docs/plugins/html/gst-plugins-good-plugins-audiofirfilter.html

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  24 <a href="#gst-plugins-good-plugins-audiofirfilter.synopsis" class="shortcut">Top</a>
  25                    |
  26                   <a href="#gst-plugins-good-plugins-audiofirfilter.description" class="shortcut">Description</a>
  27                    |
  28                   <a href="#gst-plugins-good-plugins-audiofirfilter.object-hierarchy" class="shortcut">Object Hierarchy</a>
  29                    |
  30                   <a href="#gst-plugins-good-plugins-audiofirfilter.properties" class="shortcut">Properties</a>
  31                    |
  32                   <a href="#gst-plugins-good-plugins-audiofirfilter.signals" class="shortcut">Signals</a>
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  35 <div class="refentry">
  36 <a name="gst-plugins-good-plugins-audiofirfilter"></a><div class="titlepage"></div>
  37 <div class="refnamediv"><table width="100%"><tr>
  38 <td valign="top">
  39 <h2><span class="refentrytitle"><a name="gst-plugins-good-plugins-audiofirfilter.top_of_page"></a>audiofirfilter</span></h2>
  40 <p>audiofirfilter — Generic audio FIR filter with custom filter kernel</p>
  41 </td>
  42 <td valign="top" align="right"></td>
  43 </tr></table></div>
  44 <div class="refsynopsisdiv">
  45 <a name="gst-plugins-good-plugins-audiofirfilter.synopsis"></a><h2>Synopsis</h2>
  46 <a name="GstAudioFIRFilter"></a><pre class="synopsis">struct              <a class="link" href="gst-plugins-good-plugins-audiofirfilter.html#GstAudioFIRFilter-struct" title="struct GstAudioFIRFilter">GstAudioFIRFilter</a>;
  47 </pre>
  48 </div>
  49 <div class="refsect1">
  50 <a name="gst-plugins-good-plugins-audiofirfilter.object-hierarchy"></a><h2>Object Hierarchy</h2>
  51 <pre class="synopsis">
  52   <a href="http://library.gnome.org/devel/gobject/unstable/gobject-The-Base-Object-Type.html#GObject">GObject</a>
  53    +----<a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstObject.html">GstObject</a>
  54          +----<a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElement.html">GstElement</a>
  55                +----<a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer-libs/html/GstBaseTransform.html">GstBaseTransform</a>
  56                      +----<a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-libs/html/gst-plugins-base-libs-gstaudiofilter.html#GstAudioFilter">GstAudioFilter</a>
  57                            +----GstAudioFXBaseFIRFilter
  58                                  +----GstAudioFIRFilter
  59 </pre>
  60 </div>
  61 <div class="refsect1">
  62 <a name="gst-plugins-good-plugins-audiofirfilter.properties"></a><h2>Properties</h2>
  63 <pre class="synopsis">
  64   "<a class="link" href="gst-plugins-good-plugins-audiofirfilter.html#GstAudioFIRFilter--kernel" title='The "kernel" property'>kernel</a>"                   <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Value-arrays.html#GValueArray"><span class="type">GValueArray</span></a>*          : Read / Write
  65   "<a class="link" href="gst-plugins-good-plugins-audiofirfilter.html#GstAudioFIRFilter--latency" title='The "latency" property'>latency</a>"                  <span class="type">guint64</span>               : Read / Write
  66 </pre>
  67 </div>
  68 <div class="refsect1">
  69 <a name="gst-plugins-good-plugins-audiofirfilter.signals"></a><h2>Signals</h2>
  70 <pre class="synopsis">
  71   "<a class="link" href="gst-plugins-good-plugins-audiofirfilter.html#GstAudioFIRFilter-rate-changed" title='The "rate-changed" signal'>rate-changed</a>"                                   : <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Signals.html#G-SIGNAL-RUN-LAST:CAPS"><code class="literal">Run Last</code></a>
  72 </pre>
  73 </div>
  74 <div class="refsect1">
  75 <a name="gst-plugins-good-plugins-audiofirfilter.description"></a><h2>Description</h2>
  76 <p>
  77 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
  78 "kernel" property has to be set to the filter kernel that should be
  79 used and the "latency" property has to be set to the latency (in samples)
  80 that is introduced by the filter kernel. Setting a latency of n samples
  81 will lead to the first n samples being dropped from the output and
  82 n samples added to the end.
