Python send and receive RTP packets

Question

I want to send multimedia data over RTP. What I wnat to know is how to send and receive RTP packets with Python. I found the python class DPKT. But couldn't able to find a good reference to visualize how to generate each filed in RTP.

I would appreciate if someone could help me generate and receive rtp packets at the server.

Answer 1

After several days of studies I was able to use gstreamer in ubuntu terminal to achieve the above task. My main scope was to learn about synchronization of the streams. I used RTP and RTCP functionalities in gstreamer. I divided a video in to four parts vertically and send from one PC to another and displayed in the second PC. Following is the code used.

Sender:

gst-launch -v \
\
gstrtpbin name=rtpbin1 \
filesrc location=/home/x101.avi ! decodebin ! x264enc ! rtph264pay ! rtpbin1.send_rtp_sink_0 \
rtpbin1.send_rtp_src_0 ! udpsink host=192.168.1.100 port=5011 \
rtpbin1.send_rtcp_src_0 ! udpsink host=192.168.1.100 port=5012 \
udpsrc port=5013 ! rtpbin1.recv_rtcp_sink_0 \
\
gstrtpbin name=rtpbin2 \
filesrc location=/home/x102.avi ! decodebin ! x264enc ! rtph264pay ! rtpbin2.send_rtp_sink_0 \
rtpbin2.send_rtp_src_0 ! udpsink host=192.168.1.100 port=5021 \
rtpbin2.send_rtcp_src_0 ! udpsink host=192.168.1.100 port=5022 \
udpsrc port=5023 ! rtpbin2.recv_rtcp_sink_0 \
\
gstrtpbin name=rtpbin3 \
filesrc location=/home/x103.avi ! decodebin ! x264enc ! rtph264pay ! rtpbin3.send_rtp_sink_0 \
rtpbin3.send_rtp_src_0 ! udpsink host=192.168.1.100 port=5031 \
rtpbin3.send_rtcp_src_0 ! udpsink host=192.168.1.100 port=5032 \
udpsrc port=5033 ! rtpbin3.recv_rtcp_sink_0 \
\
gstrtpbin name=rtpbin4 \
filesrc location=/home/x104.avi ! decodebin ! x264enc ! rtph264pay ! rtpbin4.send_rtp_sink_0 \
rtpbin4.send_rtp_src_0 ! udpsink host=192.168.1.100 port=5041 \
rtpbin4.send_rtcp_src_0 ! udpsink host=192.168.1.100 port=5042 \
udpsrc port=5043 ! rtpbin4.recv_rtcp_sink_0

Receiver:

gst-launch -v \
videomixer name=mix ! ffmpegcolorspace ! autovideosink sync=false async=false \
\
gstrtpbin name=rtpbin1 \
udpsrc port=5011 caps = "application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264, sprop-parameter-sets=(string)\"Z01AFeygbCPNLgIgAAADAC7msoAB4sWywA\\=\\=\\,aOvssg\\=\\=\", payload=(int)96, ssrc=(uint)861153369, clock-base=(uint)4026289255, seqnum-base=(uint)30449" ! rtpbin1.recv_rtp_sink_0 rtpbin1. ! rtph264depay ! queue ! ffdec_h264 ! videobox border-alpha=0 top=0 left=0 ! mix. \
udpsrc port=5012 ! rtpbin1.recv_rtcp_sink_0 \
rtpbin1.send_rtcp_src_0 ! udpsink port=5013 host=192.168.1.104 \
\
gstrtpbin name=rtpbin2 \
udpsrc port=5021 caps = "application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264, sprop-parameter-sets=(string)\"Z01AFeygbCPNLgIgAAADAC7msoAB4sWywA\\=\\=\\,aOvssg\\=\\=\", payload=(int)96, ssrc=(uint)861153369, clock-base=(uint)4026289255, seqnum-base=(uint)30449" ! rtpbin2.recv_rtp_sink_0 rtpbin2. ! rtph264depay ! queue ! ffdec_h264 ! videobox border-alpha=0 top=-120 left=0 ! mix. \
udpsrc port=5022 ! rtpbin2.recv_rtcp_sink_0 \
rtpbin2.send_rtcp_src_0 ! udpsink port=5023 host=192.168.1.104 \
\
gstrtpbin name=rtpbin3 \
udpsrc port=5031 caps = "application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264, sprop-parameter-sets=(string)\"Z01AFeygbCPNLgIgAAADAC7msoAB4sWywA\\=\\=\\,aOvssg\\=\\=\", payload=(int)96, ssrc=(uint)861153369, clock-base=(uint)4026289255, seqnum-base=(uint)30449" ! rtpbin3.recv_rtp_sink_0 rtpbin3. ! rtph264depay ! queue ! ffdec_h264 ! videobox border-alpha=0 top=-240 left=0 ! mix. \
udpsrc port=5032 ! rtpbin3.recv_rtcp_sink_0 \
rtpbin3.send_rtcp_src_0 ! udpsink port=5033 host=192.168.1.104 \
\
gstrtpbin name=rtpbin4 \
udpsrc port=5041 caps = "application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264, sprop-parameter-sets=(string)\"Z01AFeygbCPNLgIgAAADAC7msoAB4sWywA\\=\\=\\,aOvssg\\=\\=\", payload=(int)96, ssrc=(uint)861153369, clock-base=(uint)4026289255, seqnum-base=(uint)30449" ! rtpbin4.recv_rtp_sink_0 rtpbin4. ! rtph264depay ! queue ! ffdec_h264 ! videobox border-alpha=0 top=-360 left=0 ! mix. \
udpsrc port=5042 ! rtpbin4.recv_rtcp_sink_0 \
rtpbin4.send_rtcp_src_0 ! udpsink port=5043 host=192.168.1.104

I was able to receive the four streams in one window as expected. But still streams are not synchronized perfectly.