AN IMPROVED CANDIDATE SCHEME FOR FAST ACELP SEARCH
| Autor: | Wen-Chin Wang, 王文祺 |
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| Rok vydání: | 2003 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 91 In the era of third-generation (3G) wireless personal communications, though applications of multimedia such as video and data communication have become more and more popular, speech communication is still one of the most important mobile radio services. The ACELP algorithm is based on the Code-Excited Linear-Prediction (CELP) coding model. The ACELP (algebraic code excited linear prediction) algorithm has been adopted by many speech coding standards due to its high speech quality and inherent robustness to channel noise. But in the full search, it need 8192 operational load. To further reduce computation complexity reduction, in this thesis, we propose an improved candidate scheme for fast ACELP search. Consequently, speech coding techniques that fast search as possible is increasingly important. To achieve the goal, the use of fast search speech coders is certainly an attractive approach to retain overall high voice quality at low average search loops. The aim of this thesis is thus to the ACELP (algebraic code excited linear prediction) algorithm has been adopted by many speech coding standards due to the relative high speech quality available. To further reduce computation complexity reduction, we propose an improved candidate scheme for fast ACELP search. For further computational complexity reduction, we propose a fast ACELP algorithm using a designed pilot function to predict the predetermined candidate pulses. We to select maximum number forward difference of target signal. A region is to include prior to one point and later three points. We in accordance with speech quality to decide need regions number. In the 7.95 and 7.4 kbit/s modes for the AMR (Adaptive Multi-Rate ) codec of the 3rd Generation Partnership Project (3GPP) standard coder, sampling rate is 8 kHz with 16 bit resolution and the frame size is 20 ms. Each frame has a bit stream of 17 bits.The algebraic code excited linear prediction (ACELP) algorithm has been adopted by many speech coding standards, such as the ITU G-723.1 and G-729 as well as the GSM EFR speech coding standards, due to low complexity and high quality. Simulation results show that the computational load can be reduced by about 50-80% with almost imperceptible degradation in performance. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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