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<a name="gst-plugins-good-plugins-audiofirfilter"></a><div class="titlepage"></div>
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<h2><span class="refentrytitle"><a name="gst-plugins-good-plugins-audiofirfilter.top_of_page"></a>audiofirfilter</span></h2>
<p>audiofirfilter</p>
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<div class="refsect1">
<a name="gst-plugins-good-plugins-audiofirfilter.properties"></a><h2>Properties</h2>
<div class="informaltable"><table class="informaltable" border="0">
<colgroup>
<col width="150px" class="properties_type">
<col width="300px" class="properties_name">
<col width="200px" class="properties_flags">
</colgroup>
<tbody>
<tr>
<td class="property_type">
<a href="https://developer.gnome.org/gobject/unstable/gobject-Value-arrays.html#GValueArray"><span class="type">GValueArray</span></a> *</td>
<td class="property_name"><a class="link" href="gst-plugins-good-plugins-audiofirfilter.html#GstAudioFIRFilter--kernel" title="The “kernel” property">kernel</a></td>
<td class="property_flags">Read / Write</td>
</tr>
<tr>
<td class="property_type"><a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#guint64"><span class="type">guint64</span></a></td>
<td class="property_name"><a class="link" href="gst-plugins-good-plugins-audiofirfilter.html#GstAudioFIRFilter--latency" title="The “latency” property">latency</a></td>
<td class="property_flags">Read / Write</td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-audiofirfilter.signals"></a><h2>Signals</h2>
<div class="informaltable"><table class="informaltable" border="0">
<colgroup>
<col width="150px" class="signals_return">
<col width="300px" class="signals_name">
<col width="200px" class="signals_flags">
</colgroup>
<tbody><tr>
<td class="signal_type"><span class="returnvalue">void</span></td>
<td class="signal_name"><a class="link" href="gst-plugins-good-plugins-audiofirfilter.html#GstAudioFIRFilter-rate-changed" title="The “rate-changed” signal">rate-changed</a></td>
<td class="signal_flags"><a href="https://developer.gnome.org/gobject/unstable/gobject-Signals.html#G-SIGNAL-RUN-LAST:CAPS">Run Last</a></td>
</tr></tbody>
</table></div>
</div>
<a name="GstAudioFIRFilter"></a><div class="refsect1">
<a name="gst-plugins-good-plugins-audiofirfilter.other"></a><h2>Types and Values</h2>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="name">
<col class="description">
</colgroup>
<tbody><tr>
<td class="datatype_keyword">struct</td>
<td class="function_name"><a class="link" href="gst-plugins-good-plugins-audiofirfilter.html#GstAudioFIRFilter-struct" title="struct GstAudioFIRFilter">GstAudioFIRFilter</a></td>
</tr></tbody>
</table></div>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-audiofirfilter.object-hierarchy"></a><h2>Object Hierarchy</h2>
<pre class="screen"> <a href="https://developer.gnome.org/gobject/unstable/gobject-The-Base-Object-Type.html#GObject">GObject</a>
<span class="lineart">╰──</span> <a href="https://developer.gnome.org/gobject/unstable/gobject-The-Base-Object-Type.html#GInitiallyUnowned">GInitiallyUnowned</a>
<span class="lineart">╰──</span> <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstObject.html">GstObject</a>
<span class="lineart">╰──</span> <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElement.html">GstElement</a>
<span class="lineart">╰──</span> <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer-libs/html/GstBaseTransform.html">GstBaseTransform</a>
<span class="lineart">╰──</span> <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-gstaudiofilter.html#GstAudioFilter">GstAudioFilter</a>
<span class="lineart">╰──</span> GstAudioFXBaseFIRFilter
<span class="lineart">╰──</span> GstAudioFIRFilter
</pre>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-audiofirfilter.description"></a><h2>Description</h2>
