Audio signal encoding apparatus and method

Abstract

There are included a frame dividing part (1); an auditory mentality arithmetic part (2); a filter bank (3); a scale factor calculating part (4) for weighting the spectrum of each frequency band by use of an arithmetic result of the auditory mentality arithmetic part (2); a quantization step deciding part (7) for deciding a quantization step of the whole frame prior to a spectrum quantization by subtracting, from the auditory information amount of the whole weighted spectrum before the quantization, the information amount of the whole spectrum after the quantization and then multiplying the result of the subtraction by a factor obtained from a quantization roughness increment width; a spectrum quantizing part (8); and a bit shaping part (9) for providing a bitstream obtained by shaping the quantized spectrum. The quantization step deciding part (7) predicts, based on the bit amount assigned to a frame to be encoded, the information amount of the whole quantized spectrum.

Description

technical field [0001] The invention relates to an audio signal encoding device and method. Background technique [0002] In recent years, high-quality and efficient audio signal coding technology has been widely used in DVD-Video audio tracks, portable audio players, music distribution, and storage of music in home servers on home LANs, etc., and its importance is also increasing. [0003] Most of such audio signal coding techniques utilize transform coding techniques for time-frequency transformation. For example, MPEG-2AAC, Dolby Digital (AC-3), and the like use only an orthogonal transform such as MDCT (Modified Discrete Cosine Transform: Modified Discrete Cosine Transform) to form a filter bank. In addition, MPEG-1 Audio Layer III (MP3) and ATRAC (encoding method used in MD (Mini Disk)) combine multi-stage QMF (Quadrature Mirror Filter: Quadrature Mirror Filter) and other sub-band division filters. Alternate connections to form filter banks. [0004] These transform...

AI Technical Summary

Problems solved by technology

Since 11 different Huffman code tables are searched during bit calculation, if all the Huffman code tables are searched, the calculation amount of bit calculation will inevitably increase

[0022] Also, the quantization error is calculated after inverse quantization in the distortion control loop, which also requires high computational complexity

Therefore, a huge processing complexity is required until the double loop converges

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