The position of USB itself as the natural digital interface for cameras and cellphones could be under threat from HDMI, the standard interface for HDTVs, by resurrecting old claims that it could leap the gulf into mobile devices. The effort to bring HDMI to the mobile world is being led by Silicon Image, a founder of HDMI Licensing and a key patent holder. The company this week announced a dual-mode solution that supports HDMI and its proprietary, compact alternative, MHL. This product promises to reduce the bill of materials, power consumption and time to market for interfacing handsets to digital TVs.
The company is pushing its proprietary MHL (Mobile HD Link) interface as a smaller form factor option to HDMI. MHL promises to address an important concern of OEMs, the number of system-on-chip audio/video I/Os ‘ HDMI needs 19 but MHL can use as few as five. Silicon Image also hopes to create a dual-mode USB/MHL connector in future. However, the HDMI camp says the Type C profile of the standard also supports compact SoCs for handheld devices and a proprietary option should not be necessary, and Silicon Image’s main rival ADI, claims its HDMI transmitter chip combines PHY and MAC, and offers smaller chip size and lower power consumption than MHL. Also, for MHL mobile devices to connect to digital TVs, they will need a dongle that translates between MHL and HDMI, and this does not support the latest HDMI enhancement, Deep Color.
Whether Silicon Image succeeds in making HML a de facto standard, or whether HDMI vendors shrink down their technology to rival, or live alongside, USB in handheld devices, the standards picture is getting yet more complex. Also recognizing that PCs, mobile devices, TVs and in-car systems are becoming highly integrated with one another, and may require unified platforms, Sony is spearheading a new effort within the Consumer Electronics Association (CEA), which will hold a meeting this fall to decide whether to devise a new standard for portable systems and how they connect to TV, stereo and automotive products.
“The CE industry has clearly morphed beyond the traditional TV, stereo and car audio systems to a convergence of technologies, so it may be time for us to address these portable systems in a broad way,” said Dave Wilson, director of technology and standards for the CEA. The Association has tended to leave portable CE standards to other bodies apart from its Portable Digital Media Interface (PDMI), a 30-pin connector for media players that aims to be an alternative to Apple’s iPod interface. The CEA has a version of PDMI in the works that should support multiple protocols including USB 2.0, USB 3.0 and DisplayPort, and it has explored adding HDMI too.
“We’re trying to create an interface for portable devices such as media players and other systems to link to TVs, stereos and car audio products,” said Wilson. “If we could establish a connection for the digital world as ubiquitous as the RCA plug was for analog video it would be a great help to the industry.’ The CEA is particularly keen to get involved in order to push standards that do not carry high royalties or usage limitations, like proprietary systems like Apple’s.