auCDtect - is a program for determining the authenticity of musical CD records, using the character of the audio information it contains, and predict its possible source is it an original studio record or a reconstruction from a lossy encoded data (for example, MP3).
The algorithm is based on the analysis of the Fourier-spectra of the signal time segments during all the record and on the calculation of the character bound frequency on every time segment. Based on the analysis of spectral statistical properties and on a number of criteria, the source of the audio record is determined . if it is an original or lossy encoded audio file. The testing is carried out using both modern and old records of poor quality. It has shown a good accuracy of the algorithm, which differentiates original records and that reconstructed from lossy encoded data.
It is no secret that the Internet and file-exchanging networks are literally overloaded with music. The plenty of various formats which compress music files just favors this situation. Files in formats with lossy encoding and the highest degree of compression, like MP3, have got the greatest prevalence. While playing such files using cheap acoustic systems one can hardly distinguish their dissimilarity from the original ones, but all the distortions become evident when listening such disks on a Hi-Fi systems or using stereo headphones, especially if one has an opportunity to compare a record with its original. That is why when purchasing musical compact-discs a question always arises: whether the disc is a pirate fake or not. To answer this question, spectral characteristics of the signal can be used, because in contrast to the original records, the lossy algorithms significantly distort the spectral characteristics of the signal.