| 摘要 |
<p>In a high efficiency encoding method in which pre-set bit allocation is made for digital information signals of plural channels and in which coded information signals are produced by the allocated bits, it is desirable to avoid sound quality deterioration produced by pre-echo during abrupt changes in the information signals as well as to suppress pre-echo to ensure aurally desirable bit allocation. To this end, in a high efficiency encoding method in which digital information signals (31, 41) of plural channels are normalized by normalizing units (37, 47) and pre-set bit allocation is made by a bit allocation unit (38) to effect pre-set bit allocation, the amounts of bit allocation between channels are controlled on the basis of temporal changes of the information signals of the respective channels. Also, the amounts of bit allocation between channels are controlled based on temporal changes of the amplitude information of digital information signals of the respective channels. At least a part of the bits that may be used for bit allocation is preferentially allocated for channels having larger temporal changes of the information signals depending on the magnitude of temporal changes of the information signals among the plural channels. As a result, deterioration in the sound quality due to pre-echo during high efficiency encoding may be prevented in a system having plural audio signal channels. <IMAGE></p> |
