The Secret Bandwidth of Addressable Advertising
by Leslie Ellis // August 11 2008
Last summer, while talking with a small gathering of muckety-mucks from a cable program network about how cable operators use bandwidth, I was asked what I knew about the “secret bandwidth.”
Secret bandwidth. News to me.
I asked for particulars. Turns out that this executive had learned from a cable operator contact that in addition to the digital shelf-space dedicated to standard and high definition linear TV, a special reserve also existed for advanced advertising.
I resisted the urge to tell the guy that he’d been tricked into some kind of digital snipe-hunt.
A year passed. Then, last week, a muckety-muck of the advanced advertising persuasion took a pause from his heuvos rancheros to ruminate over the bandwidth implications of addressable advertising, in high definition.
In order to send a 30-second spot that is, for whatever reason, more targeted than what’s already embedded in the linear video stream for that show, he said, operators will probably need to reserve some portion of their existing bandwidth.
Tactically, it goes like this: A typical, 6 MHz digital cable channel carries 10 to 12 linear video streams, in standard definition. To do addressable advertising, the substitute ads need some carriage room, too. Like three or four of those 10 to 12 streams.
Aha! The secret bandwidth.
Predictably, different addressable advertising vendors do this differently. Some borrow streams from within a mux, as described. Others ask for dedicated capacity — one to two 6 MHz channels, to carry the addressable ads.
(Proponents of the first method say that proponents of the second method introduce latency issues, because the set-top box has to physically re-tune to another multiplex, in order to grab and display the ads from the secondary or tertiary channel. Proponents of the second method say their way is a better use of bandwidth, because of statistical multiplexing gains.)
In HD, though, the matter gets more pronounced, because only two to three HD streams fit into that same 6 MHz digital cable channel — so where do the addressable ads go?
Three options, each with an increasing level of complexity. One: Dedicate additional digital channels to the needs of addressable ads. Two: Go faster on the move toward a unicast architecture — where each household gets its own video stream, and its own ads. Three: Find a way to use advanced compression — to mix MPEG-2 and MPEG-4 traffic in the same channel.
To those of you who, like me, were stumped chumps about the secret bandwidth — there it is. To those who already knew — my apologies for assuming a digital snipe.
POST-SCRIPT: Since this column ran, several readers, all of whom work for cable operators, wrote to let me know that switched digital video implementations can tuck in addressable ads without using tangible 6 MHz channels. If an advertisement is addressed in a forest, and no tangible bandwidth is used to carry it, is it still a secret? 😉
This column originally ran in the Platforms section of Multichannel News.