wearable/docs/libs/html/GstBaseSrc.html

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  26                   <a href="#GstBaseSrc.description" class="shortcut">Description</a>
  27                    |
  28                   <a href="#GstBaseSrc.object-hierarchy" class="shortcut">Object Hierarchy</a>
  29                    |
  30                   <a href="#GstBaseSrc.properties" class="shortcut">Properties</a>
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  33 <div class="refentry">
  34 <a name="GstBaseSrc"></a><div class="titlepage"></div>
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  37 <h2><span class="refentrytitle"><a name="GstBaseSrc.top_of_page"></a>GstBaseSrc</span></h2>
  38 <p>GstBaseSrc — Base class for getrange based source elements</p>
  39 </td>
  40 <td valign="top" align="right"></td>
  41 </tr></table></div>
  42 <div class="refsynopsisdiv">
  43 <a name="GstBaseSrc.synopsis"></a><h2>Synopsis</h2>
  44 <pre class="synopsis">
  45 #include &lt;gst/base/gstbasesrc.h&gt;
  46
  47 struct              <a class="link" href="GstBaseSrc.html#GstBaseSrc-struct" title="struct GstBaseSrc">GstBaseSrc</a>;
  48 struct              <a class="link" href="GstBaseSrc.html#GstBaseSrcClass" title="struct GstBaseSrcClass">GstBaseSrcClass</a>;
  49 enum                <a class="link" href="GstBaseSrc.html#GstBaseSrcFlags" title="enum GstBaseSrcFlags">GstBaseSrcFlags</a>;
  50 <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstPad.html#GstFlowReturn"><span class="returnvalue">GstFlowReturn</span></a>       <a class="link" href="GstBaseSrc.html#gst-base-src-wait-playing" title="gst_base_src_wait_playing ()">gst_base_src_wait_playing</a>           (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>);
  51 <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            <a class="link" href="GstBaseSrc.html#gst-base-src-is-live" title="gst_base_src_is_live ()">gst_base_src_is_live</a>                (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>);
  52 <span class="returnvalue">void</span>                <a class="link" href="GstBaseSrc.html#gst-base-src-set-live" title="gst_base_src_set_live ()">gst_base_src_set_live</a>               (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>,
  53                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> live</code></em>);
  54 <span class="returnvalue">void</span>                <a class="link" href="GstBaseSrc.html#gst-base-src-set-format" title="gst_base_src_set_format ()">gst_base_src_set_format</a>             (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>,
  55                                                          <em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstFormat.html#GstFormat"><span class="type">GstFormat</span></a> format</code></em>);
  56 <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            <a class="link" href="GstBaseSrc.html#gst-base-src-query-latency" title="gst_base_src_query_latency ()">gst_base_src_query_latency</a>          (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>,
  57                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> *live</code></em>,
  58                                                          <em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstClock.html#GstClockTime"><span class="type">GstClockTime</span></a> *min_latency</code></em>,
  59                                                          <em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstClock.html#GstClockTime"><span class="type">GstClockTime</span></a> *max_latency</code></em>);
  60 <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gulong"><span class="returnvalue">gulong</span></a>              <a class="link" href="GstBaseSrc.html#gst-base-src-get-blocksize" title="gst_base_src_get_blocksize ()">gst_base_src_get_blocksize</a>          (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>);
  61 <span class="returnvalue">void</span>                <a class="link" href="GstBaseSrc.html#gst-base-src-set-blocksize" title="gst_base_src_set_blocksize ()">gst_base_src_set_blocksize</a>          (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>,
  62                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gulong"><span class="type">gulong</span></a> blocksize</code></em>);
  63 <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            <a class="link" href="GstBaseSrc.html#gst-base-src-get-do-timestamp" title="gst_base_src_get_do_timestamp ()">gst_base_src_get_do_timestamp</a>       (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>);
  64 <span class="returnvalue">void</span>                <a class="link" href="GstBaseSrc.html#gst-base-src-set-do-timestamp" title="gst_base_src_set_do_timestamp ()">gst_base_src_set_do_timestamp</a>       (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>,
  65                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> timestamp</code></em>);
  66 <span class="returnvalue">void</span>                <a class="link" href="GstBaseSrc.html#gst-base-src-set-dynamic-size" title="gst_base_src_set_dynamic_size ()">gst_base_src_set_dynamic_size</a>       (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>,
  67                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> dynamic</code></em>);
  68 <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            <a class="link" href="GstBaseSrc.html#gst-base-src-new-seamless-segment" title="gst_base_src_new_seamless_segment ()">gst_base_src_new_seamless_segment</a>   (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>,
  69                                                          <em class="parameter"><code><span class="type">gint64</span> start</code></em>,
  70                                                          <em class="parameter"><code><span class="type">gint64</span> stop</code></em>,
  71                                                          <em class="parameter"><code><span class="type">gint64</span> position</code></em>);
  72 #define             <a class="link" href="GstBaseSrc.html#GST-BASE-SRC-PAD:CAPS" title="GST_BASE_SRC_PAD()">GST_BASE_SRC_PAD</a>                    (obj)
  73 </pre>
  74 </div>
  75 <div class="refsect1">
  76 <a name="GstBaseSrc.object-hierarchy"></a><h2>Object Hierarchy</h2>
  77 <pre class="synopsis">
  78   <a href="http://library.gnome.org/devel/gobject/unstable/gobject-The-Base-Object-Type.html#GObject">GObject</a>
  79    +----<a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstObject.html">GstObject</a>
  80          +----<a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElement.html">GstElement</a>
  81                +----GstBaseSrc
  82                      +----<a class="link" href="GstPushSrc.html" title="GstPushSrc">GstPushSrc</a>
  83 </pre>
  84 </div>
  85 <div class="refsect1">
  86 <a name="GstBaseSrc.properties"></a><h2>Properties</h2>
