Media processors boost imaging-board performance

Media processors boost imaging-board performance

Andrew Wilson

Compared with the market for digital video disks (DVDs), set-top boxes, and digital televisions (DTVs), the market for image-processing and machine-vision systems appears small. Because of this, semiconductor vendors have been reluctant to build devices specifically for the image-processing market, choosing instead to target the more lucrative digital television market. With projected volumes in the millions for digital "multimedia" engines, semiconductor vendors are looking to produce powerful, integrated, very-long-instruction-word (VLIW) microprocessors for gaming, digital television, and MPEG-2 encoding/decoding applications.

"Despite the collapse of competing efforts from Chromatic Research (Sunnyvale, CA) and Samsung Semiconductor (San Jose, CA)," writes Peter Glaskowsky in The Microprocessor Report (Sebastopol, CA; Oct. 26, 1998), "processors such as the TriMedia from Philips (Eindhoven, The Netherlands) will face stiff competition from the Project X (Nuon) media processor from VM Labs (Mountain View, CA) and the MAP 1000 from Equator Technologies (Campbell, CA)."

Already in production, the TM-1000 Trimedia device from Philips is the first in what the company plans as a series of seven parts that target digital-video applications. The TM-1000 is a general-purpose microprocessor designed for real-time video, audio, communications, and graphics applications.

"In choosing the TriMedia processor for our next generation of PCI-based image-processing boards," says Joseph Sgro, chief executive officer and director of research and development for Alacron (Nashua, NH), "we saw benefits in choosing a device that would be shipped in volume by a company (Philips) whose roadmap we could believe." In addition to the TriMedia processor`s pricing, VLIW architecture, on-chip DMA controller, and performance, its on-chip logic "glue" circuits also helped to convince Sgro. "On many image-processing-board designs," he says, "glue logic consumes real-estate and adds cost to the finished product."

Because the TriMedia processor was designed as an integrated digital-television chip, all the glue logic was already included on-chip. This approach allowed Alacron to produce an image-processing board that provided four TriMedia processors, analog and digital image inputs, and VGA and NTSC outputs on a single PCI-based add-in board for about $5000 in single quantities.

The board design also allows developers to program each processor in either parallel or cascade fashion and link the processors using a crossbar switch from I-Cube (Campbell, CA). "Because of this switch," says Paul Stanton, director of engineering at Alacron, "a PCI board with a four-processor configuration is theoretically capable of performing a 1-k complex FFT in 25 ms. However, the board also can be supplied with two additional PMC mezzanine cards, each of which could hold an additional four TriMedia processors. Therefore, the maximum number of processors that can be added to the board is 12. "This total," according to Stanton, "would dramatically reduce the time taken to perform a 1-k complex FFT."

To target the board directly at the image-processing market, Alacron has added three analog, 8-bit, 40-MHz asynchronous inputs and an additional broadcast-compatible composite. Moreover, the board is capable of interfacing to digital cameras over a low-voltage differential signaling interface that can support as many as four 8-bit, asynchronous cameras at 40 MHz. This interface is also provided on the output of the board through the I-Cube crossbar switch. For image display, Alacron`s TriMedia-based board can furnish 1280 ¥ 1024 images at 72-Hz noninterlaced and an NTSC output.

By using a multimedia processor in its design, Alacron has taken a step forward in increasing the performance of its PCI image-processor board. Consequently, other image-processor-board suppliers are expected to abandon more-formal DSP designs and instead harness the power of multimedia chips such as the TriMedia, Nuon, and MAP 1000 processors.