CableLabs Spec Aims to Simplify Multiscreen VOD

With the introduction of TV Everywhere services and the growing popularity of tablets and other IP-connected devices, video-on-demand has become an increasingly complicated world for cable operators.

No longer do MSOs merely have to worry about the relatively simple task of delivering ondemand fare to set-top boxes in standard- and high-definition format. They must also prepare high-quality Internet-protocol video streams that can reach tablets, PCs, smartphones, specialized streaming boxes and gaming consoles.


To help operators and programmers simplify the initial process of reaching all of those video platforms — and to extend a bridge between the old QAM world and the new IP multiscreen realm — CableLabs has recently completed a set of specifications that essentially unify how the primary “mezzanine” file of a title is encoded before it is transformed or chopped up into a multitude of formats that can then be shuttled along to set-top boxes and other types of consumer electronics devices.

When boiled down, the new spec offers cable operators and their programming partners a uniform way to encode the master-like, nearly pristine mezzanine copy of a movie or TV show before it heads to multiple types of devices that are receiving it on a managed network or over-the-top via a best-effort Internet connection.

Vubiquity, for example, currently builds 15 different playback formats from one mezzanine copy of a movie or TV show, according to Dave  Bartolone, senior vice president of technology. That total includes four video profiles for use by QAM-based set-tops (SD and HD constant bit-rate streams delivered in MPEG-2 and MPEG-4), as well as 11 profiles for IP devices that use adaptive bit rate, a technique that varies the bit rate based on the amount of bandwidth that’s available while also supporting a variety of resolutions and screen sizes — from big screen TVs to handheld smartphones.

Published by CableLabs on Oct. 21, the new Mezzanine Encoding Specification defines a common way to ingest file-based, VOD content to be used across IP and QAM delivery platforms.

“The goal in all included scenarios is to deliver the highest-quality video available based on the originally produced content type, bit rate and codec,” the specs explain. “The formats are defined so as to obtain the best resultant quality across a number of distribution methods.”

The encoding specs are flexible in that they currently support multiple resolutions for HD and SD in three broadly used codecs: MPEG-2, H.264/AVC, and ProRes, a high-quality video compression format developed by Apple.

Creating uniform specs with a degree of flexibility should “contain the potential chaos” for a cable industry-friendly mezzanine file, Bartalone said, noting that Apple, Amazon, Hulu, Netflix and other over-the-top players all use separate mezzanine requirements.

The spec “sets the bar for quality of content,” Mark Francisco, fellow of premises technologies for Comcast Cable and one of its key contributors, said. “We wanted to make it as easy as possible for [programmers] because we are asking them for a higher-quality source. We can start with the same asset and deliver it to your PC as we can to your TV.”

Bringing some commonality to that mezzanine format will also reduce storage costs. “It avoids the situation where we would be encoding the same content twice,” Francisco said.

But migrating to this common format is a work in progress. Comcast, for example, doesn’t have all of its mezzanine content in compliance with the new specs yet, as some encoding requirements are written into carriage contracts and might, therefore, differ from the new CableLabs specs.

“I wouldn’t say we’re 100% cut over to it,” Francisco said. “We’re working on it on a programmer-by-programmer basis.”


“I think there will be wide adoption of these specifications,”   Bartolone said. He pointed out that Vubiquity has been certified by one unnamed cable operator for the new CableLabs encoding specs.

Creating a common mezzanine format for VOD is just the start, as operators and programmers continue to launch authenticated TV Everywhere apps that deliver live TV feeds both inside and outside the MSO’s footprint.

Francisco said he has also started work on a common encoding spec for linear video delivery, but acknowledged that adhering to blackout rules and supporting dynamic ad insertion make that effort a more imposing technical challenge.

“But it’s natural that you’d want to set the [quality] bar for live content, too,” he said.


A new CableLabs encoding spec will help cable operators navigate the various file formats of an increasingly complex VOD landscape.