Sorry if this is a dumb question but what does

> with television broadcast critical timing/latency on stream switching.

mean? Is this minimising the time it takes for the channel to change once the person sitting at home has clicked the remote? Or is this for live broadcasters trying to mux multiple raw video streams into a single watchable stream? Or something else?

If the former, what's special about that case over some normal network box?

The type of system I was referring to is the core within the broadcast facility, rather than extending to the home viewers (which is a separate downstream distribution encoding/mux process). Timing is important for when you switch between different video feeds to avoid on-air impacts so all the signals have to be video frame-aligned basically. In an IP system PTP timing is used to lock all the devices since greater precision is needed than NTP can provide.

Low-latency is also important for when the SDN system initiates a route to switch since it generally needs to happen according to a tight broadcast playlist schedule and we found that with SDN (central controller telling all the switches what to do) rather than IGMP type system (multicast subscribe with switches doing a lot more work parsing packets) is the best approach to handling very large volumes of routes and having them take effect in a low-latency predictable way.

Thanks for clarifying, I think I get it. It almost sounds a bit analogous to an RTOS where you dictate your deadlines to ensure they are met rather than letting everything run wild and hope for the best.