臺灣博碩士論文加值系統

針對代數碼激式線性預測編碼器(ACELP)，本論文共完成兩個主要研究項目分別為高效率的轉碼與編碼。首先，在行動通訊與網際網路的通訊上，我們提出半速率GSM與G.729語音編碼器之間的轉碼架構。其次對ACELP脈衝搜尋程序提出快速隨機碼簿搜尋演算法。
語音編碼器的轉碼方法藉由半速率GSM與G.729編碼參數的轉換被提出，通訊於無線通訊與網際網路。與傳統的解碼然後編碼(DTE)方法做比較，所提出的參數轉換方法，可以以較低的計算複雜度及編碼延遲，提供不同語音編碼器溝通。模擬結果顯示所提出的方法，可以降低約30%左右的計算量，在聽覺上聽不出語音品質的降低。
降低ACELP的計算複雜度，以聲音脈衝響應的簡化相關性矩陣為基礎，我們提出高效率碼簿搜尋技巧。更進一步提出簡化相關性矩陣和脈衝位置預選結合方法，此方法不僅在事先計算自相關矩陣時可以降低算術計算量，還可以降低脈衝位置組合的數量。實驗結果證明所提出的方法，可以有效的降低在ACELP碼簿搜尋程序中的計算量，而不降低聽覺上的語音品質。

The two major research topics for algebraic code excited linear predictive (ACELP) of this dissertation are efficient translation and coding methods. First, we proposed the architecture of transcoding between global system for mobile communications (GSM) half rate and G.729 Speech Coders across Mobile and IP Networks. Second, the fast stochastic codebook search algorithms for reduction of the algebraic code excited linear predictive (ACELP) are proposed.
The speech coding translation scheme by transferring coding parameters between GSM half rate and G.729 coders is proposed over wireless and network. Compared to the conventional decode-then-encode (DTE) scheme, the proposed parameter conversions provide speech interoperability with reducing computational complexity and coding delay. Simulation results show that the proposed methods can reduce about 30% computational load achieve almost imperceptible degradation in performance.
To reduce the computational complexity of Algebraic Code-Excited Linear Prediction (ACELP) coders, we propose an efficient codebook search mechanism based on a simplified correlation matrix of the vocal impulse response. Furthermore, proposed Joint scheme by combining the simplified correlation matrix method and a pulse position prediction scheme, it not only decreases arithmetic complexity in pre-computing autocorrelation matrix but also reduce the number of pulse position combinations. The simulation and experimental results show that the proposed method provides an effective reduction in the computational load of the ACELP codebook search procedure with no discernible degradation of the speech quality.

1. Introduction 1
1.1 Overview of speech coding 1
1.2 Organization of Thesis 3
2. Speech Coding Algorithms 6
2.1 G.729 Speech Encoder 6
2.1.1 Preprocessing and Perceptual Weighting 7
2.1.2 Linear Prediction Analysis and Quantization 9
2.1.3 Adaptive Codebook Search Algorithm 14
2.1.4 Stochastic Codebook Compensation 18
2.2 G.729 Speech Decoder 21
2.3 GSM Half Rate Speech Encoder 23
2.4 GSM Half Rate Speech Decoder 29
3.Coding Translation of Speech Coders 30
3.1 Overview of Transcoder 30
3.2 Architecture of Transcoder 33
3.3 Proposed Translation Techniques 37
3.3.1 LPC Parameters Transformation 37
3.3.2 Pitch Transformation 41
3.3.3 Fast Fixed Codebook Search 43
3.4 Simulation Results 50
3.5 Diminutive Conclusions 53
4. ACELP Codebook Search Algorithm 54
4.1 Overview of ACELP Speech Coder 54
4.2 Algebraic Codebook Search 57
4.3 Proposed Schemes 61
4.3.1 Simplified Correlation Matrix (SCM) Scheme 62
4.3.2 Joint SCM and Pulse Prediction Scheme 69
4.4 Simulation Results 71
4.5 Diminutive Conclusions 76
5. Conclusions 78
Bibliography 80

[1]A.S., Spanias, “Speech coding: a tutorial review,” Proceedings of the IEEE, vol. 82, Issue: 10, pp.1541 – 1582, Oct. 1994.