  87 <pre class="synopsis">
  88   "<a class="link" href="GstBaseSrc.html#GstBaseSrc--blocksize" title='The "blocksize" property'>blocksize</a>"                <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gulong"><span class="type">gulong</span></a>                : Read / Write
  89   "<a class="link" href="GstBaseSrc.html#GstBaseSrc--do-timestamp" title='The "do-timestamp" property'>do-timestamp</a>"             <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a>              : Read / Write
  90   "<a class="link" href="GstBaseSrc.html#GstBaseSrc--num-buffers" title='The "num-buffers" property'>num-buffers</a>"              <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a>                  : Read / Write
  91   "<a class="link" href="GstBaseSrc.html#GstBaseSrc--typefind" title='The "typefind" property'>typefind</a>"                 <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a>              : Read / Write
  92 </pre>
  93 </div>
  94 <div class="refsect1">
  95 <a name="GstBaseSrc.description"></a><h2>Description</h2>
  96 <p>
  97 This is a generice base class for source elements. The following
  98 types of sources are supported:
  99 </p>
 100 <div class="itemizedlist"><ul class="itemizedlist" type="disc">
 101 <li class="listitem"><p>random access sources like files</p></li>
 102 <li class="listitem"><p>seekable sources</p></li>
 103 <li class="listitem"><p>live sources</p></li>
 104 </ul></div>
 105 <p>
 106 </p>
 107 <p>
 108 The source can be configured to operate in any <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstFormat.html#GstFormat"><span class="type">GstFormat</span></a> with the
 109 <a class="link" href="GstBaseSrc.html#gst-base-src-set-format" title="gst_base_src_set_format ()"><code class="function">gst_base_src_set_format()</code></a> method. The currently set format determines
 110 the format of the internal <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstSegment.html#GstSegment"><span class="type">GstSegment</span></a> and any <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstEvent.html#GST-EVENT-NEWSEGMENT:CAPS"><span class="type">GST_EVENT_NEWSEGMENT</span></a>
 111 events. The default format for <a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> is <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstFormat.html#GST-FORMAT-BYTES:CAPS"><span class="type">GST_FORMAT_BYTES</span></a>.
 112 </p>
 113 <p>
 114 <a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> always supports push mode scheduling. If the following
 115 conditions are met, it also supports pull mode scheduling:
 116 </p>
 117 <div class="itemizedlist"><ul class="itemizedlist" type="disc">
 118 <li class="listitem"><p>The format is set to <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstFormat.html#GST-FORMAT-BYTES:CAPS"><span class="type">GST_FORMAT_BYTES</span></a> (default).</p></li>
 119 <li class="listitem"><p><a class="link" href="GstBaseSrc.html#GstBaseSrcClass.is-seekable"><code class="function">GstBaseSrcClass.is_seekable()</code></a> returns <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a>.</p></li>
 120 </ul></div>
 121 <p>
 122 </p>
 123 <p>
 124 Since 0.10.9, any <a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> can enable pull based scheduling at any time
 125 by overriding <a class="link" href="GstBaseSrc.html#GstBaseSrcClass.check-get-range"><code class="function">GstBaseSrcClass.check_get_range()</code></a> so that it returns <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a>.
 126 </p>
 127 <p>
 128 If all the conditions are met for operating in pull mode, <a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> is
 129 automatically seekable in push mode as well. The following conditions must
 130 be met to make the element seekable in push mode when the format is not
 131 <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstFormat.html#GST-FORMAT-BYTES:CAPS"><span class="type">GST_FORMAT_BYTES</span></a>:
 132 </p>
 133 <div class="itemizedlist"><ul class="itemizedlist" type="disc">
 134 <li class="listitem"><p>
 135     <a class="link" href="GstBaseSrc.html#GstBaseSrcClass.is-seekable"><code class="function">GstBaseSrcClass.is_seekable()</code></a> returns <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a>.
 136   </p></li>
 137 <li class="listitem"><p>
 138     <a class="link" href="GstBaseSrc.html#GstBaseSrcClass.query"><code class="function">GstBaseSrcClass.query()</code></a> can convert all supported seek formats to the
 139     internal format as set with <a class="link" href="GstBaseSrc.html#gst-base-src-set-format" title="gst_base_src_set_format ()"><code class="function">gst_base_src_set_format()</code></a>.
 140   </p></li>
 141 <li class="listitem"><p>
 142     <a class="link" href="GstBaseSrc.html#GstBaseSrcClass.do-seek"><code class="function">GstBaseSrcClass.do_seek()</code></a> is implemented, performs the seek and returns
 143      <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a>.
 144   </p></li>
 145 </ul></div>
 146 <p>
 147 </p>
 148 <p>
 149 When the element does not meet the requirements to operate in pull mode, the
 150 offset and length in the <a class="link" href="GstBaseSrc.html#GstBaseSrcClass.create"><code class="function">GstBaseSrcClass.create()</code></a> method should be ignored.
 151 It is recommended to subclass <a class="link" href="GstPushSrc.html" title="GstPushSrc"><span class="type">GstPushSrc</span></a> instead, in this situation. If the
 152 element can operate in pull mode but only with specific offsets and
 153 lengths, it is allowed to generate an error when the wrong values are passed
 154 to the <a class="link" href="GstBaseSrc.html#GstBaseSrcClass.create"><code class="function">GstBaseSrcClass.create()</code></a> function.
 155 </p>
 156 <p>
 157 <a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> has support for live sources. Live sources are sources that when
 158 paused discard data, such as audio or video capture devices. A typical live
 159 source also produces data at a fixed rate and thus provides a clock to publish
 160 this rate.
 161 Use <a class="link" href="GstBaseSrc.html#gst-base-src-set-live" title="gst_base_src_set_live ()"><code class="function">gst_base_src_set_live()</code></a> to activate the live source mode.
 162 </p>
 163 <p>
 164 A live source does not produce data in the PAUSED state. This means that the
 165 <a class="link" href="GstBaseSrc.html#GstBaseSrcClass.create"><code class="function">GstBaseSrcClass.create()</code></a> method will not be called in PAUSED but only in
 166 PLAYING. To signal the pipeline that the element will not produce data, the
 167 return value from the READY to PAUSED state will be
 168 <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElement.html#GST-STATE-CHANGE-NO-PREROLL:CAPS"><span class="type">GST_STATE_CHANGE_NO_PREROLL</span></a>.
