Background

The new optical formats (Blu-Ray, HD DVD) will support HD video at 1280x760(720)/60.  It only makes sense that high definition sound will be included on these new discs.  The next generation audio formats DTS HD and Dolby Digital HD are going to be the answer.  If the term high definition sound, sounds to you like a bunch hyperbole there are actually numbers behind the hype.  What makes sound high def?  It’s all about sampling rates using something called Pulse Code modulation.  If you’re a little unclear on exactly what is meant by 24/96 audio, check this out.

Next is lossless, the opposite of lossy.  Lossy compression is what occurs when you use most audio compression formats like MP3.  This means that little pieces of sound are removed from the whole analogue audio signal, to digitize it into a small form so it can be transferred across your bit torrent.  It may come as an horrific surprise to some that Dolby Digital 5.1 and DTS are both considered lossy compression formats.  So when you’re watching Batman Begins on DVD and everybody’s going on about how awesome it sounds, you can tell them it sounds pretty good for being encoded in a lossy compression format.  But that you’ll take your 16 bit CD audio over it any day.  You’ll sound like a hi-fi geek.

DD/DTS HD

Enter the new audio formats.  The next gen audio formats are a long time coming if you ask me (and you probably didn’t).  We niche market hi-fi geeks have been farting around with DVD-Audio and SACD for long enough now.  It’s time everybody else got on board what we’ve been amazed by.  If you have a speaker system that will do high resolution PCM audio justice these new hi-res/lossless audio formats certainly will amaze you. 

Dolby Digital True HD

Dolby has given us a little more information so far than DTS and will feature up to 18Mbit/second throughput to eight discreet full range channels of 24-bit/96kHz audio. 

DTS HD

Supposedly will be technically superior, but we’re used to that.  DTS says it:  “…supports a virtually unlimited number of surround sound channels, can downmix to 5.1- and two-channel, and can deliver audio quality at bit rates extending from DTS Digital Surround up to lossless.”

The facts are still a little ambiguous.  Both DTS and DD say they’ll be compatible with their older encoding systems.  But that begs the questions; will I need a new receiver to get the lossless hi-res sound?  What hardware specs should my new receiver have if I get one to take advantage of this?

Here is what we know through best guess, press releases and educated conjecture.

These new methods of encoding to be able to at least downsample to regular DTS/Dolby Digital bitstreams so they’re at least backward compatible.  Forward compatibility or the ability to decode DTD/DD HD using your old standard DD/DTS chipsets in your old receiver is not bloody likely.  When did you ever see an advanced standard that could be decoded with the old process?  The new audio formats will require HDMI inputs on your receiver.  Since HDMI is higher bandwidth and HDCP capable, S/PDIF isn’t going to cut it.  That means the services of your receiver’s optical or coax digital audio inputs won’t be required by this new standard.  Blu-Ray/HD DVD to S/PDIF:  “You’re fired!”

The analogue only 5.1 inputs on your receiver will facilitate downmixed audio from the new audio formats.  DTS says their number of channels is virtually unlimited but what does this mean?  Well, it doesn’t matter because the Blu-Ray and HD DVD standards themselves say that the number of channels will be limited to 8.  So, in terms of the purity of the audio signal, DTS HD and DD HD will be equal with PCM sampling rates and both lossless.  This is a great breakthrough.  Until someone figures out how to use that virtually unlimited channel overhead in DTS to their advantage, there is not going to be an on paper advantage to DTS.  But I’m sure differences will be heard or imagined, it’ll be what it’s always been about, the mix.  The engineers mixing the sound will either do a great job or not.  

This raises some interesting problems for anyone in the market for a new receiver.  If you must buy now, HDMI is your best guess at a future proof option (you might get away with an off-board DD/DTS HD decoding option).  As you know, HDMI receivers are damned expensive right now.  How many years will HD DVD and Blu-Ray be fighting … who knows?  It could drag on for years with both vying for your attention.  But one thing is for sure, when the first is released and we know for certain exactly how to get the proper hi-res audio out of them, the cost of receivers that can’t do the hi-res audio is going to drop like a stone.  If you’re not interested in the new HD hi-res audio formats you still have reason to wait.  Sometime in Q1-2 of ’06 HDMI receivers are going to really kick in and all those non-HDMI receivers are going to drop in price.  Personally, I’m happy with my current non-HDMI receiver and it’ll be a long while before I buy again.  If I do buy another receiver in the next three years it’ll have HDMI or possibly even whatever comes next.