c++ GStreamer RTP Receive Stream - c++

Question

Hi I'm trying run the rtp receiving string in c++. When I use gst-launch-1.0 -v udpsrc port=5000 caps = "application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264, payload=(int)96" ! rtph264depay ! decodebin ! videoconvert ! autovideosink sync=false line i can get stream using cmd.
Code in the c++ also works when i use parse launch pipeline = gst_parse_launch("gst-launch-1.0 -v udpsrc port=5000 caps="application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264, payload=(int)96" ! rtph264depay ! decodebin ! videoconvert ! autovideosink sync=false",NULL);
Here is the question when I'm trying to write line by line the code in c++ I think I'm getting linking error because of sometimes pad. Here what I tried.
To easily debug the code tried to link elements one by one like this
int res = gst_element_link(udp, depay);
However, it seems like i can't link udpsrc to rtph264depay or decodebin to videoconvert.
Can you help me where I am doing mistake?
#include <gst/gst.h>
#include <iostream>
static void pad_added(GstElement* element, GstPad* pad, gpointer data)
{
gchar* name;
name = gst_pad_get_name(pad);
std::cout<<"A new pad is created:\n"<< name;
g_free(name);
}
int main()
{
GstElement* pipeline, * conv, * dec, * depay, * udp,*videosink;
GstCaps* udpcaps;
GMainLoop* loop;
// init GStreamer
gst_init(NULL, NULL);
loop = g_main_loop_new(NULL, FALSE);
//pipeline = gst_parse_launch("gst-launch-1.0 -v udpsrc port=5000 caps=\"application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264, payload=(int)96\" ! rtph264depay ! decodebin ! videoconvert ! autovideosink sync=false",NULL);
// setup pipeline
pipeline = gst_pipeline_new("pipeline");
conv = gst_element_factory_make("videoconvert", "conv");
videosink = gst_element_factory_make("autovideosink", "videosink");
//enc = gst_element_factory_make("x264enc", "enc");
depay = gst_element_factory_make("rtph264depay", "depay");
dec = gst_element_factory_make("decodebin", "decode");
//g_object_set(G_OBJECT(depay), "config-interval", 1, NULL);
udp = gst_element_factory_make("udpsrc", "udp");
//g_object_set(G_OBJECT(udp), "address", "127.0.0.1", NULL);
g_object_set(G_OBJECT(udp), "port", 5000, NULL);
udpcaps = gst_caps_new_simple("application/x-rtp",
"media", G_TYPE_STRING, "video",
"clock-rate", G_TYPE_INT, 9000,
"encoding-name", G_TYPE_STRING, "H264",
"payload", G_TYPE_INT, 96,
NULL);
g_object_set(G_OBJECT(udp), "caps", udpcaps , NULL);
gst_caps_unref(udpcaps);
gst_bin_add_many(GST_BIN(pipeline), udp, depay, dec, conv, videosink, NULL);
// g_signal_connect(udp, "pad-added", G_CALLBACK(pad_added), depay);
// int res2= gst_element_link(dec, conv);
int res = gst_element_link(conv, videosink);
//int res = gst_element_link_many(udp,depay, dec, conv, videosink, NULL);
if (res!=TRUE)
{
std::cout << "Error!\n"<<res<<"\n";
// return -1;
}
// play
gst_element_set_state(pipeline, GST_STATE_PLAYING);
g_main_loop_run(loop);
// clean up
gst_element_set_state(pipeline, GST_STATE_NULL);
gst_object_unref(GST_OBJECT(pipeline));
g_main_loop_unref(loop);
return 0;
}