本文選題：嵌入式語(yǔ)音編碼 + G.718��； 參考：《安徽工業(yè)大學(xué)》2016年碩士論文

【摘要】：隨著移動(dòng)通信技術(shù)和網(wǎng)絡(luò)通信技術(shù)的不斷提高,當(dāng)前語(yǔ)音壓縮編碼技術(shù)正朝著寬帶、變速率和嵌入式的方向發(fā)展。ITU-T于2008年6月制定了全新的寬帶變速率嵌入式語(yǔ)音和音頻編解碼標(biāo)準(zhǔn)G.718,該算法迎合了當(dāng)前語(yǔ)音編碼技術(shù)的發(fā)展趨勢(shì),采用了多項(xiàng)新技術(shù),具有結(jié)構(gòu)靈活,合成語(yǔ)音質(zhì)量高,能夠?qū)⒂芯�網(wǎng)絡(luò)通信系統(tǒng)和無線網(wǎng)絡(luò)通信系統(tǒng)互聯(lián)互通等優(yōu)點(diǎn),在音/視頻會(huì)議、3G、4G、多媒體流等場(chǎng)合具有良好的應(yīng)用前景。本課題在深入理解G.718編解碼原理的基礎(chǔ)上,討論了G.718算法L1~L5層的結(jié)構(gòu)特點(diǎn)。分析了G.718核心層L1層以及ACELP增強(qiáng)層L2層使用的預(yù)處理、信號(hào)分類、ACELP等關(guān)鍵技術(shù),比較了G.718同其他寬帶語(yǔ)音算法核心層編碼的異同點(diǎn)。研究了G.718中L3、L4、L5層使用的變換域編碼技術(shù),針對(duì)全頻帶信號(hào)輸入下,對(duì)語(yǔ)音特性信號(hào)采用的代數(shù)矢量量化技術(shù)以及對(duì)音頻特性信號(hào)采用的頻帶選擇波形增益編碼技術(shù)和階乘脈沖編碼技術(shù)。介紹了G.718變換域編碼使用的MDCT技術(shù),引入了一種基于FFT的MDCT快速算法。由于G.718算法對(duì)不同類型輸入語(yǔ)音采用不同的編碼模式,導(dǎo)致其算法非常復(fù)雜,而且ITU-T提供的C源代碼主要側(cè)重于嚴(yán)謹(jǐn)?shù)孛枋鏊惴?使得算法執(zhí)行效率差,無法實(shí)時(shí)實(shí)現(xiàn)。本課題通過解讀C源代碼中各函數(shù)的功能、各模塊之間的關(guān)系及各模塊的復(fù)雜度分布,提出了基于DSP全匯編實(shí)現(xiàn)G.718語(yǔ)音編解碼器總體開發(fā)方案,結(jié)合DSP C55x匯編語(yǔ)言特點(diǎn),制定了各模塊編寫方案。在維持C源代碼總體框架不變的前提下,編寫了G.718編解碼器各函數(shù)模塊的全匯編程序。為了提升全匯編代碼的執(zhí)行效率,采用循環(huán)體優(yōu)化、并行指令等匯編指令優(yōu)化方法對(duì)編寫的全匯編代碼進(jìn)行優(yōu)化。為了測(cè)試全匯編優(yōu)化后G.718編解碼器的還原語(yǔ)音質(zhì)量,本課題基于TMS320VC5505 EVM設(shè)計(jì)了G.718的實(shí)時(shí)測(cè)試系統(tǒng),經(jīng)過WB_PESQ客觀評(píng)估方法測(cè)試,G.718編解碼器還原出的語(yǔ)音質(zhì)量達(dá)到實(shí)時(shí)通信要求。
[Abstract]:With the continuous improvement of mobile communication technology and network communication technology, the current speech compression coding technology is moving towards broadband,In June 2008, ITU-T formulated a new broadband variable rate embedded speech and audio coding and decoding standard G.718. this algorithm caters to the development trend of current speech coding technology and adopts many new technologies.It has the advantages of flexible structure, high synthetic voice quality, and the ability to connect wired network communication system with wireless network communication system, etc. It has a good application prospect in audio / video conference, multimedia stream and so on.Based on the deep understanding of G. 718 encoding and decoding principle, this paper discusses the structure characteristics of G.718 algorithm L1~L5 layer.The key technologies such as pretreatment and signal classification in L1 layer of G.718 core layer and L2 layer of ACELP enhancement layer are analyzed. The similarities and differences between G.718 and other wideband speech algorithms are compared.In this paper, the transform domain coding technique used in L3 / L4 / L5 layer in G.718 is studied.The algebraic vector quantization technique for speech characteristic signal, the gain coding technique for frequency band selection waveform and the factorial pulse coding technique for audio characteristic signal are adopted.This paper introduces the MDCT technology used in G.718 transform domain coding, and introduces a fast MDCT algorithm based on FFT.Because G.718 adopts different coding modes for different types of input speech, the algorithm is very complex, and the C source code provided by ITU-T mainly focuses on describing the algorithm strictly, which makes the algorithm execution inefficient and can not be implemented in real time.By interpreting the function of each function in C source code, the relationship between each module and the complexity distribution of each module, the overall development scheme of G.718 speech codec based on DSP is put forward, and the characteristics of DSP C55x assembly language are combined.The program of each module is worked out.On the premise of maintaining the whole frame of C source code, the whole assembly program of each function module of G.718 codec is written.In order to improve the execution efficiency of full assembly code, the optimization methods such as loop volume optimization, parallel instruction and so on are used to optimize the whole assembly code.In order to test the restored speech quality of G.718 codec after full assembly optimization, a real-time test system of G.718 is designed based on TMS320VC5505 EVM. The quality of speech restored by G.718 codec is tested by WB_PESQ objective evaluation method to meet the requirements of real-time communication.
【學(xué)位授予單位】：安徽工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TN912.3

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