If mobile video is the next killer app, then erotic content is quickly becoming that killer app’s biggest booster.

Mobile TV industry sources say that outside the U.S. as much as 30 percent of the video content viewed on mobile devices is pornography. (See Mobile TV Gets Moving.)

"The main types of content driving mobile TV is sports, news, and what is sometimes called, uh, exotic," says Snell & Wilcox VP of systems and architecture David Brooks. Snell & Wilcox manufacturers video processing solutions for broadcasters and production and post-production studios.

TV services on mobile devices have yet to catch on in a big way in the U.S., but operators in Europe and Asia are reporting steady mobile video uptake. And North American wireless operators are already shunning the idea of offering adult video content for the small screen.

Why? "We don't assertively offer some content because, given our position in the marketplace, it would not be responsible to do so," wrote Verizon Wireless spokesman Jeffrey Nelson in an email to Light Reading.

"If American customers are demanding that wireless operators offer it, I'm sure somebody eventually will, but that doesn't mean it's going to be us," Nelson wrote.

“In the U.S. it is buried, if it is available at all," says Daniel Scalisi, VP of new media services at Weathernews Americas Inc. of mobile adult content. "In Europe it could be as much as 30 percent. It's one of the key content drivers, and there are multiple carriers that are very willing to serve it to consumers."

In fact, numerous mobile video executives at the NAB show confirmed that adult content has to date been a key driver of mobile TV viewing. The 30 percent number came up several times.

Juniper Research Ltd. says sales of adult mobile services worldwide will triple between 2004 and 2009 to reach $2.1 billion. Sales of the stuff in the U.S. alone will be a $1.5 billion-a-year business by 2009, says Boston-based research house Yankee Group Research Inc.

The Yankee Group believes reaching that sales number will depend a lot on wireless operators' ability to establish parental controls around the content.

But regardless of how racy the content, experts say content owners and distributors must make sure that mobile video is visually clear and appealing. (See Mobile NGN.)

Format is definitely important, and experts say mobile viewers prefer short-form video to long-form, although this could change as video quality and formatting evolves. Scenery, lighting, and the complexity of an image are also crucial to mobile devices -- and also reasons why mobile porn has taken off in some places.

“You’re probably not going to want to watch Lawrence of Arabia on a mobile device,” Brooks says. “In [large screen] TV you will have wide shots with people moving through them, but if you put that same shot on a mobile screen you won’t see the whole thing.".

HBO CTO Bob Zitter notes that lightness and darkness spectrums must be compressed for mobile devices. “HBO has wide ranges of darkness to lightness. On Deadwood we had a campfire shot where on a mobile handset the fire looked like just a little dot of light on a black screen.”

— Mark Sullivan, Reporter, Light Reading