Method and apparatus for encoding/decoding multi-channel audio signal
Methods of encoding and decoding a multi-channel audio signal and apparatuses for encoding and decoding a multi-channel audio signal are provided. The apparatus for decoding a multi-channel audio signal includes an unpacking extracting which extracts a pilot and data regarding a quantized CLD between a pair of channels of the plurality of channels from the bitstream, a differential decoding unit which restores a quantized CLD by adding the extracted pilot to the extracted data, and an inverse quantization unit which inversely quantizes the restored quantized CLD using a quantization table that considers the location properties of the pair of channels. The methods of encoding and decoding a multi-channel audio signal and the apparatuses for encoding and decoding a multi-channel audio signal can enable an efficient encoding/decoding by reducing the number of quantization bits required.
1. A method of decoding an audio signal, comprising:
receiving a bitstream of an audio signal with a plurality of channels;
obtaining a pilot reference value corresponding to information, the information being related to a quantized channel level difference between two channels among the plurality of channels;
obtaining a pilot difference value corresponding to the pilot reference value;
obtaining the information related to the quantized channel level difference by adding the pilot reference value to the pilot difference value; and
inverse-quantizing the information related to the quantized channel level difference using a quantization table.
2. The method of claim 1 , wherein the inverse-quantizing step comprises:
extracting a quantization mode; and
inverse-quantizing the information related to the quantized channel level difference using a first quantization table when the quantization mode is a first mode, and using a second quantization table when the quantization mode is a second mode.
3. The method of claim 2 , wherein a quantization resolution of the first quantization table is different from that of the second quantization table.
4. The method of claim 3 , wherein the first quantization table have a number of quantization step more than the second quantization table.
5. The method of claim 3 , wherein the first quantization table have a smaller quantization step size than the second quantization table.
6. The method of claim 2 , wherein the quantization mode is determined based on an energy level of a signal to be quantized.
7. The method of claim 1 , wherein the pilot reference value is one of a mean, median and mode of the set of quantized channel level difference.
8. The method of claim 1 , further comprising:
extracting Huffman-encoded information from the bitstream, the Huffman-encoded information being related to a channel level difference between two channels; and
performing Huffman decoding on the extracted Huffman-encoded information.
9. An apparatus of decoding an audio signal, comprising:
an unpacking unit receiving a bitstream of an audio signal with a plurality of channels, obtaining a pilot reference value corresponding to information, the information being related to a quantized channel level difference between two channels among the plurality of channels, and obtaining a pilot difference value corresponding to the pilot reference value;
a differential decoding unit obtaining the information related to the quantized channel level difference by adding the pilot reference value to the pilot difference value; and
an inverse quantization unit inverse-quantizing the information related to the quantized channel level difference using a quantization table.
10. A computer-readable recording medium having recorded thereon a program for executing the method of claim 1 .