Reading streaming video frame by frame

[Saket Chawla]

Hello all,

I am extremely new to gstreamer.

I am trying to read frame data for a live streaming video through gstreamer
in C to create an opengl texture.

Currently going through online repositories and tutorials I could come up
code below, which is still not working. I was hoping if somebody could
point me in the right direction  or point out errors in code or errors in
the approach I am using. Any help would be appreciated.

The code below is not creating texture. I am just accessing frame data on
line 21 as a first milestone.
Code lines which I feel are important to approach are marked as bold.

   1. #include <gst/gst.h>
   2. #include <string.h>
   3. #include <stdio.h>
   4.
   5. typedef struct _CustomData {
   6.   GstElement *pipeline,*sink,*bin;
   7.   GstPad *pad,*ghost_pad;
   8.   GstBus *bus;
   9.   GstMessage *msg;
   10.   GMainLoop *loop;
   11.   gboolean is_live;
   12. } CustomData;
   13.
   14. //signal handling function
   15. *void frame_func(GstElement *sink, CustomData *data){*
   16.   printf("frame signal\n");
   17.   GstSample *sample;
   18.   GstBuffer *buf;
   19.   g_signal_emit_by_name(sink,"pull_sample",&sample);
   20.   buf=gst_sample_get_buffer(sample);
   21.   printf("%c\n",buf[0])
   22.   if(sample){
   23.     gst_sample_unref(sample);
   24.   }
   25. }
   26.
   27. int main(int argc, char *argv[]) {
   28.   GstElement *pipeline,*sink;
   29.   GstBus *bus;
   30.   GMainLoop *main_loop;
   31.   GstStateChangeReturn ret;
   32.   CustomData data;
   33.
   34. //initialize
   35.   gst_init (&argc, &argv);
   36.   memset (&data, 0, sizeof (data));
   37.
   38. //setup pipeline
   39.  * pipeline = gst_parse_launch ("uridecodebin
   uri=rtsp://192.168.1.221/stream2.sdp <http://192.168.1.221/stream2.sdp>!
   decodebin ! appsink name=video-sink
   caps=\"video/x-raw,format=RGB,pixel-aspect-ratio=1/1\"", NULL);*
   40.
   41.  //access sink to create signal
   42. *  sink=gst_bin_get_by_name(GST_BIN(pipeline),"video-sink");*
   43.
   44. //setting video to play
   45.   ret = gst_element_set_state (pipeline, GST_STATE_PLAYING);
   46.   if (ret == GST_STATE_CHANGE_FAILURE)  {
   47.     g_printerr ("Unable to set the pipeline to the playing
   state.\n");
   48.     gst_object_unref (pipeline);
   49.     return -1;
   50.   } else{
   51.      if (ret == GST_STATE_CHANGE_NO_PREROLL)
   52.       printf("for live sources, state changed but data could not be
   produced\n");
   53.     else if (ret == GST_STATE_CHANGE_ASYNC)
   54.       printf("state will change async\n");
   55.     else if (ret == GST_STATE_CHANGE_SUCCESS)
   56.       printf("successfully played\n");
   57.     else
   58.       printf("unknown %d\n",ret);
   59.     data.is_live=TRUE;
   60.   }
   61.   bus = gst_element_get_bus (pipeline);
   62.
   63. *//setting up signals from sink*
   64. *  g_object_set(G_OBJECT(sink),"emit-signals",TRUE,NULL);*
   65. *  g_signal_connect (sink, "new-sample", G_CALLBACK(frame_func),
   &data);*
   66.
   67. //setting up loop
   68.   main_loop = g_main_loop_new (NULL, FALSE);
   69.   data.loop = main_loop;
   70.   data.pipeline = pipeline;
   71.   data.sink = sink;
   72.
   73.   g_main_loop_run (main_loop);
   74.
   75. //cleanup
   76.   if(msg!=NULL)
   77.     gst_message_unref(msg);
   78.   g_main_loop_unref (main_loop);
   79.   gst_object_unref (bus);
   80.   gst_element_set_state (pipeline, GST_STATE_NULL);
   81.   gst_object_unref (pipeline);
   82.   return 0;
   83. }
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