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Adaptive grid construction method and device for bandwidth extension coding

A bandwidth expansion and self-adaptive technology, applied in the field of bandwidth expansion encoding and decoding, can solve the problems of high resolution in the frequency domain, the signal cannot track the original audio signal changes well, and the harmonic signal cannot be accurately restored, so as to improve the encoding efficiency effect

Active Publication Date: 2019-01-08
广东广晟研究开发院有限公司
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Problems solved by technology

[0007] The bandwidth extension coding technology of 3GPP AMR-WB+ has the following problems: (1) high-frequency coding in the time domain cannot obtain higher frequency resolution, because this method can be considered as only one high-frequency area division; The starting frequency band of high-frequency encoding is fixed, which can only be Fs / 4. For 48khz sampling frequency, the starting frequency point of high-frequency encoding is 12khz; (3) the harmonic signal in high frequency cannot be accurately recovered; (4) high The envelope restoration of the frequency signal is not accurate enough
[0008] In addition, there are some bandwidth extension coding techniques. The time-frequency transformation unit uses traditional FFT, and then divides the high frequency into several regions in the frequency domain, and encodes the spectral energy of each region, so each frame can only provide a time-resolved rate multiple frequency resolution
This FFT-based high-frequency reconstruction technology has high frequency-domain resolution but too low time-domain resolution. When a rapidly changing audio signal is input, the high-frequency reconstructed signal cannot track the changes of the original audio signal well.

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Embodiment Construction

[0063] In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

[0064] figure 2 A flowchart of an adaptive grid construction method 100 for bandwidth extension coding according to an embodiment of the present invention is shown. Such as figure 1 As shown, the method 100 includes the following steps:

[0065] Step S110 , based on the transient analysis of the input monophonic audio signal for frequency resolution selection, adaptive multi-resolution QMF filtering is performed on the input monophonic audio signal to obtain an optimal time-frequency filtered signal.

[0066] In this step, first analyze the transient properties of the input mono audio signal in...

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Abstract

The invention relates to a self-adaptive grid construction method and device used for bandwidth extended coding. The method comprises the steps of: S1, based on transient property analysis of input monophonic audio signals, carrying out frequency resolution selection, carrying out self-adaptive multi-resolution filtering on the input monophonic audio signals, and obtaining an optimum time frequency filtering signal; and S2, carrying out transient detection and positioning on each sub-band signal output after the filtering, carrying out self-adaptive grid construction respectively in a frequency direction and a time direction according to the transient property analysis of each sub-band signal and by considering set high frequency band code rates and ear critical frequency band characteristics, and obtaining an optimum time frequency grid under a current code rate. The invention further relates to bandwidth extended coding and decoding methods based on the method. According to the invention, based on audio signal characteristics and high frequency signal available code rate limits, multi-resolution filtering and self-adaptive time frequency grid construction are carried out, and the coding efficiency of high frequency parts of digital audio signals and the sound quality of the high frequency part signals are obviously improved.

Description

technical field [0001] The present invention relates to digital audio codec technology, more specifically, relates to an adaptive grid construction method and device for bandwidth extension coding, and bandwidth extension coding and decoding methods using the method. Background technique [0002] The stereo typical working bit rate of traditional perceptual audio coding technologies (DRA, AAC, MP3, etc.) is 96-128kbps, and the coding quality has obvious subjective perception distortion when it is below 64kbps / stereo. The typical coding bit rate of FM broadcasting application is 48kbps~64kbps / stereo. At this time, the subjective sound quality of traditional sensory audio coding technology can no longer meet the requirements of FM broadcasting. [0003] To this end, a bandwidth extension (BandWidth Extension, BWE for short) coding technology for digital audio signals is proposed. There are many bandwidth extension coding technologies at present, and their performances are als...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G10L21/038G10L19/24
Inventor 闫建新王磊
Owner 广东广晟研究开发院有限公司
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