Audio copy protection system
AssigneeDCS Copy Protection Limited
InventorsDavid John Michael Robinson, Baolin Tan
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Abstract
An apparatus for applying an anti-copy protection signal for use with switchable head recorders, such as Video Hi-Fi recorders, is described. A high frequency pulsed signal is added to an original signal. The pulses interfere with the compensator circuitry such that the switching of the record head cannot adequately be masked on recording of a signal. On playback, the switching of the recording heads can subsequently be heard. In Video Hi-Fi recorders, the effect of the high frequency signals also interferes with the compressor-expander circuits to worsen the sound of the head switching.
Claims52
An apparatus for applying an anti-copy signal to a signal to be protected, comprising:
- an input for receiving a signal to be protected;
- a compensating circuit configured to add a protection signal to the audio component of the signal to form a protected signal such that when the protected signal is recorded, at least an audio component of the signal is recorded with discontinuities;
- a compensating circuit configured to mask the discontinuities on recording and/or playback, wherein the protection signal impairs the operation of the compensating circuit such that the attempts to mask the discontinuities are audible on playback of a copy;
- and
- an output for outputting the protected signal.
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An anti-copy signal protection method for use by a recording device in which at least an audio component of the signal is recorded with discontinuities, and in which a compensating circuit is employed to mask the discontinuities on recording and/or playback, the method comprising adding a protection signal to the audio component of the signal that impairs the operation of the compensating circuit during recording such that the attempts to mask the discontinuities are audible on playback of a copy.
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A detector for detecting an anti-copy protection signal in a received signal, the detector comprising:
- a pulse detector arranged to identify pulses occurring in the received signal
- an analyzer for determining values for one or more parameters of the pulses detected by the pulse detector;
- control logic associating different values of each parameter with a control instruction for a recording device;
- and
- an output for outputting a signal indicative of the control instruction associated with the values of the parameters of the analyzed pulse to the recording device.
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Dependencies are inferred from the claim text.