 169 </p>
 170 <p>
 171 A typical live source will timestamp the buffers it creates with the
 172 current running time of the pipeline. This is one reason why a live source
 173 can only produce data in the PLAYING state, when the clock is actually
 174 distributed and running.
 175 </p>
 176 <p>
 177 Live sources that synchronize and block on the clock (an audio source, for
 178 example) can since 0.10.12 use <a class="link" href="GstBaseSrc.html#gst-base-src-wait-playing" title="gst_base_src_wait_playing ()"><code class="function">gst_base_src_wait_playing()</code></a> when the
 179 <a class="link" href="GstBaseSrc.html#GstBaseSrcClass.create"><code class="function">GstBaseSrcClass.create()</code></a> function was interrupted by a state change to
 180 PAUSED.
 181 </p>
 182 <p>
 183 The <a class="link" href="GstBaseSrc.html#GstBaseSrcClass.get-times"><code class="function">GstBaseSrcClass.get_times()</code></a> method can be used to implement pseudo-live
 184 sources. It only makes sense to implement the <a class="link" href="GstBaseSrc.html#GstBaseSrcClass.get-times"><code class="function">GstBaseSrcClass.get_times()</code></a>
 185 function if the source is a live source. The <a class="link" href="GstBaseSrc.html#GstBaseSrcClass.get-times"><code class="function">GstBaseSrcClass.get_times()</code></a>
 186 function should return timestamps starting from 0, as if it were a non-live
 187 source. The base class will make sure that the timestamps are transformed
 188 into the current running_time. The base source will then wait for the
 189 calculated running_time before pushing out the buffer.
 190 </p>
 191 <p>
 192 For live sources, the base class will by default report a latency of 0.
 193 For pseudo live sources, the base class will by default measure the difference
 194 between the first buffer timestamp and the start time of get_times and will
 195 report this value as the latency.
 196 Subclasses should override the query function when this behaviour is not
 197 acceptable.
 198 </p>
 199 <p>
 200 There is only support in <a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> for exactly one source pad, which
 201 should be named "src". A source implementation (subclass of <a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a>)
 202 should install a pad template in its class_init function, like so:
 203 </p>
 204 <div class="informalexample">
 205   <table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
 206     <tbody>
 207       <tr>
 208         <td class="listing_lines" align="right"><pre>1
 209 2
 210 3
 211 4
 212 5
 213 6
 214 7
 215 8
 216 9
 217 10
 218 11</pre></td>
 219         <td class="listing_code"><pre class="programlisting"><span class="gtkdoc kwb">static void</span>
 220 <span class="function">my_element_class_init</span> <span class="gtkdoc opt">(</span>GstMyElementClass <span class="gtkdoc opt">*</span>klass<span class="gtkdoc opt">)</span>
 221 <span class="gtkdoc opt">{</span>
 222   GstElementClass <span class="gtkdoc opt">*</span>gstelement_class <span class="gtkdoc opt">=</span> <span class="function">GST_ELEMENT_CLASS</span> <span class="gtkdoc opt">(</span>klass<span class="gtkdoc opt">);</span>
 223   <span class="gtkdoc slc">// srctemplate should be a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstPadTemplate.html#GstStaticPadTemplate">GstStaticPadTemplate</a> with direction</span>
 224   <span class="gtkdoc slc">// <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstPad.html#GST-PAD-SRC:CAPS">GST_PAD_SRC</a> and name &quot;src&quot;</span>
 225   <span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElement.html#gst-element-class-add-pad-template">gst_element_class_add_pad_template</a></span> <span class="gtkdoc opt">(</span>gstelement_class<span class="gtkdoc opt">,</span>
 226       <span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstPadTemplate.html#gst-static-pad-template-get">gst_static_pad_template_get</a></span> <span class="gtkdoc opt">(&amp;</span>srctemplate<span class="gtkdoc opt">));</span>
 227   <span class="gtkdoc slc">// see <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElementFactory.html#GstElementDetails">GstElementDetails</a></span>
 228   <span class="function"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElement.html#gst-element-class-set-details">gst_element_class_set_details</a></span> <span class="gtkdoc opt">(</span>gstelement_class<span class="gtkdoc opt">, &amp;</span>details<span class="gtkdoc opt">);</span>
 229 <span class="gtkdoc opt">}</span></pre></td>
 230       </tr>
 231     </tbody>
 232   </table>
 233 </div>
 234
 235 <p>
 236 </p>
 237 <p>
 238 </p>
 239 <div class="refsect2">
 240 <a name="idp8473536"></a><h3>Controlled shutdown of live sources in applications</h3>
 241 <p>
 242 Applications that record from a live source may want to stop recording
 243 in a controlled way, so that the recording is stopped, but the data
 244 already in the pipeline is processed to the end (remember that many live
 245 sources would go on recording forever otherwise). For that to happen the
 246 application needs to make the source stop recording and send an EOS
 247 event down the pipeline. The application would then wait for an
 248 EOS message posted on the pipeline's bus to know when all data has
 249 been processed and the pipeline can safely be stopped.
 250 </p>
 251 <p>
 252 Since GStreamer 0.10.16 an application may send an EOS event to a source
 253 element to make it perform the EOS logic (send EOS event downstream or post a
 254 <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstMessage.html#GST-MESSAGE-SEGMENT-DONE:CAPS"><span class="type">GST_MESSAGE_SEGMENT_DONE</span></a> on the bus). This can typically be done
 255 with the <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElement.html#gst-element-send-event"><code class="function">gst_element_send_event()</code></a> function on the element or its parent bin.
 256 </p>
 257 <p>
 258 After the EOS has been sent to the element, the application should wait for
 259 an EOS message to be posted on the pipeline's bus. Once this EOS message is
 260 received, it may safely shut down the entire pipeline.
 261 </p>
 262 <p>
 263 The old behaviour for controlled shutdown introduced since GStreamer 0.10.3
 264 is still available but deprecated as it is dangerous and less flexible.
