Multimedia processors

Abstract

This paper describes recent large-scale-integration programmable processors designed for multimedia processing such as real-time compression and decompression of audio and video as well as the generation of computer graphics. As the target of these processors is to handle audio and video in real time, the processing capability must be increased tenfold compared to that of conventional microprocessors, which were designed to handle mainly texts, figures, tables, and photographs. To clarify the advantages of a high-speed multimedia processing capability, we define these chips as multimedia processors. Recent general-purpose microprocessors for workstations and personal computers (PC's) use special built-in hardware for multimedia processing, so the multimedia processors described in this paper include these modified general-purpose microprocessors. After briefly reviewing the history of programmable processors, we classify multimedia processors into five categories depending on their basic architecture. The categories are reduced instruction set computer (RISC) microprocessors for workstations, complex instruction set computer microprocessors for PC's, embedded RISC's, low-power digital signal processors (DSP's), which are mainly used for mobile communications devices, and media processors that support PC's for multimedia applications. These five classes are then grouped into two: microprocessors with a multimedia instruction set and highly parallel DSP's. An architectural comparison between these two groups on the basis of Moving Picture Experts Group decoding applications is made, and the advantages and disadvantages of each class are clarified. Future processors, including "system on a chip," and their applications are also discussed.

Predictive line search: an efficient motion estimation algorithm for MPEG-4 encoding systems on multimedia processors

“…There are three main features of multimedia processors [2], [10], [11] that may impact the performance of motion estimation. They are: 1) wider data path compared with general purpose processors; 2) subword parallel architecture (SWP) to deal with multiple pixels simultaneously; and 3) special instructions for SAD calculation.…”

“…In order to support these complex functionalities, the video-coding system must be built on a platform that is both flexible enough for various tools and powerful enough to achieve real-time requirements. Therefore, multimedia processors [2] are the natural choice to implement such a real-time video-coding system because they combine the flexibility of programmable processors and the processing power of parallel architectures.…”

On the Scalability of 1- and 2-Dimensional SIMD Extensions for Multimedia Applications

“…In this way DSPs manufacturers are including SIMD extensions to their base architectures. VLIWs DSPs like Analog Devices Tiger Sharc, Motorola and Lucent's StarCore and Texas Instruments TMS320C6xx and superscalar-based DSPs like TriCore also include SIMD capabilities [3].…”

A Versatile Computation Module for Adaptable Multimedia Processors

“…Two PEs are grouped together to perform a 16-bit multiplication, with each PE calculating an 8-bit partical product. A 16-bit multiplication is executed as in (2). However, the connect network and the SIMD adder in the second stage are used to shift and align the partial products and add them together.…”

“…Multimedia applications usually involves large amount of data, require high data rate, real-time processing. Although the amount of data and computation throughput varies over a wide range depending on the required quality of the applications, multimedia data processing has the following characteristics: The word lengths of the processing data are 8 bits, 16 bits or 24 bits, which requires frequent use of small integer operations; Arithmetic operations are highly computation-intensive and repetitive with data parallelism; Intensive memory access to a large memory space requires high bandwidth memory interface [2].…”