Self-adaptive window switching method based on TDA domain

Abstract

The invention discloses a self-adaptive window switching method based on the TDA domain, belongs to the field of audio encoding, and particularly relates to a processing method used after performing time domain aliasing (TDA) on audio transient signals. The method is characterized in that detected time domain transient signals are mapped to the TDA domain after time domain aliasing, time-frequency analysis of variable window length can be executed on TDA domain signals by aid of a self-adaptive window switching method, different window switching modes can be selected according to TDA domain transient position and time-frequency analysis effect so as to realize switching and transiting of sub-frames with different lengths, and then a window switching mode of the TDA domain is selected by adopting a strategy of combining an open loop and a closed loop. By aid of the method, self-adaptive window switching aiming at TDA domain signals can be achieved to select the optimum time resolution,the pre-echoes distortion of the transient signals is avoided, and simultaneously fine time-frequency analysis results can be kept, thereby being favorable for increasing audio encoding quality on complex conditions such as mixing of transient and steady and the like.

Description

technical field [0001] The invention relates to a TDA domain-based window switching method, in particular to a multi-resolution analysis method suitable for transient signals processed by Time Domain Aliasing (TDA, Time Domain Aliasing), and belongs to the technical field of audio coding. Background technique [0002] Audio signals can be divided into transient and steady-state signals from the transient and slow changes of time-domain waveforms. Transient signals such as the sound of percussion instruments require a higher time-domain signal in audio coding processing because of their sudden energy and short duration. resolution; while the steady-state signal is relatively stable in time but rich in frequency spectrum, it needs a higher frequency domain resolution. Most of the existing audio encoders use perceptual transformation coding methods. For example, MP3 and AAC audio coding standards proposed by MPEG all use Modified Discrete Cosine Transform (MDCT, Modified Discre...

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Problems solved by technology

[0005] In order to solve the problem that when the audio signal is mixed with transient and steady-state signals, the resolution of the time-frequency analysis effect cannot meet the requirements, resulting in pre-echo and reducing the quality of the reconstructed signal. Adaptive window switching processing method for resolution analysis, so as to improve the time-frequency analysis effect of the existing audio standard (ITU-T G.719) on the transient signal, compared with the existing transient signal of each frame in the TDA domain The fixed-length 4-subframe window switching mode (ITU-T G.719) can further reduce the pre-echo distortion of the transient signal in the audio signal, and is conducive to improving the audio coding quality in complex situations such as transient and steady state mixing

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