Enhanced aacPlus音频编解码器的研究及其解码器在XScale上的高效实现
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摘要
Enhanced aacPlus是目前最完美的开放式低码率音频编解码方案。作为MPEG-4和3GPP标准它必然在未来的无线通信、网络流媒体、数字广播等领域拥有广泛的应用前景。基于Intel XScale架构的处理器PXA272具有强大的多媒体处理能力,同时采用了独特的节电技术,适用于各类便携式设备。CMMB(China Mobile Multimedia Broadcasting)标准是广电总局最近颁布的运用于移动电视业务的行业标准,今后将在我国的广播电视领域扮演重要的角色。本文对Enhanced aacPlus编解码器的原理和实现方法作了深入的研究,并针对手机电视终端的应用,详细论述了基于XScale处理器的Enhanced aacPlus解码器的高效实现方法。
全文首先从数字音频技术的发展及基本原理出发,讨论Enhanced aacPlus编解码器的结构框架和主要算法模块,重点分析它的三个主要功能单元:AAC_LC(核心编解码器)、SBR(频带扩展工具)、PS(参数立体声工具)。
接着介绍Enhanced aacPlus解码器的一个应用——手机电视业务。并以此为背景详细论述在尽量不降低音频质量的前提下,为提高解码性能,对Enhanced aacPlus解码器的部分算法和程序所进行的改进措施和优化方法。在算法层主要包括:滤波器组模块的快速IMDCT算法改进,反量化解码模块中的快速查表算法改进,以及Huffman解码模块中的快速实现算法。在代码层则依次讨论了基本操作优化、C level优化和汇编level优化。
最后完成Enhanced aacPlus解码器在XScale处理器上的高效实现,并分析了解码器的各项性能。从最终的测试数据和结论中可以看出,课题成功实现了XScale平台上Enhanced aacPlus解码器的改进优化,解码音质达到商用标准,解码效率接近业界先进水平。
Enhanced aacPlus is the state-of-the art low bit rate open standards audio codec. As the standard of MPEG-4 and 3GPP, the application prospect of Enhanced aacPlus is very widely in the markets of mobile, Internet streaming and digital broadcasting.Processor PXA272 based on Intel XScale architecture has powerful multimedia process ability,and meanwhile adopts unique power saving technology. It is suitable for portable apparatus. CMMB(China Mobile Multimedia Broadcasting)is the standard of the digital mobile TV which is published by the state administration of radio film and television. It will be the key role in Chinese digital mobile TV for the future. This thesis investigates the principle and implementation method of Enhanced aacPlus codec ,and discusses the method of decoding efficiently based on the XScale processor for the application of mobile TV terminals.
Firstly, based on the brief introduction to the development and the fundamental principle of audio coding technology, the standard structure and algorithm techniques of Enhanced aacPlus are discussed in detail. In all of them, it focuses on the three function blocks: AAC_LC, SBR and PS.
Subsequently, based on the introduction of application of Mobile TV, the thesis investigates some important algorithmic modifications and code optimizations for the improvement of decoding performance and speed without reducing the audio quality. In the algorithm level it includes the use of fast IMDCT, the modification in the blocks of inverse scaled and Huffman decoding; in the code level it includes basic operation optimizations, C code optimizations and ASM code optimizations.
Finally, after the finishing of efficient implementation of Enhanced aacPlus decodec based on the XScale processor, this thesis analyzes the capability of the decodec.It can be seen from the final test data and conclusion that, this thesis successfully realizes the mendings and optimizations of Enhanced aacPlus on XScale. The timbre of decoding accords with the commercial demand and the efficiency approachs the best in the field.
