Cloud UIs and Latency: The Unvarnished Truth

Cliff Mercer — Chief Architect & SVP

If there’s anything that meets or exceeds expectations more than the responsiveness of cloud UIs, it’s the speed and regularity with which people bring up the “L” word—“latency”—when we talk about streaming user experiences from the cloud.

It’s the right question to ask, of course.  The logical assumption is that a set-top box or connected device processing data locally is going to be faster than the process of sending commands out to the cloud, creating or manipulating a UI and streaming back a fully-formed user interface.

But here’s the thing:  With advanced broadband infrastructures—in managed or in unmanaged networks—a round trip to the cloud can happen in well under half a second.  And much of whatever L…L…I can say it: “Latency”—that might occur is inherent in the device and the remote control.

At ActiveVideo®, we’ve spent a lot of time studying the L-word, and here’s what we’ve found:

    • Even in the perfect storm of the worst network conditions with the worst set-top box and the slowest remote, CloudTV™ latency from keyclick to visual result clocks in at under the 500 milliseconds that is acceptable to viewers.

 

  • In most cases, viewers are seeing round-trip CloudTV experiences that are under 350 milliseconds.  That’s comparable to, and often faster than, the time that a pricey STB might take to process metadata and create a UI on its own.

In a new whitepaper dissecting latency, our director, solutions architecture, Jeremy Edmonds, has studied CloudTV in native and typical network installations.  He’s pegged the biggest contributors to latency as the remote control (4-80 ms), processing that’s built into the STB or CE device (30-200 ms) and rendering delays in the display device (20-60 ms).  As for CloudTV, Jeremy has determined that the true round trip time for CloudTV, absent any other components, is approximately 127 milliseconds between keyclick and visual output.

But don’t take Jeremy’s word for it.  Here’s what Eric Meijer, the senior project manager for Ziggo’s first-in-the-world DVB-C interactive TV VOD service, had to say about how the reality of cloud performance has exceeded his expectations:

“Since this is a cloud-based solution, we expected that there would be a high latency.  In the end, it turned out that was not the case.  We did very extensive testing together with customers and we found that the overall latency—that the user experiences—is acceptable to all users.”

I couldn’t have said it better myself.