Standards, architectures strive for 'flow'

Standards, architectures strive for 'flow'
For the majority of consumers with varying broadband capabilities, the streaming-multimedia experience is still likely to be unpredictable, inconsistent and dissatisfying. Traditional network architecture is poorly adapted to the transmission of streaming media, which requires that all elements of the transmission be sent and received at the same time rate, unlike ordinary data, which is transmitted in packets. Network congestion, packet collision and packet loss cause serious degradation in picture and sound quality.

Interoperability is a key factor for success in this highly competitive market. Many believe that media delivery based upon open standards will enhance interoperability for transporting and viewing streaming media. Earlier this month, the Internet Streaming Media Alliance (ISMA) held its third forum meeting to finalize the details of the first implementation of such an open specification. Scheduled for release by year's end, it uses MPEG-4 as its compression standard for audio and video coding and refers to Internet Engineering Task Force protocols for media transport and session control.

In this week's Focus section, Sun Microsystems Inc.'s Viswanathan Swaminathan, the ISMA technical committee chair, explains the ISMA 1.0 implementation specification and describes how the two hierarchical profiles-0 for streaming to low-complexity devices, and 1 for streaming content over broadband-quality networks-will be put into practice.

De facto standards are coming into play with the success of solutions from Microsoft, RealNetworks and Apple. Although Apple Computer Inc. is a founding member and full participant in the ISMA, RealNetworks and Microsoft remain separate.

RealNetworks shares ISMA's goal of interoperability, said Ben Rotholtz, general manager of products and systems in the San Jose, Calif., company's Media Systems Division. But RealNetworks believes that standards need to be driven from the standards bodies themselves and not from a "layer above the standards body that's trying to rally the standards in a certain direction," Rotholtz said.

RealNetworks aims to accomplish interoperability by creating scenarios such as being able to take a piece of Quick Time content, put it on a Real System server and deliver it through a network of Real System IQ to a Quick Time player or Windows device.

Strategic alliances are also a prudent way to manage resources. RealNetworks has partnered with Texas Instruments Inc. to port Real Audio 8 and Real Video 8 with some of the digital media components running on a TI DSP program. (At the In Focus Web site, Vishal Markandey of TI explores the design considerations in tailoring DSPs for streaming multimedia; see site address below. )

Meanwhile, new chips are on the market to enable any content (analog, digital, DVD, camcorder, text, animation, audio) that's coming in on multiple types of networks (fiber optic, coax, DSL, twisted pair, satellite, wireless) to find the right interface for display. For example, Tvia Inc.'s (Santa Clara, Calif.) streaming-media gateway processors take up to three in-puts as well as output to multiple displays simultaneously.

This flexibility is achieved by integrating multiple media-processing engines on a single chip. According to Vahe Akay, vice president of marketing, "this is significant, because for set-top boxes and digital TVs with embedded Internet access capabilities to become a true mass consumer electronic product, they need to be agnostic to the network."

Choosing the right microprocessor for multimedia applications is critical. The considerations of memory, usage, price, speed, performance and transmission are further complicated as the number of streaming-audio and video codecs and standards increases. A standardized benchmark is an essential tool for determining an embedded processor. The Embedded Microprocessor Benchmark Consortium (EEMBC) has stepped up to meet this challenge with its Version 1.0 benchmark suite, containing 47 performance benchmarks for embedded-system processors.

Lore Devra Levin, director of corporate marketing at Trimedia Technologies Inc. (Milpitas, Calif.), and Renga Sundararajan, director software applications, provide a thorough examination of these tests. To address the coprocessor environments typical of the increasingly complex multimedia applications, EEMBC is working on its version 2.0 benchmark suite, scheduled to become available in late 2002.

Dianne Daniels is a contributor based in Peterborough, N.H.