Streaming Live Video on a Local Lan Vs. Internet

Streaming video over a local area network can take on a significantly different look than trying to live stream video over the Internet.

  • differences in local vs. internet and streaming video

  • live stream vs. video on demand

  • what does real time mean?

  • what to do with late packets?

  • UDP vs. TCP in the local network

  • RTP and UDP

  • RTP and RTCP

  • RTP and RTSP

  • RTP and Multicast

  • Tools used

TODO: workflowy outline

RTSP is a good option for streaming video in a local setup up, where minimal delay is the highest priority. However, RTSP does not typically do very well over the Internet due to the nature of RTP/UDP.

Which brings up another question: will there be more than once transmitter/reciever per office (which RTSP could serve well).

In recent years people would use RTMP to stream video over the Internet, by adding a plguin to NGINX, each camera would stream to NGINX, NGINX then create the endpoints for the video, waiting for client connections to start recieving the video.

Nowadays MPEG-DASH over HTTP is building popularity, MPEG-DASH (taking over popularity from MJPEG) is an Open Protocol supported by most browswers including Chrome, but may be lagging with Safari.

I am happy to set up a PoC with both RTSP and HTTP serving MPEG-DASH from Raspberry Pis. For generating video, I’ll be using gstreamer most likely to transmit the Raspberry Pi Video.

Video on a LAN required for Real Time control decisions, whether it is OpenCV churning through images while spitting out data used by magoo the guidance module.

Low latency is and a non-glitchy video stream are imparative to driving a high speed vehicle correctly. This is true even when the vehicle is being controlled by a human with a joystick.

A half second delay in video translates to about 43.5 foot different in where the vehicle is vs. where it appears to be, or if the we have a .5 second drop in video, we will have “jump” that 43.5 feet.

This makes safe navigation of a high speed vehicle unsafe, whether it is being drivin by human or algorithm.

Video Over the Internet

Delay is inevetible. You are crossing unknown links and firewalls. Must wrap it all up under HTTP to make things the easiest.