<p>audiofirfilter implements a generic audio <a class="ulink" href="http://en.wikipedia.org/wiki/Finite_impulse_response" target="_top">FIR filter</a>. Before usage the
"kernel" property has to be set to the filter kernel that should be
used and the "latency" property has to be set to the latency (in samples)
that is introduced by the filter kernel. Setting a latency of n samples
will lead to the first n samples being dropped from the output and
n samples added to the end.</p>
<p>The filter kernel describes the impulse response of the filter. To
calculate the frequency response of the filter you have to calculate
the Fourier Transform of the impulse response.</p>
<p>To change the filter kernel whenever the sampling rate changes the
"rate-changed" signal can be used. This should be done for most
FIR filters as they're depending on the sampling rate.</p>
<div class="refsect2">
<a name="id-1.2.20.8.5"></a><h3>Example application</h3>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
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<td class="listing_code"><pre class="programlisting"><span class="comment">/* GStreamer</span>
<span class="comment"> * Copyright (C) 2009 Sebastian Droege &lt;sebastian.droege&#64;collabora.co.uk&gt;</span>
<span class="comment"> *</span>
<span class="comment"> * This library is free software; you can redistribute it and/or</span>
<span class="comment"> * modify it under the terms of the GNU Library General Public</span>
<span class="comment"> * License as published by the Free Software Foundation; either</span>
<span class="comment"> * version 2 of the License, or (at your option) any later version.</span>
<span class="comment"> *</span>
<span class="comment"> * This library is distributed in the hope that it will be useful,</span>
<span class="comment"> * but WITHOUT ANY WARRANTY; without even the implied warranty of</span>
<span class="comment"> * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU</span>
<span class="comment"> * Library General Public License for more details.</span>
<span class="comment"> *</span>
<span class="comment"> * You should have received a copy of the GNU Library General Public</span>
<span class="comment"> * License along with this library; if not, write to the</span>
<span class="comment"> * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,</span>
<span class="comment"> * Boston, MA 02110-1301, USA.</span>
<span class="comment"> */</span>
<span class="comment">/* This small sample application creates a bandpass FIR filter</span>
<span class="comment"> * by transforming the frequency response to the filter kernel.</span>
<span class="comment"> */</span>
<span class="comment">/* FIXME 0.11: suppress warnings for deprecated API such as GValueArray</span>
<span class="comment"> * with newer GLib versions (&gt;= 2.31.0) */</span>
<span class="gtkdoc ppc">#define GLIB_DISABLE_DEPRECATION_WARNINGS</span>
<span class="gtkdoc ppc">#include &lt;string.h&gt;</span>
<span class="gtkdoc ppc">#include &lt;math.h&gt;</span>
<span class="gtkdoc ppc">#include &lt;gst/gst.h&gt;</span>
<span class="gtkdoc ppc">#include &lt;gst/fft/gstfftf64.h&gt;</span>
<span class="gtkdoc kwb">static</span> gboolean
<span class="function">on_message</span> <span class="gtkdoc opt">(</span>GstBus <span class="gtkdoc opt">*</span> bus<span class="gtkdoc opt">,</span> GstMessage <span class="gtkdoc opt">*</span> message<span class="gtkdoc opt">,</span> gpointer user_data<span class="gtkdoc opt">)</span>
<span class="gtkdoc opt">{</span>
GMainLoop <span class="gtkdoc opt">*</span>loop <span class="gtkdoc opt">= (</span>GMainLoop <span class="gtkdoc opt">*)</span> user_data<span class="gtkdoc opt">;</span>
<span class="keyword">switch</span> <span class="gtkdoc opt">(</span><span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstMessage.html#GST-MESSAGE-TYPE:CAPS">GST_MESSAGE_TYPE</a></span> <span class="gtkdoc opt">(</span>message<span class="gtkdoc opt">)) {</span>
