Send spatial audio experience – a problem with many options for solutions. We have repeatedly clashed with the idealization of sound systems, talk about full-fledged multi-channel sound that transports the listener to a given acoustic space with a lot of localized sources. But, alas, this is not real.
So far, we can only talk about a successful implementation of the closest to our real feelings – binaural. For a complete volume of information with the help of the student should be in the headphones. The prototype, built on the basis of which the main study was a dummy, where instead of left and right ear microphones were installed. As a result of composing complex mathematical model, which allowed you to create virtual sound worlds.
But these studies, though they were close to ideal, had enough common outcomes. After all, you see, each person a different form of ears, and the distance between the right and left ear – it is also an individual parameter. In general, researchers have reached an impasse. Practical application of the results of binaural models are now available in version of the subculture, developing separately from the main areas used in practice.
It may seem strange, but the most important contributions in the field of surround sound movie industry has done. During its development, it is faced with many challenges, and we can not say that her path was smooth. On the introduction of new technologies spent a lot of money, and not always justified by such investments. As an example, stereoscopic, where the viewers to wear special glasses to view the picture in the volume. Stereoscopic not become standard, and even worse – it is completely stuck. Therefore, idealized versions of binaural with headphones – the technology is not for the film.
Dolby
As an option – it is a multichannel system. Initially the movie was dumb, then came a mono sound, and the next stage – Stereo … Stereo burst with a lot of new ideas and their implementations. A simple turn of the handle panoramas led the audience and the audience into raptures. Interestingly, up to 80 concepts "stereo" and "surround" were synonymous. You know, when divided? With the transition from the standard 35 mm film to 70 mm. Initially, manufacturers began to use the so-called channel effects (effect channel) – it is located behind the audience the speaker intended to voice support sound, and often simply silent as to the place of 35 mm, the film was limited. With the introduction of a standard 70 mm, channel effects become ever be invoked, and was renamed the spatial channel (surround channel, then we call it the S-channel). And from that moment we can say about the separation of the concepts of "stereo" and "surround". In the version of 35 mm film was offered a standard Dolby Stereo (mid 70s). In 1982 the market received the first Dolby Surround devices. They cost while the equipment is hi-end-class and made available a very small number of citizens.
In parallel with the film industry developed the video industry, and cable / satellite TV. Ability to provide a surround sound at home – one of the main tasks, which was placed before the manufacturers. There were more than adequate both in price and options for the implementation of decoders Dolby Pro Logic and Pro Logic II. The latter not only allowed to play the encoded surround sound, but listen to the music from regular CD, when played over a surround-system. Pro Logic and Pro Logic II are crossovers between conventional stereo systems, and multi-channel surround. Exaggerating some features we can say that in some ways they are (stereo and surround versions of decoders Dolby Surround – Pro Logic and Pro Logic II) are interchangeable.
With the active introduction of digital technology Dolby Labs is a standard Dolby Digital AC-3 (5.1), designed for 35mm film. Feature is the Dolby Digital 5.1 surround-existence of two channels (right (RS) and left (LS), a precursor S-Channel was one, although some speakers installed) and a subwoofer. If we talk about the acronym "5.1", it stands not only as a five channels and a subwoofer. The fact that the first time in Dolby Digital and S-front channels have the same full frequency range. For example, Dolby Pro Logic S-channel is provided for the range from 100 Hz to 7KGts. Now we're talking about five full-range channels with 20 Hz – 20 kHz and above. Frequency range of subwoofer or as it is called the LFE-channel (Low Frequency Effect) is limited and is approximately 0.1 on the frequency range of five channels, so the "5.1" should be deciphered as "five and one-tenth."
Dolby Digital 5.1 files have the extension *. Ac3 and require for their interpretation a special decoder (software or hardware). In the early days of its establishment, the technology cost is not cheap. Decoders were the only hardware and issued in the form of specialized devices. Now the situation has changed for the better, and the average user can afford to purchase a sound card with built-in decoders or download a version of their software from the Internet. Thus, modern cinema and home theater all become equal in features. It is worth noting another important aspect. Along with the development of film, video and television, has opened a new range of surround-sound technologies – video and computer games. Earlier, we talked about the simplest versions of 3D-engine based on the adjustments of the phase shifts, and delays in a simple EQ, now mean a full 5.1 as a minimum.
Today, Dolby Digital 5.1 is the universal standard. Sound AC-3 can be transformed depending on the size of the apparatus. For example, among the available separation for five or six channels (dependent on the presence / ostutsviya subwoofer), it can be converted into four-channel (Dolby Pro Logic), is usually a stereo or even mono. Therefore, encoding audio for computer games in Dolby Digital 5.1 can not be afraid of what the user has to have a smaller number of speakers, will feel uncomfortable.
Of course, movie theaters need to have an advantage over domestic complexes, so for them the technology was developed by Dolby EX, which implies nothing more than a 6.1. In addition to individual S-channels for left and right (RS and LS) it provides the main S-Channel (CS).
