Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1998-07-08
2001-11-27
Rao, Andy (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
C375S240160
Reexamination Certificate
active
06324217
ABSTRACT:
The invention relates to information distribution systems and, more particularly, the invention relates to a method of generating an information stream, such as a movie information stream, suitable for use in an information distribution system.
BACKGROUND OF THE DISCLOSURE
In several communications systems the data to be transmitted is compressed so that the available bandwidth is used more efficiently. For example, the Moving Pictures Experts Group (MPEG) has promulgated several standards relating to digital data delivery systems. The first, known as MPEG-1 refers to ISO/IEC standards 11172 and is incorporated herein by reference. The second, known as MPEG-2, refers to ISO/IEC standards 13818 and is incorporated herein by reference. A compressed digital video system is described in the Advanced Television Systems Committee (ATSC) digital television standard document A/53, and is incorporated herein by reference.
The above-referenced standards describe data processing and manipulation techniques that are well suited to the compression and delivery of video, audio and other information using fixed or variable length digital communications systems. In particular, the above-referenced standards, and other “MPEG-like” standards and techniques, compress, illustratively, video information using intra-frame coding techniques (such as run-length coding, Huffman coding and the like) and inter-frame coding techniques (such as forward and backward predictive coding, motion compensation and the like). Specifically, in the case of video processing systems, MPEG and MPEG-like video processing systems are characterized by prediction-based compression encoding of video frames with or without intra- and/or inter-frame motion compensation encoding.
Information distribution systems utilizing information streams conforming to the above standards or subsets of the above standards are known. For example, an interactive digital video on demand (VOD) service known as the OnSet™ system is manufactured by DIVA Systems Corporation of Menlo Park, Calif. The OnSet™ system distributes audio-visual information to individual subscribers utilizing MPEG-like information streams. The OnSet™ system also allows subscribers to interactively control the delivery of audio-visual information using consumer-friendly commands, such as fast-forward (FF), rewind (REW), pause (PAUSE), play (PLAY) and the like.
The OnSet™ system utilizes additional information streams to provide a so-called movie information screen (MIS) feature to subscribers. The MIS feature comprises a substantially motionless image, such as from a movie or other audio-visual program, displayed on a subscriber's display device. The MIS, which is typically accompanied by a related audio track, functions as a “barker” tending to induce impulse subscriber purchases of the movie or other audio-visual program.
Unfortunately, existing methods for generating MIS information streams disadvantageously require extensive encoding of video information to produce well-behaved bitstreams, i.e., bitstreams that do not cause decoder buffer underflow or overflow. For example, an MIS information stream generated by repeatedly encoding an image will produce a well-behaved MIS bitstream at the cost of significant computational resources and time (e.g., two to 30 minutes to encode a two minute MIS display or presentation).
Therefore, it is seen to be desirable to provide a rapid, computationally efficient method for generating well-behaved MIS information streams.
SUMMARY OF THE INVENTION
The invention comprises a method and apparatus for processing an image to produce an encoded video information stream comprising a sequence of replicated group of picture (GOP) information structures, each GOP including an intra-coded frame (I-frame) and a plurality of forward predictive coded frames (P-frames), wherein the I-frame of the initial GOP is formed by intra-coding the still image, and each P-frame comprises, e.g., a substantially zero motion vector P-frame. Optionally, the encoded video information stream is multiplexed with an encoded audio information stream to produce a system stream suitable for use in an MPEG-like information processing system. The invention generates standards compliant, MPEG-like bitstreams suitable for implementing, e.g., the above-described movie information screen (MIS) feature.
Specifically, a method according to the invention for processing an image to produce a compressed information stream comprises the steps of: intra-coding the image to produce an intra-coded information frame (I-frame); associating the intra-coded information frame with a plurality of forward predicted information frames (P-frames) to form a group of pictures (GOP); and replicating the GOP to produce the compressed information stream.
An apparatus according to the invention for processing an image to produce an MPEG-like information stream comprises: a frame encoder, for producing an intra-coded (I-frame) in response to said image, and for producing N number of forward predicted information frames (P-frames) in response to said I-frame, where N is an integer; a memory, for storing said I-frame and said N number of P-frames; and a controller, for causing said memory to repetitively output said I-frame and said N number of P-frames as a video elementary stream.
REFERENCES:
patent: 5867208 (1999-02-01), McLaren
patent: 6005562 (1999-12-01), Shiga et al.
patent: 6091460 (2000-07-01), Hatano et al.
patent: 6125140 (2000-09-01), Wilkinson
patent: 6141385 (2000-10-01), Yamaji
DIVA Systems Corporation
Moser Patterson & Sheridan LLP
Rao Andy
LandOfFree
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