Anti-copy protection for a video signal
AssigneeDCS Copy Protection Limited
InventorsArie Wijnen, Baolin Tan
Life of this patent
Estimating the term…
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.
Claims20
Apparatus for applying anti-copy-protection to a raster-scanned video signal to produce a modified video signal, the apparatus comprising:
- an input for receiving a video signal, the video signal having a vertical synchronisation pulse;
- circuitry configured to modify the vertical synchronisation pulse of the video signal received by the input to produce a modified video signal, the modified signal being viewable on a display device at or near to the quality intended by the originator of the video signal but such that after recording by a recording device, the recorded signal exhibits a reduction in vertical stability when played back and viewed on the display device;
- and
- an output configured to output the modified video signal.
Apparatus for applying anti-copy-protection to a raster-scanned video signal to produce a modified video signal, the apparatus comprising:
- an input for receiving a video signal which is to be modified, the video signal having a vertical synchronisation pulse;
- circuitry configured to modify the vertical synchronisation pulse of the video signal received by the input to produce a modified video signal, the circuitry adding a waveform to the vertical synchronisation pulse with an amplitude at least equal to that of the vertical synchronisation pulse, and
- an output configured to output the modified video signal.
A method for adding anti-copy-protection to a raster-scanned video signal to produce a modified signal, comprising:
- receiving a video signal which is to be modified, the video signal having a vertical synchronisation pulse;
- modifying the vertical synchronisation pulse of the video signal such that the modified video signal is viewable on a display device at or near to the quality intended by the originator of the video signal, but such that after recording by a recording device, the recorded signal exhibits a reduction in vertical stability when played back and viewed on the display device;
- and
- outputting the modified signal.
A method for applying anti-copy-protection to a raster-scanned video signal to produce a modified video signal, the method comprising:
- receiving a video signal which is to be modified, the video signal having a vertical synchronisation pulse;
- modifying the vertical synchronisation pulse of the video signal received by the input to produce a modified video signal, the modifying means adding a waveform to the vertical synchronisation pulse with a frequency of at least 500 KHz and with an amplitude at least equal to that of the vertical synchronisation pulse, and
- outputting the modified video signal.
A method comprising:
- outputting from an electronic device a raster-scanned video signal having a modified vertical synchronisation pulse such that the video signal can be viewed on a display device at or near the quality intended by the originator of the video signal, but such that after recording by a recording device, the recorded signal exhibits a reduction in vertical stability when played back and viewed on the display device.
An apparatus comprising:
- circuitry configured to output a raster scanned video signal having a vertical synchronisation pulse modified to include a waveform with an amplitude at least equal to that of the vertical synchronisation pulse such that a time duration of the modified vertical synchronisation pulse is substantially the same as a time duration of the vertical synchronisation pulse before modification.
Dependencies are inferred from the claim text.