Resynchronization and remultiplexing for transcoding to H.264/AVC

H.264/MPEG-4 AVC standard appears highly competitive due to its high efficiency, flexibility and error resilience. In order to maintain universal multimedia access, statistical multiplexing, or adaptive video content delivery, etc., it induces an immense demand for converting a large volume of existing multimedia content from other formats into the H.264/AVC format and vice versa. In this work, we study the remultiplexing and resynchronization issue within system coding after transcoding, aiming to sustain the management and time information destroyed in transcoding and enable synchronized decoding of decoder buffers over a wide range of retrieval or receipt conditions. Given the common intention of multiplexing and synchronization mechanism in system coding of different standards, this paper takes the most widely used MPEG-2 transport stream (TS) as an example, and presents a software system and the key technologies to solve the time stamp mapping and relevant buffer management. The solution reuses previous information contained in the input streams to remultiplex and resynchronize the output information with the regulatory coding and composition structure. Experimental results showed that our solutions efficiently preserve the performance in multimedia presentation.

An efficient VLSI implementation of H.264/AVC entropy decoder

This paper proposes an efficient H.264/AVC entropy decoder.It requires no ROM/RAM fabrication process that decreases fabrication cost and increases operation speed.It was achieved by optimizing lookup tables and internal buffers,which significantly improves area,speed,and power.The proposed entropy decoder does not exploit embedded processor for bitstream manipulation, which also improves area,speed,and power.Its gate counts and maximum operation frequency are 77515 gates and 175MHz in 0.18um fabrication process,respectively.The proposed entropy decoder needs 2303 cycles in average for one macroblock decoding.It can run at 28MHz to meet the real-time processing requirement for CIF format video decoding on mobile applications.

An adaptive pipelining scheme for H.264/AVC CABAC decoder

An adaptive pipelining scheme for H.264/AVC context-based adaptive binary arithmetic coding(CABAC) decoder for high definition(HD) applications is proposed to solve data hazard problems coming from the data dependencies in CABAC decoding process.An efficiency model of CABAC decoding pipeline is derived according to the analysis of a common pipeline.Based on that,several adaptive strategies are provided.The pipelining scheme with these strategies can be adaptive to different types of syntax elements(SEs) and the pipeline will not stall during decoding process when these strategies are adopted.In addition,the decoder proposed can fully support H.264/AVC high4:2:2 profile and the experimental results show that the efficiency of decoder is much higher than other architectures with one engine.Taking both performance and cost into consideration,our design makes a good tradeoff compared with other work and it is sufficient for HD real-time decoding.

System-Level Performance Evaluation of Very High Complexity Media Applications : A H264/AVC Encoder Case Study

Given the substantially increasing complexity of embedded systems, the use of relatively detailed clock cycle-accurate simulators for the design-space exploration is impractical in the early design stages. Raising the abstraction level is nowadays widely seen as a solution to bridge the gap between the increasing system complexity and the low design productivity. For this, several system-level design tools and methodologies have been introduced to efficiently explore the design space of heterogeneous signal processing systems. In this paper, we demonstrate the effectiveness and the flexibility of the Sesame/Artemis system-level modeling and simulation methodology for efficient peformance evaluation and rapid architectural exploration of the increasing complexity heterogeneous embedded media systems. For this purpose, we have selected a system level design of a very high complexity media application;a H.264/AVC (Advanced Video Codec) video encoder. The encoding performances will be evaluated using system-level simulations targeting multiple heterogeneous multiprocessors platforms.

Frame complexity optimized selection for H.264/AVC video coding

To improve the coding performance of H.264/AVC, this paper proposes a rate control scheme composed of a novel flame complexity optimized selection and a quantization parameter （QP） value computation approach. First, it extracts the frame coding complexity from two rate distortion models, and then introduces five statistic modes to estimate the frame coding complexity. An optimal mode is selected according to the coding efficiency. Finally the paper presents a novel QP calculation method for the H.264/AVC rate control. Experimental results show that the proposed algorithra outperforms the algorithm integrated in the 3M model in obtaining precise frame coding complexity, achieving robust buffer control and improving coding quality. And the improving visual quality is high up to 0.90dB for CIF sequences.

Reversible Data Hiding Based on Run-Level Coding in H.264/AVC Video Streams

This paper presents a reversible data hiding(RDH)method,which is designed by combining histogram modification(HM)with run-level coding in H.264/advanced video coding(AVC).In this scheme,the run-level is changed for embedding data into H.264/AVC video sequences.In order to guarantee the reversibility of the proposed scheme,the last nonzero quantized discrete cosine transform(DCT)coefficients in embeddable 4×4 blocks are shifted by the technology of histogram modification.The proposed scheme is realized after quantization and before entropy coding of H.264/AVC compression standard.Therefore,the embedded information can be correctly extracted at the decoding side.Peak-signal-noise-to-ratio(PSNR)and Structure similarity index(SSIM),embedding payload and bit-rate variation are exploited to measure the performance of the proposed scheme.Experimental results have shown that the proposed scheme leads to less SSIM variation and bit-rate increase.

