| 摘要 |
<p>When e.g., digital audio signals of at least two channels are orthogonally transformed to perform the bit compression, the temporal size and the shape of the window of the orthogonal transforming block are changed with a drastical change of amplitude of the input signal. At this time, if the correlation between the channels is high to a certain degree, the temporal length of the orthogonal transforming block of each channel is equalized. As a result, the difference of tone quality between the channels is suppressed, the feeling of localization of sound image is improved, and an excellent sound quality is obtained. In addition, at the same bit rate, a better sound quality is achieved, and at a lower bit rate, an equivalent sound quality is enabled. An aurally desirable temporal length of the processing block for the compression of temporally varying information signals can be determined. Therefore, high-efficiency compression and expansion can be performed with an aurally excellent sound quality. <MATH></p> |
