| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a low-bit-rate audio encoding system which achieve transparent audio signal reproduction while reducing the bit rate of a multichannel audio signal. <P>SOLUTION: A low-bit-rate digital audio encoding system includes an encoder which allocates a codebook to a group of quantization indexes based upon local characteristics thereof, and generates an application range of the codebook independent of a block quantization border. Further, a resolution filter bank or a 3-mode resolution filter bank is also incorporated which can be switched selectively between a high- and a low-frequency resolution mode, or among a high, a low, and an intermediate mode when detecting a transient in a frame. Consequently, a multichannel audio signal is actualized which has bits greatly reduced for efficient transmission or storage. A decoder has a structure and a method which are substantially reverse to those of the encoder, and generates a reproduced audio signal which cannot be auditorily discriminated from the original signal. <P>COPYRIGHT: (C)2012,JPO&INPIT |
