【正文】 原文 指導(dǎo)教師評(píng)語(yǔ)： 簽名： 年 月 日 畢業(yè)設(shè)計(jì)（論文）外文資料 1 Dolby laboratory on Dolby Author: Tiger Multichannel perceptual coding Dolby AC3is a kind of efficiency, quality and functional aspects with unprecedented effect perceptual digital audio coding technology. From the beginning of 1992, it has been for the cinema provide multichannel digital audio system and achieved in 1994into the two channel I BS application. It in the cassette and disc type family television system for transmitting multichannel digital sound function has been to the consumer electronics industry with very excited. In the United States, high definition television ( HDTV ) broadcasting the selected Dolby digital surround sound transmission, estimated that in 1996will be put into a test screening. Many have been announced and the potential applications of the technology of test shows, Dolby AC3decoder has a beautifully versatility. AC3 is not a single machine system, but a kind of use can make such as bit rate and number of channels such parameters to adapt to different special application flexible procedures for the treatment of familial. Various types of all decoder in order to work on the same principle as the foundation, and designed to take full account of the future need for patibility and adaptability. Important is, Dolby AC3will be high quality sound and excellent digital efficiency is very perfect bination. Because of the Dolby Laboratory for more than 20 years focus on human auditory research, in the development of signal processing field has accumulated rich experience, so, although AC3than in the CD disk to the last channel lower bit rate to create a multichannel surround sound, however, it makes the sound quality fully meet the listener expectations. Audio : past present and future In 30, the famous Baer Laboratories began using the three channel stereo sound. In 50, when the stereo into public movie, it uses the channel in four above, sometimes reaching over seven channels. A few years later, the stereo into families, since all of the phonograph records only with dual channel matching, so the family leave acoustic device only by dual channel playback, the technical limitations, can not the listener will generally twochannel stereo as the home audio selection criteria. But the film makers have channel 1( left, right, center ) and surround channel2as a pelling vivid sound minimum requirements. This can be from 70 time end, eighty time period the film industry widely adopted Dolby stereo to record film confirmed, Dolby stereo is the principle, let four channel matrix coding input two optical sound track, then an appropriate audio processor will restore it into four channels matrix coding reproduction. When Dolby stereo film is converted into audio signals, four channel coding retained the dubbing integrity, from 80 time begin first, Dolby surround has made multiple channel decoding into family time, today, tens of thousands of home audio systems are equipped with Dolby surround sound system, in fact, multichannel surround sound system sales has been far 畢業(yè)設(shè)計(jì)（論文）外文資料 2 beyond the twochannel stereo system sales, at present, Dolby surround sound has been widely used in film, TV and music on CD recording studio, and its acpanying family Dolby surround systems on the market rapid development. With multichannel audio in consumer electronics in the field of rapid growth, a more advanced technology was born, the technology is born there is nothing parable to this, it has simulated realistic sound effects, and can satisfy various listening conditions and high demand cannot imagine adaptability, this is Dolby AC3decoding technology Dolby AC3 decoder, the successful development and application, is the world39。s electroacoustic industry a major achievement. Dolby AC3 In 1987, highdefinition television channel in the United States has officially bee the standard process, its audio track is used for the first time in the four channel matrix encoding conversion for transmission of digital code stereo. However, by 1990, in order to avoid audio matrix are affected, four mono or stereo bined configuration as the optimal configuration. Due to time technical limitations, such an arrangement would have to increase by at least a bit rate. It is in this context, Dolby AC3was born. It has the advantage of only two independent stereo more code rates can realize multichannel audio code. Dolby advanced to the transmission of the code technology, such as Dolby AC2 decoder for Dolby AC339。s first production of magic tape recording equipment manufacturers. Later, he is responsible for the development of the pany developed the world39。s degree in physics. In 1963, he accepted the UN appointed to India as a twoyear consultant. As an amateur recording enthusiasts, Dr. Dolby over the years to recognize on the tape recording audio or video signal when background noise on the recording quality damage. While in India he began thinking seriously about a noise reduction without promising the recording quality approach. His exploration of these became the Dolby A B noise reduction and noise reduction, noise reduction system based on C. In 1965, returning to England, in London he established his own laboratory in order to carry out in India he thought scheme. Set up in 1968 to the Dolby lab named pany. Although the pany was founded10 years ago, the work of the centre in the UK, but it has been an American pany. After 1976, the pany39。s piano concerto. In 1966November, Decca published the first application of Dolby A type noise reducer record by Ge Solti / Muller second symphony. Subsequently, the recording industry began to recognize and use a large amount of