32_new ()"><code class="function">gst_fft_f32_new()</code></a> for
allocating a <a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> instance with the appropriate parameters and
then call <a class="link" href="gst-plugins-base-libs-gstfftf32.html#gst-fft-f32-fft" title="gst_fft_f32_fft ()"><code class="function">gst_fft_f32_fft()</code></a> or <a class="link" href="gst-plugins-base-libs-gstfftf32.html#gst-fft-f32-inverse-fft" title="gst_fft_f32_inverse_fft ()"><code class="function">gst_fft_f32_inverse_fft()</code></a> to perform the
FFT or inverse FFT on a buffer of samples.
</p>
<p>
After use free the <a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> instance with <a class="link" href="gst-plugins-base-libs-gstfftf32.html#gst-fft-f32-free" title="gst_fft_f32_free ()"><code class="function">gst_fft_f32_free()</code></a>.
</p>
<p>
For the best performance use <a class="link" href="gst-plugins-base-libs-gstfft.html#gst-fft-next-fast-length" title="gst_fft_next_fast_length ()"><code class="function">gst_fft_next_fast_length()</code></a> to get a
number that is entirely a product of 2, 3 and 5 and use this as the
<em class="parameter"><code>len</code></em> parameter for <a class="link" href="gst-plugins-base-libs-gstfftf32.html#gst-fft-f32-new" title="gst_fft_f32_new ()"><code class="function">gst_fft_f32_new()</code></a>.
</p>
<p>
The <em class="parameter"><code>len</code></em> 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 <em class="parameter"><code>len</code></em>/2 + 1. To get n samples in the frequency domain use 2*n - 2 as <em class="parameter"><code>len</code></em>.
</p>
<p>
Before performing the FFT on time domain data it usually makes sense
to apply a window function to it. For this <a class="link" href="gst-plugins-base-libs-gstfftf32.html#gst-fft-f32-window" title="gst_fft_f32_window ()"><code class="function">gst_fft_f32_window()</code></a> can comfortably
be used.
</p>
<p>
Be aware, that you can't simply run <a class="link" href="gst-plugins-base-libs-gstfftf32.html#gst-fft-f32-inverse-fft" title="gst_fft_f32_inverse_fft ()"><code class="function">gst_fft_f32_inverse_fft()</code></a> on the
resulting frequency data of <a class="link" href="gst-plugins-base-libs-gstfftf32.html#gst-fft-f32-fft" title="gst_fft_f32_fft ()"><code class="function">gst_fft_f32_fft()</code></a> 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.
</p>
</div>
<div class="refsect1">
<a name="gst-plugins-base-libs-gstfftf32.details"></a><h2>Details</h2>
<div class="refsect2">
<a name="GstFFTF32"></a><h3>GstFFTF32</h3>
<pre class="programlisting">typedef struct _GstFFTF32 GstFFTF32;</pre>
</div>
<hr>
<div class="refsect2">
<a name="GstFFTF32Complex"></a><h3>struct GstFFTF32Complex</h3>
<pre class="programlisting">struct GstFFTF32Complex {
gfloat r;
gfloat i;
};
</pre>
<p>
Data type for complex numbers composed of
32 bit float.
</p>
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<td><p><span class="term"><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gfloat"><span class="type">gfloat</span></a> <em class="structfield"><code><a name="GstFFTF32Complex.r"></a>r</code></em>;</span></p></td>
<td>Real part</td>
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<tr>
<td><p><span class="term"><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gfloat"><span class="type">gfloat</span></a> <em class="structfield"><code><a name="GstFFTF32Complex.i"></a>i</code></em>;</span></p></td>
<td>Imaginary part</td>
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</div>
<hr>
<div class="refsect2">
<a name="gst-fft-f32-new"></a><h3>gst_fft_f32_new ()</h3>
<pre class="programlisting"><a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="returnvalue">GstFFTF32</span></a> * gst_fft_f32_new (<em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint"><span class="type">gint</span></a> len</code></em>,
<em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> inverse</code></em>);</pre>
<p>
This returns a new <a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> instance with the given parameters. It makes
sense to keep one instance for several calls for speed reasons.
</p>
<p>
<em class="parameter"><code>len</code></em> 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
<a class="link" href="gst-plugins-base-libs-gstfft.html#gst-fft-next-fast-length" title="gst_fft_next_fast_length ()"><code class="function">gst_fft_next_fast_length()</code></a>.