  83 </p>
  84 <p>
  85 The filter kernel describes the impulse response of the filter. To
  86 calculate the frequency response of the filter you have to calculate
  87 the Fourier Transform of the impulse response.
  88 </p>
  89 <p>
  90 To change the filter kernel whenever the sampling rate changes the
  91 "rate-changed" signal can be used. This should be done for most
  92 FIR filters as they're depending on the sampling rate.
  93 </p>
  94 <p>
  95 </p>
  96 <div class="refsect2">
  97 <a name="idp6117040"></a><h3>Example application</h3>
  98 <div class="informalexample">
  99   <table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
 100     <tbody>
 101       <tr>
 102         <td class="listing_lines" align="right"><pre>1
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 262 161</pre></td>
 263         <td class="listing_code"><pre class="programlisting"><span class="comment">/* GStreamer</span>
 264 <span class="comment"> * Copyright (C) 2009 Sebastian Droege &lt;sebastian.droege&#64;collabora.co.uk&gt;</span>
 265 <span class="comment"> *</span>
 266 <span class="comment"> * This library is free software; you can redistribute it and/or</span>
 267 <span class="comment"> * modify it under the terms of the GNU Library General Public</span>
 268 <span class="comment"> * License as published by the Free Software Foundation; either</span>
 269 <span class="comment"> * version 2 of the License, or (at your option) any later version.</span>
 270 <span class="comment"> *</span>
 271 <span class="comment"> * This library is distributed in the hope that it will be useful,</span>
 272 <span class="comment"> * but WITHOUT ANY WARRANTY; without even the implied warranty of</span>
 273 <span class="comment"> * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU</span>
 274 <span class="comment"> * Library General Public License for more details.</span>
 275 <span class="comment"> *</span>
 276 <span class="comment"> * You should have received a copy of the GNU Library General Public</span>
 277 <span class="comment"> * License along with this library; if not, write to the</span>
 278 <span class="comment"> * Free Software Foundation, Inc., 59 Temple Place - Suite 330,</span>
 279 <span class="comment"> * Boston, MA 02111-1307, USA.</span>
 280 <span class="comment"> */</span>
 281
 282 <span class="comment">/* This small sample application creates a bandpass FIR filter</span>
 283 <span class="comment"> * by transforming the frequency response to the filter kernel.</span>
 284 <span class="comment"> */</span>
 285
 286 <span class="gtkdoc ppc">#include &lt;string.h&gt;</span>
 287 <span class="gtkdoc ppc">#include &lt;math.h&gt;</span>
 288
 289 <span class="gtkdoc ppc">#include &lt;gst/gst.h&gt;</span>
 290 <span class="gtkdoc ppc">#include &lt;gst/fft/gstfftf64.h&gt;</span>
 291
 292 <span class="gtkdoc kwb">static</span> gboolean
 293 <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>
 294 <span class="gtkdoc opt">{</span>
 295   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>
 296
 297   <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/gstreamer-GstMessage.html#GST-MESSAGE-TYPE:CAPS">GST_MESSAGE_TYPE</a></span> <span class="gtkdoc opt">(</span>message<span class="gtkdoc opt">)) {</span>
 298     <span class="keyword">case</span> GST_MESSAGE_ERROR<span class="gtkdoc opt">:</span>
 299       <span class="function"><a href="http://library.gnome.org/devel/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>
 300       <span class="function"><a href="http://library.gnome.org/devel/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>
 301       <span class="keyword">break</span><span class="gtkdoc opt">;</span>
 302     <span class="keyword">case</span> GST_MESSAGE_WARNING<span class="gtkdoc opt">:</span>
 303       <span class="function"><a href="http://library.gnome.org/devel/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>
 304       <span class="function"><a href="http://library.gnome.org/devel/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>
 305       <span class="keyword">break</span><span class="gtkdoc opt">;</span>
 306     <span class="keyword">case</span> GST_MESSAGE_EOS<span class="gtkdoc opt">:</span>
 307       <span class="function"><a href="http://library.gnome.org/devel/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>
 308       <span class="keyword">break</span><span class="gtkdoc opt">;</span>
 309     <span class="keyword">default</span><span class="gtkdoc opt">:</span>
