Apparatus for recording an audio signal with protection against re-recording thereof, and recording apparatus which indicates the presence of such protection
First Claim
1. Apparatus for recording on a record carrier an audio signal comprising a left-hand and a right-hand channel, which apparatus has a first and a second input terminal for receiving the left-hand and the right-hand channel respectively, said first and said second input terminal being coupled respectively to a first and a second input respectively of the recording unit to record the signals applied to its inputs on the record carrier;
- characterized in that;
the first and the second input terminal are coupled to an input of a first and a second filter respectively, which filters are adapted to extract a first and a second low-frequency signal component from the left-hand and the right-hand channel respectively and to apply the first and the second low-frequency signal component to an output;
the output of the first filter is coupled to an input of a first signal-processing unit and the output of the second filter is coupled to an input of the second signal-processing unit;
the outputs of the first and the second signal-processing unit are coupled to the first input and the second input respetively of the recording unit;
the first signal-processing unit is adapted to add a first auxiliary signal to the signal applied to its input and to supply the signal thus processed to its output, and the second signal-processing unit is adapted to add a second auxiliary signal to the signal applied to its input and to supply the signal thus processed to its output; and
the first and second auxiliary signals being such that during reproduction of the audio signal, including the first and the second auxiliary signal added thereto, via two loudspeaker units arranged in a stereo configuration, the auxiliary signals are substantially inaudible to a listener.
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Accused Products
Abstract
Low-frequency components of the left and right channels of the audio signal to be recorded are derived by means of filters (3, 4). First and second auxiliary signals are added to such low-frequency components in such a way that during reproduction of the audio signal so recorded, including the first and the second auxiliary signals added thereto, by means of two loudspeaker units arranged in a stereo configuration, the two auxiliary signals are not audible. However, they will inhibit re-recording by apparatus for recording audio signals which are not copy-protected in the form of the aforesaid two auxiliary signals, or will cause such apparatus to indicate that the audio signal to be re-recorded is protected.
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Citations
23 Claims
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1. Apparatus for recording on a record carrier an audio signal comprising a left-hand and a right-hand channel, which apparatus has a first and a second input terminal for receiving the left-hand and the right-hand channel respectively, said first and said second input terminal being coupled respectively to a first and a second input respectively of the recording unit to record the signals applied to its inputs on the record carrier;
- characterized in that;
the first and the second input terminal are coupled to an input of a first and a second filter respectively, which filters are adapted to extract a first and a second low-frequency signal component from the left-hand and the right-hand channel respectively and to apply the first and the second low-frequency signal component to an output; the output of the first filter is coupled to an input of a first signal-processing unit and the output of the second filter is coupled to an input of the second signal-processing unit; the outputs of the first and the second signal-processing unit are coupled to the first input and the second input respetively of the recording unit; the first signal-processing unit is adapted to add a first auxiliary signal to the signal applied to its input and to supply the signal thus processed to its output, and the second signal-processing unit is adapted to add a second auxiliary signal to the signal applied to its input and to supply the signal thus processed to its output; and the first and second auxiliary signals being such that during reproduction of the audio signal, including the first and the second auxiliary signal added thereto, via two loudspeaker units arranged in a stereo configuration, the auxiliary signals are substantially inaudible to a listener. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13)
- characterized in that;
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2. Apparatus for recording on a record carrier an audio signal comprising a left-hand and a right-hand channel, which apparatus has a first and a second input terminal for receiving the left-hand and the right-hand channel respectively, said first and said second input terminal being coupled respectively to a first and a second input of a recording unit to record the signals applied to its inputs on the record carrier, characterized in that:
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the first and the second input terminal are coupled to an input of a first and a second filter respectively, the first and the second filter being adapted to extract a first and a second low frequency signal component respectively from the left-hand and the right-hand channel respectively and to supply the first and the second low-frequency signal component to an output; the output of at least one of the two filters is coupled to an input of a detector unit adapted to detect the presence of an auxiliary signal in the low-frequency signal component of at least one of the two signal channels and to generate a control signal upon detection of the auxiliary signal and supply the control signal to an output; and the output of the detector unit is coupled to a control-signal input of the recording unit, the recording unit being adapted to inhibit recording in the presence of the control signal and to record the audio signal in the absence of the control signal. - View Dependent Claims (4, 5)
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3. Apparatus for recording on a record carrier an audio signal comprising a left-hand and a right-hand channel, which apparatus has a first and a second input terminal for receiving the left-hand and the right hand channel respectively, said first and said second input terminal being coupled respectively to a first and a second input of a recording unit to record the signals applied to its inputs on the record carrier, characterized in that:
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the first and the second input terminal are coupled to an input of a first and a second filter respectively, the first and the second filter filters being adapted to extract a first and a second low-frequency signal component from the left-hand and the right-hand channel respectively and to supply the first and the second low-frequency signal component to an output; the output of at least one of the two filters is coupled to an input of a detector unit adapted to detect the presence of an auxiliary signal in the low-frequency signal component of at least one of the two channels and to generate a control signal upon detection of the auxiliary signal,, and to supply the control signal to an output; and
the output of the detector unit is coupled to a signalling unit which is adapted to indicate that in the presence of the control signal the audio signal to be recorded is an audio signal which includes the auxiliary signal. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification