With the excitement of the coming high definition optical disc formats building, yet the unstoppable threat of another format war brewing, I wanted to take a look at the details concerning the changes that are forthcoming from enhanced bit-for-bit digital audio, to be paired with Blu-Ray and HD-DVD. Both Dolby and DTS have developed new audio formats to complement the high definition visual content that will be present on both of the new optical disc formats.
You had to know that the continued development and advancement of home theater was not going to stop at the audio portion. Nobody would expect to see the same compressed Dolby Digital and DTS soundtracks ushering in the audio portion of the high definition HD-DVD and Blu-Ray optical discs. That's why we will see all new high definition versions of Dolby (named Dolby True HD) and DTS (DTS HD) that will transport the audio portion of the high definition optical discs that will soon be invading our home theaters. Change is, for the most part, good. But in home theater audio, change is almost certainly expected. As with all of the various audio enhancements seen over the years (Dolby Stereo, Dolby Surround, Dolby Pro-Logic, DTS, DTS-ES) to name just a few, these latest enhancements will require a bit of education followed by acceptance, then finally becoming appreciated for all it has to offer. That's where a little planning will make all of the difference for you getting the most from your new high definition home theater.
The dawn of DVD brought Dolby Digital 5.1 presentations into our living rooms, shortly followed by DTS, which left a few early adopters without the means to process DTS, and were left scrambling a bit. I was unfortunately one of those early adopter "lost souls." I then chose to wait until DTS got a good foothold and then I jumped at the right moment to upgrade my home theater receiver to one that processed DTS as well as Dolby Digital. Shortly after that, there were musings going on concerning the option of 6.1 and 7.1 surround sound set-ups. This again was no good for me as my receiver was only capable of producing 5.1. Before I started thinking here we go again, I re-evaluated my home theater needs and decided that 6.1 or 7.1 at the time might just be a tad overkill. As we started to see Dolby Digital EX and DTS ES soundtracks emerge, I waited and wondered. Now I am glad that I chose to wait it out. Just as there are developments that change the way we normally do things and truly revolutionize out lives, there are also advancements that only enhance them. In this case it was the introduction of the Dolby Digital EX and DTS ES surround sound options. Sure, they offered us an enriched enveloping surround sound experience, but for me it seemed slightly unnecessary to once again abandon my current receiver. I won't bother going into details of which of those formats performed better or not, because they simply were never exploited on a grand scale to maximize their full potential and the few DVDs that did offer those soundtracks were few and far in between.
Before I continue, this is something that has to be dealt with. Debates have raged on ever since Dolby and DTS went head to head in the home theater arena. Audiophiles alike compare the two audio codecs; Dolby Digital and DTS simply arguing the point that one or the other "sounds" or "is" inherently better, yet a general consensus is rarely reached. The long standing arguments go something like this; dts is much less compressed than Dolby Digital, in this context "better" means closer to the original source before the compression occurred. Dolby Digital on the other hand claims to have a more efficient codec that doesn't need the extra bits to create an accurate recreation of the original sound. Thereby mentioning that the portions left out in the Dolby Digital process are not really heard by the human ear, so the extra data isn't missed upon playback, simply put the bit-rate savings allow a higher video bit-rate (in the context of DVD). Now given that Dolby True HD and DTS HD are planning on both offering a bit-for-bit presentation identical to the studio master, this might become a moot point from here on in. Only time will tell if one format performs better than the other, as I'm sure each side of the digital audio pond will have their personal opinions.
So, with consumers awaiting the promise of improved picture offered by the coming high definition optical disc formats and HDTV adding vast improvements to the way we view our entertainment, we are now engaged to learn of even better audio to sweeten the high definition package. Enter Dolby True HD and DTS HD fully high definition audio formats that offer the purest of pure bit-for-bit signal processing and taking a lossless approach to delivering their medium.
Lossless? Bit-for-bit? What did you just say?
I will now describe what some of the following terms mean as they are important to me explaining the differences between the Dolby Digital and DTS audio formats that we currently enjoy and the new high definition enhancements waiting on the not-to-distant horizon.
Uncompressed audio formats, such as PCM (or Pulse Code Modulation, what is widely used on CDs and the like) uses no forms of compression, meaning that all the data is available at the risk of larger audio files. PCM will carry each uncompressed audio channel found in Dolby True HD and DTS HD from an HD-DVD or Blu-Ray Player to an A/V receiver equipped with HDMI capable inputs.
Lossy compression results in some loss of data as the compression algorithm eliminates redundant or unnecessary or irrelevant information. Lossy compression is widely used from MP3 files to soundtracks present on standard DVDs.
