Guest Blog by – Peter Chave, Technical Engineering Leader, Cisco Video Software and Solutions
For as long as there’s been cause for broadcast video engineers to get together to talk shop, there’s been that big blob in the middle of the topological diagram — the frame-accurate crosspoint router, based on the coaxial workhorse that is the SDI (Serial Digital Interface.)
And at this week’s National Association of Broadcasters, in Las Vegas, broadcast video technologists will again assess the fate of SDI-based technologies, along the prism that is the inevitable and worldwide shift to their Internet Protocol (IP)-based successors.
The quest for an IP-based video switch — built from the off-the-shelf hardware that rides the cost curves happening in data centers, and capable of frame-accurate, deterministic behaviors — is at least three NABs old. Along the way, we and others in the broadcast video engineering community experimented with how to implement IP-based switching, at the source, in the network, and at the destination.
Necessity is the Mother of Invention
It’s not experimentation for experimentation’s sake. Broadcasters want and need to experience the tangible paybacks that emanate from IP-based video technologies: Internal and external service velocity; troubleshooting transparency; supplier independence; lowered capital and operational costs.
“We believe that the move from the SDI coax infrastructure to one based on IP networks will be a key driver in enhancing the flexibility and agility of our broadcast plant,” says Thomas Edwards, VP Engineering and Development for FOX Network Engineering and Operations. “We’re glad to see Cisco’s demonstration of synchronous switching of live video, as this is a key capability that is required.”
And with that cat out of the bag, here’s the detail: At this week’s NAB, in our booth, #N802, we’re taking the wraps off of a Proof of Concept video switcher. It doesn’t yet have a name, let alone a part number. The point of it is to explore the use of time to switch one video to another, in the vertical blanking interval (VBI), using off-the shelf components.
“The Cisco demo showing frame accurate video switching is a game changer,” said Al Kovalick, of Media Systems Consulting. “Finally – solid proof that an off-the-shelf (COTS) IP router can indeed replace an SDI switch.”
Game changer or not, the intent is to explore some of the theories postulated so far, and to demonstrate some of the pitfalls, timing challenges and practicalities of making an IP-based video switch work. In essence, it’s us opting to explore network-based switching at a deeper level.
Here’s what you’ll see, should you come by: Various video sources, encapsulated in IP, and fed into a small device with a precision time protocol reference on board, which performs the frequency lock calculations and off-set commands. Press a button, boom! See a clean switch. And because it’s kind of difficult to see, naked-eye, a switch that’s happening in the VBI, we’ve added the ability to offset it, such that you see a sort of “tear” in the screen, to force the switch into view.
We think it’s a pretty big deal, if not the be-all-and-end-all to what is a transitional point in time. Again, it’s a research effort — which is why it’s important to gather your feedback. Come by and see for yourself at Booth N802, at North Hall of the Las Vegas Convention Center this week at the #NABshow.
Tweet us with your pictures, questions or comments at @CiscoSP360.