Synthetic sub-band filtering method for audio decoding and synthetic sub-band filter

An audio decoding and synthesizer technology, applied in the field of audio decoding, can solve the problems of difficult chip cost and large area occupied by storage units, and achieve the effects of saving computing resources and storage resources, reducing area overhead, and good scalability.

Inactive Publication Date: 2007-08-29
SHANGHAI MAGIMA DIGITAL INFORMATION
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AI Technical Summary

Problems solved by technology

When implemented in hardware, these multiplication and addition units and storage units for intermediate results need to occupy a large amount of area, especially in a system on a chip, which poses a difficult problem for reducing the cost of the entire chip

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  • Synthetic sub-band filtering method for audio decoding and synthetic sub-band filter
  • Synthetic sub-band filtering method for audio decoding and synthetic sub-band filter
  • Synthetic sub-band filtering method for audio decoding and synthetic sub-band filter

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Embodiment Construction

[0053] During audio decoding, the SubBand Synthesis Filter is usually used to map the demultiplexed multiple (for example, 32) subband frequency domain samples to the time domain, and finally superimpose and output, for example, 32 PCM samples. Complete the audio decoding inverse mapping (inverse mapping) part, which is the largest and most complex unit in the entire MPEG decoding algorithm.

[0054] In the MPEG decoding algorithm, the IDCT coefficient matrix size is, for example, 32*64, and the IDCT coefficient generation formula is as follows:

[0055] IM [ i ] [ k ] = cos [ ( i + 16 ) * ( 2 * k ...

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Abstract

The invention relates to a synthesis subband filtering method and a synthesis subband filter during the audio decoding process, which includes: (a) It inputs a number of frequency-domain samples to form a new point group. (b) During the first stage of IDCT, it converts the new samples group into two intermediate variable arrays and puts them into memory for temporary preservation. (c) During the second stage of IDCT, it gets the intermediate variable arrays from the memory and eliminates redundant IDCT of symmetry by using of the intermediate variables arrays to obtain the IDCT data of time domain samples and puts them into the memory for temporary preservation. (d) It addresses the memory and takes out a number of time domain IDCT data of different frequency of a point sample. (e) It adds window for the IDCT sample data, then it outputs the PCM samples. (f) It repeats step (d) and (e) till it completes all the window-adding about a point sample group.

Description

Technical field [0001] The present invention relates to audio decoding, in particular to a synthetic subband filtering method and a synthetic subband filter in audio decoding. Background technique [0002] The MPEG audio standard is a widely used audio coding and decoding algorithm. This algorithm significantly reduces the transmission bandwidth and storage capacity of audio data, while ensuring the transmission quality of audio data. The sub-band coding method is used in MPEG audio coding. The sub-band coding method uses a set of band-pass filters to divide the frequency band of the input audio signal into several frequency bands, each frequency band is a sub-band, and the audio signal in each sub-band is encoded with a separate coding scheme. In this way, each sub-band signal can be adaptively controlled, and the quantized size can be adjusted according to the energy level of each sub-band. At the same time, each sub-band signal can be assigned according to the perceptual impor...

Claims

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Application Information

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IPC IPC(8): G10L19/14G10L19/00G10L19/022
Inventor 周振亚宋东海刘彦
Owner SHANGHAI MAGIMA DIGITAL INFORMATION
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