Opinion: HDC Surround Will Drive HD Radio

Coding Technologies, Philips, Fraunhofer and Agere Collaborate on MPEG Standard for Parametric Surround
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Coding Technologies, Philips, Fraunhofer and Agere Collaborate on MPEG Standard for Parametric Surround

This is one in a series of commentaries from companies adapting their surround sound technology to radio. Frerichs is vice president and U.S. general manager of Coding Technologies, which has teamed with Orban/CRL on a 5.1 surround sound system.

"Digital radio is coming to the United States, but will the consumer care?"

This phrase is fixed in the minds and sometimes on the lips of many station owners, radio manufacturers and others in the industry.

In the AM world, HD Radio provides such a clear quality advantage that the answer is a resounding "yes." Not tied to the tiny world of standard AM and not bound by the lack of adoption for AM stereo, HD Radio transforms AM stations into a high-quality conduit for all sorts of programming that was previously limited to FM.

But what about FM HD Radio? The touted differentiator, quality, isn't as easy to notice here.

Coding Technologies is the brains behind the superior performance of Ibiquity Digital's HDC codec used in its HD Radio technology, and there definitely is a real difference. However, most consumers would be hard pressed to hear it as they drive to work in the morning.

If HD Radio is to succeed on FM, it needs to have a hook. That hook is the same as the one that will drive AM HD Radio: unique content.

Distinctive content possible

Unique content can take multiple forms. Telematics data services have gained much attention, but this is a new business concept that will take stations a while to master.

Just notice how, even today, few stations put artist and title information into the RDS channel, and that should be a relative no-brainer. The unique content that will drive HD Radio will come in the form of distinctive audio programming.

So-called "Tomorrow Radio" style multiple program broadcasting for HD Radio is compelling. In this system, HD Radio signals can be subdivided into multiple audio programs.

Since HD Radio has 96 kbps of bandwidth on FM, and the HDC codec can maintain a high quality of performance even as the bit rate drops (note the AM capability), a single HD Radio broadcast easily can contain two or more audio programs. These extra channels would be sent in the Supplemental Audio Program, opening the door to niche markets that could otherwise not be effectively reached via radio broadcast.

However, to prevent monopolization of the airwaves and to prevent a repeat of the "same-old, same-old" from being sent over the HD Radio SAP channels, the FCC is taking time to craft regulation for this type of broadcast. This delay leaves a gap that urgently needs to be filled.

In comes surround sound to fill it.

Surround sound has captured the attention of consumers through the rise of DVD. As more DVD players are being installed in cars, surround sound in the car is becoming a check-box item.

Consumers want surround and will view it as a compelling reason to move to HD Radio, even before SAP content becomes available. There are a number of competing solutions vying to be the method for surround on HD Radio.

Any successful surround sound technology for HD Radio needs to have the following features: backward compatibility with existing radios, good for both single-program and multi-program stations and scalable from "pseudo surround" to true surround, impact on radio stations. It must also be built with industry collaboration. Only one solution, HDC Surround, fits all of these requirements.

HDC Surround from Coding Technologies is the combination of the existing HDC codec and the forthcoming MPEG Parametric Surround. The latter is an enabling technology that allows the encoding of multichannel audio based on the normally coded stereo signal with low additional bit rate. Instead of coding each channel discretely, MPEG Parametric Surround extracts information at encode time on the difference between the stereo mix and the 5.1 channel signal.

This extra information is sent along with the encoded stereo to be interpreted by the decoder. The more bits that are allocated to the Parametric Surround, the more accurate is the end result to the original 5.1 mix. This technique reduces the 5.1 channel overhead from 150 percent to 15 percent.

First demonstrated through a collaboration of Coding Technologies and Orban at the NAB Radio Show this fall, HDC Surround can achieve a single-stream 5.1 surround sound broadcast in a single HD Radio Main Audio Program.

When heard on an existing stereo-only HD Radio, the stereo sounds great. When heard in full HDC Surround, the results are incredible. While no commercial radios with HDC Surround are available today, this demonstration shows that technology is not the barrier to adoption of HDC Surround.

Upgrade, not throw out

The demo at the NAB Radio Show used an 80 kbps stereo core with 16 kbps of surround for a true surround experience. But the surround information in HDC Surround can be scaled up as high as 24 kbps or as low as 1kbps. This low-bit-rate capability means that stations today can start with full surround on a single program and retain the pseudo-surround effects similar to the other solutions if they move to multiple program broadcasts.

Coding Technologies is working with Orban to ensure that HDC Surround systems can be deployed into today's digital radio stations without requiring a complete overhaul. The last thing stations want to do is throw out all their existing equipment just to upgrade to 5.1 audio.

This reality has been the primary driver of pseudo-surround technologies like matrix audio and watermark audio. While admittedly easier to deploy, their results are not the best and cannot scale up to provide a true surround experience.

Due to the stereo-mixdown nature of HDC Surround, stations can be HDC Surround-enabled through additions to the existing stereo chain, not a replacement of the entire system. In the end, stations and equipment manufacturers need to decide whether they want the quick fix of a solution limited to matrix and watermark, or a long-lasting solution like HDC Surround which can also leverage the digital nature of HD Radio for maximum benefit.

Since the NAB Radio Show, MPEG has moved forward on the standardization of Parametric Surround. Where there were once two competing solutions, Coding Technologies and Philips have committed to work together with Fraunhofer and Agere to create a single MPEG standard for Parametric Surround.

Instead of keeping their solutions proprietary, the best minds in audio coding are cooperating to ensure that the performance and flexibility of MPEG Parametric Surround are unmatched. When this technology is added to the power of HDC already in HD Radio, the resulting HDC Surround is a future-proof solution that provides maximum benefit to broadcasters and consumers.

Reach the author via e-mail to info@codingtechnologies.com.

RW welcomes other points of view to radioworld@imaspub.com.

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