Well the real draw of SDDS is for VERY large venues that need the additional front channels for propper imaging. 99.9% of HTs don't have a huge front soundstage area in need of the additional front channels for propper pans and imaging. SDDS does not offer any additional surround channels, lfe channels, heigh channels, effects channels, or any thing else that the other formats don't already bring to the table. It is truly a large venue format which has no need in the home market. Surely if Sony thought in any way they could force another proprietary format down our throats i'm sure they would try, but there is no reason in this case.
Stephen is on the right track, but below are Sony's reasons and why it was created for added clarity.
What is SDDS?
Sony Dynamic Digital Sound® (SDDS®), is the film industry's most advanced digital sound format. In developing SDDS, Sony applied its experience in professional and home audio to give the movie-going audience the highest quality sound presentation. SDDS is provided by Sony Cinema Products Corporation (SCPC)¾a Sony Electronics company¾which has the mission of supplying the cinema exhibition industry with advanced technologies and products. SCPC is headquartered in Culver City, California, (within the Los Angeles area) with a European office located in London, England.
Why did Sony develop SDDS?
A central part of Sony's business is to improve the way people listen to and enjoy sound. Sony has developed the best in audio recording technology with innovations such as the compact cassette, the audio tape and the compact disc. In recent years, Sony has expanded its business into the production of quality software for both music and film. With Sony's venture into Hollywood and its commitment to the motion picture industry, Sony has also chosen to apply its expertise in digital audio to improving the cinema experience.
How is SDDS different from other digital film sound formats?
While all digital soundtrack formats offer audible improvement over the analog formats of a few years ago, the SDDS system is superior in its ability to deliver the highest quality. SDDS excels over other formats in several areas; the number of channels, its built-in digital redundancy, and its audio coding technique. While the other formats have a maximum capacity of six channels, SDDS can accommodate eight. SDDS uses a data reduction technique known as ATRAC that delivers excellent quality while keeping each recording channel truly discrete. When these elements are brought together under the renowned Sony name, the audience hears a presentation that cannot be duplicated by any other digital format.
Why eight channels and how are they used?
The expanded loudspeaker configuration has its roots in the widescreen Cinerama and 70mm formats of the 1950 and 1960s. These used five full range loudspeakers behind the screen and a single surround channel giving the audience six channels. Variations economized by not using the Left Center (LC) and Right Center (RC) screen loudspeakers but used their film tracks for split or stereo surrounds (LS and RS). Although the addition of the stereo surround and sub-woofer channels was an improvement, the loss of the LC and RC screen loudspeakers created problems for sound engineers who wanted to create a sweeping sound to fill the larger screens. Today, SDDS with five screen loudspeakers, two surround channels, and a sub-woofer channel takes the best of 70mm sound and returns the missing LC and RC loudspeakers.
What is the difference between SDDS and THX?
SDDS is a digital soundtrack format, which involves both the recording in the studio and playback of digital sound in the theatre. THX® is a certification program and consulting service that advises theaters primarily on quality amplifiers, loudspeakers, and proper room acoustics. THX certification is independent of the film's format. Theatres who conform to specifications and recommendations by THX use their logo to identify conformance to these standards. Any manufacturer's sound system that conforms to THX standards is frequently identified as a THX Sound System.
Does SDDS have a consumer equivalent for DVD and Laserdisc?
SDDS is a professional format intended only for the motion picture theatres. Its eight-channel configuration, with five loudspeakers behind the screen, would be inappropriate for smaller 5.1 channel home systems. Sony intends to keep SDDS as an exclusive experience for the movie theatre. In fact, both competing formats put the exhibitor at a disadvantage in that their home versions have higher performance than their professional systems. While the DVD specifications have provided a designation for a potential SDDS bit stream, Sony has no current plans to develop a consumer version of SDDS.
What about Surround EX ?
