History

One of the company’s initial investors was film director Steven Spielberg, who felt that theatrical sound formats up until the company’s founding were no longer state of the art, and as a result were no longer optimal for use on projects where quality sound reproduction was of the utmost importance. Work on the format started in 1991, four years after Dolby Labs started work on their new codec, Dolby Digital. The basic and most common version of the format is a 5.1 channel system, supporting five primary speakers and a subwoofer, referred to as an LFE (Low Frequency Effects) channel. Note however that encoders and decoders support numerous channel combinations and stereo, four-channel and four-channel+LFE soundtracks have been released commercially on DVD, CD and LaserDisc.

Other newer DTS variants are also currently available, including versions that support up to 7 primary audio channels plus 1 LFE channel (DTS-ES). DTS’s main competitors in multichannel theatrical audio are Dolby Digital and SDDS, although only Dolby Digital and DTS are used on DVDs and implemented in home theater hardware. Spielberg debuted the format with his 1993 production of Jurassic Park, which came slightly less than a full year after the official theatrical debut of Dolby Digital (Batman Returns). In addition, Jurassic Park also became the first home video release to contain DTS sound when it was released on Laserdisc in January 1997, two years after the first Dolby Digital home video release (Clear and Present Danger on LaserDisc) which debuted in January of 1995.

In theatrical use, information in the form of a modified time code is optically imaged onto the film. An optical LED reader reads the timecode data off the film and sends it to the DTS processor which uses this timecode to synchronize the projected image with the soundtrack audio. The actual audio is recorded in compressed form on standard CD-ROM media at a bitrate of 1103 kbit/s. The processor also acts as a transport mechanism, as it holds and reads the audio discs. Newer units can generally hold 3 discs, allowing a single processor/transport to handle 2-disc film soundtracks along with a 3rd disc containing sound for theatrical trailers. In addition, specific elements of the imprinted timecode allow identifying data to be embedded within the code, ensuring that a certain film’s soundtrack will only run with that film.

DTS and Dolby Digital (AC-3), DTS’s chief competitor in the cinema and home-theater market, are often compared due to their similarity in product goals. In theatrical installations, DTS can deliver better audio fidelity (due to the higher data-rate afforded by CD-ROM media.) AC-3 audio is placed between sprocket holes, leaving the audio content susceptible to physical damage due to film aging and mishandling. However, AC-3 (and SDDS), are stored entirely on the 35 mm film itself, and do not require delivery of separate CD-ROM discs to theaters, simplifying distribution. Disregarding the CD-ROM as a potential point of failure in a cinema audio system, the CD-ROM media is not damaged/degraded by repeated screenings, and rarely require replacement during the theatrical run of a given movie title.

In the consumer (home-theater) market, AC-3 and DTS are closer in terms of audio performance. When the DTS audiotrack is encoded at its highest legal bitrate (1.5 MBps), most technical experts regard DTS as achieving perceptual transparency (i.e. indistinguishable to the uncoded-source in a double-blind test.) At AC-3′s maximum bitrate of 640 Kbps, Dolby claims similar transparency. However, the DVD format limits AC-3 audiotracks to 448 Kbps, and some publishers limit the AC-3 bitrate further (to 384 Kbps.) Even at 448 Kbps, (DVD) AC-3 operates at a higher bitrate than theatrical (35 mm movie) AC-3, therefore a properly-equipped home-theater already achieves surround sound superior to a cinema AC-3 installation. Likewise, DTS-audio on movie DVDs is commonly encoded at a reduced bitrate, allowing a single title to fit multiple 5.1 soundtracks (AC-3 + DTS.) At this reduced rate (769 Kbps), DTS no longer retains audio-transparency.

It should be noted, that AC-3 and DTS use different coding tools and syntax to perceptually compress audio, and therefore, the raw bitrates of the two formats do not indicate an objective measure of sound-quality. Regardless, DTS proponents claim that the extra bits give higher fidelity and more dynamic range, providing a richer and more life-like sound. A DTS track is often louder with less hiss, even at the same relative playback volume.

