发明授权
US5327182A Method and apparatus for reading photographically recorded digital audio soundtracks 失效
用于读取照相录制的数字音频声轨的方法和装置

Method and apparatus for reading photographically recorded digital audio
soundtracks
摘要:
A method and apparatus for reading digital audio signals photographically recorded on a medium (such as motion picture film). If the medium has multiple, spatially separated digital and analog audio soundtracks, a photosensitive detector array is employed for each of the digital audio soundtrack areas, and a separate analog soundtrack read head is employed. Preferably, digital error code is recorded in a digital soundtrack area of the medium (with digital audio bits), and error detection and correction are performed on the recorded digital audio bits read from the medium. Preferably, the apparatus includes switching circuitry for substituting a corresponding analog audio signal for one or more corrupted digital soundtrack channels, when such digital soundtrack channels have an error rate which exceeds a selected threshold. Also preferably, the invention reads recorded digital audio information by projecting a laser beam (having a near infrared wavelength) on a row of a digital soundtrack area of a motion picture film, to modulate the beam as it passes through the row. The radiation transmitted through each digital soundtrack bit area is projected onto a spot in the detector plane that is substantially larger than the dimension of each individual detector which receives the spot. As the film translates continuously relative to the radiation source so that the projection of the spot translates relative to each receiving detector, the output of each receiving detector is integrated over the period during which a portion of the spot is projected thereon.
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