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MPEG AND DSP INTEGRATION

by Priyesh Surati & David Austin

Start ý MPEG Audio Encoding and Decoding ý Encoder Technology ý Decoder Technology ý Affect on the Music Industry ý Current Uses ý Sources and PDF

A final-year team project in an electrical engineering program can be both fun and frustrating. Fun because you and your team get a chance to work on something major of your choosing. The frustration is par for the course but good training for the experiences found in many projects, whether within the university or the real world. There are time constraints conflicting with unfulfilled expectations from yourself, your teammates, and your project manager.

For our project, we decided to learn enough about the MPEG protocol and DSP processors to demonstrate the concepts of MPEG decoding running on an Analog Devicesý SHARC 21061 evaluation board. The project naturally broke off into a number of parts. One component adds additional memory to the SHARC board, and another component finds a suitable algorithm and ports it to the SHARC board. We tackled these components with the help of our teammates, Matthew Mastracci and Luigi Iuliano, and our faculty advisor, Dr. Mike Smith.

The first step was to understand something about MPEG itself. The five of us had heard of it, had used it, but what was it? This article is the result of our background research into MPEG. It will cover MPEG history, current uses, future perspectives, and MP3ýs affect on industry.

STARTING AT THE BEGINNING

The Motion Picture Experts Group (MPEG) audio compression algorithm is an International Organization for Standardization (ISO) standard for high-fidelity audio compression. [1] The MPEG standard is a high-complexity, high-compression, and high-audio-quality algorithm. [2] Digital compression allows more efficient storage and transmission of data, and the many forms of compression offer a range of encoder and decoder complexity.

Already, the MPEG standard has gone through a number of stages. These are illustrated in the timeline shown in Figure 1.

Figure 1ýA timeline showing the various MPEG standards dating from 1992 to the present and possible future standards.

When MPEG began its work to develop a standard for digital compression, its goal was to develop an algorithm that could compress a video signal and then be able to play it back off a CD-ROM or over telephone lines at a low bit rate. The intention of the group was to achieve a quality level that could deliver full-motion full-screen VHS quality from a variety of sources.

This initial standard was not broadcast quality, but it was good enough to display on a computer monitor or to playback from a consumer multimedia device. Because of the need for increased compression and better quality, a new standard was needed that would suit the purposes of the broadcast industry. MPEG started a second effort that is known as MPEG-2.

Along with the development of MPEG-2, work began on the MPEG-3 standard, which was directed towards the market of High-Definition Television (HDTV). MPEG-3 targeted HDTV applications with sampling dimensions up to 1920 ý 1080 ý 30 Hz and coded bit rates between 20 and 40 Mbps. However, research established that, after finding an optimal balance between sample rate and coded bit rate, MPEG-2 and MPEG-1 syntax could work well together for HDTV rate video. MPEG-3 no longer exists because HDTV became part of the MPEG-2 standard.

The development of MPEG-4 began in September of 1993 in Brussels, Belgium. This standard targeted low bit rate coding of audio-visual programs and required the development of fundamentally new algorithmic techniques. The sampling dimensions were up to 174 ý 144 ý 10 Hz with coded bit rates between 4800 and 64,000 Mbps. The MPEG-4 standard enables many new applications including interactive mobile multimedia communications, videophones, mobile audio-visual communication, remote sensing, interactive multimedia databases, games, interactive computer imagery, and sign language captioning.

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