| 摘要 |
PURPOSE:To reduce the deterioration in the localization of a reproduced sound by equalizing the quantization bit number of a sub-band with a small level difference between channels when an audio signal comprising plural channels is subjected to high efficiency coding. CONSTITUTION:Frequency analysis filters 111, 121 apply frequency analysis to a digital audio signal for each channel and provide the output of a sub-band signal. Maximum value detectors 112, 122 obtain the maximum absolute value of the sub-band signal for each frame. Required bit number calculation devices 117, 127 calculate the number of bits required for quantizing each sub-band signal. Initial bit allocation devices 118, 128 allocate an initial bit to a sub-band whose bit request number is a threshold number or over. When additional allocation is attained, an additional bit allocation device 19 allocates additional bit so that the bit allocation value of the sub band having a small level difference between channels is equal to each other based on a maximum value signal. |