 310       <span class="keyword">break</span><span class="gtkdoc opt">;</span>
 311   <span class="gtkdoc opt">}</span>
 312
 313   <span class="keyword">return</span> TRUE<span class="gtkdoc opt">;</span>
 314 <span class="gtkdoc opt">}</span>
 315
 316 <span class="gtkdoc kwb">static void</span>
 317 <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>
 318 <span class="gtkdoc opt">{</span>
 319   GValueArray <span class="gtkdoc opt">*</span>va<span class="gtkdoc opt">;</span>
 320   GValue v <span class="gtkdoc opt">= {</span> <span class="number">0</span><span class="gtkdoc opt">, };</span>
 321   GstFFTF64 <span class="gtkdoc opt">*</span>fft<span class="gtkdoc opt">;</span>
 322   GstFFTF64Complex frequency_response<span class="gtkdoc opt">[</span><span class="number">17</span><span class="gtkdoc opt">];</span>
 323   gdouble tmp<span class="gtkdoc opt">[</span><span class="number">32</span><span class="gtkdoc opt">];</span>
 324   gdouble filter_kernel<span class="gtkdoc opt">[</span><span class="number">32</span><span class="gtkdoc opt">];</span>
 325   guint i<span class="gtkdoc opt">;</span>
 326
 327   <span class="comment">/* Create the frequency response: zero outside</span>
 328 <span class="comment">   * a small frequency band */</span>
 329   <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>
 330     <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>
 331       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>
 332     <span class="keyword">else</span>
 333       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>
 334
 335     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>
 336   <span class="gtkdoc opt">}</span>
 337
 338   <span class="comment">/* Calculate the inverse FT of the frequency response */</span>
 339   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>
 340   <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>
 341   <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>
 342
 343   <span class="comment">/* Shift the inverse FT of the frequency response by 16,</span>
 344 <span class="comment">   * i.e. the half of the kernel length to get the</span>
 345 <span class="comment">   * impulse response. See http://www.dspguide.com/ch17/1.htm</span>
 346 <span class="comment">   * for more information.</span>
 347 <span class="comment">   */</span>
 348   <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>
 349     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>
 350
 351   <span class="comment">/* Apply the hamming window to the impulse response to get</span>
 352 <span class="comment">   * a better result than given from the rectangular window</span>
 353 <span class="comment">   */</span>
 354   <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>
 355     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>
 356
 357   va <span class="gtkdoc opt">=</span> <span class="function"><a href="http://library.gnome.org/devel/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>
 358
 359   <span class="function"><a href="http://library.gnome.org/devel/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>
 360   <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>
 361     <span class="function"><a href="http://library.gnome.org/devel/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>
 362     <span class="function"><a href="http://library.gnome.org/devel/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>
 363     <span class="function"><a href="http://library.gnome.org/devel/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>
 364   <span class="gtkdoc opt">}</span>
 365   <span class="function"><a href="http://library.gnome.org/devel/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="http://library.gnome.org/devel/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>
 366   <span class="comment">/* Latency is 1/2 of the kernel length for this method of</span>
 367 <span class="comment">   * calculating a filter kernel from the frequency response</span>
 368 <span class="comment">   */</span>
 369   <span class="function"><a href="http://library.gnome.org/devel/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="http://library.gnome.org/devel/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>
 370   <span class="function"><a href="http://library.gnome.org/devel/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>
 371 <span class="gtkdoc opt">}</span>
 372
 373 gint
 374 <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>
