Audio-frequency decoding method, audio-frequency decoder and mooth filtering-wave method therein

An audio decoder and filter technology, which is applied in the field of smoothing and filtering, can solve the problems of increasing hardware and reducing costs, and achieve the effects of filtering out high-frequency interference, eliminating the need for smoothing filters and buffers, and reducing costs

Inactive Publication Date: 2007-06-13
SHANGHAI MAGIMA DIGITAL INFORMATION
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AI Technical Summary

Problems solved by technology

[0005] The audio decoder shown in Figure 3 performs smoothing and filtering on the sampled values ​​in the case of errors in the time domain. Although the high-frequency interference is filtered to a certain extent, due to the addition of additional filters and corresponding buffers, the hardware , so that the cost cannot be reduced

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  • Audio-frequency decoding method, audio-frequency decoder and mooth filtering-wave method therein
  • Audio-frequency decoding method, audio-frequency decoder and mooth filtering-wave method therein
  • Audio-frequency decoding method, audio-frequency decoder and mooth filtering-wave method therein

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Embodiment Construction

[0037] Referring to FIG. 4A and FIG. 4B , the audio decoder of the present invention includes an input buffer 41 , a decoding unit 43 , a filter 45 and an output buffer 47 .

[0038] The input buffer serves as an interface between the audio decoder and the outside, receives the ES stream (elementary code stream) sent by the demultiplexing module (not shown), and sends it to the decoding unit. The decoding unit includes an analysis module 431 and a reconstruction module (reconstruction) 433 . The parsing module parses the ES stream, decodes header information, determines header parameters, and provides control word information for other decoding modules. The reconstruction module analyzes the frame structure of MPEG AudioLayer1 / Layer2, and decodes the bit allocation information of a frame of data; then decodes the scale factor (scale factor), retakes the sampling point, and dequantizes the sample point; Normalization (de-normalize) operation. The signal output by the reconstr...

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Abstract

The audio decoder includes following parts: input buffer in use for receiving external essential stream (ES); decoding unit in use for decoding ES to obtain sampled value in spatial (S) domain; carrying out discrete cosine transform (DCT) and adding window process for sampled value in S domain so as to obtain filter for PCM sampled value; output buffer in use for outputting PCM sampled value. The decoding unit also receives interpolation input to filter from underflow signal fed back from the output buffer. In the invention, smoothed filter carries out before IDCT transform; mute or playback signal are inserted in sampled values in frequency domain, and smoothed filtering is carried out by multiplexing synthesized filter. Thus, the invention not only filters out high frequency interference, but also gets quit of need of additional filter and buffer; moreover, the invention saves circuit area, and reduces cost.

Description

technical field [0001] The invention relates to an audio decoding method and an audio decoder, in particular to an audio decoder capable of smoothing filtering and a smoothing filtering method in the audio decoder. Background technique [0002] Digital audio and video compression technology is a very important research topic in the multimedia field. The audio and video compression technology defined by the MPEG standard is widely used in multimedia products. The MPEG standard was established by the Moving Pictures Experts Group (Moving Pictures Experts Group) of the International Standards Organization ISO. Its audio standard includes three different coding algorithms, namely, MPEG Layer 1, MPEG Layer 2 and MPEG Layer 3. The complexity of the algorithm is different, so the compression rate is also different. Audio signals can usually be sampled and encoded according to one of these algorithms. The audio decoder is used to decode the received coded sample values, and usuall...

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Application Information

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IPC IPC(8): H04N7/52
Inventor 周振亚刘彦宋东海
Owner SHANGHAI MAGIMA DIGITAL INFORMATION
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