<span class="keyword">case</span> GST_MESSAGE_ERROR<span class="gtkdoc opt">:</span>
<span class="function"><a href="https://developer.gnome.org/glib/unstable/glib-Message-Logging.html#g-error">g_error</a></span> <span class="gtkdoc opt">(</span><span class="string">&quot;Got ERROR&quot;</span><span class="gtkdoc opt">);</span>
<span class="function"><a href="https://developer.gnome.org/glib/unstable/glib-The-Main-Event-Loop.html#g-main-loop-quit">g_main_loop_quit</a></span> <span class="gtkdoc opt">(</span>loop<span class="gtkdoc opt">);</span>
<span class="keyword">break</span><span class="gtkdoc opt">;</span>
<span class="keyword">case</span> GST_MESSAGE_WARNING<span class="gtkdoc opt">:</span>
<span class="function"><a href="https://developer.gnome.org/glib/unstable/glib-Message-Logging.html#g-warning">g_warning</a></span> <span class="gtkdoc opt">(</span><span class="string">&quot;Got WARNING&quot;</span><span class="gtkdoc opt">);</span>
<span class="function"><a href="https://developer.gnome.org/glib/unstable/glib-The-Main-Event-Loop.html#g-main-loop-quit">g_main_loop_quit</a></span> <span class="gtkdoc opt">(</span>loop<span class="gtkdoc opt">);</span>
<span class="keyword">break</span><span class="gtkdoc opt">;</span>
<span class="keyword">case</span> GST_MESSAGE_EOS<span class="gtkdoc opt">:</span>
<span class="function"><a href="https://developer.gnome.org/glib/unstable/glib-The-Main-Event-Loop.html#g-main-loop-quit">g_main_loop_quit</a></span> <span class="gtkdoc opt">(</span>loop<span class="gtkdoc opt">);</span>
<span class="keyword">break</span><span class="gtkdoc opt">;</span>
<span class="keyword">default</span><span class="gtkdoc opt">:</span>
<span class="keyword">break</span><span class="gtkdoc opt">;</span>
<span class="gtkdoc opt">}</span>
<span class="keyword">return</span> TRUE<span class="gtkdoc opt">;</span>
<span class="gtkdoc opt">}</span>
<span class="gtkdoc kwb">static void</span>
<span class="function">on_rate_changed</span> <span class="gtkdoc opt">(</span>GstElement <span class="gtkdoc opt">*</span> element<span class="gtkdoc opt">,</span> gint rate<span class="gtkdoc opt">,</span> gpointer user_data<span class="gtkdoc opt">)</span>
<span class="gtkdoc opt">{</span>
GValueArray <span class="gtkdoc opt">*</span>va<span class="gtkdoc opt">;</span>
GValue v <span class="gtkdoc opt">= {</span> <span class="number">0</span><span class="gtkdoc opt">, };</span>
GstFFTF64 <span class="gtkdoc opt">*</span>fft<span class="gtkdoc opt">;</span>
GstFFTF64Complex frequency_response<span class="gtkdoc opt">[</span><span class="number">17</span><span class="gtkdoc opt">];</span>
gdouble tmp<span class="gtkdoc opt">[</span><span class="number">32</span><span class="gtkdoc opt">];</span>
gdouble filter_kernel<span class="gtkdoc opt">[</span><span class="number">32</span><span class="gtkdoc opt">];</span>
guint i<span class="gtkdoc opt">;</span>
<span class="comment">/* Create the frequency response: zero outside</span>
<span class="comment"> * a small frequency band */</span>
<span class="keyword">for</span> <span class="gtkdoc opt">(</span>i <span class="gtkdoc opt">=</span> <span class="number">0</span><span class="gtkdoc opt">;</span> i <span class="gtkdoc opt">&lt;</span> <span class="number">17</span><span class="gtkdoc opt">;</span> i<span class="gtkdoc opt">++) {</span>
<span class="keyword">if</span> <span class="gtkdoc opt">(</span>i <span class="gtkdoc opt">&lt;</span> <span class="number">5</span> <span class="gtkdoc opt">||</span> i <span class="gtkdoc opt">&gt;</span> <span class="number">11</span><span class="gtkdoc opt">)</span>
frequency_response<span class="gtkdoc opt">[</span>i<span class="gtkdoc opt">].</span>r <span class="gtkdoc opt">=</span> <span class="number">0.0</span><span class="gtkdoc opt">;</span>
<span class="keyword">else</span>
frequency_response<span class="gtkdoc opt">[</span>i<span class="gtkdoc opt">].</span>r <span class="gtkdoc opt">=</span> <span class="number">1.0</span><span class="gtkdoc opt">;</span>
