METHOD OF IDENTIFYING AUDIO FILE CONTAINING DIGITAL WATERMARK Russian patent published in 2010 - IPC G06K9/00 

FIELD: information technology.

SUBSTANCE: invention relates to methods of identifying audio files (AF) containing digital watermarks (DW). The format of the audio file is determined before multilevel discrete wavelet transformation. If the format is compressed, the compressed audio file is converted to an analogue signal. After that voltage of the input analogue signal is converted to digital pulses in a digital reading device, where the said pulses are converted to a code which corresponds to the voltage value of the input signal. Based on multilevel discrete wavelet transformation, a characteristic vector is formed, the Mahalanobis distance to centre of gravity of the first (audio file contains a digital watermark) and second (audio file does not contain digital watermark) classes is calculated and the class to which the analysed audio file belongs is determined from the minimum calculated distance.

EFFECT: possibility of identifying compressed and uncompressed format audio files containing digital watermarks when there is no prior information on presence of a watermark in the given audio file and information on the rule for embedding the digital watermark.

2 dwg, 2 tbl