Signal modification method for variable bit rate wide-band speech coding
| Autor: | V.T. Ruoppila, M. Tammi, Milan Jelinek |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Code-excited linear prediction
Acoustics and Ultrasonics Computer science Speech recognition Speech coding Full Rate Linear predictive coding Codec2 Adaptive Multi-Rate audio codec Computer Vision and Pattern Recognition Electrical and Electronic Engineering Vector sum excited linear prediction Software Harmonic Vector Excitation Coding |
| Zdroj: | IEEE Transactions on Speech and Audio Processing. 13:799-810 |
| ISSN: | 1063-6676 |
| Popis: | This paper introduces a novel signal modification method for wide-band code-excited linear prediction (CELP) speech codecs to improve pitch prediction at low bit rates. The method is enabled only in stable voiced speech frames, and preserves the original time scale at the end of each frame. This feature helps to avoid artifacts and simplifies an encoder implementation. The signal modification includes a classification algorithm as an integral part. The classification algorithm detects the frames most suitable for signal modification and low bit rate coding, and can be employed in a rate selection module of variable bit rate (VBR) codecs. In this paper, the signal modification method is applied in an experimental VBR wide-band speech codec derived from the 3GPP adaptive multirate wideband (AMR-WB) standard (ITU-T Recommendation G.722.2). The codec fulfills the system requirements of IS-95/CDMA2000 Rate Set II, operating at source coding bit rates 12.65, 6.2, and 1.0 kb/s. The signal modification is used in the 6.2 kb/s mode dedicated for voiced speech frames. Listening test results demonstrate the good performance of the proposed method. The signal modification method is used in the Nokia/VoiceAge codec that was declared in April 2003 as the winner of the selection phase in the 3GPP2 CDMA2000 wide-band speech codec standardization. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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