frequency_response<span class="gtkdoc opt">[</span>i<span class="gtkdoc opt">].</span>i <span class="gtkdoc opt">=</span> <span class="number">0.0</span><span class="gtkdoc opt">;</span>
<span class="gtkdoc opt">}</span>
<span class="comment">/* Calculate the inverse FT of the frequency response */</span>
fft <span class="gtkdoc opt">=</span> <span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-gstfftf64.html#gst-fft-f64-new">gst_fft_f64_new</a></span> <span class="gtkdoc opt">(</span><span class="number">32</span><span class="gtkdoc opt">,</span> TRUE<span class="gtkdoc opt">);</span>
<span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-gstfftf64.html#gst-fft-f64-inverse-fft">gst_fft_f64_inverse_fft</a></span> <span class="gtkdoc opt">(</span>fft<span class="gtkdoc opt">,</span> frequency_response<span class="gtkdoc opt">,</span> tmp<span class="gtkdoc opt">);</span>
<span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-gstfftf64.html#gst-fft-f64-free">gst_fft_f64_free</a></span> <span class="gtkdoc opt">(</span>fft<span class="gtkdoc opt">);</span>
<span class="comment">/* Shift the inverse FT of the frequency response by 16,</span>
<span class="comment"> * i.e. the half of the kernel length to get the</span>
<span class="comment"> * impulse response. See http://www.dspguide.com/ch17/1.htm</span>
<span class="comment"> * for more information.</span>
<span class="comment"> */</span>
<span class="keyword">for</span> <span class="gtkdoc opt">(</span>i <span class="gtkdoc opt">=</span> <span class="number">0</span><span class="gtkdoc opt">;</span> i <span class="gtkdoc opt">&lt;</span> <span class="number">32</span><span class="gtkdoc opt">;</span> i<span class="gtkdoc opt">++)</span>
filter_kernel<span class="gtkdoc opt">[</span>i<span class="gtkdoc opt">] =</span> tmp<span class="gtkdoc opt">[(</span>i <span class="gtkdoc opt">+</span> <span class="number">16</span><span class="gtkdoc opt">) %</span> <span class="number">32</span><span class="gtkdoc opt">];</span>
<span class="comment">/* Apply the hamming window to the impulse response to get</span>
<span class="comment"> * a better result than given from the rectangular window</span>
<span class="comment"> */</span>
<span class="keyword">for</span> <span class="gtkdoc opt">(</span>i <span class="gtkdoc opt">=</span> <span class="number">0</span><span class="gtkdoc opt">;</span> i <span class="gtkdoc opt">&lt;</span> <span class="number">32</span><span class="gtkdoc opt">;</span> i<span class="gtkdoc opt">++)</span>
filter_kernel<span class="gtkdoc opt">[</span>i<span class="gtkdoc opt">] *= (</span><span class="number">0.54</span> <span class="gtkdoc opt">-</span> <span class="number">0.46</span> <span class="gtkdoc opt">*</span> <span class="function">cos</span> <span class="gtkdoc opt">(</span><span class="number">2</span> <span class="gtkdoc opt">*</span> G_PI <span class="gtkdoc opt">*</span> i <span class="gtkdoc opt">/</span> <span class="number">32</span><span class="gtkdoc opt">));</span>
va <span class="gtkdoc opt">=</span> <span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-Value-arrays.html#g-value-array-new">g_value_array_new</a></span> <span class="gtkdoc opt">(</span><span class="number">1</span><span class="gtkdoc opt">);</span>
<span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-Generic-values.html#g-value-init">g_value_init</a></span> <span class="gtkdoc opt">(&amp;</span>v<span class="gtkdoc opt">,</span> G_TYPE_DOUBLE<span class="gtkdoc opt">);</span>
<span class="keyword">for</span> <span class="gtkdoc opt">(</span>i <span class="gtkdoc opt">=</span> <span class="number">0</span><span class="gtkdoc opt">;</span> i <span class="gtkdoc opt">&lt;</span> <span class="number">32</span><span class="gtkdoc opt">;</span> i<span class="gtkdoc opt">++) {</span>