DTS as a codec

DTS is an enhanced copy of a French patent called LC Concept, first used in 1990 for the movie Cyrano de Bergerac.

On the consumer level, DTS is the oft-used shorthand for the DTS Coherent Acoustics codec, transportable through S/PDIF and used on DVDs, CDDAs, LDs and in wave files. This system is the consumer version of the DTS standard, using a similar codec without needing separate DTS CD-ROM media.

DTS playback

Both music and movie DVDs allow delivery of DTS-audiotracks. But DTS was not part of the original DVD specification (1997), so early DVD-players did not recognize DTS-audiotracks at all. The DVD specification was revised to allow optional inclusion of DTS-audiotracks. The DVD-title must carry 1 (or more) primary audiotrack of AC-3, MPEG-1, or LPCM format. The DTS-audiotrack, if present, can be selected by the user. Modern DVD-players generally rely on an external audio-receiver to decode DTS audiotracks. (DVD-players with integrated AC-3/DTS 5.1 decoders were built and sold in limited quantity.) Nearly all standalone-audio receivers and many integrated (home theater in a box) DVD-player/receivers manufactured today can decode DTS (in addition to AC-3.)

For PC playback, many software players support the decoding of DTS. The VideoLAN project has created a decoding module for DTS called libdca (formerly libdts), which is the first open source implementation of DTS.

DTS variants

In addition to the standard 5.1 channel DTS Surround codec, the company has several other technologies in its product range designed to compete with similar systems from Dolby Labs. The primary new technologies are:

DTS-ES (DTS Extended Surround) – includes two variants, DTS-ES Matrix and DTS-ES Discrete 6.1, depending on how the sound was originally mastered and stored.[2] DTS-ES Discrete provides 6.1 discrete channels, with a discretely recorded (non-matrixed) center-surround channel; in home theater systems with a 7.1 configuration, the two rear-center speakers play in mono. DTS-ES Matrix provides 5.1 discrete channels with a matrixed center-surround audio channel. DTS-ES commonly works on a Matrix system, whereby processors that are compatible with the ES codec look for and recognize “flags” built into the audio coding and “un-fold” the rear-center sound from data that would otherwise be sent to rear surround speakers. This is notated as DTS-ES 5.1. Less frequently, DTS-ES data can be encoded with a Discrete 6th audio channel (the rear-center), meaning that the audio data for the 6th channel is stored separately from the other information, and is not embedded or matrixed among other channels. This
is notated as DTS-ES 6.1, as the center rear is completely discrete from the other channels. ES capable processors can recognize the discrete 6th channel, and play it back if connected to the necessary speaker(s). In contrast, Dolby’s competing EX codec, which also boasts a center rear channel, can only handle matrixed data and does not support a discrete 6th channel. DTS-ES is backward compatible with standard DTS setups, so non-ES equipment which does not recognize the flags or with ES enabled equipment that lack the extra speaker connections, sound plays back in 5.1 as if it were standard DTS. Only a few DVD titles have been released with DTS-ES Discrete.

DTS NEO:6 – Neo:6, like Dolby’s Pro-Logic IIx system, can take stereo content and convert the sound into 5.1 or 6.1 channel format.

DTS 96/24 – Allows the delivery of 5.1 channels of 24-bit, 96 kHz audio and high quality video on the DVD-Video format. Prior to the invention of DTS 96/24, it was only possible to deliver two channels of 24-bit, 96 kHz audio on DVD-Video. DTS 96/24 can also be placed in the video zone on DVD-Audio discs, making these discs playable on all existing DVD players.

DTS-HD Master Audio – Previously known as DTS++ and DTS-HD, DTS-HD Master Audio 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. DTS-HD Master Audio is selected as an optional surround sound format for Blu-ray and HD-DVD. DTS-HD Master Audio and Dolby TrueHD are the only technologies that deliver compressed lossless surround sound for these new disc formats, ensuring the highest quality audio performance available in the new standards. (n.b. DTS Coherent Acoustics coding system has been selected as mandatory audio technology for both the Blu-ray Disc (BD) and High Definition Digital Versatile Disc (HD-DVD)[3])

DTS Connect – This is a function pack available on the computer platform only. It is found on soundcards with CMedia CMI8788/CMI8770 Soundcontroller.

