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| <a href="#gst-plugins-base-libs-gstffts16.description" class="shortcut">Description</a> |
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| <div class="refentry"> |
| <a name="gst-plugins-base-libs-gstffts16"></a><div class="titlepage"></div> |
| <div class="refnamediv"><table width="100%"><tr> |
| <td valign="top"> |
| <h2><span class="refentrytitle"><a name="gst-plugins-base-libs-gstffts16.top_of_page"></a>gstffts16</span></h2> |
| <p>gstffts16 — FFT functions for signed 16 bit integer samples</p> |
| </td> |
| <td valign="top" align="right"></td> |
| </tr></table></div> |
| <div class="refsynopsisdiv"> |
| <a name="gst-plugins-base-libs-gstffts16.synopsis"></a><h2>Synopsis</h2> |
| <pre class="synopsis"> |
| #include <gst/fft/gstffts16.h> |
| |
| <a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16">GstFFTS16</a>; |
| struct <a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16Complex" title="struct GstFFTS16Complex">GstFFTS16Complex</a>; |
| <a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="returnvalue">GstFFTS16</span></a> * <a class="link" href="gst-plugins-base-libs-gstffts16.html#gst-fft-s16-new" title="gst_fft_s16_new ()">gst_fft_s16_new</a> (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a> len</code></em>, |
| <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/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-gstffts16.html#gst-fft-s16-fft" title="gst_fft_s16_fft ()">gst_fft_s16_fft</a> (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</span></a> *self</code></em>, |
| <em class="parameter"><code>const <span class="type">gint16</span> *timedata</code></em>, |
| <em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16Complex" title="struct GstFFTS16Complex"><span class="type">GstFFTS16Complex</span></a> *freqdata</code></em>); |
| <span class="returnvalue">void</span> <a class="link" href="gst-plugins-base-libs-gstffts16.html#gst-fft-s16-inverse-fft" title="gst_fft_s16_inverse_fft ()">gst_fft_s16_inverse_fft</a> (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</span></a> *self</code></em>, |
| <em class="parameter"><code>const <a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16Complex" title="struct GstFFTS16Complex"><span class="type">GstFFTS16Complex</span></a> *freqdata</code></em>, |
| <em class="parameter"><code><span class="type">gint16</span> *timedata</code></em>); |
| <span class="returnvalue">void</span> <a class="link" href="gst-plugins-base-libs-gstffts16.html#gst-fft-s16-window" title="gst_fft_s16_window ()">gst_fft_s16_window</a> (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</span></a> *self</code></em>, |
| <em class="parameter"><code><span class="type">gint16</span> *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-gstffts16.html#gst-fft-s16-free" title="gst_fft_s16_free ()">gst_fft_s16_free</a> (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</span></a> *self</code></em>); |
| </pre> |
| </div> |
| <div class="refsect1"> |
| <a name="gst-plugins-base-libs-gstffts16.description"></a><h2>Description</h2> |
| <p> |
| <a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</span></a> provides a FFT implementation and related functions for |
| signed 16 bit integer samples. To use this call <a class="link" href="gst-plugins-base-libs-gstffts16.html#gst-fft-s16-new" title="gst_fft_s16_new ()"><code class="function">gst_fft_s16_new()</code></a> for |
| allocating a <a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</span></a> instance with the appropriate parameters and |
| then call <a class="link" href="gst-plugins-base-libs-gstffts16.html#gst-fft-s16-fft" title="gst_fft_s16_fft ()"><code class="function">gst_fft_s16_fft()</code></a> or <a class="link" href="gst-plugins-base-libs-gstffts16.html#gst-fft-s16-inverse-fft" title="gst_fft_s16_inverse_fft ()"><code class="function">gst_fft_s16_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-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</span></a> instance with <a class="link" href="gst-plugins-base-libs-gstffts16.html#gst-fft-s16-free" title="gst_fft_s16_free ()"><code class="function">gst_fft_s16_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-gstffts16.html#gst-fft-s16-new" title="gst_fft_s16_new ()"><code class="function">gst_fft_s16_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-gstffts16.html#gst-fft-s16-window" title="gst_fft_s16_window ()"><code class="function">gst_fft_s16_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-gstffts16.html#gst-fft-s16-inverse-fft" title="gst_fft_s16_inverse_fft ()"><code class="function">gst_fft_s16_inverse_fft()</code></a> on the |
| resulting frequency data of <a class="link" href="gst-plugins-base-libs-gstffts16.html#gst-fft-s16-fft" title="gst_fft_s16_fft ()"><code class="function">gst_fft_s16_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-gstffts16.details"></a><h2>Details</h2> |
| <div class="refsect2"> |
| <a name="GstFFTS16"></a><h3>GstFFTS16</h3> |
| <pre class="programlisting">typedef struct _GstFFTS16 GstFFTS16;</pre> |
| </div> |
| <hr> |
| <div class="refsect2"> |
| <a name="GstFFTS16Complex"></a><h3>struct GstFFTS16Complex</h3> |
| <pre class="programlisting">struct GstFFTS16Complex { |
| gint16 r; |
| gint16 i; |
| }; |
| </pre> |
| <p> |
| Data type for complex numbers composed of |
| signed 16 bit integers. |
| </p> |
| <div class="variablelist"><table border="0"> |
| <col align="left" valign="top"> |
| <tbody> |
| <tr> |