<span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-Standard-Parameter-and-Value-Types.html#g-value-set-double">g_value_set_double</a></span> <span class="gtkdoc opt">(&amp;</span>v<span class="gtkdoc opt">,</span> filter_kernel<span class="gtkdoc opt">[</span>i<span class="gtkdoc opt">]);</span>
<span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-Value-arrays.html#g-value-array-append">g_value_array_append</a></span> <span class="gtkdoc opt">(</span>va<span class="gtkdoc opt">, &amp;</span>v<span class="gtkdoc opt">);</span>
<span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-Generic-values.html#g-value-reset">g_value_reset</a></span> <span class="gtkdoc opt">(&amp;</span>v<span class="gtkdoc opt">);</span>
<span class="gtkdoc opt">}</span>
<span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-The-Base-Object-Type.html#g-object-set">g_object_set</a></span> <span class="gtkdoc opt">(</span><span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-The-Base-Object-Type.html#G-OBJECT:CAPS">G_OBJECT</a></span> <span class="gtkdoc opt">(</span>element<span class="gtkdoc opt">),</span> <span class="string">&quot;kernel&quot;</span><span class="gtkdoc opt">,</span> va<span class="gtkdoc opt">,</span> NULL<span class="gtkdoc opt">);</span>
<span class="comment">/* Latency is 1/2 of the kernel length for this method of</span>
<span class="comment"> * calculating a filter kernel from the frequency response</span>
<span class="comment"> */</span>
<span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-The-Base-Object-Type.html#g-object-set">g_object_set</a></span> <span class="gtkdoc opt">(</span><span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-The-Base-Object-Type.html#G-OBJECT:CAPS">G_OBJECT</a></span> <span class="gtkdoc opt">(</span>element<span class="gtkdoc opt">),</span> <span class="string">&quot;latency&quot;</span><span class="gtkdoc opt">, (</span>gint64<span class="gtkdoc opt">) (</span><span class="number">32</span> <span class="gtkdoc opt">/</span> <span class="number">2</span><span class="gtkdoc opt">),</span> NULL<span class="gtkdoc opt">);</span>
<span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-Value-arrays.html#g-value-array-free">g_value_array_free</a></span> <span class="gtkdoc opt">(</span>va<span class="gtkdoc opt">);</span>
<span class="gtkdoc opt">}</span>
gint
<span class="function">main</span> <span class="gtkdoc opt">(</span>gint argc<span class="gtkdoc opt">,</span> gchar <span class="gtkdoc opt">*</span> argv<span class="gtkdoc opt">[])</span>
<span class="gtkdoc opt">{</span>
GstElement <span class="gtkdoc opt">*</span>pipeline<span class="gtkdoc opt">, *</span>src<span class="gtkdoc opt">, *</span>filter<span class="gtkdoc opt">, *</span>conv<span class="gtkdoc opt">, *</span>sink<span class="gtkdoc opt">;</span>
GstBus <span class="gtkdoc opt">*</span>bus<span class="gtkdoc opt">;</span>
GMainLoop <span class="gtkdoc opt">*</span>loop<span class="gtkdoc opt">;</span>
<span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-Gst.html#gst-init">gst_init</a></span> <span class="gtkdoc opt">(</span>NULL<span class="gtkdoc opt">,</span> NULL<span class="gtkdoc opt">);</span>
pipeline <span class="gtkdoc opt">=</span> <span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElementFactory.html#gst-element-factory-make">gst_element_factory_make</a></span> <span class="gtkdoc opt">(</span><span class="string">&quot;pipeline&quot;</span><span class="gtkdoc opt">,</span> NULL<span class="gtkdoc opt">);</span>
src <span class="gtkdoc opt">=</span> <span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElementFactory.html#gst-element-factory-make">gst_element_factory_make</a></span> <span class="gtkdoc opt">(</span><span class="string">&quot;audiotestsrc&quot;</span><span class="gtkdoc opt">,</span> NULL<span class="gtkdoc opt">);</span>
