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<div class="title">basics/bus.cc</div> </div>
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<p>A gstreamermm <a class="el" href="classGst_1_1Bus.html" title="A class that encompasses the GStreamer asynchronous message bus subsystem. ">Gst::Bus</a> example.</p>
<div class="fragment"><div class="line"><span class="comment">/*</span></div><div class="line"><span class="comment"> * This example presents basic usage of the Gst::Bus class.</span></div><div class="line"><span class="comment"> */</span></div><div class="line"><span class="preprocessor">#include <gstreamermm.h></span></div><div class="line"><span class="preprocessor">#include <glibmm/main.h></span></div><div class="line"></div><div class="line"><span class="preprocessor">#include <<a class="codeRef" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a01265.html">iostream</a>></span></div><div class="line"></div><div class="line">Glib::RefPtr<Glib::MainLoop> main_loop;</div><div class="line"></div><div class="line"><span class="comment">// Message watch function</span></div><div class="line"><span class="keywordtype">bool</span> bus_message_watch(<span class="keyword">const</span> Glib::RefPtr<Gst::Bus>& <span class="comment">/* bus */</span>, <span class="keyword">const</span> Glib::RefPtr<Gst::Message>& message)</div><div class="line">{</div><div class="line"> <span class="comment">// Print type of the message posted on the bus, and the source object name.</span></div><div class="line"> <a name="a0"></a>std::cout << <span class="stringliteral">"Got message of type "</span> << <a name="a1"></a><a class="code" href="namespaceGst_1_1Enums.html#a0378724782d11e29da8cfb6e708f66c9">Gst::Enums::get_name</a>(message->get_message_type()) << <a name="a2"></a><a class="codeRef" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a01616.html#a8b3758bb8f17c440c7963363f42f69f3">std::endl</a>;</div><div class="line"></div><div class="line"> <span class="keywordflow">if</span> (message->get_source())</div><div class="line"> {</div><div class="line"> std::cout << <span class="stringliteral">"Source object: "</span> << message->get_source()->get_name() << <a class="codeRef" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a01616.html#a8b3758bb8f17c440c7963363f42f69f3">std::endl</a>;</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keywordflow">switch</span> (message->get_message_type())</div><div class="line"> {</div><div class="line"> <span class="comment">// Handle ERROR message - print error and debug information</span></div><div class="line"> <span class="keywordflow">case</span> <a name="a3"></a><a class="code" href="namespaceGst.html#ga704e8de3c3f9698d3c3ca15d61190a86a758493cee50de74b68fa2fe29ba4bad9">Gst::MESSAGE_ERROR</a>:</div><div class="line"> {</div><div class="line"> <span class="keyword">auto</span> error_msg = Glib::RefPtr<Gst::MessageError>::cast_static(message);</div><div class="line"> std::cout << <span class="stringliteral">"Error: "</span> << error_msg->parse_error().what() << <a class="codeRef" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a01616.html#a8b3758bb8f17c440c7963363f42f69f3">std::endl</a>;</div><div class="line"> std::cout << <span class="stringliteral">"Debug: "</span> << error_msg->parse_debug() << <a class="codeRef" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a01616.html#a8b3758bb8f17c440c7963363f42f69f3">std::endl</a>;</div><div class="line"> <span class="keywordflow">break</span>;</div><div class="line"> }</div><div class="line"> <span class="comment">// Handle EOS message - quit the loop</span></div><div class="line"> <span class="keywordflow">case</span> <a name="a4"></a><a class="code" href="namespaceGst.html#ga704e8de3c3f9698d3c3ca15d61190a86abeac2aa69521997263a705f48468cc1e">Gst::MESSAGE_EOS</a>:</div><div class="line"> main_loop->quit();</div><div class="line"> <span class="keywordflow">break</span>;</div><div class="line"> <span class="comment">// Handle state changed message - print details</span></div><div class="line"> <span class="keywordflow">case</span> <a name="a5"></a><a class="code" href="namespaceGst.html#ga704e8de3c3f9698d3c3ca15d61190a86a5e5e2670b33ceaf72a35dadbdb72bfe4">Gst::MESSAGE_STATE_CHANGED</a>:</div><div class="line"> {</div><div class="line"> <span class="keyword">auto</span> state_changed_msg = Glib::RefPtr<Gst::MessageStateChanged>::cast_static(message);</div><div class="line"> std::cout << <span class="stringliteral">"Old state: "</span> << <a class="code" href="namespaceGst_1_1Enums.html#a0378724782d11e29da8cfb6e708f66c9">Gst::Enums::get_name</a>(state_changed_msg->parse_old_state()) << <a class="codeRef" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a01616.html#a8b3758bb8f17c440c7963363f42f69f3">std::endl</a>;</div><div class="line"> std::cout << <span class="stringliteral">"New state: "</span> << <a class="code" href="namespaceGst_1_1Enums.html#a0378724782d11e29da8cfb6e708f66c9">Gst::Enums::get_name</a>(state_changed_msg->parse_new_state()) << <a