| <td><p><span class="term"><span class="type">gint16</span> <em class="structfield"><code><a name="GstFFTS16Complex.r"></a>r</code></em>;</span></p></td> |
| <td>Real part</td> |
| </tr> |
| <tr> |
| <td><p><span class="term"><span class="type">gint16</span> <em class="structfield"><code><a name="GstFFTS16Complex.i"></a>i</code></em>;</span></p></td> |
| <td>Imaginary part</td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| <hr> |
| <div class="refsect2"> |
| <a name="gst-fft-s16-new"></a><h3>gst_fft_s16_new ()</h3> |
| <pre class="programlisting"><a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="returnvalue">GstFFTS16</span></a> * gst_fft_s16_new (<em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a> len</code></em>, |
| <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/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-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</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> |
| <div class="variablelist"><table border="0"> |
| <col align="left" valign="top"> |
| <tbody> |
| <tr> |
| <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="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if the <a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</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-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</span></a> instance.</td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| <hr> |
| <div class="refsect2"> |
| <a name="gst-fft-s16-fft"></a><h3>gst_fft_s16_fft ()</h3> |
| <pre class="programlisting"><span class="returnvalue">void</span> gst_fft_s16_fft (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</span></a> *self</code></em>, |
| <em class="parameter"><code>const <span class="type">gint16</span> *timedata</code></em>, |
| <em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16Complex" title="struct GstFFTS16Complex"><span class="type">GstFFTS16Complex</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-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</span></a> instance with <a class="link" href="gst-plugins-base-libs-gstffts16.html#gst-fft-s16-new" title="gst_fft_s16_new ()"><code class="function">gst_fft_s16_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-gstffts16.html#GstFFTS16Complex" title="struct GstFFTS16Complex"><span class="type">GstFFTS16Complex</span></a> frequency |
| domain samples. |
| </p> |
| <div class="variablelist"><table border="0"> |
| <col align="left" valign="top"> |
| <tbody> |
| <tr> |
| <td><p><span class="term"><em class="parameter"><code>self</code></em> :</span></p></td> |
| <td> |
| <a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</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-s16-inverse-fft"></a><h3>gst_fft_s16_inverse_fft ()</h3> |
| <pre class="programlisting"><span class="returnvalue">void</span> gst_fft_s16_inverse_fft (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</span></a> *self</code></em>, |
| <em class="parameter"><code>const <a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16Complex" title="struct GstFFTS16Complex"><span class="type">GstFFTS16Complex</span></a> *freqdata</code></em>, |
| <em class="parameter"><code><span class="type">gint16</span> *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-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</span></a> instance with <a class="link" href="gst-plugins-base-libs-gstffts16.html#gst-fft-s16-new" title="gst_fft_s16_new ()"><code class="function">gst_fft_s16_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> |
| <div class="variablelist"><table border="0"> |
| <col align="left" valign="top"> |
| <tbody> |
| <tr> |
| <td><p><span class="term"><em class="parameter"><code>self</code></em> :</span></p></td> |
| <td> |
| <a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</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-s16-window"></a><h3>gst_fft_s16_window ()</h3> |
| <pre class="programlisting"><span class="returnvalue">void</span> gst_fft_s16_window (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</span></a> *self</code></em>, |
| <em class="parameter"><code><span class="type">gint16</span> *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> |
| <div class="variablelist"><table border="0"> |
| <col align="left" valign="top"> |
| <tbody> |
| <tr> |
| <td><p><span class="term"><em class="parameter"><code>self</code></em> :</span></p></td> |
| <td> |
| <a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</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> |
| </tr> |
| <tr> |
| <td><p><span class="term"><em class="parameter"><code>window</code></em> :</span></p></td> |
| <td>Window function to apply</td> |
| </tr> |
| </tbody> |
| </table></div> |
| </div> |
| <hr> |
| <div class="refsect2"> |
| <a name="gst-fft-s16-free"></a><h3>gst_fft_s16_free ()</h3> |
| <pre class="programlisting"><span class="returnvalue">void</span> gst_fft_s16_free (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</span></a> *self</code></em>);</pre> |
| <p> |
| This frees the memory allocated for <em class="parameter"><code>self</code></em>. |
| </p> |
| <div class="variablelist"><table border="0"> |
| <col align="left" valign="top"> |
| <tbody><tr> |
| <td><p><span class="term"><em class="parameter"><code>self</code></em> :</span></p></td> |
| <td> |
| <a class="link" href="gst-plugins-base-libs-gstffts16.html#GstFFTS16" title="GstFFTS16"><span class="type">GstFFTS16</span></a> instance for this call</td> |
| </tr></tbody> |
| </table></div> |
| </div> |
| </div> |
| </div> |
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