Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Reexamination Certificate
1996-12-19
2001-06-19
Rao, Andy (Department: 2613)
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
Reexamination Certificate
active
06249551
ABSTRACT:
FIELD OF THE INVENTION
My invention relates to video playback of compressed digital video signals, and more particularly to interactive video playback from an MPEG-compressed bitstream.
BACKGROUND OF THE INVENTION
MPEG is a series of software standards for digital video compression with good efficiency for a package type medium, such as for entertainment and educational software. In “interactive video playback,” the user expects that the video playback is instantaneous from a compressed bitstream recorded, for example, on a CD-ROM. However, time is required for the read head to search for the target track, and unlike other media that record video in raw data format, such as a laser disk (using PCM recording by FM), video playback from a CD-ROM introduces certain unavoidable delays. This has become a key problem in using MPEG technology for real time entertainment and educational software.
The two predominant MPEG standards are referred to as MPEG-1 and MPEG-2. The MPEG-1 standard generally concerns inter-field data reduction using block-based motion compensation prediction (MCP), which generally uses temporal differential pulse code modulation (DPCM). The MPEG-2 standard is similar to the MPEG-1 standard, but includes extensions to cover a wider range of applications, including interlaced digital video such as high definition television (HDTV).
SUMMARY OF THE INVENTION
My invention analyzes the problem of this delay time from two aspects and offers a solution called interactive buffering (I-buffering). Generally, the delay in video playback relative to the time at which it was accessed includes the times required for the read head to move to the target track on the disk and for conducting error correction, and delays occurring because the decoding buffer of the MPEG decoder has filled the bitstream.
Because high speed video recording equipment requires high-density-storage media, such as CD-ROMs, complex error corrections must be performed at high speed. As a result, large scale data interleaving and error correction must be performed, increasing the processing time an order of magnitude. Also, MPEG decoding converts variable-rate input data into expanded, constant-rate output data. Thus, to enable a constant-rate output of decoded video signal, a large quantity of the MPEG-encoded signal should be prestored in a decoding buffer upstream of the MPEG decoder. To indicate the upstream buffer size, a parameter indicating the VBV-buffer size can be encoded in the data bitstream.
In a first embodiment of my video playback method (post-buffering), first, by means of a first access, a video playback signal is output based on a signal held in a special buffer called an I-buffer. Then, by means of a second access, the video playback signal from the MPEG decoding means is consecutively output. Also, in a second embodiment (pre-buffering), by means of a first access, a signal held in the I-buffer is output as a video playback signal by decoding at the MPEG decoding means, and by means of a second access, a portion of signal that has not been held by the I-buffer is connected at the MPEG decoding means, and output as an decoded consecutive video playback signal.
In a separate configuration of my invention, a video playback system is offered that uses pre-buffering.
REFERENCES:
patent: 5521918 (1996-05-01), Kim
patent: 5576736 (1996-11-01), Miwa et al.
patent: 5617502 (1997-04-01), Ort et al.
patent: 5664044 (1997-09-01), Ware
patent: 5734862 (1998-03-01), Kulas
patent: 5751893 (1998-05-01), Shimoda et al.
Petersen Bret J.
Rao Andy
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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