DTS Interactive This is a realtime DTS stream encoder. It is a part of DTS Connect, or can found on stand alone devices (e.g. Surround Encoder, HD DVD / BluRay Player). Nearly a dozen titles on the Playstation 2 feature the “DTS Interactive” realtime stream encoder, such as Grand Theft Auto: Vice City, and Terminator 3: Rise of the Machines

DTS Virtual – A relatively new development. Intended for use in conjunction with a Dolby Headphone processor. It allows a virtual (as the name suggests) 5.1 surround sound to be heard through a standard pair of headphones. It provides a better spatial awareness than Dolby Headphone on its own (which is primarily intended to provide a surround sound effect from standard stereo sources).

Source: Wikipedia article Digital Theater System

DTS webiste: DTS Online

© Shop Assistant for GBP Shop - Great Bargains to Your Door!, 2007. | Permalink | No comment | Add to del.icio.us
Post tags: Audio

Feed enhanced by Better Feed from Ozh

One of the most common questions asked by consumers faced with purchasing cables for their audio or home theater system is, “What is so important about cables anyway?” They can cost as much or more than some of the hardware in the system and to many it is difficult to understand why wire isn’t just wire.

To begin to understand how audio cables work, we have to start with the two fundamentally different types of audio cables you are likely to have in your system. The first type of cable is called an interconnect, which is used to connect various components together (such as a CD player to a receiver). The second type of cable is called the loudspeaker cable (this is the wire going from the receiver or amplifier to the speakers). It is important to realize that both types of cables are carrying the same information, just with different amounts of energy.

Interconnects carry a signal with very little energy. These cables only need just enough energy to convey the information from the source, for example a CD player, to the amplifier. The low energy requirement means that the signal in interconnects has very little current (usually in the range of thousandths of an amp).

Loudspeaker cables on the other hand, carry a large amount of energy. All of the energy required to move the speaker cones and make sound must come through the loudspeaker cables. Because of the high-energy requirement in these cables the current is relatively high (currents can reach 10 amps or more).

The very basic reason why audio cables are important is because they change the signal going through them. There are two different, fundamental ways that an audio cable can change the signal. The cable itself can change the signal, or the cable can allow outside sources of energy to change the signal.

In order to understand how these two situations can occur, some basic background electrical knowledge is needed.

Signals in all types of wires are conveyed by the combination of voltage and current. Every signal has some amount of voltage and some amount of current. The larger the difference in voltage between two places, say the beginning and the end of a cable, the larger the amount of current, and vice-versa. The direct analogy to voltage and current is the flow of water through a hose. The amount of water flowing through the hose is analogous to current. The water pressure in the hose is analogous to voltage. The higher the amount of water pressure, the more water will flow through the hose. The higher the amount of voltage, the more current will flow through the wire.

Every cable has a set of electrical properties that can be measured using standard electrical testing equipment. The three most basic properties are resistance, capacitance and inductance. While a detailed description of these three different electrical properties is outside the scope of this article, a basic description of the relevant effects of these three properties can be given.

- Resistance opposes current. The higher the resistance the greater the amount of energy that is removed from the current and turned into heat.

- Capacitance opposes changes in voltage. If a voltage is increasing, capacitance will cause the voltage to increase more slowly. If a voltage is decreasing, capacitance will cause the voltage to decrease more slowly.

- Inductance opposes changes in current. If current is increasing, inductance will cause the current to increase more slowly. If current is decreasing, inductance will cause the current to decrease more slowly.

The final piece of background knowledge that is needed for this article is what the audio signal looks like. If one were to take the speaker cover off a speaker to look at the speaker cone while music is playing, you would see that it is moving back and forth. In order to move the speaker cone back and forth, the electrical signal must push and then pull the cone in rapid and repeating fashion. This is accomplished by having an Alternating Current, or AC. Alternating Current simply means that the voltage oscillates between positive and negative. Because the voltage drives the current, this means that the current also goes positive and negative. In other words, the current is going back and forth in the wire, just like the speaker cone. The subtle variations in how fast the voltage and current go back and forth creates the different sounds that we hear when listening to music.

