rt-ai is progressing nicely and now supports multi-node operation (i.e. multiple networked servers participating in a processing network) along with real-time monitoring. The screen capture shows a simple processing network where the video feed from a camera is passed through a DeepLab-v3+ stream processing element (SPE) and then on to two separate media viewers. At the top of each SPE block in the Designer window is some text like Cam(Default). Here, Cam is the name given to the SPE while Default is the name of the node (server) on which the SPE is running. In this design there are two nodes, Default and rtai0.
The code underlying the common SPE API communicates with the Designer window and supplies the stats about bytes and messages in and out. Soon, this path will also allow SPE-specific real-time parameter tweaking from the Designer window.
To add a node to the system, it just needs to have all of the prerequisites installed and run a special NodeManager SPE. This also communicates with the Designer and supports SPE deployment and runtime control, activated when the user presses the Deploy design button. Moving an SPE between nodes is just a case of reassigning it, generating the design and then deploying the design again.
The green outlines around each SPE indicate the state of the SPE and the node on which it is running. When it is all green, as in the first screen capture, this indicates that both SPE and node are running. For the second screen capture, I manually terminated the View2 SPE on rtai0. The inner part of the outline has now gone red. This indicates that the node is up but the SPE is down. If the outline is all red, it means that the node is down and not communicating with the Designer.
It’s interesting to note that DeepLab-v3+ is processing around 5 frames per second using a GTX-1080 GPU. The input rate from the camera is 30 frames per second. The processor drops frames while it is still processing an earlier frame, ensuring that queues do not build up and latency is kept to a minimum.