Adaptive block length, constant converting audio frequency decoding method

Abstract

The invention discloses the method used to supply the audio signal from the compressing audio code stream, it includes the below steps: the code stream can be conducted the unbinding format to distill the changing modulus and the number of the changing modulus of the every blocks; the gained changing modulus are separated into these blocks: the length of the block is equal to the power of the two, and the length of the block is more length than the times of then the number of the changing modulus of every blocks through the unbinding format; the constant length of the reverse scatter changing is used to process the reverse transform of the changing modulus after the blocking, so the transformed reversely sampling buffer is gained; the time field sampling is distilled from the gained reverse changing sampling buffer; the block through the window changing are folded by the composing window conducting the window changing to the distilled time domain sampling block. Thereinto, the numbers of the received changing modulus can be different each other.

Description

technical field

[0001] The present invention relates to the decoding of compressed audio signals, where the compression scheme employs a method based on the Modified Discrete Cosine Transform (MDCT), also known as time-domain aliasing cancellation. More specifically, the present invention relates to the decoding of compressed audio streams by varying the block length, wherein the block length is given as side information in the compressed audio stream. The present invention provides a method for constant length inverse transform of audio blocks using adaptively changing block length. Such approaches are sometimes necessary in the use of Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) or Programmable Logic Devices (PLDs). Background technique

[0002] In audio coding, compressing the space used to store audio data is a focus. Current state-of-the-art methods for high-quality audio employ perceptual coding for compression. Typically,...

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