全文首先从数字音频技术的发展及基本原理出发,讨论Enhanced aacPlus编解码器的结构框架和主要算法模块,重点分析它的三个主要功能单元:AAC_LC(核心编解码器)、SBR(频带扩展工具)、PS(参数立体声工具)。
接着介绍Enhanced aacPlus解码器的一个应用——手机电视业务。并以此为背景详细论述在尽量不降低音频质量的前提下,为提高解码性能,对Enhanced aacPlus解码器的部分算法和程序所进行的改进措施和优化方法。在算法层主要包括:滤波器组模块的快速IMDCT算法改进,反量化解码模块中的快速查表算法改进,以及Huffman解码模块中的快速实现算法。在代码层则依次讨论了基本操作优化、C level优化和汇编level优化。
最后完成Enhanced aacPlus解码器在XScale处理器上的高效实现,并分析了解码器的各项性能。从最终的测试数据和结论中可以看出,课题成功实现了XScale平台上Enhanced aacPlus解码器的改进优化,解码音质达到商用标准,解码效率接近业界先进水平。
Enhanced aacPlus is the state-of-the art low bit rate open standards audio codec. As the standard of MPEG-4 and 3GPP, the application prospect of Enhanced aacPlus is very widely in the markets of mobile, Internet streaming and digital broadcasting.Processor PXA272 based on Intel XScale architecture has powerful multimedia process ability,and meanwhile adopts unique power saving technology. It is suitable for portable apparatus. CMMB(China Mobile Multimedia Broadcasting)is the standard of the digital mobile TV which is published by the state administration of radio film and television. It will be the key role in Chinese digital mobile TV for the future. This thesis investigates the principle and implementation method of Enhanced aacPlus codec ,and discusses the method of decoding efficiently based on the XScale processor for the application of mobile TV terminals.
Firstly, based on the brief introduction to the development and the fundamental principle of audio coding technology, the standard structure and algorithm techniques of Enhanced aacPlus are discussed in detail. In all of them, it focuses on the three function blocks: AAC_LC, SBR and PS.
Subsequently, based on the introduction of application of Mobile TV, the thesis investigates some important algorithmic modifications and code optimizations for the improvement of decoding performance and speed without reducing the audio quality. In the algorithm level it includes the use of fast IMDCT, the modification in the blocks of inverse scaled and Huffman decoding; in the code level it includes basic operation optimizations, C code optimizations and ASM code optimizations.
Finally, after the finishing of efficient implementation of Enhanced aacPlus decodec based on the XScale processor, this thesis analyzes the capability of the decodec.It can be seen from the final test data and conclusion that, this thesis successfully realizes the mendings and optimizations of Enhanced aacPlus on XScale. The timbre of decoding accords with the commercial demand and the efficiency approachs the best in the field.
引文
[1]卢官明,宗昉.数字音频原理及应用.机械工业出版社.2005.1:28-35,37-42,48-56.
[2]韩宪柱.数字音频技术及应用.中国广播电视出版社.2003.1:72-74,98-98,191-113.
[3] [美]Andrew N.Sloss,[英]Dominic Symes,[美]Chris Wright.沈建华(译).ARM嵌入式系统开发——软件设计与优化.北京航空航天大学出版社.2005:199-205,244-247.
[4] 3GPP TS 26.401.Enhanced aacPlus general audio codec: General description.2005.06:6-10.
[5] 3GPP TS 26.402.Enhanced aacPlus general audio codec:Additional Decoder Tools.2005.09:7-17.
[6]陈景铭.利用高频重建之MPEG音讯编解码器设计及其系统实现.[硕士学位论文],台湾云林科技大学.2005:34-37,76-89.
[7] 3GPP TS 26.404.Enhanced aacPlus general audio codec: Encoder Specification SBR part.2004.09:7-32.
[8] 3GPP TS 26.405.Enhanced aacPlus general audio codec: Encoder Specification parametric stero part.2005.03:5-13.
[9] ISO/IEC 14496-3. Information Technology-Coding of Audio-Visual Objects-part3:Audio. ISO/IEC JTC1/SC29 WG11,2001:473-480.
[10] ISO/IEC 13818-7. Information Technology- Generic Coding of Moving Picture and Associated Audio Information– part 7:Advanced Audio Coding (AAC). ISO/IEC JTC1/SC29 WG11,1999:43-75.
[11] 3GPP TS 26.403.Enhanced aacPlus general audio codec: Encoder Specification AAC part.2006.06:7-22.
[12]任军刚.Enhanced aacPlus编解码器的研究和实现.[硕士学位论文],西安电子科技大学.2006.06:7-11,18-26.
[13]张益贞,刘滔. Visual C++实现MPEG/JPEG编解码技术.人民邮电出版社,2002.01:30-47.
