| 摘要 |
A method and apparatus to encode/decode a low bit-rate audio signal. The method of encoding a low bit-rate audio signal, includes quantizing and losslessly-encoding a specific frequency component of an audio signal in a frequency domain, generating codebooks using the audio signal in the frequency domain, detecting an envelope of a frequency component of the audio signal other than the specific frequency component in a specific band unit and quantizing and losslessly-encoding the detected envelope of the other frequency component, selecting a codebook that is most similar to the other frequency component of the audio signal to be encoded from among the generated codebooks and determining a codebook index (fine structure), losslessly-encoding the determined codebook index, and generating a bit stream using the specific frequency component, the envelope of the other frequency component, and the determined codebook index. The method of decoding a low bit-rate audio signal, includes restoring and dividing a bit stream into a specific frequency component and a frequency component other than the specific frequency component, losslessly-decoding and inversely quantizing the specific frequency component, restoring codebook index information and envelope information about the other frequency component, generating codebooks using the specific frequency component which is inversely quantized, and restoring the other frequency component using the restored codebook index information and the restored envelope information about the other frequency component.
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