Sound coding and decoding apparatus and sound coding and decoding method

Abstract

The invention relates to a Sound coding and decoding apparatus and a sound coding and decoding method. The sound coding and decoding method is characterized in that a digital sound signal is mapped from a time domain to an MDCT domain, a low frequency spectrum and a high frequency spectrum on the MDCT domain are switched to an MDFT domain, the low frequency spectrum on the MDCT domain is subjected to waveform coding operation, and the low frequency spectrum and the high frequency spectrum on the MDFT domain are subjected to parameter coding operation, wherein a specific frequency range of the low frequency spectrum is mapped to a specific frequency range of the high frequency spectrum; at a coding end, the high frequency spectrum before and after frequency spectrum mapping operation is subjected to MDFT domain boundary preprocessing operation; at a decoding end, the high frequency spectrum after frequency spectrum mapping operation is subjected to MDFT boundary preprocessing operation, and the high frequency spectrum after parameter decoding operation is subjected to MDFT domain boundary postprocessing operation. Problems brought by frequency band dividing operation and low frequency spectrum to high frequency spectrum mapping operation in high frequency parameter coding operation are overcome, frequency spectrum continuity and frequency band signal naturalness are improved, harmonic wave interference noise and aliasing noise caused by sidelobe leakage are eliminated, and high frequency parameter coding quality is further improved under the condition of a low code rate.

Description

technical field [0001] The present invention relates to a sound codec device and method, in particular to a monophonic sound codec device and its method, and a stereo sound codec device and method thereof. Background technique [0002] Patent ZL200610087481.X discloses a sound encoding device and method, including: [0003] The time-varying predictive analysis module is used to perform time-varying predictive analysis on digital sound signals to obtain time-domain excitation signals; [0004] A time-frequency mapping module, configured to map the time-domain excitation signal to the transform domain, to obtain the excitation signal on the transform domain; [0005] The encoding module is used to quantize and encode the low frequency spectrum and the middle frequency spectrum in the excitation signal on the transform domain to obtain the low frequency waveform coded data and the intermediate frequency waveform code data; and according to the low frequency spectrum and the mi...

AI Technical Summary

Problems solved by technology

[0009] Since the technology of recovering the high frequency spectrum from the low frequency spectrum and the medium frequency spectrum changes the natural positional relationship and energy size between the frequency bands of the original signal, it will bring a series of problems and affect the coding quality of the high frequency parametric coding

For example: the frequency band division in the high-frequency parameter coding cuts off the correlation between the spectral lines of the original signal, especially when the frequency resolution of the mapped domain signal is very high, the transition band between the frequency bands is very narrow, which destroys the spectrum. Continuity and naturalness of frequency band signals; low spectrum to high spectrum mapping may also cause superposition of two harmonic signals at the splicing point, resulting in harmonic interference noise; for the splicing between the frequency bands after low spectrum to high spectrum mapping, Aliasing noise is introduced due to sidelobe leakage due to suboptimal performance of the prototype filter

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