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Flexible video encoder tailored for use with PCs

Posted: 19 Aug 2002 ?? ?Print Version ?Bookmark and Share

Keywords:video compression chip? wis technologies? video encoder? videoconferencing?

WIS Technologies is rolling out a video compression chip with an architecture that is "as cost-effective as an ASIC but as flexible as a media processor," said Jack He Ouyang, chairman and CTO at the 25-person San Jose, California, startup.

Tailored for the PC market, the chip, together with company-developed software, is designed for high-quality videoconferencing and video e-mail applications. WIS' goal is to keep the chip flexible enough to interoperate with a host of current and new ISO/ITU video specs.

The GO7007 takes video input from a PC video camera, digital video camcorder, video capture device or analog source and compresses it in real-time into WIS Technologies' proprietary intermediate video stream, called the Go Stream format. With the assistance of an external processor such as a PC's host CPU, the Go Stream format can be translated into almost any standard video format, including MPEG-1, 2, and 4, H.261 and H.263. As a result, the GO7007 delivers streaming video up to NTSC/PAL resolutions at a full frame rate over the Web and emerging broadband networks, according to the company.

WIS Technologies' engineering team made a conscious design decision to have its chip do only common encoding tasks, such as discrete cosine transform (DCT) and inverse DCT, motion estimation, quantization and dequantization--jobs Ouyang called "often very taxing to a host CPU." All format translations are left to the software, allowing "developers and users to choose whatever format they like," he said.

By running WIS' decoding/ transcoding, postprocessing and videoconferencing software on a PC's host processor, users can produce a high-quality video stream in any available video format, the company said. The GO7007 can produce a compressed video stream in the Go Stream format at a scalable bit rate ranging from 20Kbps to 8Mbps, Ouyang said.

The video output formats enabled by the GO7007 and its associated software on a PC include DivX, H.263, H.261, MPEG-4 Advanced Simple Profile@L3 plus Fine Granularity Scalability, MPEG-2 Main Profile@Main Level, MPEG-1 and user-defined formats.

Block interconnect

The chip integrates a glueless logic interface to CMOS image sensors, SDRAM and USB controllers as well as I2C and HPI interfaces. It uses WIS Technologies' homegrown 16bit RISC processor core for scheduling and housekeeping tasks. The core and a number of hardware blocks - such as a motion-estimation and compensation engine, quantizer/dequantizer and variable-length coding encoder - are interconnected over a common bus on the ASIC.

IC vendors designing video compression chips face the challenge of keeping pace with the new standards proliferating on the market. "Tiny changes in a standard could completely destroy your video chip and make it useless," observed Ouyang.

Describing the GO7007 as a middle ground between a fully programmable media processor and a dedicated ASIC, Ouyang said it differs from other hybrid solutions in that "we've made sure that our architecture is superflexible, and we took advantage of our software engineering talent to offer a number of associated software packages, such as a real-time decoder in all the different video standards that can run on Windows, Linux and Mac" OSs.

Ouyang said the GO7007 is not for consumer systems such as personal video recorders or DVD recorders, but is specifically designed for the PC. "This will make PCs much more interesting," he said. Without a real-time, high-quality encoder, users have had a very limited multimedia experience on PCs even though many can now take advantage of broadband access, he said.

TSMC did the chip's layout and fabricates the GO7007 using its 0.185m CMOS process technology. The device will go into production by the end of next month.

When samples arrived in early June, Ouyang said, the chips "compressed live video within a few hours after we received them." So far, he said, "we have not found any bugs in them."

- Junko Yoshida

EE Times

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