MPEG-4 High-Efficiency Advanced Audio Coding (HE-AAC) is designed for low bit rate applications, such as audio streaming in mobile communications. The HE-AAC audio codec offers a better coding efficiency since variabl...MPEG-4 High-Efficiency Advanced Audio Coding (HE-AAC) is designed for low bit rate applications, such as audio streaming in mobile communications. The HE-AAC audio codec offers a better coding efficiency since variable-length codes (VLCs) are adopted. However, HE-AAC has originally been designed for storage and error-free transmission conditions. For the transmission over bit error-prone channels, error propagation is a serious problem for the VLCs. Therefore, a robust HE-AAC decoder is desired, especially for mobile communications. In contrast to traditional hard-decision decoding, utilizing bit-wise channel reliability information, softdecision (SD) decoding has been known to offer better audio quality. In HE-AAC, the global gain parameter is coded with fixedlength codes (FLCs), while the scale factors and quantized spectral coefficients are coded with VLCs. In this work, we apply FL/SD decoding to the global gain parameter, VL/SD decoding to the parameters scale factors and quantized spectral coefficients. Especially, in order to apply VL/SD decoding to the quantized spectral coefficients, a new modified trellis representation in VL/SD decoding is proposed. An improved HE-AAC performance is clearly observed, with the support of both instrumental measurements and a subjective listening test.展开更多
Most of multimedia schemes employ variable-length codes （VLCs） like Huffman code as core components in obtaining high compression rates. However VLC methods are very sensitive to channel noise. The goal of this pape...Most of multimedia schemes employ variable-length codes （VLCs） like Huffman code as core components in obtaining high compression rates. However VLC methods are very sensitive to channel noise. The goal of this paper is to salvage as many data from the damaged packets as possible for higher audiovisual quality. This paper proposes an integrated joint source-channel decoder （I-JSCD） at a symbol-level using three-dimensional （3-D） trellis representation for first-order Markov sources encoded with VLC source code and convolutional channel code. This method combines source code and channel code state-spaces and bit-lengths to construct a two-dimensional （2-D） state-space, and then develops a 3-D trellis and a maximum a-posterior （MAP） algorithm to estimate the source sequence symbol by symbol. Experiment results demonstrate that our method results in significant improvement in decoding performance, it can salvage at least half of （50%） data in any channel error rate, and can provide additional error resilience to VLC stream like image, audio, video stream over high error rate links.展开更多
设计了一种可应用于国家标准AVS(Audio Video Coding Standard)的变字长解码器,根据码流特点进行硬件模块划分;采用桶形移位器并行解码,每个时钟解一个码字,采用Verilog语言进行设计、模拟,通过了FPGA验证。用0.18μmCMOS工艺库综合,电...设计了一种可应用于国家标准AVS(Audio Video Coding Standard)的变字长解码器,根据码流特点进行硬件模块划分;采用桶形移位器并行解码,每个时钟解一个码字,采用Verilog语言进行设计、模拟,通过了FPGA验证。用0.18μmCMOS工艺库综合,电路规模为1.6万门左右,最高频率能够达到166MHz,可实时解码720p/1080i高清AVS码流。展开更多
This paper presents an efficient VLSI architecture of the contest-based adaptive variable length code （CAVLC） decoder with power optimized for the H.264/advanced video coding （AVC） standard. In the proposed design...This paper presents an efficient VLSI architecture of the contest-based adaptive variable length code （CAVLC） decoder with power optimized for the H.264/advanced video coding （AVC） standard. In the proposed design, according to the regularity of the codewords, the first one detector is used to solve the low efficiency and high power dissipation problem within the traditional method of table-searching. Considering the relevance of the data used in the process of runbefore＇s decoding, arithmetic operation is combined with finite state machine （FSM）, which achieves higher decoding efficiency. According to the CAVLC decoding flow, clock gating is employed in the module level and the register level respectively, which reduces 43% of the overall dynamic power dissipation. The proposed design can decode every syntax element in one clock cycle. When the proposed design is synthesized at the clock constraint of 100 MHz, the synthesis result shows that the design costs 11 300 gates under a 0.25 μm CMOS technology, which meets the demand of real time decoding in the H.264/AVC standard.展开更多
