Television – Image signal processing circuitry specific to television – Special effects
Reexamination Certificate
1997-04-08
2001-03-13
Lee, Michael (Department: 2714)
Television
Image signal processing circuitry specific to television
Special effects
C348S554000, C348S705000, C348S663000, C348S552000
Reexamination Certificate
active
06201580
ABSTRACT:
BACKGROUND OF THE INVENTION
1. The Field of the Invention
The present invention relates generally to computer video systems and, more specifically, to computer video systems that support multiple video resources. More specifically still, the present invention relates to apparatus for providing the multiplexing of a plurality of video sources for processing within a computer system for display.
2. Prior Art
Video processing in a computer system, along with the use of a graphics controller for display of the processed video signal, is well-known in the computer arts. Multimedia computer systems utilize video processing in order to provide more and greatly diversified resources in a computer system. Various resources of video include S-video, composite video, and RF sources such as over-the-air broadcast or cable input. These types of video sources are analog signals that must be converted to digital signals for processing prior to output to a video monitor typically connected to the graphic controller of the computer system.
Before the signal can be decoded and transformed into digital signals, the analog signal must be broken into separate components, specifically, the Y signal or luma and the C component or chroma. When the signal is an S-video analog signal, the Y and C components of the signal are already separated. In a composite signal, both the Y and the C component are combined to form a composite signal that must be separated into the luma and chroma portions before further processing of the analog signal can be performed.
Currently, computer systems may be able to accept input from selected analog video sources such as a composite signal or an S-video signal, but have not been able to handle multiple input signals, whether from the same source, or in a more complicated arrangement, from different types of sources. The different types of sources may be one signal input of a composite signal and another of an input signal may be an S-video analog signal. Further complicating this is when a signal tuner is provided that tunes an analog video signal from a broadcast source, which also has a composite type signal combining the Y and the C components of the analog signal.
Without being able to handle multiple video resources, a computer system would be limited to showing but a single display source in along a single video path. In today's multimedia environment, it is often desirable to be able to switch between a first and a second source, as well as to be able to display a primary source with a secondary source in a picture-in-picture (PIP) window much smaller than the primary image somewhere on the display screen or to be able to simultaneously extract vertical blanking interval (VBI) information. Thus, to display multiple video sources, a system must be able to receive multiple input sources, decode the analog video sources and then pass them to the appropriate signal decoders and graphics processors for translating the analog signals into a digital format for display on a video monitor or other processing.
SUMMARY OF THE INVENTION
According to the present invention, a multiplexing apparatus for use in a computer system is disclosed. The multiplexing system is typically designed for multiplexing various sources of video signal inputs for subsequent processing. The multiplexing apparatus includes at least one analog video input, but preferably has more than one, a programmable analog switch, and a plurality of video outputs. The programmable analog switch couples to the analog video inputs and selectively multiplexes the analog video input signal. The plurality of video outputs are further coupled to the programmable analog switch, and they receive the multiplexed video signal from the analog video input for processing through at least a first video stream. Additional video streams are also possible for processing for a single input signal.
Proper signal isolation typically requires an isolation capacitor be provided for each of the plurality of video inputs. Further, a signal input buffering means is also provided for at least one of the at least one analog video inputs. The programmable analog switch further includes a first stage and a second stage. Each stage is capable of receiving at least one of the analog video inputs and being output to at least one of the plurality of video output connectors. The first stage receives a first portion of an analog video signal input through the video connector, while the second stage receives a second portion of the analog video signal. These analog video signals can include an S-video signal or a composite video signal, both of which include a chroma portion and a luma portion corresponding to the first portion and second portion, respectively. This particular video multiplexing system is implemented in a computer system and further includes a method of multiplexing.
The method of directing signals to various output sources is as follows. Initially, at least one analog video signal is input. Next, this particular analog signal is then controlled in a selective manner via a programmable design for subsequent output to at least one video stream. Further, additional video streams are contemplated as are additional input analog video signals that would be handled much in the same way as the at least one input analog video signal.
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Philips Semiconductors, TDA8540 4×4 Video Switch Matrix, Philips Semiconductors, p. 1, Feb. 6, 1995.
Barker John C.
Voltz Christopher
Compaq Computer Corporation
Desir Jean W.
Lee Michael
Sharp Comfort & Merrett P.C.
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