Abstract:
Auxiliary data (x(m)) is transported in a primary data signal (s(t)) by hiding the data in the form of colored noise. The colored noise has a spectrum that simulates the spectrum of the primary data signal. The data to be transported is first converted to a spread spectrum signal d(t). The primary data signal is analyzed to determine its spectral shape. The same spectral shape is imparted to the spread spectrum signal, which is then combined with the primary data signal for transmission. The spectral shaping can be performed using time domain modeling and synthesis such as linear predictive coding (88, 94) or by using subband coding techniques such as fast Fourier transforms (174). A plurality of different auxiliary information streams (280, 290, 300) can be transported on the primary data signal. By adjusting the gain (287, 297, 307, 309) of individual spread spectrum signal carrier(s) and the power (96) of the colored noise, the auxiliary information stream(s) can be rendered at any desired level below or above an interference threshold in the primary data signal.
Abstract:
Reproduction of a data signal which is stored on a source media (140) or distributed via a communication network is controlled by inserting master tag data (130) and control tag data (160) into the data signal. A player/recorder (150) inserts an additional generation of control tag information each time a copy of the media is made. If the number of generations of the control tag information is above a threshold value, reproduction of the data signal may be inhibited. For example, if the data signal comprises audio data, the player/recorder may only allow playing of the audio signal over speakers but will not allow recording. The playing and recording of associated signals, which accompany an audio signal, may also be controlled. The master tag data (130) and control tag data (160) may be provided as spread spectrum signals which are spectrally shaped and power-adjusted according to the data signal to render them imperceptible in the data signal.
Abstract:
Auxiliary data (x(m)) is transported in a conventional audio signal (s(t)) by hiding the data in the form of colored noise (y(t)). The colored noise has a spread spectrum that simulates the spectrum of the primary audio signal. The data to be transported is first converted to a spread spectrum signal (p(n)). The primary audio signal is analyzed to determine its spectral shape (88). The same spectral shape is imparted to the spread spectrum signal (94), which is then combined with the primary audio signal for transmission (100). The spectral shaping can be performed using time domain modeling and synthesis such as linear predictive coding (88) or by using subband coding techniques such as fast Fourier transforms. A plurality of different auxiliary information streams can be transported on the audio signal. By adjusting the gain of individual spread spectrum signal carrier(s) and the power of the colored noise (98), the auxiliary information stream(s) can be rendered inaudible in the primary audio signal, or at any desired level below or above an audible threshold.
Abstract:
Auxialiary data subband samples representing an auxiliary data signal (315) are transported in a subband-coded compressed digital audio signal without decompressing the data. A pre-existing packetized data stream (305) is provided to an input of an encoder (310). Subband audio samples (406) are extracted from the packet stream and normalized (408). The data to be transported modulates data carrier subbands (SPD0, SPD1, ---SPDN-1) including a pseudo-noise (PN) spread spectrum signal, each subband of which has a bandwidth corresponding to those of the digital audio signal. The modulated data carrier sequence is combined with the audio subband samples (SS1, SS2---SSN-1) to form a combined signal (452), then multiplexed (460) into pre-existing packet stream (407). In the decoder (368), the combined signal is demodulated to recover the auxiliary data signal (672). The recovered auxiliary data signal is carried substantially inaudibly in the audio signal and is spectrally shaped according to the audio signal to enhance concealment.