Video time-shifting apparatus - Patent Review 5701383

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FIELD OF THE INVENTION

The present invention relates generally to the storage and retrieval of video programming and, more particularly, to a system operative to produce a time-shifted version of an incoming video program to give an operator the type of control over the program ordinarily associated with local storage,

BACKGROUND OF THE INVENTION

One reason for the immense popularity of the video rental industry is that cassette-stored programming gives the viewer total control over playback operations. Not only can the purchaser choose to watch a movie when desired, but also functions such as PAUSE, FAST FORWARD and REWIND may be used to take a break from viewing, review material of interest, or advance beyond portions which previously have been viewed or which may be of no interest to the viewer.

Programs broadcast in real time do not offer such viewer conveniences. With the advent of cable distribution and the ongoing increase in channel capacity, a greater number of video programs will become available, including numerous feature-length movies. Accordingly, some industry observers have proposed two-way cable systems wherein the same movie may be broadcast over different channels at slightly staggered starting times, so that viewers may be able to switch between these channels, thereby simulating VCR-like operator controls such as PAUSE, FAST FORWARD and REWIND. However, these schemes do a poor job of simulating operator control, due to the relatively large temporal transitions involved; furthermore, they are extremely wasteful of bandwidth, which could otherwise be used for entirely different programs, thereby satisfying a larger audience.

Sara et al. (U.S. Pat. No. 5,134,499) disclose an apparatus for recording video to provide the equivalent of a variable-length "tape-delay," preferably by way of magneto-optical disc storage. However, recording capacity is limited, and when the record optical head assembly reaches the end of the track at the outer edge of the disc, it must be repositioned rapidly to the beginning of the track, which requires the use of buffer means to ensure that no signal content is lost during the mechanical repositioning process. Furthermore, Sara et al. provide only minimal provisions for control of the operation of the read optical head assembly, including only those provisions necessary to position the read optical head assembly at a particular point at which to begin playback of the program material.

Goldwasser et al, U.S. Pat. No. 5,241,428 discloses a variable-delayed video recorder, including a user control panel which enables playback of previously recorded material to be temporarily stopped and then resumed without interrupting the recording of new material. If there are portions of the program that the user does not wish to see (e.g., commercials), he can speed (i.e., FAST FORWARD) through those recorded portions and catch up to the live broadcast. The user can also rewind and replay portions of the program as the video recorder continues to record the program. However, in all embodiments of the invention the video program material is effectively stored in a FIFO (first-in, first-out) buffer of variable length so that the user can view the video material in the sequence in which it is broadcast, while varying the delay between recording and playback. Additionally, the "random access" embodiment of the invention is based upon retrieving stored samples from a memory, thus requiring an algorithm to control the storage and retrieval of such samples, a complication that could be avoided through a continuous and uninterrupted recording.

Therefore there remains an unsatisfied need for a video time-shifting apparatus capable of recording a full-length program without discontinuity and without the need for extensive, auxiliary buffering. Such a system should not only support asynchronous recall of the program, but should provide a user with sophisticated, VCR-like controls over the program, such as PAUSE/RESUME, REVIEW, REWIND, and FAST FORWARD. Additionally, as the user may be interested in accessing particular points in either the incoming or any time-shifted version of the program, facilities to communicate playback progress and to mark points of interest would also prove convenient.

SUMMARY OF THE INVENTION

The present invention is directed toward a video time-shifting system including storage means, disposed in a video path between a video input and output, and configured as a continuous recording track accessed by separate, asynchronous read and write facilities. Broadly, under operator control, reading may occur at any point on the continuous recording track, and playback of the program may begin therefrom, thus simulating VCR-like program control features such as PAUSE/RESUME, REVIEW, REWIND, and FAST FORWARD. The system may be disposed in a separate housing or form part of a video cassette recorder, television receiver, monitor, personal computer, or any other piece of equipment associated with the viewing of video-based programming.

In the preferred embodiment, the video storage means takes the form of a magnetic disk drive having multiple, asynchronous read and write heads, and a controller which links separate recording tracks which may be present on separate recording surfaces, into a single, continuous recording track. More specifically, a dual-sided disk is used with a pair of write heads directly above and below one another, and the positioning system which moves them as an integral unit inwardly and outwardly along a radial path. A pair of read heads are further provided and mechanically linked above and below one another to access the upper and lower surfaces of the disk for playback purposes, using separately controlled actuators so that the write and read heads do not interfere mechanically. With such a configuration, the disk may spin at constant speed, with the write heads moving slowly as a unit between the inner and outer edges associated with their respective disk surfaces, with one of the write heads recording information representative of the incoming video program as a continuous spiral track. When the writing head reaches an innermost or outermost extent of its associated track, recording is immediately switched to the other write head, and movement of the heads is reversed, thereby linking the tracks present on the upper and lower surfaces into a single, continuous track, without the need for extensive buffering of the program as received. Switching of the read heads, being similarly joined into a physical unit, may also immediately switch at such turnaround points, to ensure that readout may likewise occur on a smooth, continuous basis. Although, in the preferred embodiment, a pair of read and write heads are used in conjunction with a two-sided recording surface, different write and read heads may be used in conjunction with different recording surfaces, so long as the system controller is able to perform the necessary switching to link separate recording tracks into a single track so as to avoid discontinuities in the reading and writing program.

A memory is used to store information relating to various points in the program so that, for example, when a PAUSE command is received, the memory stores information relating to that point in the program, and when a RESUME command is received, playback automatically commences from that point, thereby outputting the program time shifted by the delay between the receipt of the two commands. When paused, the system preferably outputs a FREEZE FRAME, and even upon receipt of multiple PAUSE commands, the system automatically keeps track of correct program re-entry.

In the case of a REVIEW command, previously recorded points of the program are rapidly accessed and displayed. That is, the program moves backwards while the REVIEW command is activated, for example, using an associated button on a remote control, until such time that the button is no longer depressed, at which time normal display of the program commences, but from a point in the program previous to real time. The system is also capable of REWIND in the sense that any previously recorded point of the program may be immediately accessed, with playback commencing therefrom, similar to a REWIND function with a VCR in the STOP mode, except that, owing to the advantageous implementation of the invention, such an operation is carried out in a near instantaneous manner.

If a time-shifted version of the program is being output for any reason, a FAST FORWARD command may be entered, in which case playback is speeded up until deactivation of the command, at which time normal playback resumes, resulting in the output of the program exhibiting a reduced time shift, including a zero time shift in the event the operator "catches up" with the incoming program as it is being received.

Optional operator controls enable the viewer to jump ahead in the program, for example, to advance in increments of 30 seconds so as to avoid the viewing of commercial advertisements.

The system preferably further includes a video display generator to output for viewing on the display device visual indicia relating to the program and, additionally, symbols relating to one or more points in the program and/or the time-shifted version thereof. The system is optionally further operative to accept a MARK command associated with a user-defined point in the program, and commence playback directly therefrom.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a system which provides operator control over an incoming v