Lossless compression applies compression to an uncompressed audio file, without the removal of any information or causing any degradation in the quality of the original audio file. Now this is a basic explanation of what Dolby True HD and DTS HD will utilize. Since new high definition optical discs allow for far more capacity than current standard DVDs, this will be the preferred method of pairing the digital audio with the high definition visuals that will be present on the coming HD-DVD and Blu-Ray optical disc formats.
Bit-for-bit, which will allow soundtracks to be presented identical to the studio master, will in-turn permit home theater listeners to experience exactly what the artist intended, pure uninterrupted audio with every sonic detail accounted for.
Here now is a look at all of the technological specifications and all around fun stuff that make up these two exciting new audio format improvements. As we have started to witness at select theaters across the country already, fully digital systems of delivering a completely film-less presentation complete with true to life digital sound are already in place. But for the sake of this article, I want to focus on the changes that will be present in the home theater environment.
With Dolby Digital, the early beginnings of what will come to be known as Dolby True HD all started with something called Meridian Lossless Packing. This is a proprietary lossless compression technique for compressing PCM audio data. MLP is the standard lossless compression method for DVD-Audio content (sometimes referred to as Advanced Resolution) and typically provides about 2:1 compression on most music material. It is also known as Packed PCM (PPCM) and with the next generation of DVDs it will be known as Dolby True HD, adding higher sample rates, higher bit rates, 8 full-range channels, extensive metadata (dialogue normalization, dynamic range control), custom speaker placements and time code.
Dolby True HD will offer bit-for-bit sound reproduction identical to the studio master. Over seven full-range 24-bit/96kHz discrete channels are supported, with the Low Frequency Channel (LFE) providing the .1 to make up the full 7.1 audio spectrum. Theoretically, Dolby True HD can support more channels, but the overall offering has been limited to 8 channels (7, plus the LFE) for its use on HD-DVD and Blu-Ray.
Now I want to take a look at the enhancements brought forth by DTS. With HD-DVD and Blu-Ray, DTS will launch DTS HD at the same time as Dolby True HD and both have been accepted by the competing optical disc formats. I would like to mention the fact that DTS on standard DVDs typically offered greater dynamic range adding more realism by retaining more of the original soundtrack than other audio formats available on current DVDs. With their introduction of dts 96/24 (or 24-bit/96kHz) for standard DVD applications, DTS was and still remains at the forefront of providing the best possible sound for both music and video playback. Simply put, extending the frequency range greatly increases sound quality by reproducing far more natural sounding audio. All of these advancements have remained backward compatible with any system that can decode DTS. If your system is not equipped with DTS 96/24, then you will hear 48 kHz at 24 bits (48/24), this is achieved by DTS 96/24 being encoded as core + extension data. This is how the new DTS HD and Dolby True HD will be backwards compatible with current audio set ups, by providing the "enhancements" as data "add-ons". So in other words, the improvements will be available on HD DVD and Blu-ray (both DTS HD and Dolby True HD are standard), but if your system is not fully capable of processing the new audio formats, then you will still be treated to basic DTS and Dolby Digital that we currently utilize on standard DVDs. Not the end of the world is it?
To fully take advantage of the high definition audio that will be present on HD-DVD and Blu-Ray, you will need a receiver that is equipped with HDMI as a switching option or at least have one HDMI input and one HDMI output to take advantage of DTS HD and Dolby True HD. As mentioned above, these new formats will be fully compatible with your current DTS and Dolby Digital capable receivers, but you will not be able to take advantage of the full bit-for-bit lossless audio unless your receiver is able to do so. An almost backwards compatible approach to bringing all home theater enthusiasts and average home theater users up to speed, until that day when it comes time to upgrade your receiver to one that is fully HDMI compatible.
On the positive side, if your receiver has a multi-channel analog audio connection (currently used in the connection of DVD-Audio or SACD) you may receive the signal from the high definition player (if capable) in analog separate 6 or 8 line level multi-channel inputs (both your high definition player and receiver must have these connections and be able to pass 24bit/96kHz) then the signal will pass to the receiver for processing. If your receiver can only handle optical or coaxial inputs/outputs, like many of us do, then the high definition player will convert the either Dolby True HD or DTS HD signal to a compressed Dolby Digital or DTS 5.1 or 7.1 signal that can be passed to your receiver in a similar mix that we have become accustomed to with the current standard DVDs today.
That's the basics of what to expect with the coming Dolby True HD and DTS HD high definition audio mixes to be offered on HD DVD and Blu-ray high definition optical discs.