Quantization Skipping Method for H.264/AVC Video Coding

This paper presents a quantization skipping method for H. 264/AVC video coding standard. In order to reduce the conputational-cost of quantization process coming from integer discrete cosine transform of H. 264/AVC, a quantization skipping condition is derived by the analysis of integer transform and quantization procedures. The expeerimental results show that the proposed algorithm has the capability to reduce the computional cost about 10% -2.5%.

Very Low Bit-Rate Video Coding by Combining H.264/AVC Standard and 2-D Discrete Wavelet Transform

In this paper, we propose a new method for very low bit-rate video coding that combines H.264/AVC standard and two-dimensional discrete wavelet transform. In this method, first a two dimensional wavelet transform is applied on each video frame independently to extract the low frequency components for each frame and then the low frequency parts of all frames are coded using H.264/AVC codec. On the other hand, the high frequency parts of the video frames are coded by Run Length Coding algorithm, after applying a threshold to neglect the low value coefficients. Experiments show that our proposed method can achieve better rate-distortion performance at very low bit-rate applications below 16 kbits/s compared to applying H.264/AVC standard directly to all frames. Applications of our proposed video coding technique include video telephony, video-conferencing, transmitting or receiving video over half-rate traffic channels of GSM networks.

基于纹理特征的H.264/AVC顽健视频水印算法

在分析现有视频水印算法的基础上,结合H.264压缩编码标准的特性,提出了一种新的基于纹理特征的视频顽健水印算法。算法先对当前帧4×4块进行整数离散余弦变换,判断其是否是纹理块,再采用能量差的方式自适应选择系数嵌入水印。实验结果表明,该算法对视频质量和码率的影响较小,并且能有效抵抗高斯噪声、低通滤波、重编码等常见的视频水印攻击。

H．264／AVC码率控制优化算法

提出了一种新颖的编码特性预测机制,较为充分地利用了视频信源的时空相关性,改进了率失真建模的有效性;利用Lagrangian优化理论推导出两种率失真优化的位分配方案,并实现了相应的码率控制算法,即线性模型算法和二次模型算法.大量实验数据表明:线性模型算法和二次模型算法的编码效率基本上相同,而前者的码率控制能力稍优于后者;和H.264/AVC参考软件中所采用的JVTG012码率控制算法相比,两种新算法在获得更高编码效率的同时,能够更加准确地控制输出码率.

基于H.264/AVC的视频信息隐藏算法

在H.264/AVC的帧内预测环节,调制H.264/AVC编码中I帧4×4亮度块的帧内预测模式实现信息隐藏.这种调制基于该模式与待隐藏比特之间的映射规则进行.宿主4×4块的具体位置由各块自身特点结合密钥所指定的嵌入位置模板确定.信息的提取过程不需要原始视频内容,也不需完全解码,而只要对码流中的帧内预测模式进行解码即可.

一种基于自相关法的H.264/AVC高效帧内预测算法

H.264/AVC是最新的视频压缩标准,具有极高的压缩率,但由于编码时间较长,无法达到实时应用的要求.本文提出了一种新的基于自相关法的高效帧内预测算法.该算法在进行帧内预测之前先对宏块预判,从两种预测模式中选择一种,从而减少了算法的复杂度.实验结果表明,本文提出的算法在码率只有少许增加的情况下,速度平均提高了26.9%,SNR值基本维持不变.

H.264/AVC压缩域鲁棒视频水印

针对现有H.264/AVC压缩域开环水印方法存在误差漂移及鲁棒性差的问题,分析了该类水印算法的特点及误差漂移机制,提出了一种无误差漂移的鲁棒视频水印算法。首先,基于视频重建过程,分析了开环回路水印方法的误差漂移机制,得到由水印信息造成的独立重建误差。然后,采用误差间的线性组合得到4个可以避免误差漂移的水印模板。最后,通过调制残差系数与相应水印模板之间的正负相关性,将水印嵌入在非零系数多的4×4子块上,而不像以往算法将水印直接添加在残差系数上。实验结果表明:所提算法造成的平均结构相似度下降在0.005以内;码率的增长在1.00%左右;对重量化转码、加性高斯白噪声、亮度调节等常见水印攻击,误码率均在0.15以下。得到的结果满足视频水印算法对透明性,码率稳定性,鲁棒性的要求。

一种面向H.264/AVC的快速帧内预测选择算法

为提高I帧的编码效率,最新的视频压缩编码标准H.264/AVC,在空间域上从多个方向进行多种模式的帧内预测,并使用率失真优化算法选择最佳模式,算法复杂度很高.为此,提出了一种快速的帧内预测算法.针对亮度块的模式选择过程,提出了基于图像熵值和滑动窗口机制自适应地调整熵值阈值的方法对宏块模式进行预判;针对亮度模式中多个预测方向的选择,充分利用中间结果,预先排除一些可能性小的预测方向;在亮度块和色度块相结合的率失真统计中,改变算法结构,预先计算色度块最佳模式.实验结果表明,算法在不降低图像质量的基础上,编码速度平均提高76%,码率平均增加2.6%.