class="codeRef" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a01616.html#a8b3758bb8f17c440c7963363f42f69f3">std::endl</a>;</div><div class="line"> <span class="keywordflow">break</span>;</div><div class="line"> }</div><div class="line"> <span class="comment">// Unhanlded messages</span></div><div class="line"> <span class="keywordflow">default</span>:</div><div class="line"> <span class="keywordflow">break</span>;</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="keywordflow">return</span> <span class="keyword">true</span>;</div><div class="line">}</div><div class="line"></div><div class="line"><span class="keywordtype">int</span> main(<span class="keywordtype">int</span> argc, <span class="keywordtype">char</span> *argv[])</div><div class="line">{</div><div class="line"> <a name="a6"></a><a class="code" href="namespaceGst.html#a4368f0336db20f7dae336c97ebce0ef1">Gst::init</a>(argc, argv);</div><div class="line"></div><div class="line"> <span class="comment">// Create some elements</span></div><div class="line"> Glib::RefPtr<Gst::Element> source = <a name="a7"></a><a class="code" href="classGst_1_1ElementFactory.html#a6a85a2a3c4f69383cad2686d381e10e9">Gst::ElementFactory::create_element</a>(<span class="stringliteral">"videotestsrc"</span>, <span class="stringliteral">"source"</span>);</div><div class="line"> Glib::RefPtr<Gst::Element> sink = <a class="code" href="classGst_1_1ElementFactory.html#a6a85a2a3c4f69383cad2686d381e10e9">Gst::ElementFactory::create_element</a>(<span class="stringliteral">"autovideosink"</span>, <span class="stringliteral">"sink"</span>);</div><div class="line"></div><div class="line"> <span class="comment">// Create pipeline</span></div><div class="line"> Glib::RefPtr<Gst::Pipeline> pipeline = <a name="a8"></a><a class="code" href="classGst_1_1Pipeline.html#a128afc567b461f52e180b37d76dc1c4d">Gst::Pipeline::create</a>(<span class="stringliteral">"my-pipeline"</span>);</div><div class="line"></div><div class="line"> <span class="comment">// Add elements to a pipeline</span></div><div class="line"> <span class="keywordflow">try</span></div><div class="line"> {</div><div class="line"> pipeline->add(source)->add(sink);</div><div class="line"> }</div><div class="line"> <span class="keywordflow">catch</span> (<span class="keyword">const</span> <a name="_a9"></a><a class="codeRef" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a00912.html">std::runtime_error</a>& ex)</div><div class="line"> {</div><div class="line"> <a name="a10"></a>std::cerr << <span class="stringliteral">"Exception while adding: "</span> << ex.what() << <a class="codeRef" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a01616.html#a8b3758bb8f17c440c7963363f42f69f3">std::endl</a>;</div><div class="line"> <span class="keywordflow">return</span> 1;</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="comment">// Link elements</span></div><div class="line"> <span class="keywordflow">try</span></div><div class="line"> {</div><div class="line"> source->link(sink);</div><div class="line"> }</div><div class="line"> <span class="keywordflow">catch</span> (<span class="keyword">const</span> <a class="codeRef" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a00912.html">std::runtime_error</a>& ex)</div><div class="line"> {</div><div class="line"> std::cerr << <span class="stringliteral">"Exception while linking: "</span> << ex.what() << <a class="codeRef" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a01616.html#a8b3758bb8f17c440c7963363f42f69f3">std::endl</a>;</div><div class="line"> }</div><div class="line"></div><div class="line"> <span class="comment">// Get a bus object of the pipeline</span></div><div class="line"> Glib::RefPtr<Gst::Bus> bus = pipeline->get_bus();</div><div class="line"></div><div class="line"> <span class="comment">// Add watch to the bus</span></div><div class="line"> bus->add_watch(<a name="a11"></a><a class="codeRef" href="http://gcc.gnu.org/onlinedocs/libstdc++/latest-doxygen/a01676.html#gaee61fcee12458d9d61b10f07de908134">sigc::ptr_fun</a>(bus_message_watch));</div><div class="line"></div><div class="line"> <span class="comment">// Start pipeline</span></div><div class="line"> pipeline->set_state(<a name="a12"></a><a class="code" href="namespaceGst.html#gabb043e1d41659fd842f10949f91e7a7fa396ac09161e15f45f8dc574a91bfef2b">Gst::STATE_PLAYING</a>);</div><div class="line"></div><div class="line"> main_loop = Glib::MainLoop::create();</div><div class="line"> main_loop->run();</div><div class="line"></div><div class="line"> <span class="comment">// Stop playing the pipeline</span></div><div class="line"> pipeline->set_state(<a name="a13"></a><a class="code" href="namespaceGst.html#gabb043e1d41659fd842f10949f91e7a7fa07cf1506b030700024ecf1654c3796c2">Gst::STATE_NULL</a>);</div><div class="line"></div><div class="line"> <span class="keywordflow">return</span> 0;</div><div class="line">}</div><div class="line"></div></div><!-- fragment --> </div><!-- contents -->
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