Dolby Digital technology allows you to compress data and send them with a minimum flow rate 320 kbps (standard – 384 kbps). Of course, the compressed data are more transportable and occupy less space on the media, whether it be film or a regular hard drive. But the technology also has drawbacks – it is designed for only one cycle of coding-decoding and does not solve the problem of relaying and editing of compressed data. In addition, even though we are winning in the place, we lose the fact that the sound of a standard AC-3 is not synchronized with video data, so the editing of this material is very problematic.
Of course, require multiple encoding / decoding. The solution to this problem was introduced by the new technology of Dolby-E. It allows you to transfer, multiple encode / decode eight channels of full frequency range. Total allowed ten cycles of coding / decoding. Above all, the standard provides for metadata – the special instructions that describe the basic data. In addition, they can synchronize to tell us the settings for each channel compressor, etc. By the way, these data can not use it, they are no more nor less, and more information ..
DTS
In the majority of users associated with the concept of surround Dolby. This is not the case. Dolby Digital – a promoted brand, nothing more. In the mid-'80s, Terry Byrd, president and founder of Nuoptix, teamed with Jim Ketchamom. Tasks that have set themselves the experimenters, were as follows – to create a single standard for digital audio and cinema-quality accommodation to solve the problems of multi-channel audio on a film. Initially, experiments were carried out using digital tape (DAT) and the projector. Already at an early stage of development addressed the synchronization (as we know, in the version they Dolby only resolved with the introduction of Dolby-E). After a while, instead of the DAT were used in conventional CD-ROM. When using compression algorithm apt-X100, designed by Stephen Smith and his colleagues at Audio Processing Technology, which allows to compress data 4:1 on a CD-ROM was placed 100 minutes of multi-channel audio (data transfer rate 884 kbps). Thus, on two discs could be stored for a three-hour audio of the film.
After obtaining a patent in 1990 was a demonstration of new technology for members of the SMPTE. By 1992, the ninth year the technology was shown to Steven Spielberg, however, based on the hard drive, and the director agreed to use it in his new film "Jurassic Park" ("Jurassic Park"). Studio Universal, which is the owner of the picture, decided to test the technology in several of the two "lesser" films. The test results were acceptable. Moreover – Universal and Steven Spielberg have become co-owners Terry Byrd of the new company known as Digital Theatre Systems. Only during a time when the company was formed (and it took four months), in movie theaters were installed 876 systems DTS. To date, more than 19,000 of add around the world. It was planned to implement two technological standards:
DTS-S – DTS-stereo, is designed for movie theaters that want to use digital audio, but can not afford a full six-channel version.
DTS-6 – three front channels (left L, central C, R R), two S-channels (LS and RS) and a subwoofer. It should be noted that the standards are somewhat different from Dolby. For example the frequency range of the subwoofer in the DTS – from 20 to 80 Hz, -120 Hz instead of 3 in Dolby Digital.
One of the main differences from Dolby Digital DTS is that DTS is designed for 70mm film. Accordingly, the problem is not the place was so important as in the embodiment of Dolby Digital, issues of implementation of hi-res-sync audio and solved almost immediately from the time of the standard.
Now, referring to DTS, we can speak of eight or more channels of hi-res-sound, the latest data compression techniques and their practical application active.
Dolby vs DTS
Standards DTS distributed just like Dolby. At the same time, competitors have time to quarrel. And they still do? Dolby has a much stronger support from ordinary consumers and producers of technology for the consumer market. Thus, in Dolby Surround music albums released record label Delos, RCA Victor / BMG Classic, Concord Jazz. The documentation for this standard is constantly in demand by developers of modern video games. Modern satellite television also broadcasts the majority of the sound mode in Dolby Surround. In the last 114 meters AES Convention in Amsterdam have been teaching seminars on recording, mixing and mastering in Dolby 4.0, 5.0, 5.1, 6.0, 6.1, and 10.2.
DTS is the privilege of filmmaking. Today, already successfully resolved vospros with hi-res-audio with fantastic today standards 64 bits or higher, 192 kHz and above. By the way, Dolby Digital also allows the use of hi-res-tracks.
Software producers and studio techniques resolved the issue of confrontation is very simple – is supported by something, and more. It can be seen in Steinberg Nuendo – one of the most professional and versatile tools for surround-sound, and in the line of audio interfaces Audiotek – MAYA 5.1, 7.1, EX, EX7, PRODIGY 7.1. There you will find the support of two technologies – Dolby Digital and DTS. In addition, the standard software application designed for audio playback in the DVD are also decoders for both standards.
If we look at the confrontation, DTS and Dolby, sometimes comes to the ridiculous. Dolby released a press release – DTS is responsible. For example: "Dolby has conducted research on the unknown with an unknown studio equipment to play with the unknown material was used, which tested the experts … unknown." And sometimes, talking about surround sound and DVD, Dolby really forgotten by assigning major accomplishments, etc. in their favor.
In general, the usual corporate war.