by Kazaam
However, in technical terms, mutli-channel simply means utilizing more than the two speaker channels that are commonly found in stereo recordings. As such, it is possible to mix an album using just 3 front channels (left/center/right), with absolutely no surround channels at all, and still be considered multi-channel. In fact, there are no set requirements beyond having three or more speaker channels. Maybe the disc has a center channel, maybe it doesn't. Is there a subwoofer channel? Maybe, maybe not. It all depends on the mixing style chosen for that particular album.
Beyond the number of speaker channels, a surround mix can also vary in the way it sounds. One mix might be extremely subtle, providing just enough ambience to help recreate the feel of a live performance. On the other hand, another disc might be totally discrete and sound experimental. You might have drums, keyboards, or even vocals emanating directly from the surround speakers found in the back of the room.
There are numerous formats available that allow the listener to experience multi-channel music. Here's a brief glimpse of what the multi-channel music offerings look like:
The Past - "Quadraphonics"
In the 1970s, there was Quad. Generally speaking, it was a 4-channel presentation with 2 speakers up front and 2 speakers in the back. There were numerous vinyl quadraphonic formats, each varying in their effectiveness. Additionally, there were quadraphonic 8-Track tapes as well as reel-to-reel tapes.
The Present: Part 1 - Dolby Digital / DTS
The 1980s saw an end to the quadraphonic era. During this period, albums were only available in 2-channel (stereo) on regular CDs, cassettes, and--for a short while--on vinyl records. This continued throughout most of the 1990s until the advent of the newer audio formats, Dolby Digital and DTS, which were (and still are) used for movie soundtracks on DVDs and some Laserdiscs. Through the guise of the video realm, these audio formats helped to re-introduced to the public the idea of "surround sound".
Dolby Digital / DTS sound quality isn't as good as CD because the audio is compressed and some of the original signal is literally thrown away. Typically, these are sounds which would be masked by other more dominant sounds, and are less noticeable by human hearing. It's a compromise designed to shrink an entire 5.1-channels of audio onto a disc that has limited storage capacity----capacity that needs to be primarily dedicated to the video realm in order to provide the high-quality picture we've all come to love and expect from DVD-Video. Nonetheless, the results can still sound quite good with both voices and even music. Moreover, Dolby Digital and DTS are very effective methods of delivering discrete and precise surround sound, something not possible with standard stereo CD or even most of surround sound's predecessor formats, such as Dolby Pro Logic.
Unlike some previous analog matrixed methods, whose surround sound effect was often unimpressive, Dolby Digital and DTS made it possible to precisely locate sounds into a specific speaker. You want to clearly hear a voice yell from the back of the room? You've got it! Low rumble from a dedicated subwoofer channel? That's there, too. In fact, these formats are so effective at creating surround sound that, toward the end of the 1990s, we began to see a few specialty-market DTS-encoded music CDs released, many utilizing the old existing catalog of 1970s quadraphonic mixes of albums such as Paul McCartney / Wing's "Band On The Run" album. We also began to see that surround sound would be a staying force in many consumers' homes thanks to the popularity of Home Theater. Perhaps, the music industry---needing something new and attractive to combat music piracy---could make a successful go-around with multi-channel music this time? They had already dabbled in concert videos on DVD. But what putting out entire albums remixed for surround sound? Enter DVD-Audio... and SACD. And yet another format war.
The Present: Part 2 - SACD & DVD-Audio
Both SACD and DVD-Audio released a number of discs starting around the early 2000s. Both are designed not only to provide surround sound, but also to provide superior sound quality to both regular CDs and Dolby Digital/DTS. SACD and DVD-Audio presumably are capable of keeping all the so-called 'analog' warmth of vinyl, but by benefit of their digital nature also remove the annoying clicks and the pops that plague the 33-1/2 LP. And, unlike Dolby Digital/DTS, they could store all of the original audio signal at better-than-CD-quality in 5.1 surround sound.
