Download: Surround and conquer: Digital audio technology

Surround and conquer: Digital audio technology

By Craig Birkmaier

The ability to represent information using the binary code of ones and zeros was well established before the development of modern computers. But the practical use of these binary codes did not begin to transform the world until the invention of the transistor, followed by the rapid evolution of solid-state processing devices. The microprocessor led to a rapid succession of transitions affecting all forms of media — print, still imaging, audio, and now video and motion pictures.

Figure 1. The marriage of surround sound audio and DVD technologies in home theater systems has led to a dramatic increase in consumer purchases over the past three years. Source: NPDTechworld, May 2002.

Equally important, the digitization of traditional analog media has enabled the development of new forms of media that combine all of these building blocks in new and innovative ways. That we now go to the Internet to search for news or the MP3 of a pop music hit is testament to the speed with which the digital transition has swept around the world. Audio — with the exception of radio broadcasting — has been at the forefront of this transition. Audio's move to digital is all but complete, having begun with the introduction of the audio CD in 1983, followed by the “desktop audio” revolution in the late '80s and the Internet audio revolution, fueled by MP3 audio compression.

Digital audio technology

Today, surround sound audio systems are an integral part of the home theater experience. Consumers are expecting more of their home theater systems as digital technology offers better picture quality and better audio. According to a new CEA report, home theater is driving component audio system design. Digital 5.1 channel surround sound, either Dolby Digital or DTS, is a standard feature in receivers priced as low as $199. In 1999, the first preamp/processors compatible with 6.1 channel DVD soundtracks appeared. In 2000, the first 6.1 channel-compatible A/V receivers appeared.

DVD is the key to delivery of 5.1 channel sound and higher quality images for Digital TV monitors equipped with analog component video inputs. The popularity of the DVD is having a tremendous impact on sales of home theater components, according to the latest sales figures released by NPDTechworld (see Figure 1). Sales of home theater systems with DVD increased 230 percent in 2001 vs. 2000, and more than 987 percent during the first five months of 2002 when compared with the same period in 2001.

Dolby Labs reports that they have licensed more than 17 million 5.1 channel Dolby Digital decoders for use in home receivers and decoders, and just over one-half million 5.1 channel Dolby Digital decoders for DBS set-top boxes and integrated Digital TV receivers. These numbers are dwarfed by the number of DVD players (64 million) and DVD-ROM drives (103 million) that include Dolby Digital decoders (numbers current as of July 6, 2002).

Factory-level sales of Home Theater in a Box (HTiB) systems grew 124 percent in 2001 to $794 million, almost 60 percent of the size of the component-audio market. In 2001, DVD-equipped models accounted for 52 percent of the 2.3 million HTiBs shipped by manufacturers to dealers and 62 percent of HTiB dollar volume of $794 million.

The CEA reports that home theater is a major factor in the development of component audio systems. This elaborate system in St. Louis features an Onkyo 7.1 surround receiver and PSB speakers. Photo by Michael Marxer.

These systems take many forms. They traditionally consist of a full-size component A/V receiver, five satellite speakers, usually a powered subwoofer and sometimes a component-size DVD/video player. Another type integrates the receiver and DVD player into a single standard-size component. A third type moves all amplification and most electronics into the enclosure that houses the powered subwoofer, allowing for a main unit that takes up little space.

Audio and television

Radio, television and motion pictures are at the tail end of the digital transition — partly because video is among the most demanding applications with respect to processing requirements and distribution bandwidth.

Television broadcasters could learn a great deal by studying audio's transition to digital, and just how important audio is to their transition to digital.

DVD and surround sound audio systems are a major factor in the sale of Digital TV monitors, a.k.a. HDTV. The CEA reports that 1.4 million Digital TV products were sold in 2001 and that sales are increasing this year. Given the numbers for DVD systems and HTiBs, it's a safe bet that most of these big-screen TVs are going into home theater systems.

DVD is setting consumer expectation levels for what they expect to hear when watching an HDTV program. Unfortunately, broadcasters apparently have not heard the message. Of the major broadcast networks, only ABC has been producing programming with 5.1 channel audio.

Most broadcast facilities are not equipped to handle 5.1 channel sound, and many digital video recorders cannot accommodate six digital audio tracks. To help broadcasters, Dolby Labs has created a family of products that allow 5.1 channel sound to be carried via an existing two-channel digital distribution infrastructure.

Dolby E enables up to eight audio channels plus accompanying metadata to be passed via regular routers and satellite links, and stored on video servers and digital videotape recorders. The Dolby E output bit stream looks like two-channel AES/EBU digital audio, enabling distribution of multichannel audio via either a single AES3 pair or by recording it on two audio tracks of digital videotape.

Changing business models

Digital technology is shifting control to the consumer. Consumers want control over the consumption of information and entertainment in their homes. They don't want to be told to sit down at 8 p.m. Tuesday to watch a TV show. The personal video recorder threatens to change forever the way television content is consumed.

Some broadcasters and content production organizations view digital products like the PVR as a major threat, in much the same way that Hollywood viewed the VCR as a threat in the early '80s. But those who learn how to use these technologies to their advantage are likely to be the survivors, maybe even the beneficiaries, of the new business models being shaped by digital. Unfortunately, to date, broadcasters have treated the DTV transition as a burden rather than the opportunity it represents to regain a competitive advantage in an increasingly crowded marketplace.

Craig Birkmaier is a technology consultant at Pcube Labs, and hosts and moderates the Open DTV Forum.

Web Links

Digital America 2002, the U.S. Consumer Electronics Industry Today

Dolby Product Guide: Equipping for Surround Sound


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