 375 <span class="gtkdoc opt">{</span>
 376   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>
 377   GstBus <span class="gtkdoc opt">*</span>bus<span class="gtkdoc opt">;</span>
 378   GMainLoop <span class="gtkdoc opt">*</span>loop<span class="gtkdoc opt">;</span>
 379
 380   <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>
 381
 382   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>
 383
 384   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>
 385   <span class="function"><a href="http://library.gnome.org/devel/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="http://library.gnome.org/devel/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>
 386
 387   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>
 388   <span class="function"><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Signals.html#g-signal-connect">g_signal_connect</a></span> <span class="gtkdoc opt">(</span><span class="function"><a href="http://library.gnome.org/devel/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>
 389       <span class="function"><a href="http://library.gnome.org/devel/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>
 390
 391   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>
 392
 393   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>
 394   <span class="function"><a href="http://library.gnome.org/devel/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>
 395
 396   <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>
 397   <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>
 398     <span class="function"><a href="http://library.gnome.org/devel/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>
 399     <span class="keyword">return</span> <span class="gtkdoc opt">-</span><span class="number">2</span><span class="gtkdoc opt">;</span>
 400   <span class="gtkdoc opt">}</span>
 401
 402   loop <span class="gtkdoc opt">=</span> <span class="function"><a href="http://library.gnome.org/devel/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>
 403
 404   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>
 405   <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>
 406   <span class="function"><a href="http://library.gnome.org/devel/gobject/unstable/gobject-Signals.html#g-signal-connect">g_signal_connect</a></span> <span class="gtkdoc opt">(</span><span class="function"><a href="http://library.gnome.org/devel/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="http://library.gnome.org/devel/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>
 407   <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>
 408
 409   <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>
 410           GST_STATE_PLAYING<span class="gtkdoc opt">) ==</span> GST_STATE_CHANGE_FAILURE<span class="gtkdoc opt">) {</span>
 411     <span class="function"><a href="http://library.gnome.org/devel/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>
 412     <span class="keyword">return</span> <span class="gtkdoc opt">-</span><span class="number">3</span><span class="gtkdoc opt">;</span>
 413   <span class="gtkdoc opt">}</span>
 414
 415   <span class="function"><a href="http://library.gnome.org/devel/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>
 416
 417   <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>
 418
 419   <span class="function"><a href="http://library.gnome.org/devel/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>
 420   <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>
 421
 422   <span class="keyword">return</span> <span class="number">0</span><span class="gtkdoc opt">;</span>
 423 <span class="gtkdoc opt">}</span></pre></td>
 424       </tr>
 425     </tbody>
 426   </table>
 427 </div>
 428
 429 </div>
 430 <p>
 431 </p>
 432 <div class="refsynopsisdiv">
 433 <h2>Synopsis</h2>
 434 <div class="refsect2">
 435 <a name="idp6786656"></a><h3>Element Information</h3>
 436 <div class="variablelist"><table border="0">
 437 <col align="left" valign="top">
 438 <tbody>
 439 <tr>
 440 <td><p><span class="term">plugin</span></p></td>
 441 <td>
 442             <a class="link" href="gst-plugins-good-plugins-plugin-audiofx.html#plugin-audiofx">audiofx</a>
 443           </td>
 444 </tr>
 445 <tr>
 446 <td><p><span class="term">author</span></p></td>
 447 <td>Sebastian Dröge &lt;sebastian.droege@collabora.co.uk&gt;</td>
 448 </tr>
 449 <tr>
 450 <td><p><span class="term">class</span></p></td>
 451 <td>Filter/Effect/Audio</td>
 452 </tr>
