Apparatus and method for encoding a multi-channel signal and a program pertaining thereto

An encoding method of encoding for compression a multi-channel signal including digital signals from a plurality of channels by framing the multi-channel signal, determining a number of steps of quantizing data in the frame, and performing entropy coding of the digital signals, the method comprising the steps of:

• calculating a sum of code length in a current frame as a provisional number of in-use bits for each channel of the plurality of channels by performing entropy coding of the digital signals based on a provisional number of quantizing steps provisionally determined for quantizing the digital signals;
• allocating a number of bits usable for each channel based on a ratio of the provisional number of in-use bits for each channel with a total provisional number of in-use bits, which is a sum of the provisional numbers of in-use bits for all the plurality of channels, and
• adjusting the number of in-use bits for each channel based on the number of usable bits allocated to the channel,
• in which the calculating step includes dividing data in the current frame into units of coding, normalizing data included in the units of coding using a number of scale factors to obtain normalized data, determining the provisional number of quantizing steps based on the number of scale factors, quantizing the normalized data on the basis of the determined provisional number of quantizing steps to obtain quantized normalized data, and entropy coding the quantized normalized data and obtaining the provisional number of in-use bits
• in which the adjusting step includes:
• calculating a re-calculated number of quantizing steps on the basis of the provisional number of quantizing steps for each channel and a comparison of the provisional number of in-use bits for each channel with the corresponding number of usable bits, wherein the re-calculated number of quantizing steps is greater than the provisional number of quantizing steps when the provisional number of in-use bits is less than the number of usable bits for the corresponding channel and is less than the provisional number of quantizing steps when the provisional number of in-use bits is greater than the number of usable bits for the corresponding channel,
• quantizing the normalized data on the basis of the re-calculated number of quantizing steps, and
• entropy encoding the re-calculated quantized normalized data and obtaining a number of in-use bits, wherein the entropy encoding includes comparing the number of in-use bits for each channel with the corresponding number of usable bits and obtaining an adjusted number of in-use bits, which is less than or equal to the usable bits, by increasing the number of quantizing steps of the re-calculated quantized normalized data when the number of in-use bits for each channel is less than the corresponding number of usable bits and by decreasing the number of quantizing steps of the re-calculated quantized normalized data when the number of in-use bits for each channel is greater than the corresponding number of usable bits.

A computer readable recording medium having a program recorded therein for allowing a computer to encode for compression a multi-channel signal including digital signals from a plurality of channels by framing the multi-channel signal, determining a number of steps of quantizing data in the frame, and performing entropy coding of the signals, the program comprising the digital steps of:

• calculating a sum of code length in a current frame as a provisional number of in-use bits for each channel of the plurality of channels by entropy coding of the digital signals based on a provisional number of quantizing steps provisionally determined for quantizing the digital signals;
• allocating a number of bits usable for each channel based on a ratio of a provisional number of in-use bits for each channel with the total provisional number of in-use bits, which is a sum of the provisional numbers of in-use bits for all the plurality of channels, and
• adjusting the number of in-use bits for each channel based on the number of usable bits allocated to the channel,
• in which the calculating step includes dividing data in the current frame into units of coding, normalizing data included in the units of coding using a number of scale factors to obtain normalized data, determining the provisional number of quantizing steps based on the number of scale factors, quantizing the normalized data on the basis of the determined provisional number of quantizing steps to obtain quantized normalized data, and entropy coding the quantized normalized data and obtaining the provisional number of in-use bits, and
• in which the adjusting step includes:
• calculating a re-calculated number of quantizing steps on the basis of the provisional number of quantizing steps for each channel and comparison of the provisional number of in-use bits for each channel with the corresponding number of usable bits, wherein the re-calculated number of quantizing steps is greater than the provisional number of quantizing steps when the provisional number of in-use bits is less than the number of usable bits for the corresponding channel and is less than the provisional number of quantizing steps when the provisional number of in-use bits is greater than the number of usable bits for the corresponding channel, the re-calculated number of quantizing steps is less than the provisional number of quantizing steps,
• quantizing the normalized data on the basis of the re-calculated number of quantizing steps, and
• entropy encoding the re-calculated quantized normalized data and obtaining a number of in-use bits, wherein the entropy encoding includes comparing the number of in-use bits for each channel with the corresponding number of usable bits and obtaining an adjusted number of in-use bits, which is less than or equal to the usable bits, by increasing the number of quantizing steps of the re-calculated quantized normalized data when the number of in-use bits for each channel is less than the corresponding number of usable bits and by decreasing the number of quantizing steps of the re-calculated quantized normalized data when the number of in-use bits for each channel is greater than the corresponding number of usable bits.