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Method for implementing audio coder-decoder

A technology of an audio codec and an implementation method, applied in the implementation field of low-complexity high-quality wideband audio codec, can solve the problem of increasing the fixed data storage requirement of the codec, affecting the quality of decoded audio, and reducing the quality of decoded audio, etc. problem, to achieve sufficient dynamic range, sufficient auditory positioning, and reduce the effect of sound quality loss

Inactive Publication Date: 2007-01-31
昆山杰得微电子有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the disadvantages of doing so are obvious, mainly in that, firstly, using the frequency band analysis model based on human acoustic hearing will significantly increase the amount of calculation in the process of encoding and decoding; The constants used to represent the model need to be saved additionally in the corresponding codec
However, the number of model constants that need to be saved in the commonly used auditory model is very considerable (for example, the number of constants that need to be used in the psychological model of MPEG layer 3 (MP3) exceeds 4700), thus significantly increasing the codec. Fixed data storage requirements; in addition, because the "redundant" frequency band information is considered to be removed, especially at lower bit rates, the decoded audio will appear "sandy"
Once the audio "sanding" phenomenon occurs, the decoded audio quality will be significantly reduced
Also, some audio encoders (such as WMA) use noise shaping (noise shaping) technology to diffuse quantization noise into the corresponding spectral coefficients, which may reduce the fidelity of the audio, thereby affecting the quality of the decoded audio

Method used

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  • Method for implementing audio coder-decoder
  • Method for implementing audio coder-decoder
  • Method for implementing audio coder-decoder

Examples

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Embodiment 1

[0045] Embodiment 1: Assume that the code table is TA_3, and the code stream is: 1 0 1 0 1.... First, match the corresponding code word according to the code table: 1 0 1 0, and then get the corresponding code value: 4, convert the code value 4 into a 4-bit binary with the low bit first and the high bit behind: 0 0 1 0, then Next, the sign bit 1 (expressed as a negative value) is taken out from the code stream, and the values ​​of the corresponding four frequency subbands are obtained in sequence: 0, 0, -1, 0.

Embodiment 2

[0046] Embodiment 2: Assume that the code table is TA_2, and the code stream is: 0.... First, match the corresponding codeword according to the code table: 0, and then get the corresponding code value: 0, and convert the code value 0 into a 3-bit binary with the low bit first and the high bit behind: 0 0 0. Secondly, because they are all zero, there are unsigned bits in the code stream. Thus, the values ​​of the corresponding three frequency subbands are obtained in turn: 0, 0, 0

[0047] Among them, Class B frequency band decoding, refer to the attached Figure 6 As shown, the following two examples are given for illustration.

[0048] Embodiment 1: Assume that the code table is TB_8, and the code stream is: 1 1 0 0 0.... First, get the corresponding code word according to the code table matching: 1 1 0 0, and then get the corresponding code value: 2, and then take out the sign bit 0 from the code stream (expressed as a positive value), then get the corresponding frequency...

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Abstract

The invention discloses an audio codec implementing method, having low calculating complexity and low storage capacity and able to assure audio compression quality, and it is an audio compressing coding technique applied to handheld equipment, system on chip (SOC) or application specific integrated circuits (ASICs) products and embedded systems. At the coder end: 1. making time-frequency transform on audio signals and transforming them into frequency domain and obtaining non-quantized spectrum data; 2. according to the mentioned non-quantized spectrum data and target allowable code quantity, and obtaining corresponding optimum quantization factor information, frequency band group information, code table index information and quantized spectrum information; 3. calculating and formatting code flow; and 4. outputting formatted code flow; at the decoder end: by code flow formatted resolution, it decodes and inversely quantizes spectrum of each frame, makes frequency-time transform and reconstructs time-domain audio data and finally reconstructs time-domain signal of each channel.

Description

technical field [0001] The present invention relates to an audio compression coding technology applied to handheld devices, SoC (System on Chip) or ASIC (Application Specific Integrated Circuit) products and embedded systems, in particular to a method for realizing a low-complexity high-quality wideband audio codec . Background technique [0002] At present, in the audio compression coding technology, most of the wideband audio compression is based on the division of frequency sub-bands and the method of compression using the human acoustic auditory mental model. In the process of analyzing the frequency spectrum using the human acoustic auditory mental model, the so-called "redundant" information will be removed to the greatest extent according to the human auditory masking effect, so that in the actual audio signal, the signal in certain frequency bands will be because the human ear " I can't feel it" and remove it. The advantage of this is that more bits can be used to ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03M7/30G10L19/02
CPCG10L19/032G10L19/002
Inventor 欧阳合周毅吴秉惠罗霖万凯
Owner 昆山杰得微电子有限公司
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