Using FPGAs to make affordable, high-quality entertainment a reality
Affordable, high-quality entertainment seems like an oxymoron. As HD video and audio become more prevalent, the professional media industry is grappling with ways to deliver the sharp-as-life images and crystal-clear sound that consumer's demand - without breaking the bank.
Multimedia demands added functionality
Traditional media processing architectures are based on multiple DSPs and a time-slice bus model, resulting in inefficient resource usage, large form factors, and higher associated costs. Replicating true analog performance forces digital audio and video equipment makers to confront the resource limitations of DSP processors. To provide the desired functionality, such as recording, editing and mixing for hundreds of audio channels, color-grading for uncompressed HD video, or processing Super HD and emerging 3D audio standards, cards that host multiple DSPs and each cost hundreds of dollars must be continually added to the design. A typical video processing block diagram is shown in Figure 1.
Traditionally based on microprocessors, DSP devices typically process computationally intensive algorithm blocks. Multiple DSP devices are generally needed to accommodate all the functions required in a given design . For designers, this creates a more complex design requiring a sizeable footprint, greater power consumption management, and a long development cycle.
FPGAs achieve logical resource usage, lower power
By contrast, a single FPGA, with its hardware- and software-level reprogrammability and massive parallel processing capabilities, can deliver a vastly superior price-performance ratio compared to DSPs for the algorithms commonly used in media processing.
Owing to parallel processing options not available in DSP processors, DSP algorithms running on FPGAs can perform much faster than when running on DSPs. As for the budget impact, FPGAs can deliver cost improvements of 10-100x over DSPs in signal processing applications.
Using an FPGA, a design engineer can place blocks of math processing, memory registers, and communications paths wherever they are most effective without structural restrictions. In addition, an FPGA can be programmed to include many of the standard parts in a computer system, including memory, processing engines, communication pathways, I/O voltage level controls, and switching logic. By keeping many functions on the device instead of in peripheral hardware and placing these functions at the most efficient location in the logic flow, the engineer can achieve a smaller, faster system that generates less heat. What's more, the engineer also can gain a simpler design process, reduced costs, and better productivity, yielding faster time to market (see Figure 2).
Reprogrammability results in reusable design
Replacing dozens of DSPs with a single FPGA allows media equipment designers to create larger, more sophisticated audio/video systems that provide performance excellence at low cost. To achieve these substantial performance gains offered by FPGAs and dramatically reduce hardware complexity, an Australia-based media creation tools developer and manufacturer created a media technology platform for an array of real-time audio and video processing products.
The CC-1 engine (Figure 3) from Fairlight Ltd. relies on an architecture comprising a single Altera Stratix FPGA-based PCI Express card that fits into a host PC. FPGAs provide hardware-coded DSP blocks that deliver dedicated processing power for common DSP functions, such as Finite Impulse Response (FIR) filtering and Fast Fourier Transform (FFT) processing. As a result, the FPGA-based card provides the processing power equivalent to eight boards of Fairlight's previous media processing engine, in which each board has eight individual floating-point DSPs.
Using a single FPGA to do the work of 64 DSPs, they also achieved significant power savings; the card consumes only 12 W total, compared to 600 W for the equivalent DSP processor-based system. The size benefit of the FPGA-based implementation is correspondingly dramatic, going from eight boards in the older system to a single PCI Express board with the new engine, which also increases overall product reliability.
Finally, by leveraging the greater integration and a comprehensive FPGA development tool, the CC-1 product was completed in one-third the time it would have taken to complete an architecture based on DSPs.
This type of media technology platform can be integrated into a variety of systems, from low-cost recording and editing platforms to large format consoles with integrated HD video, thus demonstrating the adaptability FPGAs provide through reprogrammability. On the audio side, the technology results in more than 200 channels of recording, editing, mixing, I/O, and plug-ins, with extremely low latency and full processing capability on each channel. The platform can be deployed for sound design, redeployed as an HD video color grader, and then repurposed again for music recording. On the video side, a single chip can play back and color-grade a full, uncompressed HD stream.
In contrast to the fixed bit width of DSPs, FPGAs offer the hardware flexibility to simultaneously run multiple processes at different bit widths. Using this capability, a feature such as Dynamic Resolution Optimization (DRO) allows audio engineers to choose the best precision for processing each system task.
Older DSP-based systems perform all processes at a single precision and cannot be changed. With DRO, equalization processing can be performed at 72-bit floating-point precision, while mixing is performed with 36-bit floating-point precision and metering functions at 16-bit fixed-point resolution. The FPGA-based implementation enables higher-precision processing where it is required and lower precision in other areas where it is adequate. Traditional DSP-based systems must maintain the highest precision required from end to end using either fixed-point or floating-point paradigms, but not both. From this perspective, the FPGA-based approach provides greater performance at a lower system cost.
Taking entertainment to greater heights
In the highly competitive professional media industry, FPGA technology answers the call for high-quality, cost-effective video and audio streaming. Flexible FPGAs help media equipment designers stay ahead of their competitors, keep pace with evolving market requirements, and satisfy their customers' expectations for affordable, high-quality entertainment.
Martin Won is a senior technical staff member at Altera Corporation, where he joined in August 1990 as an applications engineer, specializing in customer applications for programmable logic devices. Having held various positions in the company, he founded Altera's customer training program and managed several other technical and marketing programs. Martin holds a BSEE from the University of California at Santa Barbara.