 265 </p>
 266 <p>
 267 Last reviewed on 2007-12-19 (0.10.16)
 268 </p>
 269 </div>
 270 <p>
 271 </p>
 272 </div>
 273 <div class="refsect1">
 274 <a name="GstBaseSrc.details"></a><h2>Details</h2>
 275 <div class="refsect2">
 276 <a name="GstBaseSrc-struct"></a><h3>struct GstBaseSrc</h3>
 277 <pre class="programlisting">struct GstBaseSrc;</pre>
 278 <p>
 279 The opaque <a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> data structure.
 280 </p>
 281 </div>
 282 <hr>
 283 <div class="refsect2">
 284 <a name="GstBaseSrcClass"></a><h3>struct GstBaseSrcClass</h3>
 285 <pre class="programlisting">struct GstBaseSrcClass {
 286   GstElementClass parent_class;
 287
 288   /* virtual methods for subclasses */
 289
 290   /* get caps from subclass */
 291   GstCaps*      (*get_caps)     (GstBaseSrc *src);
 292   /* notify the subclass of new caps */
 293   gboolean      (*set_caps)     (GstBaseSrc *src, GstCaps *caps);
 294
 295   /* decide on caps */
 296   gboolean      (*negotiate)    (GstBaseSrc *src);
 297
 298   /* generate and send a newsegment (UNUSED) */
 299   gboolean      (*newsegment)   (GstBaseSrc *src);
 300
 301   /* start and stop processing, ideal for opening/closing the resource */
 302   gboolean      (*start)        (GstBaseSrc *src);
 303   gboolean      (*stop)         (GstBaseSrc *src);
 304
 305   /* given a buffer, return start and stop time when it should be pushed
 306    * out. The base class will sync on the clock using these times. */
 307   void          (*get_times)    (GstBaseSrc *src, GstBuffer *buffer,
 308                                  GstClockTime *start, GstClockTime *end);
 309
 310   /* get the total size of the resource in bytes */
 311   gboolean      (*get_size)     (GstBaseSrc *src, guint64 *size);
 312
 313   /* check if the resource is seekable */
 314   gboolean      (*is_seekable)  (GstBaseSrc *src);
 315   /* unlock any pending access to the resource. subclasses should unlock
 316    * any function ASAP. */
 317   gboolean      (*unlock)       (GstBaseSrc *src);
 318
 319   /* notify subclasses of an event */
 320   gboolean      (*event)        (GstBaseSrc *src, GstEvent *event);
 321
 322   /* ask the subclass to create a buffer with offset and size */
 323   GstFlowReturn (*create)       (GstBaseSrc *src, guint64 offset, guint size,
 324                                  GstBuffer **buf);
 325
 326   /* additions that change padding... */
 327   /* notify subclasses of a seek */
 328   gboolean      (*do_seek)      (GstBaseSrc *src, GstSegment *segment);
 329   /* notify subclasses of a query */
 330   gboolean      (*query)        (GstBaseSrc *src, GstQuery *query);
 331
 332   /* check whether the source would support pull-based operation if
 333    * it were to be opened now. This vfunc is optional, but should be
 334    * implemented if possible to avoid unnecessary start/stop cycles.
 335    * The default implementation will open and close the resource to
 336    * find out whether get_range is supported and that is usually
 337    * undesirable. */
 338   gboolean      (*check_get_range) (GstBaseSrc *src);
 339
 340   /* called if, in negotiation, caps need fixating */
 341   void          (*fixate)       (GstBaseSrc *src, GstCaps *caps);
 342
 343   /* Clear any pending unlock request, as we succeeded in unlocking */
 344   gboolean      (*unlock_stop)  (GstBaseSrc *src);
 345
 346   /* Prepare the segment on which to perform do_seek(), converting to the
 347    * current basesrc format. */
 348   gboolean      (*prepare_seek_segment) (GstBaseSrc *src, GstEvent *seek,
 349                                          GstSegment *segment);
 350 };
 351 </pre>
 352 <p>
 353 Subclasses can override any of the available virtual methods or not, as
 354 needed. At the minimum, the <em class="parameter"><code>create</code></em> method should be overridden to produce
 355 buffers.
 356 </p>
 357 <div class="variablelist"><table border="0">
 358 <col align="left" valign="top">
 359 <tbody>
 360 <tr>
 361 <td><p><span class="term"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElement.html#GstElementClass"><span class="type">GstElementClass</span></a> <em class="structfield"><code><a name="GstBaseSrcClass.parent-class"></a>parent_class</code></em>;</span></p></td>
 362 <td>Element parent class</td>
 363 </tr>
 364 <tr>
 365 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.get-caps"></a>get_caps</code></em> ()</span></p></td>
 366 <td>Called to get the caps to report</td>
 367 </tr>
 368 <tr>
 369 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.set-caps"></a>set_caps</code></em> ()</span></p></td>
 370 <td>Notify subclass of changed output caps</td>
 371 </tr>
 372 <tr>
 373 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.negotiate"></a>negotiate</code></em> ()</span></p></td>
 374 <td>Negotiated the caps with the peer.</td>
 375 </tr>
 376 <tr>
 377 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.newsegment"></a>newsegment</code></em> ()</span></p></td>
 378 <td>Generate and send a new_segment event (UNUSED)</td>
 379 </tr>
 380 <tr>
 381 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.start"></a>start</code></em> ()</span></p></td>
 382 <td>Start processing. Subclasses should open resources and prepare
 383 to produce data.</td>
 384 </tr>
 385 <tr>
 386 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.stop"></a>stop</code></em> ()</span></p></td>
 387 <td>Stop processing. Subclasses should use this to close resources.</td>
 388 </tr>
 389 <tr>
 390 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.get-times"></a>get_times</code></em> ()</span></p></td>
 391 <td>Given a buffer, return the start and stop time when it
 392 should be pushed out. The base class will sync on the clock using
 393 these times.</td>
 394 </tr>
 395 <tr>
 396 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.get-size"></a>get_size</code></em> ()</span></p></td>
 397 <td>Return the total size of the resource, in the configured format.</td>
 398 </tr>
 399 <tr>
 400 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.is-seekable"></a>is_seekable</code></em> ()</span></p></td>
 401 <td>Check if the source can seek</td>
 402 </tr>
 403 <tr>
 404 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.unlock"></a>unlock</code></em> ()</span></p></td>
 405 <td>Unlock any pending access to the resource. Subclasses should
 406 unblock any blocked function ASAP. In particular, any <code class="function">create()</code> function in
 407 progress should be unblocked and should return GST_FLOW_WRONG_STATE. Any
 408 future <em class="parameter"><code>create</code></em>() function call should also return GST_FLOW_WRONG_STATE
 409 until the <em class="parameter"><code>unlock_stop</code></em>() function has been called.</td>
 410 </tr>
 411 <tr>
 412 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.event"></a>event</code></em> ()</span></p></td>
 413 <td>Override this to implement custom event handling.</td>
 414 </tr>
 415 <tr>
 416 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.create"></a>create</code></em> ()</span></p></td>
 417 <td>Ask the subclass to create a buffer with offset and size.
