Multimedia devices or systems can range from a very basic consumer audio video player to a highly complex audio video capture, edit, and playback system used in a professional studio environment. Different types of technology have been applied to implement this wide range of applications; this includes application specific standard products (ASSPs), dedicated digital signal processors (DSPs), RISC processors and programmable logic. Each one of these technologies offers unique advantages as well as limitations. Programmable logic has the benefit of being a highly scalable and reconfigurable technology that can be applied to multimedia signal processing. The typical building blocks are multipliers, memories, protocol interfaces, and clock circuits such as PLLs. These blocks are scalable and can be designed to accommodate a small to a complex system of multimedia processing.
Video and embedded DSP blocks
Consumer demand for innovation, such as 1080p high-definition television (HDTV), multimedia home networking gateways, and bandwidth efficient set top box decoders continue to drive the rapid evolution of video and image processing applications. Low-cost FPGAs such as the Cyclone III family provide the benefits of DSP performance, flexibility, and faster time-to-market, all at application specific integrated circuit (ASIC) prices. The lowest cost member of the family, the EP3C5 device, has enough embedded multiplier and logic resources to perform real-time 7x7 pixel filtering on HDTV 1080p video. For higher end products, the DSP blocks contained in Stratix III FPGAs provide over 600 MHz performance for 18 x 18 multipliers. The Stratix III DSP block also supports variable bit-widths with the 9X9, 36X36, and the new 12x12 mode. The DSP block provides two 9X9 or one and a half 12X12 multipliers for each 18X18 multiplier. The cascade modes feed the input of one DSP block to the next for superior overall performance as shown in Figure 1. Logic and memory fabric of the Stratix III FPGA are also optimized for DSP applications, with the MLAB for tapped delay lines and the fast 3-input adders in the ALM for efficient and fast adder trees.
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Figure 1: Stratix III DSP Blocks in Cascaded Mode
With major advancements in image capture and display resolutions, advanced compression techniques, and video intelligence, the processing bandwidth required for video applications continues to grow. Also, rapid change in standards and higher resolutions are pushing designers away from off-the-shelf technology. Programmable logic continues to address these trends with modular, programmable video, and image processing solutions that offer high performance, flexibility, upgrade ease, low development cost, and a migration path to lower cost when applications mature and volume production ramps.
Embedded digital signal processing (DSP) intellectual property (IP) inside the FPGA can serve as either a stand-alone system solution or together with a standard digital signal processor utilized as a coprocessor. The main advantage of using FPGAs as compared to using a standard digital signal processor is that FPGAs have a built-in high level of parallel processing as shown in Figure 2. Dedicated RISC processors cannot meet all the processing requirements of many video and imaging applications.
Figure 2: A Comparison of Parallel Processing between DSPs vs. FPGAs
Next: Price-to-performance ratio, embedded memory