Code rate automatic control system applicable to variable bit rate voice and audio coding

Abstract

The invention discloses a code rate automatic control system applicable to variable bit rate voice and audio coding. Coding code rate is automatically regulated by calculating signal to noise ratio of a signal sub-band, when compressed code stream is compared with the compressed code stream with equivalent fixed code rate in the prior art, signal-to-noise ratio decompressed by adopting the code rate automatic control system disclosed by the invention is obviously improved. The automatic code rate regulating manner disclosed by the invention has better robustness compared with the traditional energy judging method; rate control to voice coding is supported, and variable bit rate coding to an audio signal is also supported, and the code rate automatic control system disclosed by the invention can be applied to packet domain mobile voice communication under the condition that bandwidth is limited, so as to improve quality of the transmitted voice and audio signals.

Description

technical field [0001] The present invention relates to the automatic control technology of voice and audio code rate, and more specifically relates to an automatic code rate control technology of voice and audio coding applied to mobile Internet voice communication, mobile streaming media server and the like. Background technique [0002] Speech and audio code rate control technology means that before the speech and audio signals are encoded, the encoding rate is automatically adjusted according to the importance of the content of the signal, and when important information is sampled at a relatively high bit rate for encoding, in secondary information (such as Noise) is encoded at a relatively low bit rate when sampling, so that under the condition of limited bandwidth, it can not only have better voice quality, but also save bandwidth. This technology is generally used in packet domain (PS) mobile voice communication, mobile streaming media server and other applications. ...

AI Technical Summary

Problems solved by technology

[0003] Most of the speech coding technologies in the existing packet domain (PS) mobile voice communication adopt the AMR (adaptive multi-rate) speech coding technology in the third generation mobile communication system, and the rate control of the traditional circuit domain (CS) AMR speech coding It is controlled by the base station. Since the AMR itself does not provide the code rate control function, the AMR coding in the packet domain (PS) actually uses a fixed rate for coding. This is under the condition of limited bandwidth of the mobile Internet. It is difficult to strike a good balance between

Several other traditional variable rate speech coding (such as QCELP, EVRC and SMV, etc.) are generally only used in traditional circuit domain (CS) speech communication, and basically use voice activity detection (VAD, Voice Activity Detector) to detect and add signals The method of energy judgment is used to control the rate. This kind of method relies too much on the size of the signal energy. In fact, the importance of the signal content cannot be fully reflected in the energy size.

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