How a cable itself affects the audio signal

Now, going back to the ways that the cable itself can change the signal going through it, let’s consider both types of cables separately.

As stated previously, interconnect cables carry a very small amount of current. Relative to the current the voltage is large. Because of that fact, capacitance is important, but inductance is relatively unimportant. As the voltage oscillates between being positive and negative, the capacitance slows the voltage changes down, and causes delays. This can cause audible distortion in the sound. Because interconnects have very little current, resistance is not much of a factor. Even an interconnect with extremely high resistance will only remove an infinitesimally small amount of energy.

The signal in loudspeaker cables is essentially the opposite of the signal in interconnects. Both cables have the same information, but in loudspeaker cables, the voltage is small and the current is large, relatively speaking. Because of the high current, both resistance and inductance are important in loudspeaker cables. The higher the resistance, the greater the amount of energy that will be absorbed by the cables. The resistance will not cause any distortion, but it will decrease the volume of the sound. The inductance on the other hand, can cause distortion. As the current oscillates between being positive and negative, the inductance slows the current changes down, and causes delays.

How a cable lets outside sources of energy affect the signal

As stated previously, the second fundamental way of altering a signal passing through an audio cable is to introduce outside sources of energy. This outside energy is typically termed “noise”. By definition, if any energy is absorbed by the signal, the signal has been distorted.

There are many potential sources of noise around audio cables. Some of the more common sources of noise, such as radio frequency waves, are familiar to most people. When wiring up a radio, frequently a consumer must attach an antenna. Antennae are intentionally designed to channel radio frequency energy into a stereo. Just like an antenna, it is entirely possible for an audio cable to pick up radio frequency energy. If you are not intending to listen to the radio, this is not a welcome effect. Electronic components, electrical cords, sound waves, and even the sun, are all capable of creating noise. Electrical cords create electromagnetic fields around them that can transfer energy to a cable. Sound waves create mechanical vibrations that can be transformed into electrical energy that is added to an audio signal. Because there are so many different types of noise, there are many methods used to prevent a cable from picking up noise. Shielding, twisting of conductors, and mechanical damping are all common noise protection methods in cables.

While noise affects both interconnects and loudspeaker cables, generally the effects are far more significant in interc
onnects. This is because the signals in the interconnects have far less energy. Since most forms of noise are inherently low energy to begin with, this means that it is far easier for them to modify the low energy interconnect signals than the high-energy loudspeaker cable signals.

Macro vs. Micro

The parameters discussed so far have been primarily “macro” effects. These are for the most part the top-level parameters that effect cables. These parameters as well as others not discussed here also exist at a “micro” level. Taking capacitance as an example, a given cable will have an overall capacitance that can be measured. This overall capacitance is a “macro” level parameter. The same cable can also be analyzed as 1000 separate but connected pieces. Each piece will have a local capacitance. These local parameters are “micro” effects and can have their own impact on the signal separate from the “macro” effects.

The impact that the “micro” level parameters have on an audio signal is usually less than the impact of the “macro” level parameters. However, they do still make a difference in the signal transfer. The various ways that audio companies choose to either mitigate or ignore these “micro” level details is, in part, responsible for the vast array of different cable designs. From cryogenic treatments and precious metal wires, to fine silk insulation and fluid filled cable jackets; extreme cable designs abound. Will I hear the difference?

The fact of the matter is that cables do alter the sound going through them, and that it is audible. You do not need to be an expert, or an audiophile, to hear the difference. To demonstrate this point, simply listen to your stereo. If you close your eyes, does it sound like the music is being played live right in front of you? This is what audiophiles strive for, and unless you have a very high-fidelity system, your answer to this question will most likely be no. You may have a hard time describing what exactly does not sound right about your system, but you know that it doesn’t sound like a live performance.