 418 When the subclass returns GST_FLOW_OK, it MUST return a buffer of the
 419 requested size unless fewer bytes are available because an EOS condition
 420 is near. No buffer should be returned when the return value is different
 421 from GST_FLOW_OK. A return value of GST_FLOW_UNEXPECTED signifies that the
 422 end of stream is reached.</td>
 423 </tr>
 424 <tr>
 425 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.do-seek"></a>do_seek</code></em> ()</span></p></td>
 426 <td>Perform seeking on the resource to the indicated segment.</td>
 427 </tr>
 428 <tr>
 429 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.query"></a>query</code></em> ()</span></p></td>
 430 <td>Handle a requested query.</td>
 431 </tr>
 432 <tr>
 433 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.check-get-range"></a>check_get_range</code></em> ()</span></p></td>
 434 <td>Check whether the source would support pull-based
 435 operation if it were to be opened now. This vfunc is optional, but
 436 should be implemented if possible to avoid unnecessary start/stop
 437 cycles. The default implementation will open and close the resource
 438 to find out whether get_range is supported, and that is usually
 439 undesirable.</td>
 440 </tr>
 441 <tr>
 442 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.fixate"></a>fixate</code></em> ()</span></p></td>
 443 <td>Called during negotiation if caps need fixating. Implement instead of
 444 setting a fixate function on the source pad.</td>
 445 </tr>
 446 <tr>
 447 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.unlock-stop"></a>unlock_stop</code></em> ()</span></p></td>
 448 <td>Clear the previous unlock request. Subclasses should clear
 449 any state they set during <code class="function">unlock()</code>, such as clearing command queues.</td>
 450 </tr>
 451 <tr>
 452 <td><p><span class="term"><em class="structfield"><code><a name="GstBaseSrcClass.prepare-seek-segment"></a>prepare_seek_segment</code></em> ()</span></p></td>
 453 <td>Prepare the GstSegment that will be passed to the
 454 do_seek vmethod for executing a seek request. Sub-classes should override
 455 this if they support seeking in formats other than the configured native
 456 format. By default, it tries to convert the seek arguments to the
 457 configured native format and prepare a segment in that format.
 458 Since: 0.10.13</td>
 459 </tr>
 460 </tbody>
 461 </table></div>
 462 </div>
 463 <hr>
 464 <div class="refsect2">
 465 <a name="GstBaseSrcFlags"></a><h3>enum GstBaseSrcFlags</h3>
 466 <pre class="programlisting">typedef enum {
 467   GST_BASE_SRC_STARTED           = (GST_ELEMENT_FLAG_LAST &lt;&lt; 0),
 468   /* padding */
 469   GST_BASE_SRC_FLAG_LAST         = (GST_ELEMENT_FLAG_LAST &lt;&lt; 2)
 470 } GstBaseSrcFlags;
 471 </pre>
 472 <p>
 473 The <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElement.html"><span class="type">GstElement</span></a> flags that a basesrc element may have.
 474 </p>
 475 <div class="variablelist"><table border="0">
 476 <col align="left" valign="top">
 477 <tbody>
 478 <tr>
 479 <td><p><a name="GST-BASE-SRC-STARTED:CAPS"></a><span class="term"><code class="literal">GST_BASE_SRC_STARTED</code></span></p></td>
 480 <td>has source been started
 481 </td>
 482 </tr>
 483 <tr>
 484 <td><p><a name="GST-BASE-SRC-FLAG-LAST:CAPS"></a><span class="term"><code class="literal">GST_BASE_SRC_FLAG_LAST</code></span></p></td>
 485 <td>offset to define more flags
 486 </td>
 487 </tr>
 488 </tbody>
 489 </table></div>
 490 </div>
 491 <hr>
 492 <div class="refsect2">
 493 <a name="gst-base-src-wait-playing"></a><h3>gst_base_src_wait_playing ()</h3>
 494 <pre class="programlisting"><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstPad.html#GstFlowReturn"><span class="returnvalue">GstFlowReturn</span></a>       gst_base_src_wait_playing           (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>);</pre>
 495 <p>
 496 If the <a class="link" href="GstBaseSrc.html#GstBaseSrcClass.create"><code class="function">GstBaseSrcClass.create()</code></a> method performs its own synchronisation
 497 against the clock it must unblock when going from PLAYING to the PAUSED state
 498 and call this method before continuing to produce the remaining data.
 499 </p>
 500 <p>
 501 This function will block until a state change to PLAYING happens (in which
 502 case this function returns <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstPad.html#GST-FLOW-OK:CAPS"><span class="type">GST_FLOW_OK</span></a>) or the processing must be stopped due
 503 to a state change to READY or a FLUSH event (in which case this function
 504 returns <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstPad.html#GST-FLOW-WRONG-STATE:CAPS"><span class="type">GST_FLOW_WRONG_STATE</span></a>).
