| 摘要 |
<P>PROBLEM TO BE SOLVED: To implement transparent audio signal reproduction while significantly reducing a bit rate of multi-channel audio signals for efficient transmission or storage. <P>SOLUTION: A low bit rate digital audio coding system includes an encoder which assigns codebooks to groups of quantization indexes based on their local properties, resulting in codebook application ranges that are independent of block quantization boundaries. The invention also incorporates a resolution filter bank or a tri-mode resolution filter bank, which is selectively switchable between high and low frequency resolution modes or high, low and intermediate modes, for example, when detecting transient in a frame. The result is a multichannel audio signal having a significantly lower bit rate for efficient transmission or storage. A decoder is essentially an inverse of the structure and methods of the encoder, and generates a reproduced audio signal that cannot be audibly distinguished from the original signal. <P>COPYRIGHT: (C)2012,JPO&INPIT |