Of course, the reason why the music does not sound live cannot be blamed solely on the cables. The degradation of the sound occurs in every component of your system. However, the point here is that even a casual listener can detect the subtle distortions that can prevent music playback from sounding live. Improving the quality of your audio cables will improve the sound quality of your system.

It is fairly safe to say that no matter what cable you use, the modifications to the sound will be small. Audio cables will never cause a listener to hear a piano when a flute is being played. However, it is the small detail that makes all the difference between good and bad quality sound. That is why very strong opinions are formed about various cables. As audio systems continue to improve in accuracy, listening to a “live” performance in your living room gets closer to reality. Cables are an enabling factor for advancements in audio reproduction and can play a remarkably important role in your system.

Written by: Adam Blake CEO / Co-Founder Pear Cable, Inc. www.pearcable.com For a more detailed explanation of cable design theory that Pear Cable thinks is relevant, see the “cable design” white paper available on pearcable.com

About the Author: Adam Blake is CEO and Co-Founder of Pear Cable, Inc., a manufacturer of high-fidelity audio cables. www.pearcable.com

© Shop Assistant for GBP Shop - Great Bargains to Your Door!, 2007. | Permalink | No comment | Add to del.icio.us
Post tags: Audio, cables, home cinema

Feed enhanced by Better Feed from Ozh

Sound Systems

To create surround sound, you can go any one of several different directions. The simplest and probably the oldest way, would be to set up a bunch of speakers surrounding the audience, so that the sound comes in to the listeners from all over, from the different directions.

A different method is to combine the use of headphones with localized audio production with psychoacoustics. The result is a simulated three-dimensional effect.

And another way to create surround sound is with ambisonics where you reconstruct the sound at a central point. However, you get a gradual decline in quality as you move outward.

Still another way is to use wave field synthesis (WFS), with multiple loudspeakers and a computer aid.

Popular today are everyday devices like stereo, PC soundcards, some camcorders and AV receivers. These feature digital signal or audio processors that create surround sound via stereo sources, or have add-ons, as in some camcorder cases.

Formats

Just as nothing stays the same, ditto with sound formats. Top ones have included discrete 5.1 Surround sound format with DVD-Audio, also known as DVD-A and SACD which stands for Super Audio CD. Moving on you have ambisonics, quadraphonic then Dolby 5.1 Surround sound. And later are: DTS, DVD-Video or DVD-V and the latest MP3 Surround.

Surround Sound Specs

3.0 Surround (matrixed): 3 audio channels: 2 for speakers front – left, right; 1 rear

4.0 Surround (matrixed Quadraphonic): 4 audio channels: 2 for speakers front – left, right; 2 rear

4.1 Surround (matrixed Prologic): 4 audio channels: 3 for speakers front – left, center, right; 1 rear (.1 = subwoofer)

5.1 Surround (matrixed Prologic II): 5 audio channels: 3 for speakers front – left, center, right; 2 at rear or side (.1 = subwoofer)

5.1 Surround (discrete Dolby Digital, DTS): 5 digital audio channels: 3 for speakers front – left, center, right; 2 at rear or side (.1 = subwoofer)

6.1 Surround (discrete Dolby Digital EX, DTS-ES): 6 digital audio channels: 3 for speakers front – left, center, right; 3 for the rear / side (.1 = subwoofer)

7.1 Surround (discrete SDDS): 7 digital audio channels: left, right, center, left surround, right surround, left rear, right rear positions (.1 = subwoofer)

About the Author

Hyun Kim is a freelance writer who writes about home audio & home theater topics. He loves to visit Stereo|411 to discuss home theater audio & he uses turntables.

© Shop Assistant for GBP Shop - Great Bargains to Your Door!, 2007. | Permalink | No comment | Add to del.icio.us
Post tags: Audio

Feed enhanced by Better Feed from Ozh

The most important thing to recognize is that a cable cannot improve the sound of a home stereo system any more than an electrical wire can create extra electricity when you plug it into the wall. That’s actually a very good example, because when you’re listening to audio for instance, what we’re hearing is an electronic representation of acoustic sounds – that is to say, the actual sounds have not been captured and stuffed into a compact disc like fireflies in a child’s jar – they have been copied, imitated, and a representation stored on the disc as a series of numbers.