为了进一步提高通信系统的可靠性,提出一种联合信源信道译码(JSCD)方案。该方案利用一个软输入软输出(SISO)译码器对可变长码(VLC)实施软译码。SISO-VLC译码器利用信源符号的先验信息,采用BCJR算法,得到压缩比特的后验概率。该方案将VL...为了进一步提高通信系统的可靠性,提出一种联合信源信道译码(JSCD)方案。该方案利用一个软输入软输出(SISO)译码器对可变长码(VLC)实施软译码。SISO-VLC译码器利用信源符号的先验信息,采用BCJR算法,得到压缩比特的后验概率。该方案将VLC与低密度奇偶校验(LDPC)码串行级联,在译码端SISO-VLC译码器将外信息传递给LDPC译码器,实现信源信道联合译码。在加性高斯白噪声环境下,对该方案的误码率和误符号率进行评估,并与分离信源信道译码(SSCD)比较。仿真结果表明,在一定复杂度的情况下,该方案在低信噪比下具有很高的可靠性;与SSCD相比,能获得0.2 d B的编码增益。展开更多
文摘MPEG-4 High-Efficiency Advanced Audio Coding (HE-AAC) is designed for low bit rate applications, such as audio streaming in mobile communications. The HE-AAC audio codec offers a better coding efficiency since variable-length codes (VLCs) are adopted. However, HE-AAC has originally been designed for storage and error-free transmission conditions. For the transmission over bit error-prone channels, error propagation is a serious problem for the VLCs. Therefore, a robust HE-AAC decoder is desired, especially for mobile communications. In contrast to traditional hard-decision decoding, utilizing bit-wise channel reliability information, softdecision (SD) decoding has been known to offer better audio quality. In HE-AAC, the global gain parameter is coded with fixedlength codes (FLCs), while the scale factors and quantized spectral coefficients are coded with VLCs. In this work, we apply FL/SD decoding to the global gain parameter, VL/SD decoding to the parameters scale factors and quantized spectral coefficients. Especially, in order to apply VL/SD decoding to the quantized spectral coefficients, a new modified trellis representation in VL/SD decoding is proposed. An improved HE-AAC performance is clearly observed, with the support of both instrumental measurements and a subjective listening test.
基金Supported by the Foundation of Ministry of Education of China (211CERS10)
文摘Most of multimedia schemes employ variable-length codes （VLCs） like Huffman code as core components in obtaining high compression rates. However VLC methods are very sensitive to channel noise. The goal of this paper is to salvage as many data from the damaged packets as possible for higher audiovisual quality. This paper proposes an integrated joint source-channel decoder （I-JSCD） at a symbol-level using three-dimensional （3-D） trellis representation for first-order Markov sources encoded with VLC source code and convolutional channel code. This method combines source code and channel code state-spaces and bit-lengths to construct a two-dimensional （2-D） state-space, and then develops a 3-D trellis and a maximum a-posterior （MAP） algorithm to estimate the source sequence symbol by symbol. Experiment results demonstrate that our method results in significant improvement in decoding performance, it can salvage at least half of （50%） data in any channel error rate, and can provide additional error resilience to VLC stream like image, audio, video stream over high error rate links.
文摘设计了一种可应用于国家标准AVS(Audio Video Coding Standard)的变字长解码器,根据码流特点进行硬件模块划分;采用桶形移位器并行解码,每个时钟解一个码字,采用Verilog语言进行设计、模拟,通过了FPGA验证。用0.18μmCMOS工艺库综合,电路规模为1.6万门左右,最高频率能够达到166MHz,可实时解码720p/1080i高清AVS码流。
基金Project supported by the Applied Materials Shanghai Research and Development Foundation (Grant No.08700741000)the Foundation of Shanghai Municipal Education Commission (Grant No.2006AZ068)
文摘This paper presents an efficient VLSI architecture of the contest-based adaptive variable length code （CAVLC） decoder with power optimized for the H.264/advanced video coding （AVC） standard. In the proposed design, according to the regularity of the codewords, the first one detector is used to solve the low efficiency and high power dissipation problem within the traditional method of table-searching. Considering the relevance of the data used in the process of runbefore＇s decoding, arithmetic operation is combined with finite state machine （FSM）, which achieves higher decoding efficiency. According to the CAVLC decoding flow, clock gating is employed in the module level and the register level respectively, which reduces 43% of the overall dynamic power dissipation. The proposed design can decode every syntax element in one clock cycle. When the proposed design is synthesized at the clock constraint of 100 MHz, the synthesis result shows that the design costs 11 300 gates under a 0.25 μm CMOS technology, which meets the demand of real time decoding in the H.264/AVC standard.
文摘为了进一步提高通信系统的可靠性,提出一种联合信源信道译码(JSCD)方案。该方案利用一个软输入软输出(SISO)译码器对可变长码(VLC)实施软译码。SISO-VLC译码器利用信源符号的先验信息,采用BCJR算法,得到压缩比特的后验概率。该方案将VLC与低密度奇偶校验(LDPC)码串行级联,在译码端SISO-VLC译码器将外信息传递给LDPC译码器,实现信源信道联合译码。在加性高斯白噪声环境下,对该方案的误码率和误符号率进行评估,并与分离信源信道译码(SSCD)比较。仿真结果表明,在一定复杂度的情况下,该方案在低信噪比下具有很高的可靠性;与SSCD相比,能获得0.2 d B的编码增益。
