MPEG-4 Expanding Beyond Distribution

MPEG-4 (h.264) compression has already transformed the consumer TV landscape, allowing companies like DirecTV to distribute hundreds of HD channels to their subscribers.

Now, the compression scheme that promises twice the bandwidth efficiency as MPEG-2 is edging into the professional applications. Visitors at NAB 2009 will find electronic news gathering products with the capability, but will have to wait awhile for gear that can handle the rapid action of sports.

"We're at the beginning on the MPEG-4 implementation," says Lisa Hobbs, a business development VP at Tandberg Television. "We're looking forward to continuous improvements in both the technology and the marketplace for these products."

It's been a few years since MPEG-4 first took off in the satellite TV business. For those servicing that industry, things are looking up despite the economic down.

"Our business is rocketing," says Bob Wilson, general manager of Motorola's networked video solutions group. "It's gratifying, but kind of scary wondering if it will hold up under the circumstances. The whole MPEG-4 space is very hot right now."

Wilson adds that the service providers can't get HD channels up fast enough.

"What's driving a big part of business is both the uplink business in MPEG-4 and a series of products that allow transcoding back to MPEG-2 in the cable headend," he says. "That's so you don't have to trade out the rest of the infrastructure including set-top boxes."

Making a contribution to contribution

Transmission is just MPEG-4's first stop. According to David Mitchinson, business development director, DSNG Systems, Tandberg Television, contribution and helping TV stations and networks get content from the field back to a broadcast operations center is the next frontier and will open the door to more economical HD newsgathering.

"Currently our products are very much focused on using MPEG-4 for newsgathering and general purpose contribution," he says. "It is a big market for us."

Mitchinson's technical paper for NAB 2009, The Role of MPEG-4 within Contribution, explains the key to unlocking MPEG-4's potential in this application.

Contribution is a different use for MPEG-4 than transmission, he says. With transmission, coding/decoding delays are unimportant. There's time to bring the entire MPEG-4 toolset into play with enormous gains in efficiency. But where time is a factor, things aren't quite so simple.

"For a lot of contribution applications, latency is critical," he says. "Because of the way MPEG-4 works, you have to start making compromises and choose the tools you can use quite carefully. Where you need to achieve 500 ms or less for encode/decode, the biggest advantages [over MPEG-2] are with low bitrate applications like newsgathering and general purpose contribution."

The highs and lows of MPEG-4

Why is MPEG-4 ready to deliver for low bitrate applications like newsgathering while high bitrate applications like sports lay farther down the road?

The answer comes down to mathematics. Percentage-wise, MPEG-4's gains over MPEG-2 are much higher at the low end of the bitrate spectrum. According to Mitchinson, this means bandwidth efficiency gains of up to 50 percent.

Mitchinson says that looking at the difference between typical news and sports content also explains why MPEG-4 yields different savings. News images have a great deal of repetition. With sports footage, the entire frame shifts constantly.

"There is interest in using MPEG-4 to deliver high bitrate sports content," Mitchinson says. "At high bit rates and with very demanding content, MPEG-4 will still deliver efficiency savings; however, these will not be as significant as for newsgathering."

As bandwidth savings over MPEG-2 drop down to 25 percent or less for sports, Mitchinson says he expects that the adoption of "fidelity extensions" that improve HD image quality will be needed to drive future adoption of MPEG-4 for high bandwidth applications.

Will economics trump technology?

MPEG-4 looks to solve the bandwidth issues in going from SD to HD newsgathering. But right now, broadcasters are more concerned with saving money than with saving bandwidth.

"People are doing HD news in the studio, but there is still the strong belief that a 16x9 high-quality SD that you upconvert from the truck is more than adequate for a lot of the field reporting," says Tom Lattie, Harmonic's director of broadcast and satellite solutions.

Letting go of this holdover from the SD era is even harder given the current economic climate.

"[Broadcasters are] looking to save money, but don't want to spend money now," Lattie says. "We can talk about MPEG-4 versus MPEG-2 compression, but they're not necessarily going to go out and buy new [HD] cameras for these trucks and field reporters. They're staying with SD now and want easy upgrade to HD at some later date when they have more capital to throw after that."

Despite these challenges, Lattie says that NAB 2009 will feature a growing array of MPEG-4 products that open the door for those looking to produce end-to-end HD news.