Method and apparatus for encoding and decoding layered audio

Abstract

The invention discloses a hierarchical coding and decoding method and the device thereof. In the embodiment of the invention, the hierarchical and coding decoding proposal adopts the steps as following, after an input signal is converted into a MLT (Modulated Lapped Transform) coefficient, according to an auditory perception model, the input signal is divided into a kernel layer signal and an enhancement layer signal, and then an overlapped and packed coding data is obtained; during decoding, according to the auditory perception model, after the weighted calculation is performed to the importance of each sub-band in the enhancement layer, the reverse MLT is performed to the obtained MLT coefficient of the kernel layer and the enhancement layer, and the decoding flow is output. Compared with the prior hierarchical coding decoding art, in the invention, the MLT is performed to the input signal, the weighted calculation is performed to the importance of each sub-band in the enhancement layer according to the auditory perception model, thus, the quality of coding and decoding is enhanced, and the problem that the input signal with high sampling rate can not be effectively processed in the prior art is solved.

Description

technical field [0001] The present invention relates to codec technology, in particular to a layered audio codec method and device. Background technique [0002] With the rapid development of multimedia technology, audio codecs are more and more widely used in digital audio broadcasting, high-quality audio transmission on the Internet, digital movies, and so on. [0003] An important feature of the audio codec system is to make the audio codec system adaptable to different application environments. The audio layerable coding technology was developed under this requirement. The layerable feature means that the audio signal is organized in the form of layers, and the signal is divided into low-quality parts and high-quality parts. The low-quality part of the signal is the audio signal The core layer, the high-quality part of the signal is the enhancement layer of the audio signal, and the low-quality part can be decoded without any information about the high-quality part. Th...

AI Technical Summary

Problems solved by technology

However, for input signals with 32,000Hz, 44,100Hz or 48,000Hz sampling frequency, this processing method will have great defects

For example, a sub-band near 16,000 Hz has a larger envelope value, but it may not reach the perceivable threshold of the human ear, that is, the human ear is not sensitive. If more bits are allocated to this sub-band, it will As a result, the really important subbands do not have enough bits to encode and affect the encoding quality

This method may also cause the important sub-bands sensitive to the human ear to be ranked behind the code stream because of the small envelope value, and will be discarded first when the network condition is not good, which will affect the user's hearing experience

That is to say, the layered audio codec method of the prior art cannot effectively solve the situation of high sampling frequency signal input

[0032] 2) The QMF used in the prior art increases the complexity of the codec algorithm and increases the delay of the codec algorithm

The CELP encoding used for the core layer signal is designed to adapt to the characteristics of the voice signal, and it is not suitable for other types of signals with the same low frequency, which will affect the encoding and decoding effect

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