 505 </p>
 506 <div class="variablelist"><table border="0">
 507 <col align="left" valign="top">
 508 <tbody>
 509 <tr>
 510 <td><p><span class="term"><em class="parameter"><code>src</code></em> :</span></p></td>
 511 <td>the src</td>
 512 </tr>
 513 <tr>
 514 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 515 <td>
 516 <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstPad.html#GST-FLOW-OK:CAPS"><span class="type">GST_FLOW_OK</span></a> if <em class="parameter"><code>src</code></em> is PLAYING and processing can
 517 continue. Any other return value should be returned from the create vmethod.</td>
 518 </tr>
 519 </tbody>
 520 </table></div>
 521 <p class="since">Since 0.10.12</p>
 522 </div>
 523 <hr>
 524 <div class="refsect2">
 525 <a name="gst-base-src-is-live"></a><h3>gst_base_src_is_live ()</h3>
 526 <pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            gst_base_src_is_live                (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>);</pre>
 527 <p>
 528 Check if an element is in live mode.
 529 </p>
 530 <div class="variablelist"><table border="0">
 531 <col align="left" valign="top">
 532 <tbody>
 533 <tr>
 534 <td><p><span class="term"><em class="parameter"><code>src</code></em> :</span></p></td>
 535 <td>base source instance</td>
 536 </tr>
 537 <tr>
 538 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 539 <td>
 540 <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if element is in live mode.</td>
 541 </tr>
 542 </tbody>
 543 </table></div>
 544 </div>
 545 <hr>
 546 <div class="refsect2">
 547 <a name="gst-base-src-set-live"></a><h3>gst_base_src_set_live ()</h3>
 548 <pre class="programlisting"><span class="returnvalue">void</span>                gst_base_src_set_live               (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>,
 549                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> live</code></em>);</pre>
 550 <p>
 551 If the element listens to a live source, <em class="parameter"><code>live</code></em> should
 552 be set to <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a>.
 553 </p>
 554 <p>
 555 A live source will not produce data in the PAUSED state and
 556 will therefore not be able to participate in the PREROLL phase
 557 of a pipeline. To signal this fact to the application and the
 558 pipeline, the state change return value of the live source will
 559 be GST_STATE_CHANGE_NO_PREROLL.
 560 </p>
 561 <div class="variablelist"><table border="0">
 562 <col align="left" valign="top">
 563 <tbody>
 564 <tr>
 565 <td><p><span class="term"><em class="parameter"><code>src</code></em> :</span></p></td>
 566 <td>base source instance</td>
 567 </tr>
 568 <tr>
 569 <td><p><span class="term"><em class="parameter"><code>live</code></em> :</span></p></td>
 570 <td>new live-mode</td>
 571 </tr>
 572 </tbody>
 573 </table></div>
 574 </div>
 575 <hr>
 576 <div class="refsect2">
 577 <a name="gst-base-src-set-format"></a><h3>gst_base_src_set_format ()</h3>
 578 <pre class="programlisting"><span class="returnvalue">void</span>                gst_base_src_set_format             (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>,
 579                                                          <em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/gstreamer-GstFormat.html#GstFormat"><span class="type">GstFormat</span></a> format</code></em>);</pre>
 580 <p>
 581 Sets the default format of the source. This will be the format used
 582 for sending NEW_SEGMENT events and for performing seeks.
 583 </p>
 584 <p>
 585 If a format of GST_FORMAT_BYTES is set, the element will be able to
 586 operate in pull mode if the <a class="link" href="GstBaseSrc.html#GstBaseSrcClass.is-seekable"><code class="function">GstBaseSrcClass.is_seekable()</code></a> returns TRUE.
 587 </p>
 588 <p>
 589 This function must only be called in states &lt; <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstElement.html#GST-STATE-PAUSED:CAPS"><code class="literal">GST_STATE_PAUSED</code></a>.
 590 </p>
 591 <div class="variablelist"><table border="0">
 592 <col align="left" valign="top">
 593 <tbody>
 594 <tr>
 595 <td><p><span class="term"><em class="parameter"><code>src</code></em> :</span></p></td>
 596 <td>base source instance</td>
 597 </tr>
 598 <tr>
 599 <td><p><span class="term"><em class="parameter"><code>format</code></em> :</span></p></td>
 600 <td>the format to use</td>
 601 </tr>
 602 </tbody>
 603 </table></div>
 604 <p class="since">Since 0.10.1</p>
 605 </div>
 606 <hr>
 607 <div class="refsect2">
 608 <a name="gst-base-src-query-latency"></a><h3>gst_base_src_query_latency ()</h3>
 609 <pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            gst_base_src_query_latency          (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>,
 610                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> *live</code></em>,
 611                                                          <em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstClock.html#GstClockTime"><span class="type">GstClockTime</span></a> *min_latency</code></em>,
 612                                                          <em class="parameter"><code><a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstClock.html#GstClockTime"><span class="type">GstClockTime</span></a> *max_latency</code></em>);</pre>
 613 <p>
 614 Query the source for the latency parameters. <em class="parameter"><code>live</code></em> will be TRUE when <em class="parameter"><code>src</code></em> is
 615 configured as a live source. <em class="parameter"><code>min_latency</code></em> will be set to the difference
 616 between the running time and the timestamp of the first buffer.
 617 <em class="parameter"><code>max_latency</code></em> is always the undefined value of -1.
