Even with cloud DVR service, there's one major feature that a lot of thin-client cable set-tops are missing: the ability to pause and rewind live TV. Comcast, however, is working around that limitation.

With the launch of a new feature called Xfinity Instant Replay, Comcast Corp. (Nasdaq: CMCSA, CMCSK) has made all of its Xi3 cable set-top boxes capable of trick-play applications for live TV viewing, including pausing and rewinding. As reported first by Multichannel News, the feature rolled out to existing Xfinity subscribers last month and will be offered on all Xi3 boxes going forward.

Comcast's live-TV magic trick is possible thanks to integrated SD cards and a new video buffering window of up to 25 minutes. Currently, the Xfinity set-tops supporting the new feature are made by Pace Micro Technology . But a Federal Communications Commission (FCC) filing discovered by the Donohue Report shows that Samsung Corp. also has a Comcast box with an Instant Replay SD card included inside.

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Multiple cable vendors have showed off technology in the past enabling limited local storage on basic television set-tops. Among them, Alticast Corp. demonstrated a USB stick at CES 2014 capable of supporting secure video buffering for trick-play features. The USB drive served the same function as Comcast's SD card, but, because of the common interface, it had the advantage of being compatible with many legacy set-tops.

At the time, Alticast CTO John Carlucci (now also president of Alticast North America) said the technology could even be used to transform an old cable box into a full-fledged DVR. Alticast was headed into field trials with the USB solution last year. (See Alticast Primps for Vegas Spotlight.)

— Mari Silbey, special to Light Reading