[2]W.C. Chu, Speech coding algorithms: Foundation and evolution of standardized coders, Wiley Publisher, pp. 1-25, 2003.
[3]J. Youn and M. Sun, “Motion vector refinement for high performance transcoding,” IEEE Trans. on Multimedia, vol. 1, no. 1, pp. 30-40, March 1999.
[4]B. Sostawa, T. Dannemann, and J. Speidel, “DSP-Based Transcoding of Digital Video Signals with MPEG-2 Format,” IEEE Trans. on Consumer Electronics, vol. 46, no. 2, pp. 358 – 362, May 2000.
[5]S. Dogan, A.H. Sadka, A.M. Kondoz, “MPEG-4 video transcoder for mobile multi-media traffic planning,” IEE International Conference on 3G Mobile Communica-tion Technologies, pp. 109 -113, 2001.
[6]S. Dogan, A.H. Sadka, A.M. Kondoz, “Efficient MPEG-4/H/263 video transcoder for interoperability of heterogeneous multimedia networks,” Electronics Letters, vol. 35, no. 11, pp. 863 -864, May 1999.
[7]H.G. Kang, H.K. Kim, and R.V. Cox, “Improving Transcoding Capability of Speech Coders in Clean and Frame Erased Channel Environments,” Proc. IEEE Workshop on Speech Coding, pp. 78-80, 2000.
[8]Y. Ota; M. Suzuki; Y. Tsuchinaga; M. Tanaka; S. Sasaki; “Speech Coding Transla-tion for IP and 3G Mobile Integrated Network,” Proceedings of IEEE International Conference on Communications, vol. 1, pp. 114 -118, 2002.
[9]S.M. Tsai and J.F. Yang, “GSM to G.729 Speech Transcoder,” Proceedings of IEEE International Conference on Electronics, Circuits, and Systems, vol. 1, pp. 485-488, Malta, Sept. 2001.
[10]“Digital cellular telecommunications system; Half rate speech (GSM 06.20 version 5.1.1),” European Telecommunication Standard, May 1998.
[11]“Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear prediction (CS-ACELP),” ITU-T Recommendation G.729, 1996.
[12]“Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear prediction (CS-ACELP), Annex A: Reduced complexity 8kbit/s CS-ACELP speech codec,” ITU-T Recommendation G.729-Annex A, 1996.
[13]“Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear prediction (CS-ACELP), Annex B: A silence compression scheme for G.729 opti-mized for terminals conforming to Recommendation V.70,” ITU-T Recommendation G.729-Annex B, 1996.
[14]“Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear prediction (CS-ACELP), Annex D: 6.4 kbit/s CS-ACELP speech coding algorithm,” ITU-T Recommendation G.729-Annex D, 1998.
[15]“Coding of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear prediction (CS-ACELP), Annex E: 11.8 kbit/s CS-ACELP speech coding algo-rithm,” ITU-T Recommendation G.729-Annex E, 1998.
[16]I.M. Trancoso and B.S. Atal, “Efficient search procedures for selection the optimum innovation in stochastic coders,” IEEE Trans. on Acoustics, Speech, and Signal Processing, vol. 38, no. 3, pp. 385-396, March 1990.
[17]J.S. Erkelens and P.M.T. Broersen, “LPC interpolation by approximation of the sample autocorrelation function,” IEEE Trans. on Speech and Audio Processing, vol. 6, no. 6, pp. 569-573, Nov. 1998.