<span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-The-Base-Object-Type.html#g-object-set">g_object_set</a></span> <span class="gtkdoc opt">(</span><span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-The-Base-Object-Type.html#G-OBJECT:CAPS">G_OBJECT</a></span> <span class="gtkdoc opt">(</span>src<span class="gtkdoc opt">),</span> <span class="string">&quot;wave&quot;</span><span class="gtkdoc opt">,</span> <span class="number">5</span><span class="gtkdoc opt">,</span> NULL<span class="gtkdoc opt">);</span>
filter <span class="gtkdoc opt">=</span> <span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElementFactory.html#gst-element-factory-make">gst_element_factory_make</a></span> <span class="gtkdoc opt">(</span><span class="string">&quot;audiofirfilter&quot;</span><span class="gtkdoc opt">,</span> NULL<span class="gtkdoc opt">);</span>
<span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-Signals.html#g-signal-connect">g_signal_connect</a></span> <span class="gtkdoc opt">(</span><span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-The-Base-Object-Type.html#G-OBJECT:CAPS">G_OBJECT</a></span> <span class="gtkdoc opt">(</span>filter<span class="gtkdoc opt">),</span> <span class="string">&quot;rate-changed&quot;</span><span class="gtkdoc opt">,</span>
<span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-Closures.html#G-CALLBACK:CAPS">G_CALLBACK</a></span> <span class="gtkdoc opt">(</span>on_rate_changed<span class="gtkdoc opt">),</span> NULL<span class="gtkdoc opt">);</span>
conv <span class="gtkdoc opt">=</span> <span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElementFactory.html#gst-element-factory-make">gst_element_factory_make</a></span> <span class="gtkdoc opt">(</span><span class="string">&quot;audioconvert&quot;</span><span class="gtkdoc opt">,</span> NULL<span class="gtkdoc opt">);</span>
sink <span class="gtkdoc opt">=</span> <span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElementFactory.html#gst-element-factory-make">gst_element_factory_make</a></span> <span class="gtkdoc opt">(</span><span class="string">&quot;autoaudiosink&quot;</span><span class="gtkdoc opt">,</span> NULL<span class="gtkdoc opt">);</span>
<span class="function"><a href="https://developer.gnome.org/glib/unstable/glib-Warnings-and-Assertions.html#g-return-val-if-fail">g_return_val_if_fail</a></span> <span class="gtkdoc opt">(</span>sink <span class="gtkdoc opt">!=</span> NULL<span class="gtkdoc opt">, -</span><span class="number">1</span><span class="gtkdoc opt">);</span>
<span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstBin.html#gst-bin-add-many">gst_bin_add_many</a></span> <span class="gtkdoc opt">(</span><span class="function">GST_BIN</span> <span class="gtkdoc opt">(</span>pipeline<span class="gtkdoc opt">),</span> src<span class="gtkdoc opt">,</span> filter<span class="gtkdoc opt">,</span> conv<span class="gtkdoc opt">,</span> sink<span class="gtkdoc opt">,</span> NULL<span class="gtkdoc opt">);</span>
<span class="keyword">if</span> <span class="gtkdoc opt">(!</span><span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElement.html#gst-element-link-many">gst_element_link_many</a></span> <span class="gtkdoc opt">(</span>src<span class="gtkdoc opt">,</span> filter<span class="gtkdoc opt">,</span> conv<span class="gtkdoc opt">,</span> sink<span class="gtkdoc opt">,</span> NULL<span class="gtkdoc opt">)) {</span>
<span class="function"><a href="https://developer.gnome.org/glib/unstable/glib-Message-Logging.html#g-error">g_error</a></span> <span class="gtkdoc opt">(</span><span class="string">&quot;Failed to link elements&quot;</span><span class="gtkdoc opt">);</span>
<span class="keyword">return</span> <span class="gtkdoc opt">-</span><span class="number">2</span><span class="gtkdoc opt">;</span>
<span class="gtkdoc opt">}</span>
loop <span class="gtkdoc opt">=</span> <span class="function"><a href="https://developer.gnome.org/glib/unstable/glib-The-Main-Event-Loop.html#g-main-loop-new">g_main_loop_new</a></span> <span class="gtkdoc opt">(</span>NULL<span class="gtkdoc opt">,</span> FALSE<span class="gtkdoc opt">);</span>
