Computer graphics processing and selective visual display system – Computer graphics processing – Attributes
Reexamination Certificate
2000-09-30
2003-03-25
Zimmerman, Mark (Department: 2671)
Computer graphics processing and selective visual display system
Computer graphics processing
Attributes
C345S589000, C345S503000, C345S600000
Reexamination Certificate
active
06538658
ABSTRACT:
TECHNICAL FIELD
The present invention relates to computers, and more particularly to methods and apparatus for processing a Digital Versatile Disk (DVD) data stream using a computer.
BACKGROUND ART
The emergence of DVD (Digital Versatile Disk) technology presents a tremendous market growth opportunity for the personal computer (PC). It also presents a significant technical challenge to the highly cost-competitive PC market, namely providing a cost effective PC architecture that provides the digital video performance and quality that the user demands while also remaining flexible enough to support a range of other PC applications.
As known, DVD technology presents a significant leap forward for today's multimedia PC environment. In addition to providing backward compatibility to CD-ROM, current DVDs provide a storage capacity of between 4.7 GB and 17 GB, which is at least about 8 times the storage capacity of a typical CD. To support this increased storage capacity, DVD devices, such as DVD-ROM drives, typically provide bandwidths in excess of 10 Mb/s. By combining DVD technologies with video compression technologies, such as MPEG-2 video compression techniques, and audio compression technologies, such as MPEG-2 and AC-3 audio techniques, a PC can deliver better-than-broadcast quality television (TV) to a video display device and an audio reproduction device.
DVD also presents an avenue for PC technology to migrate to various new market segments. DVD is being embraced not only by the PC industry, but also by the entertainment and consumer electronics industries. As such, many PC manufacturers and software developers consider DVD to represent the next step in turning desktop PCs into full-fledged entertainment appliances. For example, new products, described as everything from entertainment PCs to set-top PCs and PC-TVs, are beginning to be promoted. By way of example, manufacturers such as Gateway and Compaq are beginning to ship products tailored specifically for delivering video and computer-based entertainment in the home. Additionally, Philips has recently announced its DVX8000 Multimedia Home Theatre product that is targeted for the living room and based on the PC architecture. Recognizing and promoting this trend, Microsoft is attempting to define a unique set of platform requirements for this new breed of “Entertainment PC”.
While the future looks very bright for DVD on various PC platforms, there's the immediate problem of how to make the technology work within the constraints of today's PC architecture as well as the extremely cost-sensitive reality of the PC marketplace. MPEG-2 standards present an especially difficult problem, because of the amount of processing that is required to decode and decompress the typical 5 Mb/second MPEG-2 video signal into a displayable video signal. Additionally, the accompanying audio signal also needs to be decoded and possibly decompressed. Consequently, PC architectures having DVD capabilities tend to be too costly for the mainstream market and/or lack the necessary performance to perform adequately.
To achieve its goals of quality, storage and data bit-rate, the DVD video standard leverages several existing audio and video compression and transmission standards, including MPEG-2 video and both AC-3 and MPEG-2 audio. By way of example,
FIG. 1
depicts a typical DVD processing pipeline in which a DVD data stream is received, for example, from a DVD-ROM drive and/or from a remote device, and converted into a decoded and decompressed digital video signal and corresponding digital audio signal(s).
A DVD data stream consists of sequential data packets, each of which typically includes various system information, video information and audio information. The DVD video decode pipeline
10
depicted in
FIG. 1
has been broken down into three high-level processing stages, namely a system stream parsing stage
12
, a video processing stage
14
, and an audio processing stage
16
. Additional information regarding these processing stages and others, and the DVD and MPEG-2 standards are provided in the DVD specification, entitled DVD Specification, Version 1.0, August 1996, and in the MPEG-2 video specification ISO/IEC 13818-1, 2, 3 is available from ISO/IEC Copyright Office Case Postale 56, CH 1211, Genève 20, Switzerland, each of which are incorporated herein, in their entirety and for all purposes, by reference.
In system stream parsing stage
12
, the incoming DVD data stream is split or demultiplexed and/or descrambled, for example using CSS decryption techniques, into three independent streams: a MPEG-2 video stream
15
, a MPEG-2 (or AC-3) audio stream
17
, and a sub-picture stream
13
. By way of example, in certain embodiments, the MPEG-2 video stream
15
can have a bit-rate as high as approximately 9 Mb per second, and the audio stream
17
(MPEG-2 or AC-3) can have a bit-rate as high as approximately 384 Kb per second. The sub-picture stream
13
tends to have a relatively lower bit-rate, and includes sub-picture information that can be incorporated into the final digital video signal as on-screen displays ( OSDs), such as menus or closed captioning data. The MPEG-2 video stream
15
and sub-picture stream
13
are then provided to video processing stage
14
for additional processing. Similarly, the audio stream
17
is provided to audio processing stage
16
for further processing.
Video processing stage
14
, as depicted in
FIG. 1
, includes three sub-stages. The first sub-stage is a DVD sub-picture decode
18
stage in which the sub-picture stream
13
is decoded in accordance with the DVD specification. For example, DVD allows up to 32 streams of sub-picture that can be decoded into a bitmap sequence composed of colors from a palette of sixteen colors. As mentioned above, the decoded sub-pictures are typically OSDs, such as menus, closed captions and sub-titles. In accordance with the DVD specification, the sub-picture(s) are intended to be blended with the video for a true translucent overlay in the final digital video signal.
The second sub-stage of video processing stage
14
is a MPEG-2 decode sub-stage
20
in which the MPEG-2 video stream is decoded and decompressed and converted to a YUV 4:2:2 digital video signal. In accordance with the MPEG-2 specification, MPEG-2 decode sub-stage
20
conducts a Variable Length Decode (VLD)
22
, an inverse quantization (IQUANT)
24
, an Inverse Discrete Cosine Transform (IDCT)
26
, motion compensation
28
, and a planar YUV 4:2:0 to interleaved 4:2:2 conversion
30
. These processing sub-stages are necessary because the MPEG-2 specifies that certain pictures, called I frames or pictures, are “intra” coded such that the entire picture is broken into 8×8 blocks which are processed via a Discrete Cosine Transform (DCT) and quantized to a compressed set of coefficients that, alone, represent the original picture. The MPEG-2 specification also allows for intermediate pictures, between “I” pictures, which are known as either predicted (“P” pictures) and/or bidirectionally-interpolated pictures (“B” pictures). In these intermediate pictures, rather than encoding all of the blocks via DCT, motion compensation information is used to exploit the temporal redundancy found in most video footage. By using motion compensation, MPEG-2 dramatically reduces the amount of data storage required, and the associated data bit-rate, without significantly reducing the quality of the image. Thus, for example, motion compensation allows for a 16×16 “macroblock” in a P or B picture to be “predicted” by referencing a macroblock in a previous or future picture. By encoding prediction pointers—called motion vectors—MPEG-2 is able to achieve high compression ratios while maintaining high quality.
The resulting YUV 4:2:2 and decoded sub-picture digital video signals are then provided to the third sub-stage
21
of video processing stage
14
which the YUV 4:2:2 and decoded sub-picture digital video signals are blended together in an alpha blend process
32
to produce a translucent ov
Koninklijke Philips Electronics , N.V.
Padmanabhan Mano
Zimmerman Mark
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