[gst-devel] how to display/grap frames for displaying them ??

[Alexander Bierbrauer]

Hi people,

I'm trying to figure out all the GStreamer stuff lately. At present, I can 
create a pipeline to decode a vid and update the corresponding bin. But how 
can I display / grab the frame data so that I can preview it for example on a 
widget of a toolkit ??

I've checked different programs and source codes how they are doing it but I 
couldn't figure it out yet. Could anyone please help out ??

Bye, Alex



--------------------
PS: Here's my initialization code so far:

void GStreamer::initialize()
{
 /* initializing GStreamer */
 if(!gst_init_check(NULL, NULL))
 {
  printf("failed to initialize GStreamer for some reason\n");
  return;
 }
 printf("initialized GStreamer\n");
 
 /* create a new bin to hold the elements */
   m_pPipeline = gst_pipeline_new ("pipeline");
   if(m_pPipeline == NULL)
 {
  printf("failed to create GStreamer pipeline\n");
  return;
 }
 printf("created GStreamer pipeline\n");
 
 /* create a disk reader */
   m_pFileSrc = gst_element_factory_make ("filesrc", "disk_source");
   if(m_pFileSrc == NULL)
 {
  printf("failed to create GStreamer file source\n");
  return;
 }
 printf("created GStreamer file source\n");
 
 /* typefinder four filesrc */
 m_pTypeFind = gst_element_factory_make ("typefind", "typefind");
 
   //g_signal_connect (G_OBJECT (filesrc), "eos", G_CALLBACK (eos), thread);
 
 /* creating our avi muxer */
 m_pAviMux = gst_element_factory_make("avimux","avisrc");
 if(m_pAviMux == NULL)
 {
  printf("failed to create GStreamer avi muxer");
  return;
 }
 printf("created GStreamer avi mux\n");
 
 /* creating queue */
 m_pQueue = gst_element_factory_make("queue","queue");
 if(m_pQueue == NULL)
 {
  printf("failed to create GStreamer queue\n");
  return;
 }
 printf("created GStreamer queue\n");
 
 /* now we add all elements to our pipeline */
 gst_bin_add_many (GST_BIN (m_pPipeline), m_pFileSrc, m_pTypeFind, m_pAviMux, 
m_pQueue, NULL);
 
 /* now let's link all elements together */
 if(!gst_element_link_many (m_pFileSrc, m_pTypeFind, m_pAviMux, 
m_pQueue,NULL))
 {
  printf("failed to link GStreamer elements\n");
  return;
 }
 printf("linked succesfully GStreamer elements\n");
 
 /* let's set it ready */
 gst_element_set_state (GST_ELEMENT (m_pPipeline), GST_STATE_READY);
 
 m_bInitialized = true;
}

void GStreamer::shutdown()
{
 if(isPlaying())
  stopPlaying();
  
 m_bInitialized = false;
}

/**
  * sets the video source for the GstElement file source
  **/
void GStreamer::setVideoSource(QString src)
{
 if(!src || src.length() <= 0)
  return;
 
 g_object_set (G_OBJECT (m_pFileSrc), "location", src.ascii(), NULL);
 printf("GStreamer file source location is: %s\n",src.ascii());
}

void GStreamer::startPlaying()
{
 gst_element_set_state (GST_ELEMENT (m_pPipeline), GST_STATE_PLAYING);
 printf("playing GStreamer\n");
}

void GStreamer::pausePlaying()
{
 gst_element_set_state (GST_ELEMENT (m_pPipeline), GST_STATE_PAUSED);
 printf("pauses GStreamer\n");
}

void GStreamer::stopPlaying()
{
 gst_element_set_state (GST_ELEMENT (m_pPipeline), GST_STATE_NULL);
 printf("stopped GStreamer\n");
}

bool GStreamer::isPlaying()
{
 if(gst_element_get_state(GST_ELEMENT(m_pPipeline)) == GST_STATE_PLAYING)
  return true;
  
 return false;
}

/**
  * call this method every frame to update the pipeline
  **/
void GStreamer::update()
{
 gst_bin_iterate (GST_BIN (m_pPipeline));
}