基于人眼视觉系统的H.264/AVC码率控制算法

提出了一种基于人眼视觉系统(HVS)特性的H.264/AVC码率控制方案以解决传统的H.264/AVC码率控制算法中由于码率分配不当造成视频质量较差的问题。该方案利用人眼视觉系统对视频场景感知的选择性设计了一种新的基于区域的码率控制算法。首先,利用当前帧和前一帧的信息快速地检测出运动区域和非运动区域。其次,根据宏块所在区域的复杂度进一步将非运动区域细分为平坦区域和复杂区域。最后,对这3种区域依据不同的视觉敏感度权重分配适当的比特数。基于不同区域峰值信噪比(PSNR)、连续帧PSNR、主观评价以及缓冲器充盈度综合评价了本文算法的性能,结果表明,提出的基于区域的码率控制方案对不同视觉特性区域的比特分配有较高的鲁棒性,与JVT-G012的码率控制算法相比能获得较好的主观和客观编码质量。

H.264/AVC中基于全零块检测的运动估计快速算法

全零块检测是面向低比特率的视频编码器常用优化方法之一。特别是与运动估计相结合,可以有效的减少编码器的计算复杂性。本文根据H.264/AVC中整数变换的特点,给出了相应的全零块检测门限,提出了一种基于全零块检测的运动搜索提前中止准则。针对H.264/AVC多编码模式的特点,进一步将全零块检测用于H.264/AVC中多种编码模式的选择,有效的提高了运动估计的效率。利用这种方法,在有效减少编码器的计算复杂性,提高H.264/AVC软件编码器编码效率的同时,可以保持比特率和图像质量基本不变。

一种快速的H.264/AVC帧内预测模式选择算法

H.264/AVC采用RDO技术选择帧内和帧间预测模式以进一步提高编码的效率,取得显著效果,但同时大幅度增加了预测的复杂度。该文提出一种RDO模式下的快速Intra_4x4模式选择算法,该算法根据SATD特征以及相邻块的预测模式之间的相关性,可以预先排除约50%可能性小的Intra_4x4模式,避免了不必要的代价(RD_Cost)计算,从而大幅度降低帧内预测的复杂度,同时基本保持了H.264/AVC的编码性能。

一种适用于H.264/AVC的自适应空域帧内预测算法

提出了帧内预测算法中邻块间预测选项的相关性、预测选项和SAD相关性的概念,在此基础上提出了一种适用于H.264/AVC的自适应空域帧内预测算法,该算法利用上述的两种相关性预测当前块的帧内预测选项;利用“半步停”技术自适应地中止预测.实验结果表明,该算法在保证重构图像质量和压缩比的同时,计算复杂度仅相当于原有算法的7%左右.

H.264/AVC视频编码标准的技术特点及应用分析

H.264／AVC是ITU-T视频编码专家组和ISO／IEC运动图像专家组(MPEG)共同开发出来的最新视频编码标准,它具备许多新的技术特点,如:多模式运动预测、柔性宏块排序、整数变换、一致性变字长编码、内容自适应二进制算术编码、分层编码、错误约束机制、错误掩盖技术及高效的比特流切换技术等等。本文在阐述该标准系统层结构的基础上,分析其主要技术特点及H.264／AVC VBR码流特性,阐述该标准在IP网络及无线网络中的应用情况。

基于编码模式的H.264/AVC视频信息隐藏算法

本文提出一种基于编码模式的H.264/AVC信息隐藏方法,通过调制某些宏块的编码模式,分别在I帧、P帧和B帧中嵌入隐秘信息。对帧内4×4预测模式的宏块,是通过调整宏块中某个4×4块的编码模式嵌入隐秘信息;对P帧和B帧其它类型的宏块,则是通过调整宏块的编码模式嵌入隐秘信息,模式调整后对宏块做了优化处理。在模式调制过程中引入率失真代价,取得了较好的率失真平衡,减小了隐秘信息嵌入后对视频质量和视频码流的影响。该算法可以实现隐秘信息的快速提取,满足视频实时处理的要求,实验仿真结果证明了该算法的有效性。