To provide a sub-band coding and decoding method used for companding a digital audio signal that enhances accuracy of a sub-band signal to improve decoding reproduction quality such as sound quality.
A sub-band division processing section 101 applies sub-band division to a received PCM signal and a scale factor extract section 104 extracts a scale factor. A difference value extract section 103 extracts a difference of a scale factor between this frame and a preceding frame and an absolute value of the difference is given to a Huffman coding section 105. A sign bit determination section 102 calculates a sign bit of each scale factor. The scale factor extract section 104 extracts the scale factor from samples of all sub- bands. A bit assignment section 106 calculates bit assignment information. A quantization processing section 107 encodes the sub-band signal on the basis of the bit assignment information as a sample value. Difference information 201 of the scale factors, a sign bit 202 and sets of sample information 203-205 are fed to a frame forming section 108, where they are formed into a frame of a bit stream.
TANIGUCHI SHOHEI
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