March Madness: A Slam-Dunk for CBS SportsLine
For the past three years, CBS has offered live online coverage of the NCAA men’s basketball championship tournament, affectionately known as March Madness. While those earlier Webcasts were successes, their audiences were limited by the paid subscription system under which games were offered. This year, CBS took the bold step of opening up the doors to their March Madness Webcasts by offering free, ad-supported access to these live streams.
The results? More than 15 millions streams of live video were served over the first three rounds of the tournament. Five million visitors logged on during the first four days of the tournament, with a peak of 268,000 simultaneous viewers on the opening day of coverage.
Reaching an audience of this size with a high-quality live stream represents a validation of both CBS’s decision to offer free access to its content and various CDNs’ claims that they can deliver a truly scalable experience to their customers. Despite its success, though, those audience and of the Webcasts also clearly demonstrated the reality that true convergence of TVs and PCs is still a few years away. What follows is a look into how CBS prepared itself for success and how this event proves the viability of the Internet for delivering high quality video to a mass-market audience.
A Little Help
Pulling off a Webcast of this magnitude inevitably requires bringing together partners that can help with various aspects of producing and delivering the stream. One such partner for CBS was MLB Advanced Media, the team behind MLB.com’s success streaming baseball games live from its site. "We used them for their expertise on the player side as well as the encoding services side," says Mark Kortekaas, CTO of CBS Digital Media.
CBS also employed the services of two CDN partners—Akamai Technologies and Limelight Networks—balancing their traffic between the two. "We’ve historically used multiple CDNs for redundancy and capacity reasons," says Kortekaas. "In this particular case, the capacity issues were really what we were managing around. We balanced traffic between the two based on what was going on with the CDNs."
The CDNs essentially took the TV broadcasts and pushed them out through the Internet to customers. "It wasn’t quite the same feed as on broadcast. The actual game content was the same, but they didn’t show the same commercials," says Mike Gordon, cofounder and chief strategy officer of Limelight, who added that typical sporting event broadcast blackout rules also applied. "Viewers couldn’t get the feed that was available to them on their local broadcast affiliate."
This was the first time that Limelight and Akamai worked together on a large-scale event where they shared delivery duties, although it wasn’t the first time that a content provider has split their traffic between CDNs. "This has been done a couple different times before where we’ve done coordinated events with other networks," says Bill Wheaton, VP of Akamai’s newly formed Digital Media division. For example, during Microsoft’s Windows Media 9 launch, Microsoft split their traffic between everyone who was a certified provider. "In that case it wasn’t a capacity issue per se, it was more of a political thing," he says.
The Great Unknown
When planning any online video delivery, one of the most important considerations is how much reserved capacity is needed in order to handle however many people actually show up to watch the stream. This is especially true for live Webcasts, and the stakes were even higher for CBS as it transitioned from a pay-to-play model to an ad-supported one. "Clearly this year we were super-sensitive on capacity because we had no historical basis on what this was going to do in terms of traffic," says Kortekaas.
Coming up with an accurate estimate can be quite the challenge, considering the numerous variables that have to be addressed. "What CBS didn’t know was how big the audience would be, how long people would stay and watch the stream for, or what (would be) the average bit rate their users would get," says Gordon.
CBS eventually settled on 200,000 concurrent streams as the number they would design their system’s capacity around. "The rationale for that number came from a couple of different places. First, we’ve run the NCAA Web sites for a number of years, so we knew what our average Web traffic has been over the years, and we know what our growth pattern has been year after year. We also knew, because of our involvement over the last couple of years with the paid subscription service, what our subscriber counts were and traffic patterns were. We also knew what our conversion rates from pay to free have historically been," says Kortekaas.