These formats were designed to be audio-oriented from the get go. DVD-Audio can only offer video in small doses, such as still photos or a single music video. Meanwhile, SACD doesn't support video at all. They both sound great! About the only downside is that special players are required. Concerning DVD-Audio, though many discs contain a Dolby Digital and/or DTS soundtrack in order to acheive backward compatibility with standard DVD-Video players, a special player capable of decoding the "DVD-Audio" format is still necesseary in order to benefit from the improved audio fidelity. Likewise, special players are required to play SACDs. But unlike DVD-Audio discs, Super Audio CDs (SACD) don't even provide any method with which to experience the surround sound through standard DVD players. (Though some SACDs include a regular CD layer for stereo use.) So new equipment must be purchased. Thankfully, there are many low-cost "universal" DVD players on the market which are capable of properly playing not only DVD-Video's Dolby Digital and DTS formats, but also the newer hi-rez surround formats, such as DVD-Audio and SACD.
Neither SACD nor DVD-Audio have become more than niche products. It's tempting to blame the format war, but that would only be a small piece to the puzzle. The bigger piece being the fact that the world is in a big hurry these days. And most consumers would prefer to have thousands of slightly worse-sounding stereo MP3's for their iPods---all in the palm of their hand---than wanting to sit down in one place for an hour listening to a complete album, surround sound or not. (And, honestly, who can really blame consumers. The iPod and MP3s are incredible even if they do have imperfect sound.) That said, for those of us who enjoy multi-channel SACD and DVD-Audio, it is extremely rewarding. (At least when listening to the good surround mixes, that is!) And we always look forward to new releases, even if they have slowed down to a trickle.
The Future
The immediate future appears to be a regression toward utilizing inferior formats, such as DTS and Dolby Digital, on standard DVD-Video discs as a more frequent method of distributing mutli-channel music albums. In a way, it makes sense since everybody and his kid brother own at least one standard DVD-Video player these days. However, on the horizon are the next-generation optical discs, HD-DVD and Blu-Ray. They will provide not only high-definition television, but also present yet another opportunity to bring multi-channel music into the homes of consumers.
Both Blu-Ray and HD-DVD will feature new and improved audio formats from Dolby and DTS. Both "Dolby TrueHD" and "DTS-HD" will offer the capability for better-than-CD sound combined with full-motion video. And, of course, mutli-channel audio! So, basically, they will provide all the sonic benefits of SACD and DVD-Audio plus a complete high-definition video program. Thanks to HD-DVD and Blu-Ray, there will no doubt be several new great-sounding movies and live-performance music discs. However, it remains to be seen if we'll get to see more of our classic albums re-mixed into surround sound on these high-definition video discs. Considering the large storage capacity of both Blu-Ray and HD-DVD, it isn't completely ludicrous to ponder the possibility of this happening, be it as the main attraction or as a simple extra thrown onto a video. I do believe it is more likely to happen, though, if one of the new formats, either HD-DVD or BluRay, quickly becomes dominant and the other relegated to the dust bins of history. That way, we will hopefully get mass adoption of equipment that is capable of high-resolution surround sound.
In the meantime, at least we've gotten to the point where many homes have some form of surround-sound equipment that works much better than the stuff that was around in the 1970s, 1980s, and early 1990s. And, of course, we've got that small, yet slowly growing catalog of multi-channel music discs to enjoy.
Update: HD-DVD officially has been discontinued. So by default Blu-Ray has "won" the format war. But now it remains to be seen if a large enough consumer base will be won over by Blu-Ray to make it more than a niche format.
WANT TO KNOW MORE?
What is a Super Audio CD (SACD) disc?
What is a DVD-Audio (DVD-A) disc?
What is a "DualDisc" disc?
What is a "DTS-CD" disc?
***
[Read my article: "SACD, DVD-Audio, & DTS-CD Titles Disappearing"]
______________________________________________________________________________________
HOME