bus <span class="gtkdoc opt">=</span> <span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstPipeline.html#gst-pipeline-get-bus">gst_pipeline_get_bus</a></span> <span class="gtkdoc opt">(</span><span class="function">GST_PIPELINE</span> <span class="gtkdoc opt">(</span>pipeline<span class="gtkdoc opt">));</span>
<span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstBus.html#gst-bus-add-signal-watch">gst_bus_add_signal_watch</a></span> <span class="gtkdoc opt">(</span>bus<span class="gtkdoc opt">);</span>
<span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-Signals.html#g-signal-connect">g_signal_connect</a></span> <span class="gtkdoc opt">(</span><span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-The-Base-Object-Type.html#G-OBJECT:CAPS">G_OBJECT</a></span> <span class="gtkdoc opt">(</span>bus<span class="gtkdoc opt">),</span> <span class="string">&quot;message&quot;</span><span class="gtkdoc opt">,</span> <span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-Closures.html#G-CALLBACK:CAPS">G_CALLBACK</a></span> <span class="gtkdoc opt">(</span>on_message<span class="gtkdoc opt">),</span> loop<span class="gtkdoc opt">);</span>
<span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstObject.html#gst-object-unref">gst_object_unref</a></span> <span class="gtkdoc opt">(</span><span class="function">GST_OBJECT</span> <span class="gtkdoc opt">(</span>bus<span class="gtkdoc opt">));</span>
<span class="keyword">if</span> <span class="gtkdoc opt">(</span><span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElement.html#gst-element-set-state">gst_element_set_state</a></span> <span class="gtkdoc opt">(</span>pipeline<span class="gtkdoc opt">,</span>
GST_STATE_PLAYING<span class="gtkdoc opt">) ==</span> GST_STATE_CHANGE_FAILURE<span class="gtkdoc opt">) {</span>
<span class="function"><a href="https://developer.gnome.org/glib/unstable/glib-Message-Logging.html#g-error">g_error</a></span> <span class="gtkdoc opt">(</span><span class="string">&quot;Failed to go into PLAYING state&quot;</span><span class="gtkdoc opt">);</span>
<span class="keyword">return</span> <span class="gtkdoc opt">-</span><span class="number">3</span><span class="gtkdoc opt">;</span>
<span class="gtkdoc opt">}</span>
<span class="function"><a href="https://developer.gnome.org/glib/unstable/glib-The-Main-Event-Loop.html#g-main-loop-run">g_main_loop_run</a></span> <span class="gtkdoc opt">(</span>loop<span class="gtkdoc opt">);</span>
<span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElement.html#gst-element-set-state">gst_element_set_state</a></span> <span class="gtkdoc opt">(</span>pipeline<span class="gtkdoc opt">,</span> GST_STATE_NULL<span class="gtkdoc opt">);</span>
<span class="function"><a href="https://developer.gnome.org/glib/unstable/glib-The-Main-Event-Loop.html#g-main-loop-unref">g_main_loop_unref</a></span> <span class="gtkdoc opt">(</span>loop<span class="gtkdoc opt">);</span>
<span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstObject.html#gst-object-unref">gst_object_unref</a></span> <span class="gtkdoc opt">(</span>pipeline<span class="gtkdoc opt">);</span>
<span class="keyword">return</span> <span class="number">0</span><span class="gtkdoc opt">;</span>
<span class="gtkdoc opt">}</span></pre></td>
</tr>
</tbody>
</table>
</div>
</div>
<div class="refsynopsisdiv">
<h2>Synopsis</h2>
<div class="refsect2">
<a name="id-1.2.20.8.6.1"></a><h3>Element Information</h3>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term">plugin</span></p></td>
<td>
<a class="link" href="gst-plugins-good-plugins-plugin-audiofx.html#plugin-audiofx">audiofx</a>
</td>
</tr>
<tr>
<td><p><span class="term">author</span></p></td>
<td>Sebastian Dröge &lt;sebastian.droege@collabora.co.uk&gt;</td>
</tr>
<tr>
<td><p><span class="term">class</span></p></td>