These numbers are then read and translated into electronic signals, which are sent to the speakers in order to approximate the actual sounds. With that in mind, it makes sense that poor quality wires don’t physically change the sound – instead it’s like a game of ‘telephone’, in which the band tells the CD, the CD tells the player, the player tells the wires, and the wires tell the speakers, with something being lost at every step so that the message “Aunt Betty baked a pie” is altered to “Fat Eddy wants to cry” or what should be a great live recording sounds tinny, distant, or otherwise just plain wrong.

A good cable will change the signal as little as possible, but all cables do damage your signal a bit – it’s simply a matter of degree. As far as which cables are the best? That’s up to you or your local audio guru to decide – much is up to personal preference, with the rest probably being left up to your budget to decide.

About the Author:
Warren Thompson is fanatic about his new home theater system. He is also a contributing writer for http://www.hometheaterfocus.com – an immensely informative guide to home theater technology.

Article Source: www.iSnare.com

© Shop Assistant for GBP Shop - Great Bargains to Your Door!, 2007. | Permalink | No comment | Add to del.icio.us
Post tags: Audio

Feed enhanced by Better Feed from Ozh

It all started in 1949 when a man named Ray Dolby went to work for Ampex Corporation part-time while still in high school. He worked on an assortment of ventures in correlation with audio instrumentation. He continued to work for Ampex while attending college at Stanford University. During this period, he branched off to unite with a small team of Ampex engineers who were determined to invent the world’s first video tape recorder. Dolby centered in on the electronic aspects of the project. The team succeeded with their introduction of this new technology in 1956. Ampex then sold its first video tape recorder for $50,000.

Dolby graduated from Stanford in 1957 and was awarded the Marshall Fellowship at Cambridge University, England. He studied at Cambridge for 6 years, earning a Ph.D. in physics. In 1965, Ray Dolby started his own company, Dolby Laboratories, Inc. His first product from this new and innovative company was identified as Dolby A-type Enoise reduction. It significantly reduced the amount of background noise or hissing sounds found in professional tape recording without jeopardizing the original content of the material being recorded. This was the beginning of the many advances Dolby would make in the complex world of audio compression and expansion.

Ray Dolby developed an ingenious method of noise reduction by separating soft signals from loud ones, then simply not processing those loud signals. He then split up the spectrum into several bands to avoid clashing or pumping, therefore generating white noise. This method would become integrated in numerous aspects of society’s rapidly growing fascination with electronic entertainment. Early on, consumers weren’t satisfied with the ‘flat’ mono sound ordinary radios and cassette players emitted. Everyone wanted to hear music in stereo.

This new sound also found its way into movie theaters. Dolby sound made its debut in the original recording of Star Wars, and continues to revolutionize the audience’s experience even today. The sound is both more spectacular and more natural at the same time. Because of this technology, even video games are more realistic; the sounds are more powerful as they are not only heard, but also felt. The sound is so tangible it is as if fantasy has in fact become reality. More people are staying home instead of going to movie theaters since Dolby surround sound was introduced into the home theater system.

Recent advancements include Dolby 5.1, 6.1, 7.1, and 9.1 (that’s right, nine full-range channels), Dolby Digital Surround EX, Dolby SR, Dolby TrueHD, and countless others. It is obvious that Dolby is the reigning “King of Sound” and most likely will be for generations to come.

About the Author:
Mitchell Medford is an author and product development consultant for several consumer electronics manufacturers. Visit his website for more information on home theater, LCD TVs, and plasma televisions: http://www.newtechnologytv.com

Article Source: www.iSnare.com

© Shop Assistant for GBP Shop - Great Bargains to Your Door!, 2007. | Permalink | No comment | Add to del.icio.us
Post tags: Audio

Feed enhanced by Better Feed from Ozh