[14] J.Herre, J.D.Johnston. Enhancing the Performance of Perceptual Audio Coders by Using Temporal Noise Shaping(TNS).AES 101 Convention, Los Angeles,1996:3-25.
[15] J.Herre. Temporal Noise Shaping, Quantization and Coding Methods in Perceptual Audio Coding. A Tutorial Introduction. AES 17th Int. Conf. on High Quality Audio Coding, Srptember 1999: 1-7.
[16]张艳.基于定点DSP的MPEG-4 AAC编解码系统研究.[硕士学位论文],成都理工大学.2005.6:26-33.
[17]陈健. AAC:21世纪音频编码的主流.电声技术,2002.09.总207期:4-7.
[18] ISO/IEC 14496-3:2001/AMD1. Bandwidth Extension.ISO/IEC JTC1/SC29 WG11,2003:1-44.
[19] M.Dietz, L.Liljeryd, K.Kjorling, and O.Kunz.Spectral Band Replication, a novel approach in audio coding. 112th AES Convention, Munich,Germany,2002.03:3-7.
[20] M.Wolters, K.Kjorling, D.Homm and H.purnhagen.A closer look into MPEG-4 High Efficiency AAC. 115th AES Convention 2003 October 10-13 New York, NY, USA:4-8.
[21] Per EKstrand, Bandwidth Extension of Audio signal by Spectral Band Replication.Proc.1st IEEE Benelux workshop on Model based Processing and Coding of Audio (MPCA-2002) ,Leuven,Belgium,2002.11:53-58.
[22] M.Dietz, S.Melzer. CT- aacplus—a State of The Art Audio Coding Scheme. EBU Technical Review, No291.2002.7:1-5.
[23]焦慧颖,安建平,卜祥元.数字广播音频编码中的频带复制技术(SBR).中国有线电视.2005.05:425-427.
[24] R.G..v.d. Waal,R.N.J.Veldhuis. Subband coding of stereophonic digital audio signals.Proc. IEEE Int. Conf. on Acoustics, Speech, Signal Processing,1991, vol.3:3601-3604.
[25] H. Purnhagen.Low Complexity Parametric Stereo Coding in MPEG-4.Proc. of the 7th International Conference on Digital Audio Effects. Naples,Italy,2004.10:1894-1897.
[26] Manuel Briand, David Birette and Nadine Martin. Parametric coding stereo audio based on principal component analysis. Proc. of the 9th Int. Conference on Digital Audio Effects(DAFx-06), Montreal, Canada, 2006.09:291-296.
[27] ISO/IEC 14496-3:2001/AMD2. Parametric Audio Extension. ISO/IEC JTC1/SC29 WG11,2004: 48-65.
[28] J.Herre. From Joint Stereo to Spatial Audio Coding– Recent Progress and Standardization. Proc. of the 7th Int. Conf. on Digital Audio Effects. Naples,Italy,2004.10:157-162.
[29] E. Schuijers, J. Breebaart, H. Purnhagen and J. Engdegard. Low Complexity Parametric Stereo Coding. AES 116th Convebtion,Berlin,Germany,2004.05:2-10.
[30]王笑雨.基于Intel XScale处理器的嵌入式系统中MPEG4解码的实现和优化.[硕士学位论文],东南大学,2006.3:6-11.
[31]徐钦桂,何文斌.东莞理工学院.XScale应用程序性能的优化策略http://sctc.guet.edu.cn/html/jichudianzi/qianrushijishu/20070104/5185_2.html.
[32]用于MPEG-4试听流的RTP负载格式(RFC3016)http://boyxsh.spaces.live.com/?_c11_BlogPart_blogpart=blogview&_c=BlogPart&partqs=amonth%3d4%26ayear%3d2006.
[33] Osamu Shimada, Toshiyuki Nomura, Akihiko Sugiyama and Masahiro Serizawa. Tradeoff Betweem Complexity and Memory Size In The 3GPP Enhanced AACPlus Decoder:speed-conscious and Memory-Conscious Decoders on A 16-bit Fixed-Point DSP. Media and Information Research Laboratories,NEC Corporation:1-6.
