Encoding method, encoding device, decoding method, and decoding device using scalar quantization and vector quantization

A decoding method comprising:

• receiving a bitstream comprising a first residual signal and a second residual signal;
• performing a lossless decoding of the first residual signal included in the bitstream;
• performing a scalar dequantization of the first residual signal to which a scalar quantization, derived through a roundoff operation, is applied;
• performing a vector dequantization of processing the second residual signal as a vector based on a table, which is expressible in a fixed bitrate;
• reconstructing the second residual signal;
• generating an output signal by applying a scale factor to a final residual signal, which is based on the first residual signal and the second residual signal;
• and
• converting the output signal from a frequency domain into a time domain.

An encoding device comprising a processor, wherein

• the processor is configured to:
• convert an input signal of a time domain into a frequency domain;
• generate a first residual signal by applying a scale factor corresponding to each sample to an input signal of a frequency domain;
• perform a scalar quantization by applying a roundoff operation to the first residual signal;
• generate a second residual signal by using the first residual signal generated based on the scale factor and the scalar-quantized first residual signal;
• perform a lossless encoding of the scalar-quantized first residual signal;
• perform a vector quantization of processing the second residual signal as a vector based on a table, which is expressible in a fixed bitrate;
• and
• transmit a bitstream comprising the lossless-encoded first residual signal and the vector-quantized second residual signal,
• wherein the scale factor is generated in every sub-band unit of a frequency domain allocated nonlinearly to the input signal converted into the frequency domain.