<td>Filter/Effect/Audio</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="id-1.2.20.8.6.2"></a><h3>Element Pads</h3>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term">name</span></p></td>
<td>sink</td>
</tr>
<tr>
<td><p><span class="term">direction</span></p></td>
<td>sink</td>
</tr>
<tr>
<td><p><span class="term">presence</span></p></td>
<td>always</td>
</tr>
<tr>
<td><p><span class="term">details</span></p></td>
<td>audio/x-raw, format=(string){ F32LE, F64LE }, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ], layout=(string)interleaved</td>
</tr>
</tbody>
</table></div>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term">name</span></p></td>
<td>src</td>
</tr>
<tr>
<td><p><span class="term">direction</span></p></td>
<td>source</td>
</tr>
<tr>
<td><p><span class="term">presence</span></p></td>
<td>always</td>
</tr>
<tr>
<td><p><span class="term">details</span></p></td>
<td>audio/x-raw, format=(string){ F32LE, F64LE }, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ], layout=(string)interleaved</td>
</tr>
</tbody>
</table></div>
</div>
</div>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-audiofirfilter.functions_details"></a><h2>Functions</h2>
<p></p>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-audiofirfilter.other_details"></a><h2>Types and Values</h2>
<div class="refsect2">
<a name="GstAudioFIRFilter-struct"></a><h3>struct GstAudioFIRFilter</h3>
<pre class="programlisting">struct GstAudioFIRFilter;</pre>
<p>Opaque data structure.</p>
</div>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-audiofirfilter.property-details"></a><h2>Property Details</h2>
<div class="refsect2">
<a name="GstAudioFIRFilter--kernel"></a><h3>The <code class="literal">“kernel”</code> property</h3>
<pre class="programlisting"> “kernel” <a href="https://developer.gnome.org/gobject/unstable/gobject-Value-arrays.html#GValueArray"><span class="type">GValueArray</span></a> *</pre>
<p>Filter kernel for the FIR filter.</p>
<p>Flags: Read / Write</p>
</div>
<hr>
<div class="refsect2">
<a name="GstAudioFIRFilter--latency"></a><h3>The <code class="literal">“latency”</code> property</h3>
<pre class="programlisting"> “latency” <a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#guint64"><span class="type">guint64</span></a></pre>
<p>Filter latency in samples.</p>
<p>Flags: Read / Write</p>
<p>Default value: 0</p>
</div>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-audiofirfilter.signal-details"></a><h2>Signal Details</h2>
<div class="refsect2">
<a name="GstAudioFIRFilter-rate-changed"></a><h3>The <code class="literal">“rate-changed”</code> signal</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
user_function (<a class="link" href="gst-plugins-good-plugins-audiofirfilter.html#GstAudioFIRFilter"><span class="type">GstAudioFIRFilter</span></a> *filter,
<a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a> rate,
<a href="https://developer.gnome.org/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a> user_data)</pre>
<p>Will be emitted when the sampling rate changes. The callbacks
will be called from the streaming thread and processing will
stop until the event is handled.</p>
<div class="refsect3">
<a name="id-1.2.20.12.2.5"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>filter</p></td>
<td class="parameter_description"><p>the filter on which the signal is emitted</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>rate</p></td>
<td class="parameter_description"><p>the new sampling rate</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>user_data</p></td>
<td class="parameter_description"><p>user data set when the signal handler was connected.</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<p>Flags: <a href="https://developer.gnome.org/gobject/unstable/gobject-Signals.html#G-SIGNAL-RUN-LAST:CAPS">Run Last</a></p>
</div>
</div>
</div>
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