Only one roll of film is used for film screening. How did that sound come from?

Sound is also on film, which includes negative film for cinematography, positive film for printing and reproduction, intermediate film for reproduction and vocal cords for recording.

The earliest talking movies had only 1 track. After the birth of stereo, the track became two. With the appearance of digital audio in the 1990s, the vacant positions in movies were occupied by several Hollywood technology tycoons in turn. Sony and Dolby took the lead.

Sony occupied both sides of the film (light blue area), and put in the 7. 1 channel cinema audio system SDDS (Sony Dynamic Digital Audio) developed by Sony itself. Dolby occupies a square area between dental holes, and like a two-dimensional code, he puts in a 5. 1 channel dolby digital sound system.

Extended data:

The recording methods of contemporary movies include synchronous recording and post-recording. The two recording methods can be used together, so there are so many movies being processed now.

With the progress of recording technology and the rise of digital music, sound engineers can not only let the audience hear sounds that can't be heard with their own ears in daily life, but also create sound effects for movies that don't exist in reality. Especially in science fiction films, disaster films and other films, digital technology is not only used in pictures, but also in sound.