Signal encoding method and apparatus and signal decoding method and apparatus
A spectrum coding method includes quantizing spectral data of a current band based on a first quantization scheme, generating a lower bit of the current band using the spectral data and the quantized spectral data, quantizing a sequence of lower bits including the lower bit of the current band based on a second quantization scheme, and generating a bitstream based on a upper bit excluding N bits, where N is 1 or greater, from the quantized spectral data and the quantized sequence of lower bits.
1. A spectrum coding method comprising:
quantizing, by at least one processor, spectral data for an important spectral component of a non-zero band based on a first quantization scheme;
extracting a lower bit from the quantized spectral data;
generating a sequence of lower bits by collecting lower bits of the quantized spectral data for all non-zero bands;
quantizing, by the at least one processor, the sequence of lower bits based on a second quantization scheme;
performing, by the at least one processor, first lossless coding on a number, a position and a sign of the important spectral component;
performing, by the at least one processor, second lossless coding on magnitude information which is constructed by excluding the lower bit from the quantized spectral data;
performing, by the at least one processor, third lossless coding on the quantized sequence of the lower bits; and
generating, by the at least one processor, a bitstream by using data provided from the first lossless coding, the second lossless coding and the third lossless coding.
2. The method of claim 1 , wherein the first quantization scheme is based on scalar quantization.
3. The method of claim 2 , wherein the scalar quantization uses a uniform quantization step size.
4. The method of claim 1 , wherein the quantizing the sequence of lower bits is performed based on a difference between the spectral data and the quantized spectral data.
5. The method of claim 1 , wherein the second quantization scheme is based on trellis coded quantization.
6. The method of claim 1 , wherein a bandwidth of the spectral data is either a super wide band or a full band.
7. The method of claim 1 , wherein the spectral data is obtained by performing modified discrete cosine transform and normalization on an input audio signal.
8. The method of claim 1 , wherein the spectral data is coded in a normal mode.
9. A spectrum coding apparatus comprising at least one processor configured to:
quantize spectral data for an important spectral component of a non-zero band based on a first quantization scheme;
extract a lower bit from the quantized spectral data;
generate a sequence of lower bits by collecting lower bits of the quantized spectral data for all non-zero bands;
quantize the sequence of lower bits based on a second quantization scheme;
perform first lossless coding on a number, a position and a sign of the important spectral component;
perform second lossless coding on magnitude information which is constructed by excluding the lower bit from the quantized spectral data;
perform third lossless coding on the quantized sequence of the lower bits; and
generate a bitstream by using data provided from the first lossless coding, the second lossless coding and the third lossless coding.
10. The spectrum coding apparatus of claim 9 , wherein the first quantization scheme is based on scalar quantization.
11. The spectrum coding apparatus of claim 10 , wherein the scalar quantization uses a uniform quantization step size.
12. The spectrum coding apparatus of claim 9 , wherein the at least one processor is configured to quantize the sequence of lower bits based on a difference between the spectral data and the quantized spectral data.
13. The spectrum coding apparatus of claim 9 , wherein the second quantization scheme is based on trellis coded quantization.
14. The spectrum coding apparatus of claim 9 , wherein a bandwidth of the spectral data is either a super wide band or a full band.
15. The spectrum coding apparatus of claim 9 , wherein the spectral data is obtained by performing modified discrete cosine transform and normalization on an input audio signal.
16. The spectrum coding apparatus of claim 9 , wherein the spectral data is coded in a normal mode.