In the three months that passed between this year's Cable Show, in Washington, D.C., and this week's IBC conference, in Amsterdam, one thing is certain: Cloud DVR. It's on.

Comcast started the buzz, with its X2 platform. Ever since, we've seen a surge of interest in cloud DVR from service providers around the globe.  Directionally, it's gone from "that sounds interesting, let's keep an eye on it," to "we need to do this - let's get a proof of concept going."

That's all good news for us, of course, and seems a good reason to share a few observations we've made along the way, as cloud DVR services go to market.

One: Linear parity matters, especially for advertising. If ever you want to create an instant imbroglio, tell the people in the ad sales department that the new service -cloud DVR, in this case -doesn't provide linear parity. Put another way: Support for basic ad zones is a table stake, when it comes to cloud DVR.

So: Putting DVR services inthe cloud raises an immediate need for dynamic ad insertion (DAI) technologies, so as to refresh the advertisements in the stored content. Preferably on the fly.

Two: For obvious reasons, most service providers seek ways to build a cloud DVR service out of their existing video on demand (VOD) systems. That's understandable.

Is it possible to adjoin a cloud DVR service to existing video on demand (VOD) systems? Yes. With a few important differences. Managing inbound streaming resources is one, as is archive management. Policy management for time-shifted recording is huge, especially when you're recording thousands of shows, on hundreds of channels. There's more, but I don't want to freak you out. Short version: You're going to need a versatile control plane.

Recall that when VOD was a youngster, 15 or so years ago, there weren't many other options, short of driving to the video store. These days? I don't have enough fingers and toes to count the number of ways people can find video entertainment.

Three: Surprise, surprise -there is no "cookie cutter" way that will work for all regions and systems. What can and cannot happen with linear and live video varies greatly from country to country, and provider to provider. What's available as a common copy from one content provider may come over as a unique copy from another.

So: Cloud DVR is coming. It's kind of like VOD, but not quite. Making sure it doesn't hobble the ad sales department is critical -especially to help offset the costs of "going cloud." And, count on lots of differences, depending on where you're building.

Want more info? Come see us! We can talk cloud DVR all day long. Booth 1.A71 at IBC.