Media source extension video player for live streaming mp4

Something strange happened. My mp4frag was receiving the buffer payload from exec
running ffmpeg and after maybe a half hour running, it received a payload with the string "yp". Is that normal? Perhaps node-red sends intermittent messages to see if nodes are alive? I am adding better input filtering to determine what this is. Happened a few times so far.

No, that won't be the case.
Perhaps you can set a conditional breakpoint in the exec node, which is triggered when the output msg payload equals "yp".