Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1998-11-30
2002-05-14
Boccio, Vincent F. (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C386S349000
Reexamination Certificate
active
06389218
ABSTRACT:
BACKGROUND OF THE DISCLOSURE
1. Field of the Invention
The invention relates to video-on-demand systems and, more particularly, the invention relates to a method and apparatus for simultaneously generating compressed play and trick play bitstreams from a video frame sequence.
2. Description of the Background Art
In a video-on-demand system such as the OnSet™ system manufactured by DIVA Systems Corporation, a file server is used for streaming video information to users (subscribers) of the system. The OnSet™ system is described in U.S. Pat. No. 6,253,375, issued Jun. 26, 2001, and the file server is described in U.S. Pat. Nos. 5,671,377 and 5,581,778. The disclosures of this application and these patents are incorporated herein by reference. The OnSet™ system contains service provider equipment coupled through an information distribution network to subscriber equipment. This system provides subscribers VCR-like controls to enable a subscriber to select information content, for example, a movie, then play, fast forward, rewind, pause, or stop the selected movie. The subscriber enters control commands through the subscriber equipment and the service provider equipment executes the commands to fulfill the purpose of the command, e.g., play, fast forward, rewind, stop or pause the movie.
A file server forms a portion of the service provider equipment and stores, for a given movie, a standard play stream (i.e., an MPEG-2 compressed video bitstream), a fast forward stream and a fast reverse play (rewind) stream. The fast forward and fast reverse streams are also MPEG-2 compressed video, where the fast forward stream is a compressed signal containing only every Nth frame of the uncompressed play video and the fast reverse stream is a compressed signal containing every Nth frame of the uncompressed play video played backwards. To store the video information, each stream is divided into portions (e.g., N-byte segments of compressed data) and striped onto a disk array. The disk array stores all the information that the file server can directly access.
The process for generating the fast forward and fast reverse streams is time consuming and expensive. The process requires a frame by frame analysis of the video stream to enable the frames to be encoded in an MPEG-2 compliant form, yet provide a fast forward and fast reverse effect when decoded. As such, the video sequence is processed to extract every Rth frame (i.e., one of every R frames, where R is an integer greater than 1) to form a fast forward sequence and then the fast forward sequence is encoded (compressed). For a fast reverse stream, a sequence of frames in reverse order is created and encoded. Such encoding can cost $17 to $20 per minute of video. This encoding process can not be used for producing fast forward and fast reverse streams in real time such that a real time program can be encoded and stored for almost immediate use of VCR-like functions.
Therefore, there is a need in the art for an improved encoding system for a video-on-demand system to ensure real-time availability of fast forward and fast reverse functions.
SUMMARY OF THE INVENTION
The disadvantages associated with the prior art are overcome by the invention of an “all-in-one” encoder that simultaneously produces an MPEG-2 compliant fast forward, fast reverse and play bitstreams from a sequence of video frames, e.g., 601-format video. The encoder of the present invention subsamples the video sequence, extracting a plurality of frames from the video sequence and buffering the subsampled frames. Simultaneous with the subsampling and buffering, the source frames are encoded within a real-time encoder, e.g., an MPEG-2 encoder. The buffered frames are recalled from the buffer and coupled to a second real-time encoder. The second encoder forms both the fast forward and fast reverse bitstreams using a time multiplexing technique wherein a group of pictures (GOP) for the fast forward stream can be formed, followed by the compression of the same GOP having the frames organized in reverse order. As such, the compressed GOPs are represented by the fast forward and fast reverse bitstreams. The play, fast forward, and fast reverse bitstreams for each GOP are organize into a file and stored on the mass storage device (e.g., disk drive array) of the file server.
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Gordon Donald F.
Ludvig Ted
Boccio Vincent F.
DIVA Systems Corporation
Moser Patterson & Sheridan LLP
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