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.

Braw

I found out that GSteamer is a very good alternative. Had to read to understand the basics of pipeline. With gstreamer I could send a audio from one machine and listened from the other, through TCP. Now I am trying to send video through RTP. Any help is really appreciated. – Shalne

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. – Shalne

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.

Braw

Come on friend, atleast post what your codes mean or add a link to learn the basics of gstreamer – Lancastrian

Answer 2

You can also pipe the audio payload from the RTP stream with rtpdump into SoX. I recently wrote a small Python script that does just that.

https://github.com/kylophone/xplay

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