I am not sure which rock you slept under, but ITTS.js 0.0.1 is a real ITTS implementation limited to the parts used in the demo mode of the ITTS VIDEOBOX. It reads the ITTS from your dump in binary and applies the necessary formatting.
I can’t add features, if I don’t have access to more real ITTS packets from tapes, but I am confident that I will be easily able to extend it to everything used on the tapes as soon as I have access to real packets and a video from a real ITTS box from the same tape.
Details and further discussion here: ITTS (DCC text) reimplementation