HDMI and the Xbox 360

Continued from 'Blue-ray: More Black-eyes'….

All this talk of audio decoding reminds me that in the interests of balanced reporting, I also need to point out a shortcoming of the Xbox 360's HD DVD peripheral. It's a $200-or-less accessory for a $299-or-less console, so keep the fiscal angle in mind in what I'm about to say. But….

According to Microsoft's Kevin Collins, the Xbox 360's current revision of HD DVD software supports the native decode of all required HD DVD audio formats. However, as currently implemented the console only has one greater-than-two channel audio output option; S/PDIF. And it currently only supports one audio codec over that output: Dolby Digital.

Looking at the console's A/V connector, you'll notice only six unused pins. That's two pins shy of what would be needed to do a full six-channel analog audio output (the connector already supports right and left front audio channels). It's also not enough spare pins to implement a HDMI interface. I don't know if those pins are really 'unused' or if they're internally connected somewhere and awaiting a future upgrade to unlock their capabilities. But unless there are hooks in the console hardware for signal multiplexing, HDMI and/or six-channel audio are going to require a design revision.

After much verbal arm-wrestling, Collins (unfortunately) pretty much confirmed my suspicions. I think his exact words were 'you've seen the pictures on the Internet of the HDMI prototypes, right?'. Collins also suggested that the Xbox team, as an intermediary step, was looking at bolstering the existing console's software so that it could transcode from the advanced audio formats not only down to Dolby Digital but also down to arguably higher quality DTS.

From a video standpoint, lack of HDMI support is a moot point, at least at the moment, since no Hollywood studio has yet enabled the Image Constraint Token (and according to Collins, to the best of his knowledge they aren't planning on doing so, although after they read this they may have second thoughts). And I'm no audio purist, although my ears are pretty 'golden' (or at least they used to be), so I'm not worked up about the Dolby Digital-only implementation. With that said, DTS output over S/PDIF would be a great addition, if the Xbox team can pull it off (I wonder if royalties are part of the reason why it hasn't yet been implemented?). And for some folks, the Xbox 360's lack of HDMI support will be a conceptual roadblock even if it's practically speaking a non-issue. It'll be interesting to see how Microsoft handles this, both for new customers and existing Xbox 360 owners.

For additional reading on the topic of the PS3 versus the Xbox 360 for blue laser optical storage-housed movie playback, see this Slashdot post and the writeup it references.