[18]J. Vass, Y. Zhao, and X. Zhuang, “Adaptive forward-backward quantizer for low bit rate high-quality speech coding,” IEEE Trans. on Speech and Audio Processing, vol. 5, no. 6, pp. 552-557, Nov. 1997.
[19]L. Juan, B. Lin, and Q. Fu, “An 8-kb/s conjugate-structure algebraic CELP (CS-ACELP) speech coding,” Proceedings of ICSP, vol. 2, pp. 1729-1732, 1998.
[20]I.M. Brandstein, J. Hardwick, and J. Lim, “The multiband excitation speech coder,” Advances in Speech Coding, pp. 215-224, Norwell, MA: Kluwer, 1991.
[21]A. Cumani, “On a covariance-lattice algorithm for linear prediction,” International Conference on Acoustics, Speech, and Signal Processing, pp. 651-654, May 1982.
[22]P. Kroon and B.S. Atal, “On the use of pitch predictors with high temporal resolu-tion,” IEEE Trans. on Signal Processing, vol. 39, no. 3, pp. 733-735, March 1991.
[23]Y.S. Choi, H.G. Kang, J.H. Yoo, I.W. Cha, and D.H. Yong, “A very low complexity vselp speech coder using regular pulse basis vectors,” IEICE Trans. Fundamentals, vol. E80-A, no. 6, pp. 996-1001, June 1997.
[24]V. Cuperman, A. Gersho, R. Pettigrew, J.J. Shynk, J.H. Yao, “Backward adaptive configurations for low-delay vector excitation coding,” Advances in Speech Coding, Kluwer Academic Publishers, London, 1991.
[25]J.F. Tasič, M. Najim, M. Ansorge, “Intelligent Integrated Media Communication Techniques,” Kluwer Academic Publishers, Boston, pp. 3, 2003.
[26]M. Kondoz, Digital Speech, Wiley Publisher, pp. 135, 1994.
[27]R.A. Salami, “Binary Pulse Excitation: A Novel Approach to Low Complexity CELP Coding,” Kluwer Academic Publishers, pp. 145-146, 1991.
[28]“Dual Rate Speech Coder for Multimedia Communications Transmitting at 5.3 and 6.3 kbit/s,” ITU-T Recommendation G.723.1, 1996.
[29]N.K. Ha, “A Fast Search Method of Algebraic Codebook by Reordering Search Se-quence,” Acoustics, Speech, and Signal Processing, Proceedings of IEEE Interna-tional Conference, vol. 1, pp. 21-24, 1999.
[30]K.J. Byun, H.B. Jung, M. Hahn, K.S. Kim, “A Fast ACELP Codebook Search Method,” Signal Processing, 2002 6th International Conference, vol. 1, pp. 422-425, August 2002.
[31]H. Park, “Efficient Codebook Search Method of EVRC Speech Codec,” IEEE Sig-nal Processing Letter, vol. 7, no. 1, pp. 1-2, Jan. 2000.
[32]M.A. Ramírez and M. Gerken, “Joint Position and Amplitude Search of Algebraic Multipulses,” IEEE Transactions on Speech and Audio Processing, vol. 8, no. 5, pp 633-637, Sept. 2000.
[33]S.M. Tsai, J.C. Wang, J.F. Yang, and J.F. Wang, "Efficient Coding Translation of GSM and G.729 Speech Coders across Mobile and IP Networks," IEICE Trans. In-formation and Systems, vol. E87-D, no.2, pp.444-452, February 2004.
[34]M.L. Wang and J.F. Yang, “Generalised Candidate Scheme for the Stochastic Code-book Search of Scalable CELP Coders,” IEE Proceedings: Vision, Image and Signal Processing, vol. 151, no. 5, pp. 443-452, Oct. 2004.
[35]F.K. Chen, J.F. Yang and Y.L. Yan,” Candidate Scheme for Fast ACELP Search,” IEE Pro.-Vis. Image and Signal Process., vol. 149, no. 1, pp. 10-16, Feb. 2002.