[34]汪国有,张成兴,廖容等.MPEG-4 AAC实时音频编解码器设计与实现研究.计算机与数字工程.2005第8期:124-128.
[35]潘岳,王建中,戎蒙恬等.MPEG-4 AAC解码器在NIOSⅡ平台上的实现和优化.数字信号处理.2006.11:46-49.
[36] P.Duhamel,Y.Mahieux,and J.P.Petit,”A fast algorithm for the implementation of filter banks based on time domain aliasing cancellation”in Proc.IEEE Int.Conf.Acoustics,Speech,and Signal Processing’91,Toronto,ON Canada,1991(5):2209-2212
[37]李玥,刘开华,曹承涛.音频系统中霍夫曼解码算法改进.电子测量技术.2005年第二期:17-18.
[38]薛英智,顾力翱,周正华,唐心悦. AAC解码器的Huffman算法选择和优化.计算机工程.2004.12第30卷:386-387,512.
[39]梅优良.基于RISC的MPEG-4 AAC编解码研究. [硕士学位论文],浙江大学.2006.03:34-41.
[40]韩纪庆,冯涛,郑贵滨等.音频信息处理技术.清华大学出版社.2007.1:35-41,65-78.
[2]韩宪柱.数字音频技术及应用.中国广播电视出版社.2003.1:72-74,98-98,191-113.
[3] [美]Andrew N.Sloss,[英]Dominic Symes,[美]Chris Wright.沈建华(译).ARM嵌入式系统开发——软件设计与优化.北京航空航天大学出版社.2005:199-205,244-247.
[4] 3GPP TS 26.401.Enhanced aacPlus general audio codec: General description.2005.06:6-10.
[5] 3GPP TS 26.402.Enhanced aacPlus general audio codec:Additional Decoder Tools.2005.09:7-17.
[6]陈景铭.利用高频重建之MPEG音讯编解码器设计及其系统实现.[硕士学位论文],台湾云林科技大学.2005:34-37,76-89.
[7] 3GPP TS 26.404.Enhanced aacPlus general audio codec: Encoder Specification SBR part.2004.09:7-32.
[8] 3GPP TS 26.405.Enhanced aacPlus general audio codec: Encoder Specification parametric stero part.2005.03:5-13.
[9] ISO/IEC 14496-3. Information Technology-Coding of Audio-Visual Objects-part3:Audio. ISO/IEC JTC1/SC29 WG11,2001:473-480.
[10] ISO/IEC 13818-7. Information Technology- Generic Coding of Moving Picture and Associated Audio Information– part 7:Advanced Audio Coding (AAC). ISO/IEC JTC1/SC29 WG11,1999:43-75.
[11] 3GPP TS 26.403.Enhanced aacPlus general audio codec: Encoder Specification AAC part.2006.06:7-22.
[12]任军刚.Enhanced aacPlus编解码器的研究和实现.[硕士学位论文],西安电子科技大学.2006.06:7-11,18-26.
[13]张益贞,刘滔. Visual C++实现MPEG/JPEG编解码技术.人民邮电出版社,2002.01:30-47.
[14] J.Herre, J.D.Johnston. Enhancing the Performance of Perceptual Audio Coders by Using Temporal Noise Shaping(TNS).AES 101 Convention, Los Angeles,1996:3-25.
[15] J.Herre. Temporal Noise Shaping, Quantization and Coding Methods in Perceptual Audio Coding. A Tutorial Introduction. AES 17th Int. Conf. on High Quality Audio Coding, Srptember 1999: 1-7.
[16]张艳.基于定点DSP的MPEG-4 AAC编解码系统研究.[硕士学位论文],成都理工大学.2005.6:26-33.
[17]陈健. AAC:21世纪音频编码的主流.电声技术,2002.09.总207期:4-7.
[18] ISO/IEC 14496-3:2001/AMD1. Bandwidth Extension.ISO/IEC JTC1/SC29 WG11,2003:1-44.
[19] M.Dietz, L.Liljeryd, K.Kjorling, and O.Kunz.Spectral Band Replication, a novel approach in audio coding. 112th AES Convention, Munich,Germany,2002.03:3-7.
