Two incompatible schemes, one from Genesis Microchip Inc. and another from Silicon Image Inc., were first outlined at the DisplaySearch FPD Conference & High Resolution Symposium held here last week, and were then aired again at the Intel roundtable on Friday. Two other proposals, one by Intel and one from Matsushita, Sony, Toshiba and Hitachi were also scheduled for the Intel session. Details of the latter two schemes were not immediately available.

DVI, an open industry spec of the Digital Display Working Group, seeks to define high-performance interfacing solutions for high-resolution digital displays.

The convergence of PC and consumer electronics — "blurring the line between displays for text/graphics and entertainment video" — is driving the need for DVI to support an audio capability, said Anders Frisk, executive vice president of marketing at Genesis Microchip (Mountain View, Calif.). "PC displays will be used for video as well as graphics," he said. "And TV displays will be used for graphics as well as video."

Equipping DVI for consumer electronics will also require color space conversion from the RGB scheme used in PCs to the YUV scheme of consumer displays, Frisk said, plus a smaller connector and protection of audio content in the context of "complete backward compatibility with DVI 1.0."

The Genesis scheme, dubbed DVI CE and co-developed with Texas Instruments Inc. and Broadcom Corp., uses time-domain audio multiplexing. It sends audio information over a DVI cable during the blanking period when a video stream is inactive. The technique "keeps proven DVI analog blocks unchanged," said Frisk, and it's "backward-compatible with existing DVI transmitters and receivers." In addition, Intel's high-bandwidth digital content protection standard (HDCP 1.0) was said to work with the scheme to cover audio content, "with absolutely no change required," and DVI CE supports "all current digital audio formats . . . with ample headroom for future multichannel formats."

On the edge

Silicon Image (Sunnyvale, Calif.) has a completely different scheme. Mike Kelley, vice president of marketing and business development, said the company's PanelLink A/V methodology packs audio into the falling edge of clock signals. "That keeps it simple and ensures that we don't put artificial limitations on what we might want to do with video," he said.

"Using the horizontal or vertical blanking period breaks compatibility as Genesis proposes, limits bandwidth and requires buffering and complex software support," Kelley said. It would also "limit future enhancements for the video portion of DVI," he said. Silicon Image expects to be sampling new chips with its audio enhancement in the third quarter.

Frisk declined to comment further on the potential controversy, saying only, "Avoiding a DVI market split is critical."

The Digital Display Working Group includes Compaq, Fujitsu, Hewlett-Packard, IBM, Intel, NEC and Silicon Image.