 618 </p>
 619 <p>
 620 This function is mostly used by subclasses.
 621 </p>
 622 <div class="variablelist"><table border="0">
 623 <col align="left" valign="top">
 624 <tbody>
 625 <tr>
 626 <td><p><span class="term"><em class="parameter"><code>src</code></em> :</span></p></td>
 627 <td>the source</td>
 628 </tr>
 629 <tr>
 630 <td><p><span class="term"><em class="parameter"><code>live</code></em> :</span></p></td>
 631 <td>if the source is live. <span class="annotation">[<acronym title="Parameter for returning results. Default is transfer full."><span class="acronym">out</span></acronym>][<acronym title="NULL is ok, both for passing and for returning."><span class="acronym">allow-none</span></acronym>]</span>
 632 </td>
 633 </tr>
 634 <tr>
 635 <td><p><span class="term"><em class="parameter"><code>min_latency</code></em> :</span></p></td>
 636 <td>the min latency of the source. <span class="annotation">[<acronym title="Parameter for returning results. Default is transfer full."><span class="acronym">out</span></acronym>][<acronym title="NULL is ok, both for passing and for returning."><span class="acronym">allow-none</span></acronym>]</span>
 637 </td>
 638 </tr>
 639 <tr>
 640 <td><p><span class="term"><em class="parameter"><code>max_latency</code></em> :</span></p></td>
 641 <td>the max latency of the source. <span class="annotation">[<acronym title="Parameter for returning results. Default is transfer full."><span class="acronym">out</span></acronym>][<acronym title="NULL is ok, both for passing and for returning."><span class="acronym">allow-none</span></acronym>]</span>
 642 </td>
 643 </tr>
 644 <tr>
 645 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 646 <td>TRUE if the query succeeded.</td>
 647 </tr>
 648 </tbody>
 649 </table></div>
 650 <p class="since">Since 0.10.13</p>
 651 </div>
 652 <hr>
 653 <div class="refsect2">
 654 <a name="gst-base-src-get-blocksize"></a><h3>gst_base_src_get_blocksize ()</h3>
 655 <pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gulong"><span class="returnvalue">gulong</span></a>              gst_base_src_get_blocksize          (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>);</pre>
 656 <p>
 657 Get the number of bytes that <em class="parameter"><code>src</code></em> will push out with each buffer.
 658 </p>
 659 <div class="variablelist"><table border="0">
 660 <col align="left" valign="top">
 661 <tbody>
 662 <tr>
 663 <td><p><span class="term"><em class="parameter"><code>src</code></em> :</span></p></td>
 664 <td>the source</td>
 665 </tr>
 666 <tr>
 667 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 668 <td>the number of bytes pushed with each buffer.</td>
 669 </tr>
 670 </tbody>
 671 </table></div>
 672 <p class="since">Since 0.10.22</p>
 673 </div>
 674 <hr>
 675 <div class="refsect2">
 676 <a name="gst-base-src-set-blocksize"></a><h3>gst_base_src_set_blocksize ()</h3>
 677 <pre class="programlisting"><span class="returnvalue">void</span>                gst_base_src_set_blocksize          (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>,
 678                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gulong"><span class="type">gulong</span></a> blocksize</code></em>);</pre>
 679 <p>
 680 Set the number of bytes that <em class="parameter"><code>src</code></em> will push out with each buffer. When
 681 <em class="parameter"><code>blocksize</code></em> is set to -1, a default length will be used.
 682 </p>
 683 <div class="variablelist"><table border="0">
 684 <col align="left" valign="top">
 685 <tbody>
 686 <tr>
 687 <td><p><span class="term"><em class="parameter"><code>src</code></em> :</span></p></td>
 688 <td>the source</td>
 689 </tr>
 690 <tr>
 691 <td><p><span class="term"><em class="parameter"><code>blocksize</code></em> :</span></p></td>
 692 <td>the new blocksize in bytes</td>
 693 </tr>
 694 </tbody>
 695 </table></div>
 696 <p class="since">Since 0.10.22</p>
 697 </div>
 698 <hr>
 699 <div class="refsect2">
 700 <a name="gst-base-src-get-do-timestamp"></a><h3>gst_base_src_get_do_timestamp ()</h3>
 701 <pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            gst_base_src_get_do_timestamp       (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>);</pre>
 702 <p>
 703 Query if <em class="parameter"><code>src</code></em> timestamps outgoing buffers based on the current running_time.
 704 </p>
 705 <div class="variablelist"><table border="0">
 706 <col align="left" valign="top">
 707 <tbody>
 708 <tr>
 709 <td><p><span class="term"><em class="parameter"><code>src</code></em> :</span></p></td>
 710 <td>the source</td>
 711 </tr>
 712 <tr>
 713 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 714 <td>
 715 <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if the base class will automatically timestamp outgoing buffers.</td>
 716 </tr>
 717 </tbody>
 718 </table></div>
 719 <p class="since">Since 0.10.15</p>
 720 </div>
 721 <hr>
 722 <div class="refsect2">
 723 <a name="gst-base-src-set-do-timestamp"></a><h3>gst_base_src_set_do_timestamp ()</h3>
 724 <pre class="programlisting"><span class="returnvalue">void</span>                gst_base_src_set_do_timestamp       (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>,
 725                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> timestamp</code></em>);</pre>
 726 <p>
 727 Configure <em class="parameter"><code>src</code></em> to automatically timestamp outgoing buffers based on the
 728 current running_time of the pipeline. This property is mostly useful for live
 729 sources.
 730 </p>
 731 <div class="variablelist"><table border="0">
 732 <col align="left" valign="top">
 733 <tbody>
 734 <tr>
 735 <td><p><span class="term"><em class="parameter"><code>src</code></em> :</span></p></td>
 736 <td>the source</td>
 737 </tr>
 738 <tr>
 739 <td><p><span class="term"><em class="parameter"><code>timestamp</code></em> :</span></p></td>
 740 <td>enable or disable timestamping</td>
 741 </tr>
 742 </tbody>
 743 </table></div>
 744 <p class="since">Since 0.10.15</p>
 745 </div>
 746 <hr>
 747 <div class="refsect2">
 748 <a name="gst-base-src-set-dynamic-size"></a><h3>gst_base_src_set_dynamic_size ()</h3>
 749 <pre class="programlisting"><span class="returnvalue">void</span>                gst_base_src_set_dynamic_size       (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>,
 750                                                          <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> dynamic</code></em>);</pre>
 751 <p>
 752 If not <em class="parameter"><code>dynamic</code></em>, size is only updated when needed, such as when trying to
 753 read past current tracked size.  Otherwise, size is checked for upon each
 754 read.