[20] M.Wolters, K.Kjorling, D.Homm and H.purnhagen.A closer look into MPEG-4 High Efficiency AAC. 115th AES Convention 2003 October 10-13 New York, NY, USA:4-8.
[21] Per EKstrand, Bandwidth Extension of Audio signal by Spectral Band Replication.Proc.1st IEEE Benelux workshop on Model based Processing and Coding of Audio (MPCA-2002) ,Leuven,Belgium,2002.11:53-58.
[22] M.Dietz, S.Melzer. CT- aacplus—a State of The Art Audio Coding Scheme. EBU Technical Review, No291.2002.7:1-5.
[23]焦慧颖,安建平,卜祥元.数字广播音频编码中的频带复制技术(SBR).中国有线电视.2005.05:425-427.
[24] R.G..v.d. Waal,R.N.J.Veldhuis. Subband coding of stereophonic digital audio signals.Proc. IEEE Int. Conf. on Acoustics, Speech, Signal Processing,1991, vol.3:3601-3604.
[25] H. Purnhagen.Low Complexity Parametric Stereo Coding in MPEG-4.Proc. of the 7th International Conference on Digital Audio Effects. Naples,Italy,2004.10:1894-1897.
[26] Manuel Briand, David Birette and Nadine Martin. Parametric coding stereo audio based on principal component analysis. Proc. of the 9th Int. Conference on Digital Audio Effects(DAFx-06), Montreal, Canada, 2006.09:291-296.
[27] ISO/IEC 14496-3:2001/AMD2. Parametric Audio Extension. ISO/IEC JTC1/SC29 WG11,2004: 48-65.
[28] J.Herre. From Joint Stereo to Spatial Audio Coding– Recent Progress and Standardization. Proc. of the 7th Int. Conf. on Digital Audio Effects. Naples,Italy,2004.10:157-162.
[29] E. Schuijers, J. Breebaart, H. Purnhagen and J. Engdegard. Low Complexity Parametric Stereo Coding. AES 116th Convebtion,Berlin,Germany,2004.05:2-10.
[30]王笑雨.基于Intel XScale处理器的嵌入式系统中MPEG4解码的实现和优化.[硕士学位论文],东南大学,2006.3:6-11.
[31]徐钦桂,何文斌.东莞理工学院.XScale应用程序性能的优化策略http://sctc.guet.edu.cn/html/jichudianzi/qianrushijishu/20070104/5185_2.html.
[32]用于MPEG-4试听流的RTP负载格式(RFC3016)http://boyxsh.spaces.live.com/?_c11_BlogPart_blogpart=blogview&_c=BlogPart&partqs=amonth%3d4%26ayear%3d2006.
[33] Osamu Shimada, Toshiyuki Nomura, Akihiko Sugiyama and Masahiro Serizawa. Tradeoff Betweem Complexity and Memory Size In The 3GPP Enhanced AACPlus Decoder:speed-conscious and Memory-Conscious Decoders on A 16-bit Fixed-Point DSP. Media and Information Research Laboratories,NEC Corporation:1-6.
[34]汪国有,张成兴,廖容等.MPEG-4 AAC实时音频编解码器设计与实现研究.计算机与数字工程.2005第8期:124-128.
[35]潘岳,王建中,戎蒙恬等.MPEG-4 AAC解码器在NIOSⅡ平台上的实现和优化.数字信号处理.2006.11:46-49.
[36] P.Duhamel,Y.Mahieux,and J.P.Petit,”A fast algorithm for the implementation of filter banks based on time domain aliasing cancellation”in Proc.IEEE Int.Conf.Acoustics,Speech,and Signal Processing’91,Toronto,ON Canada,1991(5):2209-2212
[37]李玥,刘开华,曹承涛.音频系统中霍夫曼解码算法改进.电子测量技术.2005年第二期:17-18.
[38]薛英智,顾力翱,周正华,唐心悦. AAC解码器的Huffman算法选择和优化.计算机工程.2004.12第30卷:386-387,512.
[39]梅优良.基于RISC的MPEG-4 AAC编解码研究. [硕士学位论文],浙江大学.2006.03:34-41.
[40]韩纪庆,冯涛,郑贵滨等.音频信息处理技术.清华大学出版社.2007.1:35-41,65-78.