DisplayPort: The Apple-Initiated Slow Start

To Apple’s credit, the company has a long history of leading the industry charge towards new computing standards and trends. Off the top of my head, the list includes (what else have I forgotten, folks?):

• Discarding the built-in floppy drive
• Incorporating FireWire (i.e. IEEE 1394)
• Incorporating USB v1, and later USB v2
• Rolling out both dedicated routers/access points and integrated computer support for successive Wi-Fi generations; 802.11b, 802.11g and 802.11n, and
• Embracing the OpenCL general-purpose GPU API, in upcoming OS 10.6 ‘Snow Leopard’

But Apple also has a history of tweaking industry standards in a semi-proprietary fashion. Consider, for example, the ADC (Apple Display Connector). It leveraged the same TMDS signaling scheme found in DVI and, later, HDMI. However, as the Wikipedia entry notes:

The Apple Display Connector (ADC) is a proprietary modification of the DVI connector that combines analog and digital video signals, USB, and power all in one cable.

Granted, the ADC scheme was pretty slick. If I hadn’t been able to fix the power button on my G4 Cube a few months back, for example, I could have disabled it and instead turned on/shut off the Cube via an ADC-tethered display’s power button. And ADC was a convenient one-cable means of adding more USB ports to a system via the connected display. But Apple abandoned ADC from both display and system standpoints within five years; fortunately ADC-to-DVI and ADC-to-VGA adapters enable legacy Macs to work with newer LCDs.

And Apple seems to be going this route withVESA’s DisplayPort, a digital display competitor to HDMI that I’ve written about at length before and most recently mentioned in yesterday’s editorial. Apple chose a space-optimized variant of the standard DisplayPort connector for its 13" MacBook and MacBook Air and 15" MacBook Pro, all introduced mid-last October. Mini DisplayPort more recently spread to the 17" MacBook Pro in January.

Mini DisplayPort, at the time that Apple first unveiled it, was a company-proprietary implementation of the industry standard. In late November of last year, Apple attempted to spur broader adoption by offering free licenses of the Mini DisplayPort specification, and in mid-January, VESA announced that Mini DisplayPort would be incorporated in (not-yet completed) v1.2 of the official DisplayPort specification.

Apple’s premature embrace of Mini DisplayPort has caused numerous notable headaches for early adopters. For one thing, Apple’s (perhaps not surprisingly) the only vendor currently selling Mini DisplayPort-inclusive LCDs (and in only a single 24" flavor); at least one other company has (repeatedly) announced similar products, but to the best of my knowledge they’re not yet shipping. And suggestive of the dearth of conventional DisplayPort-based LCDs, Apple doesn’t even sell a Mini DisplayPort-to-DisplayPort adapter.

Again to the best of my knowledge, and indicative of the lack of a sufficient DisplayPort-based system installed base, the few DisplayPort-inclusive LCDs sold by display manufacturers are also outfitted with more conventional interfaces such as VGA, DVI and HDMI. So it is that Apple sells Mini DisplayPort-to-VGA, -DVI and -Dual-Link DVI dongles. Unfortunately, Apple’s tech support forums are filled with customer complaints about egregious image distortion using these translation adapters, which multiple firmware updates released by the company have failed to completely squash.

Apple’s adapters are, perhaps not surprisingly, expensive…and a variant that converts directly from Mini DisplayPort to HDMI is also not offered by the company. Fortunately, third parties have stepped in to fill the breach. Monoprice’s $14 unit encompasses HDCP encryption support. And the $40 adapter from Kanex merges the digital signals from a system’s Mini DisplayPort and USB connectors, outputting not only audio-plus-video over HDMI but also analog audio and (acting as a hub) two USB2 interfaces. You might ask why Kanex’s unit’s USB-based audio support is even necessary, since the DisplayPort specification encompasses merged audio-plus-video transfer capabilities.

The answer lies in the unfortunate fact that current Mini DisplayPort-inclusive hardware from Apple outputs only images over the embryonic digital interface, not also sound. I confess that I’m somewhat underwhelmed by Kanex’s workaround, since from what I can decipher the audio support seems to be only of the two-channel variety (thereby, for example, not allowing for surround audio transmission to a HDMI-based A/V receiver). But it’s better than nothing, I guess, And if your sound system solely consists of the two tiny speakers built into your LCD, it’s good enough.