Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1997-10-08
2001-04-03
Tran, Thai (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C380S201000, C380S213000
Reexamination Certificate
active
06212325
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and an apparatus for processing a video signal and a recording medium which are arranged to reliably protect a copyright of a high-quality video signal obtained from a video disk, a digital VCR, or a receiving unit for a digital broadcast.
2. Description of the Related Art
With advance of digital technology, people are likely to easily obtain a high-quality video signal at home. For example, a pre-recorded tape (video tape package) as well as a digital broadcasting receiving terminal and a digital video disk supply a high-quality video signal.
The supplier of the high-quality video signal adds a copyguard signal to the video signal for protecting the copyright of a program represented by the video signal. This copyguard signal inhibits recording of the program with a video tape recorder (VTR). For example, the copyguard signal employs two kinds of systems called a pseudo horizontal synchronous pulse and a color stripe supplied by the Macrovision Corporation.
For realizing a copyguard function, as shown in
FIG. 1
, the system called the pseudo horizontal synchronous pulse is arranged to insert a pseudo horizontal synchronous pulse in the vertical blanking interval of the video signal for putting an AGC (Automatic Gain Control) circuit of the VTR to an erroneous operating state and thereby degrading the image quality to an impracticable level. For the same purpose, as shown in
FIG. 2
, the system called the color stripe is arranged to invert a phase of 2 to 4 lines of a color burst signal at every 20 lines, for example, for inverting the color of the image reproduced by the VTR and thereby degrading the image quality to an impracticable level.
By the way, all the influence of the copyguard signal for inhibiting to record the high-quality video signal at home is disallowed to be assured in the TV market. It means that the copyguard signal may interfere with the market of a certain TV set.
That is, in general, the TV set provides a relatively large time constant and a narrow frequency response range of an APC (Automatic Phase Control) circuit used for forming a carrier wave for color demodulation based on a color burst signal. If, therefore, the color stripe system inverts the phase of the four consecutive lines of the color burst signal at every about 20 lines, it gives no influence to the color demodulation. However, some TV sets may provide a small time constant and a wide frequency response range of the APC circuit. In those TV sets, the hue-inverted band appears on the screen.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a method and an apparatus for processing a video signal and a storage medium which are arranged to reliably prevent copying of a video signal by a VTR without interfering with the image display on the TV set and thereby supply a high-quality video signal with a high copyguard function.
An apparatus for processing a video signal according to the present invention includes: a signal generating unit for generating a copyguard signal; a selector for replacing a color burst signal of the video signal with the copyguard signal; and wherein the signal generating unit operates to generate the copyguard signal composed of at least two kinds of modulations of a burst phase, the copyguard signal having a different phase from an original phase of the color burst signal of the video signal.
In the apparatus for processing a video signal according to the present invention, the signal generating unit operates to alternately output a U-axis inverted burst signal produced by inverting a U-axis component of the burst phase and a V-axis inverted burst signal produced by inverting a V-axis component of the burst phase as the copyguard signal at each horizontal scanning period. The signal generating unit operates to alternately output a one-axis inverted burst signal produced by inverting one of a U-axis component and a V-axis component of the burst phase and a V-axis inverted burst signal produced by inverting a V-axis component as the copyguard signal at each horizontal scanning period. The signal generating unit operates to sequentially output a U-axis inverted burst signal produced by inverting a U-axis component of the burst phase, a V-axis inverted burst signal produced by inverting a V-axis component of the burst phase, and a both-axes inverted burst signal produced by inverting both of the U-axis/V-axis as the copyguard signal at each horizontal scanning period.
In the apparatus for processing a video signal according to the present invention, the selector operates to replace all of the color burst signal with the copyguard at each horizontal scanning period. The selector operates to replace part of the color burst signal with the copyguard signal at each horizontal scanning period. The selector operates to replace the color burst signal with the copyguard signal at each alternate horizontal scanning period with one middle horizontal scanning period of the normal burst phase laid therebetween.
A method for processing a video signal according to the present invention includes the steps of generating a copyguard signal composed of at least two kinds of modulations of a burst phase, the copyguard signal having a different phase from an original phase of the color burst signal of the video signal; and; replacing the color burst signal of the video signal with the copyguard signal.
In the method for processing a video signal according to the present invention, at least two of a U-axis inverted burst signal produced by inverting a U-axis component of the burst phase, a V-axis inverted burst signal produced by inverting a V-axis component of the burst signal, and a both-axes inverted burst signal produced by inverting the U-axis/V-axis components are selected as the copyguard signal at each horizontal scanning period and then each of the inverted burst signals is exchanged with the color burst signal of the video signal. In the method for processing a video signal according to the present invention, the copyguard signal is exchanged with part or all of the color burst signal at each horizontal scanning period. Further in the method for processing a video signal according to the present invention, the copyguard signal is exchanged with the color burst signal at each alternate horizontal scanning period with one middle horizontal scanning period of the normal burst phase laid therebetween.
A recording medium according to the present invention includes a recording area for recording a video signal and a control area for recording control information for copyguarding a video signal reproduced from the recording area and is characterized in that the control area records control information for specifying selection of at least two of a U-axis inverted burst signal produced by inverting a U-axis component of a burst phase, a V-axis inverted burst signal produced by inverting a V-axis component, and a both-axes inverted burst signal produced by inverting a U-axis/V-axis as a copyguard signal at each horizontal scanning period and specifying replacement of the color burst signal of the video signal with the copyguard signal.
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patent: 5784523 (1998-07-01), Quan et al.
patent: 5940134 (1999-08-01), Wirtz
patent: 5982977 (1999-11-01), Naruse et al.
patent: 6035094 (2000-03-01), Kori
patent: 6041158 (2000-03-01), Sato
patent: 0 710 020 (1996-05-01), None
Frommer William S.
Frommer Lawrence & Haug LLP.
Shallenburger Joe H.
Sony Corporation
Tran Thai
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