Optics: motion pictures – With sound accompaniment – Sound allocation
Reexamination Certificate
1998-05-22
2001-04-03
Adams, Russell (Department: 2851)
Optics: motion pictures
With sound accompaniment
Sound allocation
C352S027000, C352S037000
Reexamination Certificate
active
06211940
ABSTRACT:
TECHNICAL FIELD
The invention relates generally to a storage medium carrying symbols representing digital information, the recovery from a storage medium of symbols representing digital information and the determination of the digital information represented by such symbols. More particularly, the invention relates to storage media carrying the symbols in two dimensions and to the recovery of such symbols by oversampling in two dimensions. While the invention has many applications, the invention is described in connection with preferred embodiments in which the symbols are carried by and recovered from an optical-storage medium, namely, motion picture film, the symbols representing digital information into which motion picture soundtrack and related information is encoded.
BACKGROUND ART
The last two decades have seen an explosion of interest in motion picture sound, in large part triggered by the ever-increasing quality of home high-fidelity systems. There is a continuing interest in new and improved motion picture soundtrack release formats.
Most films today are released with either conventional monophonic (“Academy”) optical soundtracks or with stereo-variable-area (SVA) optical soundtracks with analog noise reduction, which are most widely known under the trademark “Dolby Stereo.” “Dolby” and “Dolby Stereo” are trademarks of Dolby Laboratories Licensing Corporation.
The Academy format, originated in the 1930's, suffers from an extremely poor frequency response. Even though the soundtrack itself may extend to beyond 8 kHz, other elements within the recording and playback chain associated with the format restrict the bandwidth such that the audience will hear very little above 4 or 5 kHz. In addition, the Academy format has relatively high distortion, a barely adequate signal-to-noise ratio and perhaps the greatest shortcoming of all: it is only monophonic (mono).
Dolby Stereo is possibly the first motion picture optical soundtrack format which can truly be called high fidelity, and which is available to all theaters. Even though magnetic soundtracks (on 35 mm and 70 mm film) as long ago as the 1950's had moderately acceptable specifications, the high release print costs were in large part responsible for very few audiences ever hearing the magnetic versions. Stereo optical prints, on the other hand, have no premium cost above conventional optical soundtracks, and this has resulted in wide availability. A large majority of Dolby Stereo films are released “single inventory”—that is, a separate monophonic Academy print is not released because the producer considers the Dolby Stereo film to provide acceptable audible compatibility when played in Academy mono equipped theaters.
The Dolby Stereo optical soundtrack format provides four channels of information (left, center, right and surround) matrix encoded onto the two SVA optical film soundtracks. The original Dolby Stereo format employs Dolby A-type analog audio noise reduction. In the mid-1980's Dolby Laboratories introduced an improved analog audio processing system, Dolby SR, and that system has been applied to many Dolby Stereo films. The use of Dolby SR results in a dramatic improvement in volume range and frequency response. Even in a quiet and well-equipped theater, optical print noise is below the theater's ambient noise floor, while undistorted sound peaks are amply loud for most startling special effects. Frequency response extends to 16 kHz.
In spite of these advances in analog soundtrack fidelity, film soundtracks have long been considered a candidate for digital coding. Digital audio encoding has become integrated into the mainstream of both consumer and professional use. The Compact Disc has earned wide consumer acceptance. As a result, a digital soundtrack would benefit from the popular conception that digital sound is inherently better, an undeniable added attraction at the theater box office.
In addition, a digital soundtrack may provide increased resistance to audible degradation of the soundtrack caused by the wear and tear of commercial exhibition, and can diminish the audible effects of projector wow and flutter. Multiple channels could be supplied on an optical soundtrack for both 35 mm and 70 mm print formats. The soundtrack's frequency and dynamic range specifications could exceed even that of current Dolby Stereo formats.
The recent announcements of two digitally-encoded optical soundtrack formats for 35 mm and 70 mm film, respectively, have reaffirmed the interest which exists in using digital soundtracks to improve motion picture sound in the theater. See “Digital Optical Sound on 35 mm Motion-Picture Film” by Syd Wiles et al,
SMPTE Journal,
November 1990, pp. 899-908 and “The Advent of Cinema Digital Sound” by Clyde McKinney,
The Film Journal,
August 1990, pp. 22 & 43 (a 70 mm system). Unfortunately, both of these formats locate the digital soundtrack information in the area formerly occupied by the analog soundtracks, making the these new digital formats incompatible with existing analog film formats and existing analog projection equipment.
DISCLOSURE OF INVENTION
In accordance with the teachings of the present invention, a new apparatus and method are provided for recovering symbols representing digital information carried by a storage medium. In a further aspect of the invention, a new apparatus and method are provided for determining the digital information represented by the recovered symbols. According to yet a further aspect of the invention, a new configuration of storage medium is provided for carrying symbols representing digital information.
The symbols may be any differentiable symbols capable of representing digital information and capable of being carried in two dimensions by a storage medium. In its broadest aspects, the invention contemplates the use of any medium capable of carrying differentiable symbols encoded two-dimensionally on the medium.
Many prior art techniques for digital information storage and recovery rely upon control or timing information carried by the storage medium apart from the digital information, referred to herein as “flags.” Flags include information that may (1) establish the relationship between time and distance across a storage medium, (2) identify segments of digital information, (3) provide a structure in which digital information may be stored, (4) establish the size and/or storage density of discrete information-carrying areas, or (5) establish the bounds and/or orientation of information-carrying areas. Some examples of these flags include so-called timing tracks, track indexes on random access storage media, media alignment marks, and digital symbols carrying size and/or storage density indicia.
Terms such as “encoded two-dimensionally” or “two-dimensional encoding,” as used herein with respect to symbols, mean that the information represented by the symbols can be determined from only the two-dimensional positioning of the symbols relative to either one another or to any other reference on the medium, and any differentiable characteristic intrinsic to the symbols; there is no need for any flag or flags relating to the symbols or their positions with respect to the medium itself. Examples of a differentiable characteristic intrinsic to the symbols include optical reflectivity or transmissivity, shape, color, size, and orientation. The combination of a differentiable characteristic and relative position, or a locational characteristic, is referred to herein as a differentiable-locational characteristic.
Examples of storage media capable of carrying differentiable symbols encoded two-dimensionally include optical-storage media such as paper, discs, or film; and magnetic-storage media such as paper, tape, or discs.
The invention is particularly advantageous for use with practical storage media in which the position or location and the differentiable characteristics of the symbols are subject to statistical variations, i.e., they are not uniform. For optical-storage media, nonuniformity of differentiable-locational charac
Atherton Mark Leighton
Mandell Douglas Evan
Richards Martin John
Seagrave Charles Gordon
Adams Russell
Dolby Laboratories Licensing Corporation
Fuller Rodney
Gallagher Thomas A.
Gallagher & Lathrop
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