Grass Valley Squeezes High-Def


Thomson’s Grass Valley division plans to deliver a video-encoding system this fall — based on an integrated chip it spent three years developing — which the company claimed will deliver high-definition MPEG-4 signals using as little as half the bandwidth of existing encoders.

Competitors, though, questioned Grass Valley’s explanation for claiming such savings.

The first Grass Valley ViBE MPEG-4 encoder based on the chip will support high-definition video and is set to ship in September. That will be followed by support for standard-definition MPEG-4 video, said Jean Macher, director of marketing for Grass Valley’s video-network systems unit.

Likely prospects

Grass Valley is aiming the MPEG-4 products primarily at direct-broadcast satellite players, such as DirecTV and EchoStar Communications, and telcos with Internet Protocol TV offerings. DirecTV is an existing customer, as are Cox Communications and programmers including HBO and Turner Broadcasting System.

Both DBS and telco providers are deploying MPEG-4 today, whereas cable operators are more likely to stick with less-efficient MPEG-2 technology because of their large installed base that uses the older spec.

The “breakthrough” technology in the new ViBE encoder, Macher said, is the Mustang application-specific integrated circuit, developed by 60 Thomson engineers over three years. “This dramatically changes how MPEG-4 is done,” he said.

The chip can deliver high-motion HD video at 4 Megabits per second, and 5 Mbps with an audio channel. “That’s with sports video; very tough content,” Macher said.

Mustang-based encoders will be twice as efficient as Grass Valley’s current MPEG-4 encoders, which provide high-definition MPEG-4 at between 8 Mbps and 12 Mbps. In addition, Mustang also provides 30% lower bandwidth at constant bit-rate encoding than competing products, according to Grass Valley.

How, exactly? Macher said the ASIC is optimized for MPEG-4 compression algorithms, whereas some first-generation encoders used “consumer-grade” digital-signal processors. That lets Mustang employ the full range of compression techniques available in the MPEG-4 Advanced Video Coding H.264 specification, according to Grass Valley.

“Other guys don’t have the horsepower to do this,” he said.

One example he provided was an MPEG-4 technique called weighted prediction, which can better process scenes that fade in or out by predicting the content of upcoming video frames.

Grass Valley’s two main competitors in the video-encoding market are Tandberg Television and Harmonic. The Thomson unit is still a comparative small fry, estimating its worldwide market share in the video-compression and digital TV headend equipment segment at around 10%, and Grass Valley hopes the new encoding chip gives it some additional momentum.

Corner cases?

However, both Tandberg Television and Harmonic said that the bandwidth savings claimed for Mustang sounded fishy.

Carl Furgusson, vice president of product management for Tandberg Television’s video-compression business, acknowledged that his company’s MPEG-4 offerings use various off-the-shelf chips, such as DSPs or field-programmable gateway arrays (FPGAs).

But simply having this circuitry doesn’t mean compression rates will necessarily be higher, he said.

“All of the vendors have done the quick-win techniques,” Furgusson said. “Most of the rest of the MPEG-4 toolset is really based around niche, corner-cases of video.” Weighted prediction, for example, “really doesn’t gain you much,” he added.

Greater improvements in MPEG-4 compression will be achieved in the preprocessing stage by eliminating noise in content that’s transcoded from MPEG-2 video, according to Fergusson.

Moreover, the performance of an encoder will always depend on the content, said Harmonic director of digital video product marketing J.C. Morizur.

“A movie is not as demanding as a soccer match,” he said. “If I take a non-action-packed movie, yes, I can do that at 5 Mbps. I can show you HD at 3 Mbps… But we’ve always been careful about setting the right expectations for customers.”

To Macher, the real test of how well the chip performs will be demonstrated by customer selections as the number of high-definition channels expands in the next few years. “We are geared toward a massive deployment of HD,” he said.

<p>TECH SPEC: Parsing the Streams</p><p>Grass Valley’s latest video networking system products include:</p>

ViBE MPEG-4 HD Encoder:

Able to compress high-motion, high-definition streams at 5 Mbps. Scheduled to ship September 2007.

NetProcessor 9040:

Upgraded version of video transrater and splicer will provide native MPEG-2 and MPEG-4 in the same device. Previously it was able to handle MPEG-4 only.