FR2594238A1 - Recording sound on cinema films by compact disc - Google Patents

Abstract

Device for controlling the projection of sound films by the reproduction of sound associated with the images, using a compact disc type of laser reader or any other type. With the recording of all or part of the related sound being carried out by the compact disc system, complete control of the reading (starting up, compensation for cuts, interruption and finishing) is achieved by reading the digital data written on the conventional sound track and by the installation on the reader assembly of a matched interface, controlled by the programmable internal microprocessor and associated with a decoding module.

Description

 The present invention relates to the sound system for cinematographic films by compact disc or other laser reading system.

 The recording and reproduction of sounds by electromagnetic system or by contact (microgroove) have reached levels that are difficult to improve.

 The recording and reproduction of images is obtained, to varying degrees of reliability, by chemical or electromagnetic processes.

 In recent years, thanks to the laser reader, the recording and reproduction of sounds have made considerable progress.

The object of the present invention is to link, by a digital magnetic recording, the classic reproduction of the images and the most perfect reproduction of the associated sounds.
An application of this inventive idea consists, in the case of cinematographic film, in adding to the conventional soundtrack with analog reading, a digital marking such that one can control the unfolding of the film the displacement of a laser reader on the compact-disc which will have previously received the recording of sounds (voice and music) corresponding to the images
By this double analog and digital recording on the same tape, it will be possible to broadcast in any room either the classic sound, at medium quality; 50it the sound with laser reading of superior quality. This progress will be highlighted for predominantly musical films. The sound playback equipment must be adapted to the duration of the film.
The soundtrack to the film will include dqnc, outside. of the classic analog recording, the digital indications intended for servo-control and image synchronization are
The implementation of this synchronization is greatly facilitated by the very characteristics of the compact disc.

Indeed the speed of the disk is constant, sqit
I, 25 m / second, which promotes attachment to the constant speed of the film.

 Due to the sampling frequency on the compact disc, that is 44.1 KHz, and the organization in frames of 33 bytes comprising 6 samples of 4 bytes, 8 bytes of parity and one byte of control and taking into account from the fact that I225 frames equivalent to 4 frames of the film, we see that there is an overabundance of control bytes.

 Since the film is likely to be broken and then re-glued, the synchronization information must be numbered. Using, for example, a modulo 8 synchronization, corresponding to 12 images of the film, ie every I /? seconds, it will be possible to admit a break of 4 seconds.

Synchronization dialing on the soundtrack can be done using a frequency code. It takes 3 frequencies to perform modulo 8 synchronization (2 power 3). A synchronization decoder is necessary. 3 selective filters followed by a threshold detector. The decoder must then transmit the decoded information to the board.
It is therefore necessary to provide a slight modification on the vector and install a mechanical and electrical interface; that software software (handler). Indeed, a microprocessor is able to record the program chosen by the user, it can therefore also record synchronization orders and move the reader department.

 The numbering of the synchronizations on the disc will be done from the editing and the recording. It will be written numerically in the control bytes or it will occupy 3 eight corresponding to the frequencies retained. If the control bytes are used in parallel with the synchronization, bits Additional information will be required to indicate the type of information contained in the control byte.

Attachments: 3 explanatory figures

Claims (1)

 CLAIM  Slaving system, by digital recording on the soundtrack, of the projection of images from cindma--tographic films and of the reproduction of the sounds linked to these images thanks to a laser-reader typa compact-disc or any other.  The invention is characterized by the inscription on a normal soundtrack, on which are recorded information in magnetic form which will be read by a read head then, by analogy, transformed into sounds, of a series of magnetic information digital which will allow to control the progress of the film on a compact disc with laser reading, the principle of recording and reading is also digital.  The sound recording is carried out independently of the film and the reproduction of the sounds is, thanks to the digital information recorded on the soundtrack, perfectly linked to the projection of the magi.