The Development and Current Situation of Multi-channel Stereo in Cinema

Theater sound reproduction has become an important branch of film art creation since the appearance of sound films. When people record the real world or artistic creation, they must more realistically restore the on-site sound effects and the environmental sound effects that complement the pictures. Therefore, film recording and sound effect creators have been working on the application of multi-channel technology in movies, including sound recording and restoration.

 

In the film era, sound recording has always been constrained by two aspects: one is the frequency response, and the other is the number of channels.

 

In the era of analog sound, Dolby Laboratories solved the 4-2-4 multi-channel sound reproduction solution, that is, the left, center, right, and surround sound are encoded into 2 channels and recorded on the optical channel of the film. The decoding is restored to 4 channels of left, center, right and surround sound, and after improvement, the bass information of the main channel is extracted to form a sub-bass channel.

 

The Development and Current Situation of Multi-channel Stereo in Cinema

 

In the 1980s, Dolby Laboratories further improved the encoding method, realized the separation of the left and right channels of the surround sound, and realized the 5.1-channel sound reproduction of the theater. The surround sound effect began to become an effective means to create the atmosphere of the movie picture. .

 

In the late 1990s, with the development of digital technology, the digital coding and decoding technology of film sound became mature, and digital multi-channel sound reproduction was realized. During this period, Dolby Company, DTS Company, SONY Company, etc. have all launched their own digital multi-channel solutions for movies, namely Dolby's SR? D, DTS Company's DTS and SONY's SDDS. At that time, there was an upsurge of refitting digital stereo sound reproduction in our country. Most theaters were equipped with Dolby digital stereo system, some were equipped with DOLBY and DTS dual systems, and a few were equipped with SONY SDDS digital stereo 7.1 system.

 

 

Human beings will not be satisfied with the progress that has been made. In recent years, with the continuous improvement of the quality of the sound reproduction system and the emergence of 3D images, the previous surround sound technology is essentially just a flat multi-channel surround sound technology, which can achieve surround sound restoration in the horizontal direction at most. It cannot be called stereo surround sound (3D surround sound). People expect theaters to realize the surround distribution of the sound field not only in the horizontal direction, but also in the vertical direction, and accurately position the sound image.

 

In recent years, many audio technology companies at home and abroad are exploring in this area. Although the schemes are different, there are two things in common: one is to try to use more channels and more speakers to realize the real surround of the sound; the other is to try to meet the DCI standard specification and realize multi The coding and decoding of channel information is compatible with the current technical specifications of packaging and packaging of digital movies to the greatest extent.

 

Among the many multi-channel surround sound technologies, Dolby Atmos (Atoms), Auro11. ) technology abandons the concept of multi-channel, and uses up to 64 audio channels to accurately locate sound information. Most other technologies still use the concept of channel to achieve multi-plane surround sound reproduction.

 

The common feature of these multi-plane surround sound technologies is that they can be implemented in 16 channels without changing the existing DCI technical specifications. The most important thing is to increase the ceiling speaker, which can restore the sound effect closer to reality, so as to achieve the creation of 3D sound effect.

 

In my opinion, Dolby, as the leader of movie sound reproduction technology, its panoramic sound technology has subverted the concept of multi-channel surround sound. With the concept of sound layer and sound element, it has greatly broken through the shackles of channel information, smoothing , Natural movement, and precise sound image positioning bring unprecedented space and convenience to sound effect creation. It is the development direction of multi-plane stereo surround sound technology in the future, and it is a cutting-edge technology for theater sound reproduction that deserves attention.