Audio code rate control method and system

Abstract

The embodiment of the invention discloses an audio bit rate control method and a system thereof. The method comprises the steps as follows: a sub band for initial coding is determined according to an available bit number; an initial value of the active proportion factor of the sub band is calculated according to the masking threshold value of the sub band; the active proportion factor is adjusted according to the initial value of the active proportion factor of the sub band so as to cause the quantization noise of a sub band frequency-domain coefficient to be smaller than the masking threshold value; the sub band is quantized according to the active proportion factor; coding is conducted to the frequency-domain coefficient after quantization and the bit number needed by the coding is determined; when the bit number needed by the coding is larger than the available bit number, the bit number needed by the coding can be adjusted by adjusting the active proportion factor step by step so as to cause the bit number for coding to be smaller than the available bit number. The method and the system thereof can keep good sound quality on the basis of lowering the algorithm complexity.

Description

technical field [0001] The present invention mainly relates to the field of audio coding and decoding, in particular to an audio code rate control method and system. Background technique [0002] The traditional digital audio compression technology mainly uses waveform coding to achieve data compression by reducing the entropy redundancy of data. This method does not take into account the subjective characteristics of the human hearing effect, the algorithm compression rate is low, and the sound quality is also poor. It is mainly used for the compression of narrowband audio signals, such as A-law coding. In order to transmit better sound quality on a limited network bandwidth, an audio compression technology based on the subjective perception characteristics of the human ear has been developed, and related parties have formulated MPEG-1Audio, MPEG-2Audio, MPEG-2AAC , Advanced Audio Coding), Dolby (AC-3), MPEG-4AAC and other audio compression standards. This audio data comp...

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Problems solved by technology

[0004] The inventor found in the process of realizing the present invention that the prior art has at least the following disadvantages: the prior art requires a large number of calculations, and the calculation is complicated

The inner loop quantizes and encodes the frequency domain coefficients. Each scale factor band is traversed once, and the calculation is complicated; the outer loop calculates the quantization noise of each scale factor band. As long as one subband does not meet the requirements, the inner layer will be called again Loop, resulting in an increase in the number of times the inner loop runs, and an increase in the amount of calculation of the algorithm

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