Anti-copy protection for a video signal

Abstract

An apparatus and method for applying anti-copy protection to a raster-scanned video signal are described. A square waveform 52 is added to the vertical synchronisation pulses 50 of the video signal. The effect of the waveform is not apparent until it has been recorded by a video cassette recorder. The anti-copy protected video signal can therefore be viewed normally on a display device at or near to the picture quality intended by the originator of the video signal, but once recorded, exhibits a reduction in picture quality which makes the video signal quite unattractive to view.

Description

[0001] The present application relates to a method and an apparatus for modifying a raster-scanned video signal such that the modified video signal will still be viewable on a display device, such as a television screen, but that following recording of the modified video signal, playback of the recorded modified signal will be adversely affected. [0002] The present application provides a way of preventing unauthorised copying of an original video signal, and may be used, in particular, to deter copying onto tape of Pay-Per-View video signals, and video-to-video (tape-to-tape) copying. [0003] Video piracy is a significant problem for broadcasters and distributors of video signals, since the unauthorised copying and distribution of video recordings by pirates can impact drastically on the revenue generated by a broadcaster or distributor through legitimate sales. It is therefore desirable to prevent video pirates from making unauthorised copies of video signals. [0004] This is best ac...

AI Technical Summary

Benefits of technology

[0012] An apparatus and method for applying anti-copy protection to a raster-scanned video signal embodying the invention are described in more detail below with reference to the drawings. In a first aspect, a square waveform is added to the vertical synchronisation pulses of the video signal. The effect of the waveform is not apparent until it has been recorded by a video cassette recorder. The anti-copy protected video signal can therefore be viewed normally on a display device at or near to the picture quality intended by the originator of the video signal, but once recorded, exhibits a reduction in picture quality which makes the video signal quite unattractive to view.

[0013] In a second aspect, a positive-going pulse is added to the back porch of the raster scanned video signal such that it is substantially contiguous with the negative-going horizontal synchronisation pulse. The effect of the pulse is again apparent following recording of the video signal by a video cassette recorder. A negative-going pulse 96 may be added after the colour burst 92 and a further positive-going pulse 98 at the start of the active line 84.

Problems solved by technology

The anti-copy protected video signal can therefore be viewed normally on a display device at or near to the picture quality intended by the originator of the video signal, but once recorded, exhibits a reduction in picture quality which makes the video signal quite unattractive to view.

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