[gstreamermm] examples: add example for request pad usage

[Marcin Kolny <mkolny src gnome org>]

commit 9536d4b137e9dca622073b710055470f1c41025f
Author: Marcin Kolny <marcin kolny gmail com>
Date:   Sat Nov 19 14:20:27 2016 +0100

    examples: add example for request pad usage
    
    This example uses tee element as an element with request pads

 examples/Makefile.am             |    2 +
 examples/tee_request_pad/main.cc |  152 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 154 insertions(+), 0 deletions(-)
---
diff --git a/examples/Makefile.am b/examples/Makefile.am
index 200ab02..b16de4e 100644
--- a/examples/Makefile.am
+++ b/examples/Makefile.am
@@ -53,6 +53,7 @@ noinst_PROGRAMS =                                             \
        hello_world/example                                     \
        ogg_player/example                                      \
        ogg_rewriter/example                            \
+       tee_request_pad/example                                 \
        typefind/example                                        \
        optiongroup/example                                     \
        basics/bin                                                      \
@@ -78,6 +79,7 @@ ogg_rewriter_example_SOURCES                          = ogg_rewriter/main.cc
 ogg_player_example_SOURCES                                     = ogg_player/main.cc
 opengl_filter_example_SOURCES                          = opengl_filter/main.cc 
opengl_filter/sample_gl_filter.h
 optiongroup_example_SOURCES                                    = optiongroup/main.cc
+tee_request_pad_example_SOURCES                                        = tee_request_pad/main.cc
 typefind_example_SOURCES                                       = typefind/main.cc
 
 # basic examples
diff --git a/examples/tee_request_pad/main.cc b/examples/tee_request_pad/main.cc
new file mode 100644
index 0000000..8f22739
--- /dev/null
+++ b/examples/tee_request_pad/main.cc
@@ -0,0 +1,152 @@
+/* gstreamermm - a C++ wrapper for gstreamer
+ *
+ * Copyright 2009-2016 The gstreamermm Development Team
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <gstreamermm.h>
+#include <glibmm/main.h>
+
+#include <regex>
+#include <iostream>
+
+Glib::RefPtr<Glib::MainLoop> mainloop;
+
+// Message watch function
+bool bus_message_watch(const Glib::RefPtr<Gst::Bus>& /* bus */, const Glib::RefPtr<Gst::Message>& message)
+{
+  switch (message->get_message_type())
+  {
+  case Gst::MESSAGE_ERROR:
+  case Gst::MESSAGE_EOS:
+    mainloop->quit();
+  default:
+    break;
+  }
+
+  return true;
+}
+
+int main(int argc, char** argv)
+{
+  // Initialize Gstreamermm:
+  Gst::init(argc, argv);
+
+  //Check input arguments:
+  if(argc < 2)
+  {
+    std::cout << "Usage: " << argv[0] << " <filename>" << std::endl;
+    return 1;
+  }
+
+  const std::string filename = argv[1];
+
+  // Create pipeline:
+  Glib::RefPtr<Gst::Pipeline> pipeline = Gst::Pipeline::create("my-pipeline");
+
+  // Create elements:
+  Glib::RefPtr<Gst::Element> source = Gst::ElementFactory::create_element("filesrc"),
+    decoder = Gst::ElementFactory::create_element("decodebin"),
+    tee = Gst::ElementFactory::create_element("tee"),
+    audio_queue = Gst::ElementFactory::create_element("queue"),
+    video_queue = Gst::ElementFactory::create_element("queue"),
+    audio_convert = Gst::ElementFactory::create_element("audioconvert"),
+    audio_convert_4v = Gst::ElementFactory::create_element("audioconvert"),
+    video_convert = Gst::ElementFactory::create_element("videoconvert"),
+    goom = Gst::ElementFactory::create_element("goom"),
+    resample = Gst::ElementFactory::create_element("audioresample"),
+    audio_sink = Gst::ElementFactory::create_element("autoaudiosink"),
+    video_sink = Gst::ElementFactory::create_element("autovideosink");
+
+  if (!source || !decoder || !tee || !audio_queue || !video_queue || !goom || !audio_convert_4v
+      || !audio_convert || !video_convert || !resample || !audio_sink || !video_sink)
+    std::cerr << "One of the elements could not be created." << std::endl;
+
+  // Set location property of filesrc element
+  source->set_property<Glib::ustring>("location", argv[1]);
+  
+  // We must add the elements to the pipeline before linking them:
+  try
+  {
+    pipeline->add(source)->add(decoder)->add(tee)->add(audio_queue)->add(video_queue)
+      ->add(goom)->add(audio_convert_4v)->add(audio_convert)->add(video_convert)
+      ->add(resample)->add(audio_sink)->add(video_sink);
+  }
+  catch (std::runtime_error& ex)
+  {
+    std::cerr << "Exception while adding: " << ex.what() << std::endl;
+    return 1;
+  }
+
+  // Lik tee with queues
+  Glib::RefPtr<Gst::PadTemplate> tee_src_tpl = tee->get_pad_template("src_%u");
+  if (tee->request_pad(tee_src_tpl)->link(audio_queue->get_static_pad("sink")) != Gst::PAD_LINK_OK)
+  {
+    std::cerr << "Cannot link tee pad with audio queue" << std::endl;
+    return 1;
+  }
+  if (tee->request_pad(tee_src_tpl)->link(video_queue->get_static_pad("sink")) != Gst::PAD_LINK_OK)
+  {
+    std::cerr << "Cannot link tee pad with video queue" << std::endl;
+    return 1;
+  }
+  
+  // Link other elements together:
+  try
+  {
+    source->link(decoder);
+    audio_queue->link(audio_convert)->link(resample)->link(audio_sink);
+    video_queue->link(audio_convert_4v)->link(goom)->link(video_convert)->link(video_sink);
+  }
+  catch(const std::runtime_error& error)
+  {
+    std::cerr << "Exception while linking: " << error.what() << std::endl;
+    return 1;
+  }
+
+  // Signal handler for on-pad-added signal of decoder element
+  decoder->signal_pad_added().connect([tee] (const Glib::RefPtr<Gst::Pad> &pad) {
+      Glib::RefPtr<Gst::Caps> caps = pad->get_current_caps();
+      std::string media_type = caps->get_structure(0).get_name();
+
+      std::cout << "New pad: " << pad->get_name() << ", media type: " << media_type << std::endl;
+
+      if (std::regex_search(media_type, std::regex("^audio")))
+      {
+       if (pad->link(tee->get_static_pad("sink")) != Gst::PAD_LINK_OK)
+       {
+         std::cerr << "Cannot link pad with queue" << std::endl;
+       }
+      }
+      else
+       std::cerr << "Unsupported media type" << std::endl;
+    });
+
+  // Add watch to pipeline's bus.
+  pipeline->get_bus()->add_watch(sigc::ptr_fun(&bus_message_watch));
+
+  
+  // Now set the whole pipeline to playing and start the main loop:
+  std::cout << "Setting pipeline to PLAYING." << std::endl;
+  mainloop = Glib::MainLoop::create();
+  pipeline->set_state(Gst::STATE_PLAYING);
+  std::cout << "Pipeline is playing." << std::endl;
+  mainloop->run();
+  
+  std::cout << "Returned. Stopping pipeline." << std::endl;
+  pipeline->set_state(Gst::STATE_NULL);
+
+  return 0;
+}