Optical discs for storing multimedia presentations playable in different formats

#This invention relates to the generation of audio signals during play of a software (e.g., motion picture) carrier, and more particularly to a technique by which multiple dialog languages may be recorded on separate audio tracks of the same carrier without requiring a full track for each language version.

#The most widespread medium for distributing motion pictures is the videocassette. The conventional practice is to provide only one language soundtrack on each videocassette. This means that different versions of the same motion picture must be prepared for distribution in different countries. Rather than to dedicate a different version of the same motion picture to each of several different languages, it would be far more advantageous to provide all desired sound tracks, containing different dialog languages, on the same carrier; this would require the production of far fewer versions of the same motion picture. Because of the large storage requirements, however, this has not proven to be practical. In fact, the only practical consumer use of multiple sound tracks on the same carrier is the provision of annotated and non-annotated soundtracks in some laserdisc releases. (It is possible, for example, to store different soundtracks in the digital and analog audio channels of a laserdisc.)

#Despite the fact that it has occurred to others in the prior art to provide multiple soundtracks on the same software carrier, certainly the provision of perhaps a dozen different soundtracks, in different dialog languages, all on the same consumer software carrier, is not to be found anywhere. Not only are there no consumer players capable of selecting one from among so many different soundtracks, but software publishers have just not found it practical to store so much audio information on a single carrier. The traditional approach is to publish different versions of the same motion picture for distribution in different territories where different languages are spoken.

#Further objects, features and advantages of the invention will become apparent upon consideration of the following detailed description in conjunction with the drawing, in which:

#FIG. 1 depicts a prior art system and typifies the lack of flexibility in, and the poor performance of, presently available media players;

#FIG. 2 depicts the illustrative embodiment of the invention;

#The limitations of the prior art are exemplified by the system of FIG. 1. Such a system is presently available for playing a single source of program material, usually a VHS videocassette, to generate a video signal conforming to a selected one of multiple standards. A system of this type is referred to as a multi-standard VCR, although stand-alone components are shown in the drawing. Typically, a VHS tape 7 has recorded on it an NTSC (analog) video signal, and the tape is played in a VHS player 5. The analog signal is converted to digital form in A/D converter 9, and the digital representations of successive frames are written info video frame store 11. Circuit 13 then deletes excess frames, or estimates and adds additional frames, necessary to conform to the selected standard, e.g., PAL. To convert from one standard to another, it is generally necessary to change the number of horizontal lines in a field or frame (image scaling). This is usually accomplished by dropping some lines, and/or repeating some or averaging successive lines to derive a new line to be inserted between them. The main function of circuit 13, of course, is to convert a digital frame representation to analog form as the video output

#Systems of the type shown in FIG. 1 generally degrade the video output. Conventional videocassettes deliver reduced quality video when they support more than one video standard. One reason is that there is a double conversion from analog to digital, and then back again. Another is that the image scaling is usually performed in a crude manner (deleting lines, repeating lines and averaging lines). There are known ways, however, to perform image scaling in the digital domain without degrading the picture. While not generally used, the technique is in the prior art and will therefore be described briefly as it is also used in the illustrative embodiment of the invention.

#To give a concrete example, the PAL standard has 625 lines per frame, while the NTSC standard has 525 lines per frame. Because no part of the image is formed during the vertical retrace, not all of the horizontal line scans in either system are usable for representing image information. In the PAL standard there are nominally 576 lines per frame with image information, and in an NTSC frame there are nominally 483 lines with image information.