</p>
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<td><p><span class="term"><em class="parameter"><code>len</code></em> :</span></p></td>
<td>Length of the FFT in the time domain</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>inverse</code></em> :</span></p></td>
<td>
<a href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if the <a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> instance should be used for the inverse FFT</td>
</tr>
<tr>
<td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
<td>a new <a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> instance.</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="gst-fft-f32-fft"></a><h3>gst_fft_f32_fft ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> gst_fft_f32_fft (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> *self</code></em>,
<em class="parameter"><code>const <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gfloat"><span class="type">gfloat</span></a> *timedata</code></em>,
<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32Complex" title="struct GstFFTF32Complex"><span class="type">GstFFTF32Complex</span></a> *freqdata</code></em>);</pre>
<p>
This performs the FFT on <em class="parameter"><code>timedata</code></em> and puts the result in <em class="parameter"><code>freqdata</code></em>.
</p>
<p>
<em class="parameter"><code>timedata</code></em> must have as many samples as specified with the <em class="parameter"><code>len</code></em> parameter while
allocating the <a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> instance with <a class="link" href="gst-plugins-base-libs-gstfftf32.html#gst-fft-f32-new" title="gst_fft_f32_new ()"><code class="function">gst_fft_f32_new()</code></a>.
</p>
<p>
<em class="parameter"><code>freqdata</code></em> must be large enough to hold <em class="parameter"><code>len</code></em>/2 + 1 <a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32Complex" title="struct GstFFTF32Complex"><span class="type">GstFFTF32Complex</span></a> frequency
domain samples.
</p>
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<td><p><span class="term"><em class="parameter"><code>self</code></em> :</span></p></td>
<td>
<a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> instance for this call</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>timedata</code></em> :</span></p></td>
<td>Buffer of the samples in the time domain</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>freqdata</code></em> :</span></p></td>
<td>Target buffer for the samples in the frequency domain</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="gst-fft-f32-inverse-fft"></a><h3>gst_fft_f32_inverse_fft ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> gst_fft_f32_inverse_fft (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> *self</code></em>,
<em class="parameter"><code>const <a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32Complex" title="struct GstFFTF32Complex"><span class="type">GstFFTF32Complex</span></a> *freqdata</code></em>,
<em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gfloat"><span class="type">gfloat</span></a> *timedata</code></em>);</pre>
<p>
This performs the inverse FFT on <em class="parameter"><code>freqdata</code></em> and puts the result in <em class="parameter"><code>timedata</code></em>.
</p>
<p>
<em class="parameter"><code>freqdata</code></em> must have <em class="parameter"><code>len</code></em>/2 + 1 samples, where <em class="parameter"><code>len</code></em> is the parameter specified
while allocating the <a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> instance with <a class="link" href="gst-plugins-base-libs-gstfftf32.html#gst-fft-f32-new" title="gst_fft_f32_new ()"><code class="function">gst_fft_f32_new()</code></a>.
</p>
<p>
<em class="parameter"><code>timedata</code></em> must be large enough to hold <em class="parameter"><code>len</code></em> time domain samples.
</p>
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<td><p><span class="term"><em class="parameter"><code>self</code></em> :</span></p></td>
<td>
<a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> instance for this call</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>freqdata</code></em> :</span></p></td>
<td>Buffer of the samples in the frequency domain</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>timedata</code></em> :</span></p></td>
<td>Target buffer for the samples in the time domain</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="gst-fft-f32-window"></a><h3>gst_fft_f32_window ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> gst_fft_f32_window (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> *self</code></em>,
<em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gfloat"><span class="type">gfloat</span></a> *timedata</code></em>,
<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstfft.html#GstFFTWindow" title="enum GstFFTWindow"><span class="type">GstFFTWindow</span></a> window</code></em>);</pre>
<p>
This calls the window function <em class="parameter"><code>window</code></em> on the <em class="parameter"><code>timedata</code></em> sample buffer.
</p>
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<td><p><span class="term"><em class="parameter"><code>self</code></em> :</span></p></td>
<td>
<a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> instance for this call</td>
</tr>
<tr>
<td><p><span class="term"><em class="parameter"><code>timedata</code></em> :</span></p></td>
<td>Time domain samples</td>
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<tr>
<td><p><span class="term"><em class="parameter"><code>window</code></em> :</span></p></td>
<td>Window function to apply</td>
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</tbody>
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</div>
<hr>
<div class="refsect2">
<a name="gst-fft-f32-free"></a><h3>gst_fft_f32_free ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> gst_fft_f32_free (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> *self</code></em>);</pre>
<p>
This frees the memory allocated for <em class="parameter"><code>self</code></em>.
</p>
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<td><p><span class="term"><em class="parameter"><code>self</code></em> :</span></p></td>
<td>
<a class="link" href="gst-plugins-base-libs-gstfftf32.html#GstFFTF32" title="GstFFTF32"><span class="type">GstFFTF32</span></a> instance for this call</td>
</tr></tbody>
</table></div>
</div>
</div>
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