Surround EX is a joint development of Dolby and THX that adds a Back Surround channel by incorporating an analog matrix decoder with the Left Surround and Right Surround tracks. Technically, Surround EX is not a new film format but rather a minimal enhancement to the existing 5.1 channel loudspeaker configuration. The analog matrix technique, much like Dolby’s Pro Logic for consumers, is compatible with all digital formats including SDDS. Dolby and other companies have announced external analog matrix decoders that can be added to any existing digital system.
I know it's more than you wanted to know, but figure other tech heads like me would like to know more later.
Ok here is what i found, Sony might want update their info on their site about the ATRAC info.
ATRAC3 is a compression technology based on Sony’s ATRAC (Adaptive TRansform Acoustic Coding) technology that originated with and is supported by MiniDisc. ATRAC3 achieves twice the data compression rate of ATRAC with virtually no loss in sound quality and reduces the size of audio data to 1/10 of the original audio CD source.
Using characteristics of the human auditory system, sound that is inaudible to the human ear, and data that occurs before and after loud sounds are dropped to reduce data size without losing what's most important, sound quality.
The audio data analyzing resolution is two times higher than that of the ATRAC system. This allows more effective compression with the least amount of sound quality degradation.
The original audio spectral waveform is divided in frequency bands and then processed in two different map pattern contours for efficient compression with the least amount of quality degradation.
In the digital signal sequence of 0 and 1, frequently appearing patterns are replaced with shorter sequences, resulting in a smaller amount of required data and efficient compression.
An advanced signal analysis method
-Simultaneous masking and hearing threshold in the lower audible ranges are used for quantization noise control in the frequency domain.
-Forward masking and backward masking are used for quantization noise control in the time sequence domain
Removal of data redundancy
-Quantized data are efficiently coded applying Entropy Coding.
Optimal processing is performed on signals that change over time in each sub-band by splitting input signals into 4 sub-bands.
Signal compression is performed with virtually no loss in sound quality by setting the frequency resolution at 21.5Hz. In addition, a smaller area for time to frequency transformation is made possible by hybrid processing using the band division filter.
Efficient bit allocation is performed by separately coding tonal signals such as those of trumpet or flute sounds which have signal components that unevenly distribute over certain frequencies.
Simple coding is achieved by using a smaller coding table.
ATRAC3plus is a new audio codec from Sony that differs substantially from ATRAC3 (ATRAC4 would in fact have been a better name). Though not used in the original Minidisc, ATRAC3plus is used in Hi-MD and Sony's solid-state and CD walkman products. It uses a transform window 4 times bigger than ATRAC3 (4096 samples, or 92ms) and splits the input into 16 sub-bands prior to the FFT (MDCT) and subsequent bit allocation processing.
Sony has measured ATRAC3plus fidelity at 64kbps and found its audio quality equivalent to 128kbps MP3 (mech. trans.) Sony's current PC software produces ATRAC3plus output at user selectable bitrates of 132, 105, 66, 64 and 48 kbps. AV Watch Japan has done a bit of ATRAC3plus signal analysis and comparison with ATRAC3
Short for "Adaptive TRansform Acoustic Coding 3 plus", ATRAC3plus is an enhancement of ATRAC3 incorporating advanced audio compression technology. This latest technology analyzes longer periods of audio signals to obtain more precise information of the input signals and also introduces a newly developed algorithm that achieves optimal bit allocation for a wide range of audio signals. As a result, high quality sound is achieved at high compression levels of 1/20 the original sound source.
ATRAC3plus technology achieves double the compression ratio of ATRAC3 with virtually no loss in sound quality.
Improved compression with minimal loss in sound quality is achieved through the analysis of audio signals in a division of 16 sub-bands.
Optimal processing is performed on signals that change over time in each sub-band by splitting input signals into 16 sub-bands. The filter used here can operate at high speeds and uses 20% less operating power than conventional filters.
The transform block size has been lengthened to twice that of a conventional block size, thereby providing higher coding efficiency. This enables the compression of signals with almost no loss in quality.
High quality sound is obtained by enabling concentrated bit allocation to a channel (left or right) with higher power.
Bit Allocation over 2 Channels
The chart below represents the overall flow of the audio compression process.
