Noise-Immune Marking of Digital Audio Signals in Audio Stegosystems with Multiple Inputs and Multiple Outputs
Максим Викторович Гофман · Automatic Control and Computer Sciences · 2022
Abstract Methods for the noise-immune combined marking of digital audio signals with the peculiarities of building audio stegosystems using channels with multiple (spatial) inputs and multiple (spatial) outputs are described. Such audio stegosystems include several loudspeakers (transmitters) and several microphones (receivers), which makes it possible to introduce a marker into the parameters of digital audio signals in the space, frequency, and time. The methods developed for creating, introducing, and extracting a combined marker are aimed at providing a high degree of noise immunity when transmitting a marked audio signal through an airborne audio channel at low embedding forces. The method of creating and introducing a combined marker is based on the transformation of identifying digital information using a synthesized steganographic key into a special sequence and subsequent space–frequency–time coding of digital audio signal parameters by it. Most attention is paid to the development of a method for detecting and extracting an information bit (identification) of a combined marker by an authorized receiver in an audio signal transmitted over an airborne audio channel with interference. This assumes that the authorized receiver does not know the parameters of the digital audio signal that have been marked (blind reception). In the proposed marker extraction method, the decision about its detection is made according to the threshold principle based on the estimation of the peak factor of the kurtosis of the target random variable. The values of the correlation function between the desired sequence (marker) and the sequence extracted from the audio signal received by acoustic microphones and converted to digital form are used as the values of this quantity. The results of full-scale experiments on measuring the noise immunity of the proposed marking method during the transmission of audio signals through an airborne audio channel are presented. Marked audio signals are transmitted by several acoustic speakers and received by a microphone with several capsules. The results of the experiments showed that the methods make it possible to transmit marked audio signals with a high degree of noise immunity in audio stego systems with multiple inputs and multiple outputs at the required low marker embedding forces, which ensure its auditory transparency.