 755 </p>
 756 <div class="variablelist"><table border="0">
 757 <col align="left" valign="top">
 758 <tbody>
 759 <tr>
 760 <td><p><span class="term"><em class="parameter"><code>src</code></em> :</span></p></td>
 761 <td>base source instance</td>
 762 </tr>
 763 <tr>
 764 <td><p><span class="term"><em class="parameter"><code>dynamic</code></em> :</span></p></td>
 765 <td>new dynamic size mode</td>
 766 </tr>
 767 </tbody>
 768 </table></div>
 769 <p class="since">Since 0.10.36</p>
 770 </div>
 771 <hr>
 772 <div class="refsect2">
 773 <a name="gst-base-src-new-seamless-segment"></a><h3>gst_base_src_new_seamless_segment ()</h3>
 774 <pre class="programlisting"><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="returnvalue">gboolean</span></a>            gst_base_src_new_seamless_segment   (<em class="parameter"><code><a class="link" href="GstBaseSrc.html" title="GstBaseSrc"><span class="type">GstBaseSrc</span></a> *src</code></em>,
 775                                                          <em class="parameter"><code><span class="type">gint64</span> start</code></em>,
 776                                                          <em class="parameter"><code><span class="type">gint64</span> stop</code></em>,
 777                                                          <em class="parameter"><code><span class="type">gint64</span> position</code></em>);</pre>
 778 <p>
 779 Prepare a new seamless segment for emission downstream. This function must
 780 only be called by derived sub-classes, and only from the <code class="function">create()</code> function,
 781 as the stream-lock needs to be held.
 782 </p>
 783 <p>
 784 The format for the new segment will be the current format of the source, as
 785 configured with <a class="link" href="GstBaseSrc.html#gst-base-src-set-format" title="gst_base_src_set_format ()"><code class="function">gst_base_src_set_format()</code></a>
 786 </p>
 787 <div class="variablelist"><table border="0">
 788 <col align="left" valign="top">
 789 <tbody>
 790 <tr>
 791 <td><p><span class="term"><em class="parameter"><code>src</code></em> :</span></p></td>
 792 <td>The source</td>
 793 </tr>
 794 <tr>
 795 <td><p><span class="term"><em class="parameter"><code>start</code></em> :</span></p></td>
 796 <td>The new start value for the segment</td>
 797 </tr>
 798 <tr>
 799 <td><p><span class="term"><em class="parameter"><code>stop</code></em> :</span></p></td>
 800 <td>Stop value for the new segment</td>
 801 </tr>
 802 <tr>
 803 <td><p><span class="term"><em class="parameter"><code>position</code></em> :</span></p></td>
 804 <td>The position value for the new segent</td>
 805 </tr>
 806 <tr>
 807 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 808 <td>
 809 <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if preparation of the seamless segment succeeded.</td>
 810 </tr>
 811 </tbody>
 812 </table></div>
 813 <p class="since">Since 0.10.26</p>
 814 </div>
 815 <hr>
 816 <div class="refsect2">
 817 <a name="GST-BASE-SRC-PAD:CAPS"></a><h3>GST_BASE_SRC_PAD()</h3>
 818 <pre class="programlisting">#define GST_BASE_SRC_PAD(obj)                 (GST_BASE_SRC_CAST (obj)-&gt;srcpad)
 819 </pre>
 820 <p>
 821 Gives the pointer to the <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gstreamer/html/GstPad.html"><span class="type">GstPad</span></a> object of the element.
 822 </p>
 823 <div class="variablelist"><table border="0">
 824 <col align="left" valign="top">
 825 <tbody><tr>
 826 <td><p><span class="term"><em class="parameter"><code>obj</code></em> :</span></p></td>
 827 <td>base source instance</td>
 828 </tr></tbody>
 829 </table></div>
 830 </div>
 831 </div>
 832 <div class="refsect1">
 833 <a name="GstBaseSrc.property-details"></a><h2>Property Details</h2>
 834 <div class="refsect2">
 835 <a name="GstBaseSrc--blocksize"></a><h3>The <code class="literal">"blocksize"</code> property</h3>
 836 <pre class="programlisting">  "blocksize"                <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gulong"><span class="type">gulong</span></a>                : Read / Write</pre>
 837 <p>Size in bytes to read per buffer (-1 = default).</p>
 838 </div>
 839 <hr>
 840 <div class="refsect2">
 841 <a name="GstBaseSrc--do-timestamp"></a><h3>The <code class="literal">"do-timestamp"</code> property</h3>
 842 <pre class="programlisting">  "do-timestamp"             <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a>              : Read / Write</pre>
 843 <p>Apply current stream time to buffers.</p>
 844 <p>Default value: FALSE</p>
 845 </div>
 846 <hr>
 847 <div class="refsect2">
 848 <a name="GstBaseSrc--num-buffers"></a><h3>The <code class="literal">"num-buffers"</code> property</h3>
 849 <pre class="programlisting">  "num-buffers"              <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gint"><span class="type">gint</span></a>                  : Read / Write</pre>
 850 <p>Number of buffers to output before sending EOS (-1 = unlimited).</p>
 851 <p>Allowed values: &gt;= G_MAXULONG</p>
 852 <p>Default value: -1</p>
 853 </div>
 854 <hr>
 855 <div class="refsect2">
 856 <a name="GstBaseSrc--typefind"></a><h3>The <code class="literal">"typefind"</code> property</h3>
 857 <pre class="programlisting">  "typefind"                 <a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a>              : Read / Write</pre>
 858 <p>Run typefind before negotiating.</p>
 859 <p>Default value: FALSE</p>
 860 </div>
 861 </div>
 862 <div class="refsect1">
 863 <a name="GstBaseSrc.see-also"></a><h2>See Also</h2>
 864 <a class="link" href="GstPushSrc.html" title="GstPushSrc"><span class="type">GstPushSrc</span></a>, <a class="link" href="GstBaseTransform.html" title="GstBaseTransform"><span class="type">GstBaseTransform</span></a>, <a class="link" href="GstBaseSink.html" title="GstBaseSink"><span class="type">GstBaseSink</span></a>
 865 </div>
 866 </div>
 867 <div class="footer">
 868 <hr>
 869           Generated by GTK-Doc V1.18</div>
 870 </body>
 871 </html>