Sony has chosen a confusing naming scheme for their variations of ATRAC. All Minidisc equipment before the advent of MDLP used ATRAC1 of some generation or another (note the lack of a space between ATRAC and the number 1). We should really be calling the ATRAC of the MZ-1 (Sony's very first MD machine) ATRAC1 version 1.0, and of the MDS-501 (the first high-end MD deck) ATRAC1 version 2.0, etc. By this nomenclature, Sony's current MD decks (ca. 2001) are using ATRAC1 version 4.5 and ATRAC1 Type R. MDLP uses a new and incompatible encoding called ATRAC3 version 1.0, which we shorten to just ATRAC3 (note again the lack of a space between ATRAC and the 3).
ATRAC2 was renamed to ATRAC3! Seriously though, audio coders are evolving computer programs with few natural dividing lines between them, though perhaps it's fair to rename them when their stored formats become incompatible. ATRAC2 (described briefly and in slightly more detail) differs substantially from the original, existing ATRAC system, having twice the transform window size (1024 samples [23.2ms], vs. 512 samples [11.6ms]), encoding tone components separately from other spectra, splitting the input signal into 4 bands instead of 3, and using Huffman coding on the final bit stream to squeeze out redundancy. Though ATRAC2 was never incorporated into an exported Sony product, the Sony PlanetMG FAQ states "a second format, called ATRAC Data, is used by Sony in a digital music distribution system offered via the SkyPerfecTV satellite service in Japan". This "ATRAC Data" is most likely ATRAC2, however Sony's MDS-DL1 and SkyPerfectTV press release makes no mention of "ATRAC Data", and certainly any audio stored on a Minidisc would have to conform to existing ATRAC standards for Minidisc.
ATRAC3 (as described briefly by Sony's ATRAC3 information page and in more detail by a TechnoWorld article (PDF)) appears quite similar to ATRAC2 in structure. The only difference is that ATRAC3 again uses the original ATRAC's QMF (Quadrature Mirror Filters) for band splitting, whereas ATRAC2 used PQF (Polyphase Quadrature Filters). Given the popularity of MP3, and the fact that there was no existing ATRAC2 format to be incompatible with, it seems plausible that marketing arguments, as much as anything else, convinced Sony to rename their high compression codec ATRAC3.
i know this is sorta off topic but i thought i could add my 2 cents....
my boss went to a show last year and they were debating of making a 10.2 standard for home theaters. they had some demo stuff created for the presentation with individual information for all 12 speakers. 5 fronts, 5 rears and 2 subs... im not sure if the subs were both placed in the front stage.
but as my boss had put it... most people have a hard time placing 5 speakers in their living room, how will they get around adding 5 more?
I would like to see the addition two front channels become a standard. Most action takes place from side to side. I would welcome a wider soundstage. And for the same reason, I think that more than two surround channels is a waste. Again, most action (offscreen) comes from the sides, not from behind the camera. Do we really need four speakers behind us?
I think if you did a poll most people would say that their room (viewing area) is wider than it is deep.
The day that standards are based on WAF is the day I sell off all my electronic equipment and take up knitting.
Isn't all digital "processing" a minipulation? Compressions involving subtractions and re-insertions of additions via THX, Cinema Studio EX and all other gimmicks that produce a sound that has very little to do with the original analog signal when complete? All advancments dedicated to HT and miniturization of media. I don't think too many of us are complaining.
Don't forget that to add those two channels, you have to add 2 more power amps channels to your system, as well as the two speakers. Looking at my modest-sized living room, I can already tell you that although I'd love SDDS, I don't know where I'd put the 2 extra front channels.
Also, with the exception of upper-mid-fi gear and above, mass market receivers are already compromising and underpowering the 5 channels they're supposed to power. I don't think the Best Buy model receivers are going to do 8 channel SDDS justice.
Sony's flagship receiver, the Sony STR-DA9000ES, allows for a 9.1 channel hookup - I've attended a Sony demo in the NYC HE show a couple months ago, that had it working this way. I don't remember if Sony labels this "mode" as being "SDDS".