6. The method of claim 3 , wherein the extracting a MDCT-based tempo feature from the music content summary includes: extracting the MDCT coefficients by decoding a part of the music content summary; selecting an MDCT coefficient of a predetermined sub-band from the MDCT coefficients; extracting an MDCT modulation spectrum (MS) from the selected MDCT coefficient by performing a Discrete Fourier Transformation (DFT); and dividing the extracted MDCT-MS into N sub-bands and extracting energy from the sub-bands usable as an MDCT-MS-based tempo feature.
6. The method of claim 3 , wherein the extracting a MDCT-based tempo feature from the music content summary includes: extracting the MDCT coefficients by decoding a part of the music content summary; selecting an MDCT coefficient of a predetermined sub-band from the MDCT coefficients; extracting an MDCT modulation spectrum (MS) from the selected MDCT coefficient by performing a Discrete Fourier Transformation (DFT); and dividing the extracted MDCT-MS into N sub-bands and extracting energy from the sub-bands usable as an MDCT-MS-based tempo feature. 7. The method of claim 6 , wherein, in the extracting a similarity feature for a similarity retrieval from the music content summary, a centroid, a bandwidth, a flux, and a flatness according to the MDCT-MS-based tempo feature are extracted as the similarity features.