 453 </tbody>
 454 </table></div>
 455 </div>
 456 <hr>
 457 <div class="refsect2">
 458 <a name="idp8574016"></a><h3>Element Pads</h3>
 459 <div class="variablelist"><table border="0">
 460 <col align="left" valign="top">
 461 <tbody>
 462 <tr>
 463 <td><p><span class="term">name</span></p></td>
 464 <td>sink</td>
 465 </tr>
 466 <tr>
 467 <td><p><span class="term">direction</span></p></td>
 468 <td>sink</td>
 469 </tr>
 470 <tr>
 471 <td><p><span class="term">presence</span></p></td>
 472 <td>always</td>
 473 </tr>
 474 <tr>
 475 <td><p><span class="term">details</span></p></td>
 476 <td>audio/x-raw-float, width=(int){ 32, 64 }, endianness=(int)1234, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ]</td>
 477 </tr>
 478 </tbody>
 479 </table></div>
 480 <div class="variablelist"><table border="0">
 481 <col align="left" valign="top">
 482 <tbody>
 483 <tr>
 484 <td><p><span class="term">name</span></p></td>
 485 <td>src</td>
 486 </tr>
 487 <tr>
 488 <td><p><span class="term">direction</span></p></td>
 489 <td>source</td>
 490 </tr>
 491 <tr>
 492 <td><p><span class="term">presence</span></p></td>
 493 <td>always</td>
 494 </tr>
 495 <tr>
 496 <td><p><span class="term">details</span></p></td>
 497 <td>audio/x-raw-float, width=(int){ 32, 64 }, endianness=(int)1234, rate=(int)[ 1, 2147483647 ], channels=(int)[ 1, 2147483647 ]</td>
 498 </tr>
 499 </tbody>
 500 </table></div>
 501 </div>
 502 </div>
 503 <p>
 504 </p>
 505 </div>
 506 <div class="refsect1">
 507 <a name="gst-plugins-good-plugins-audiofirfilter.details"></a><h2>Details</h2>
 508 <div class="refsect2">
 509 <a name="GstAudioFIRFilter-struct"></a><h3>struct GstAudioFIRFilter</h3>
 510 <pre class="programlisting">struct GstAudioFIRFilter;</pre>
 511 <p>
 512 Opaque data structure.
 513 </p>
 514 </div>
 515 </div>
 516 <div class="refsect1">
 517 <a name="gst-plugins-good-plugins-audiofirfilter.property-details"></a><h2>Property Details</h2>
 518 <div class="refsect2">
 519 <a name="GstAudioFIRFilter--kernel"></a><h3>The <code class="literal">"kernel"</code> property</h3>
 520 <pre class="programlisting">  "kernel"                   <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Value-arrays.html#GValueArray"><span class="type">GValueArray</span></a>*          : Read / Write</pre>
 521 <p>Filter kernel for the FIR filter.</p>
 522 </div>
 523 <hr>
 524 <div class="refsect2">
 525 <a name="GstAudioFIRFilter--latency"></a><h3>The <code class="literal">"latency"</code> property</h3>
 526 <pre class="programlisting">  "latency"                  <span class="type">guint64</span>               : Read / Write</pre>
 527 <p>Filter latency in samples.</p>
 528 <p>Default value: 0</p>
 529 </div>
 530 </div>
 531 <div class="refsect1">
 532 <a name="gst-plugins-good-plugins-audiofirfilter.signal-details"></a><h2>Signal Details</h2>
 533 <div class="refsect2">
 534 <a name="GstAudioFIRFilter-rate-changed"></a><h3>The <code class="literal">"rate-changed"</code> signal</h3>
 535 <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,
 536                                                         <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a>               rate,
 537                                                         <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gpointer"><span class="type">gpointer</span></a>           user_data)      : <a href="http://library.gnome.org/devel/gobject/unstable/gobject-Signals.html#G-SIGNAL-RUN-LAST:CAPS"><code class="literal">Run Last</code></a></pre>
 538 <p>
 539 Will be emitted when the sampling rate changes. The callbacks
 540 will be called from the streaming thread and processing will
 541 stop until the event is handled.
 542 </p>
 543 <div class="variablelist"><table border="0">
 544 <col align="left" valign="top">
 545 <tbody>
 546 <tr>
 547 <td><p><span class="term"><em class="parameter"><code>filter</code></em> :</span></p></td>
 548 <td>the filter on which the signal is emitted</td>
 549 </tr>
 550 <tr>
 551 <td><p><span class="term"><em class="parameter"><code>rate</code></em> :</span></p></td>
 552 <td>the new sampling rate</td>
 553 </tr>
 554 <tr>
 555 <td><p><span class="term"><em class="parameter"><code>user_data</code></em> :</span></p></td>
 556 <td>user data set when the signal handler was connected.</td>
 557 </tr>
 558 </tbody>
 559 </table></div>
 560 </div>
 561 </div>
 562 </div>
 563 <div class="footer">
 564 <hr>
 565           Generated by GTK-Doc V1.18</div>
 566 </body>
 567 </html>