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Voice/music dual-mode coding-decoding seamless switching method

A technology of seamless switching and voice coding, which is applied in voice analysis, radio/inductive link selection arrangement, instruments, etc., and can solve the problems of seamless switching between the two modes effectively

Inactive Publication Date: 2007-08-29
TSINGHUA UNIV
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Problems solved by technology

[0008] None of the above three methods effectively solve the problem of seamless switching between the two modes

Method used

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  • Voice/music dual-mode coding-decoding seamless switching method
  • Voice/music dual-mode coding-decoding seamless switching method
  • Voice/music dual-mode coding-decoding seamless switching method

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Embodiment Construction

[0096] The technical solution of the present invention is: when switching from voice to music, windowing and folding are carried out to the tail of the last voice frame before the switching, and the continuity is guaranteed by the overlap-add feature of MDCT transformation at this moment; when switching from music When it comes to speech, a new MDCT window type is used for the last music frame before switching so that there is no time domain overlap with successive speech frames. The continuity at this time is guaranteed by the memory of the linear prediction synthesis filter in CELP. On the other hand, in order to match the sampling rates of speech coding and music coding, a specific downsampling process is performed on speech frames. Below make in conjunction with accompanying drawing 1,2,3 give detailed description.

[0097] Figure 1 shows the overall structure of the speech / audio dual-mode encoder, which is divided into four modules: core dual-mode encoder 10, stereo encod...

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Abstract

The invention relates to a seamless switching method for voice / music dual-mode en-decoding. When a dual-mode en-decoder switches from CELP voice mode to MDCT music mode, the audio signal-rear of the final CELP frame in the time domain before switching adopts window-adding and folding process, and the overlapping nature of MDCT transforming ensures the continuity of switching. When a dual-mode en-decoder switches from MDCT music mode to CELP voice mode, the final MDCT frame before switching adopts a new window type in order to ensure there is no overlapping time domain with the first CELP frame, and the pre-coding technology ensures the continuity of switching.

Description

technical field [0001] The invention relates to the design of a low code rate speech / music dual-mode codec that can be used in mobile communication. In particular, when the speech mode adopts code-excited linear predictive coding CELP, and the music mode adopts transform coding based on modified cosine transform MDCT, the seamless switching and down-sampling processing of the two modes. Background technique [0002] Speech signals are quite different from general music signals in time-frequency statistical properties. The speech signal in the time domain exhibits quasi-periodic characteristics, its spectrum is relatively flat and its bandwidth is below 7KHz; the general music signal has great dynamic characteristics in the time domain and frequency domain, and its spectral bandwidth is mainly limited by the sampling rate, which can reach Above 16KHz. Therefore, speech coding usually adopts a coding method of linear prediction combined with long-term prediction (pitch), suc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G10L19/00G10L19/12H04Q7/20G10L19/20
Inventor 张树华窦维蓓杨华中张斌
Owner TSINGHUA UNIV
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