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De Cock J. Notebaert S. Lambert P. Van de Walle R. 《Multimedia, IEEE Transactions on》2009,11(7):1209-1224
The scalable extension of H.264/AVC (SVC) was recently standardized, and offers scalability at a minor penalty in rate-distortion efficiency when compared to single-layer H.264/AVC coding. In SVC, a scaled version of the original video sequence can easily be extracted by dropping layers from the stream. However, most of the video content nowadays is still produced in a single-layer format. While decoding and reencoding is a possible solution to introduce scalability in the existing bitstreams, this is an approach which requires a tremendous amount of time and effort. In this paper, we show that transcoding can be used to intelligently derive scalable bitstreams from existing single-layer streams. We focus on SNR scalability, and introduce techniques that are able to create multiple quality layers in the bitstreams. We also discuss bitstream rewriting from SVC to H.264/AVC, and examine how our newly proposed architectures can benefit from the changes that were introduced for bitstream rewriting. Architectures with different rate distribution flexibility and computational complexity are discussed. Rate-distortion performance of transcoding is shown to be comparable to that of reencoding at a fraction of the time needed for the latter. 相似文献
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In this work, transcoding of pre-encoded MPEG-1, 2 video into lower bit rates is realized through altering the coding algorithm into H.261/H.263 standards with lower spatio-temporal resolutions. For this heterogeneous transcoding, we extract and compose a set of candidate motion vectors, from the incoming bit stream, to comply with the encoding format of the output bit stream. For the spatial resolution reduction we generate one motion vector out of a set of input motion vectors operating on the higher spatial resolution image. Finally, for the temporal resolution reduction we compose new motion vectors from the dropped frames motion vectors. Throughout the paper, we discuss the impact of motion estimation refinement on the new motion vectors and show that for all cases a simple half-pixel refinement is sufficient for near-optimum results 相似文献
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On the impact of the GOP size in a temporal H.264/AVC-to-SVC transcoder in baseline and main profile
R. Garrido-Cantos J. De Cock J. L. Martínez S. Van Leuven P. Cuenca A. Garrido R. Van de Walle 《Multimedia Systems》2013,19(2):163-177
Scalable video coding is a recent extension of the advanced video coding H.264/AVC standard developed jointly by ISO/IEC and ITU-T, which allows adapting the bitstream easily by dropping parts of it named layers. This adaptation makes it possible for a single bitstream to meet the requirements for reliable delivery of video to diverse clients over heterogeneous networks using temporal, spatial or quality scalability, combined or separately. Since the scalable video coding design requires scalability to be provided at the encoder side, existing content cannot benefit from it. Efficient techniques for converting contents without scalability to a scalable format are desirable. In this paper, an approach for temporal scalability transcoding from H.264/AVC to scalable video coding in baseline and main profile is presented and the impact of the GOP size is analyzed. Independently of the GOP size chosen, time savings of around 63 % for baseline profile and 60 % for main profile are achieved while maintaining the coding efficiency. 相似文献
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Gerardo Fernández-Escribano Pedro Cuenca Luis Orozco-Barbosa Antonio Garrido Hari Kalva 《Multimedia Tools and Applications》2008,38(1):1-25
Recent developments have given birth to H.264/AVC: a video coding standard offering better bandwidth to video quality ratios
than MPEG-2. It is expected that the H.264/AVC will take over the digital video market, replacing the use of MPEG-2 in most
digital video applications. The complete migration to the new video-coding algorithm will take several years given the wide
scale use of MPEG-2 in the market place today. This creates an important need for MPEG-2/H264 transcoding technologies. However,
given the significant differences between both encoding algorithms, the transcoding process of such systems is much more complex
to other heterogeneous video transcoding processes. In this work, we start by analyzing the methods defined in the H.264 video
coding standard for the intra prediction: a central element of every H.264 encoder. We then introduce and evaluate six fast
intra mode decision algorithms which should enable the development of MPEG-2 to H.264 transcoders. Having evaluated all the
proposed methods, we have come out with a high-efficient method, namely DC-ABS pixel. Our results show that our algorithm
considerable reduces the complexity involved in the intra prediction with respect the mode decision algorithms used in H.264
JM reference software, while exhibiting a slight degradation on the RD function.. Finally, we analyze a comparative study
with two of the most prominent fast intra prediction methods presented in the literature. The results show that the proposed
DC-ABS pixel method achieves the best results for video transcoding applications.
相似文献
Hari KalvaEmail: |
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视频泵技术是视频服务器设计中的关键技术之一。MPEG-4视频泵的Transcoding(转换编码)机制是指在视频服务过程中,将用户请求的其它格式的视频数据实时地转换为MPEG-4视频格式。该文在MPEG-4标准的技术框架下,对MPEG-4视频泵功能进行了扩充设计,使其具有Transcoding功能,并只在首次点播服务时实现转换编码和存储。具有Transcoding功能的MPEG-4视频泵在视频服务器中的应用,是实现MPEG-4视频服务的技术核心之一。 相似文献
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主要论述了在H.264或者AVS(信息技术先进音视频编码系列标准)到MPEG-2转码过程中的QP(quantization parameter)映射问题。通过分析理论无失真的映射曲线(以下简称理论曲线)的数据保真和码率特性,发现了理论曲线和实际应用(高质量视频应用,有限带宽网络视频传输,质量自适应调整的视频点播)的不适应之处,基于对上述不同应用的具体分析,得到了一系列对应于应用的QP映射曲线,可以很好地满足相对应的应用要求。同时提出了利用这些H.264/AVS到MPEG-2转码过程中的QP映射曲线的几点建议。 相似文献
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王路 《计算机光盘软件与应用》2011,(12)
在视频会议系统中还有日常拍摄处理视频时,需要利用视频转码技术对传统和新兴视频流进行格式转换。使用转码的意义在于可以在不损失任何视频质量的前提下节省高达50%的网络带宽。转码的分类按照媒体格式可分为音频转码、视频转码,视频转码比较出名的有暴风转码、格式工厂,音频转码用大众的千千静听就能满足使用需要。本文以转码应用为研究对象,进一步分析软件转码技术的应用。 相似文献
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Eduard Sergi Joaquim Albert Marc Lluis Vicente Ramon Gabriel Michel 《Future Generation Computer Systems》2006,22(8):920-928
GridON is an application that converts high-resolution broadcast video into MPEG-2 format, thereby reducing the file size and resolution. The application uses the user controlled lightpaths (UCLP) software to create on-demand, end-to-end, high-bandwidth dedicated connections to access remote computers. The converted MPEG-2 files can be distributed much faster and further than the source files to these dispersed computers, for reassembly into the higher resolution format. This paper describes the demonstration that took place last September at the iGrid 2005 conference held in San Diego. As a proof of concept, we successfully demonstrated that a video transfer in a Grid network environment can be integrated with a user-controlled lightpath provisioning system. 相似文献
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随着数字音视频及多媒体技术的发展,迫切需要压缩巨大的视频信号数据,适用于不同领域的MPEG-1、MPEG-2、MPEG-4、H.261、H.263、H.264等国际编码标准应运而生。为了适应用户终端的多样性以及网络自身的传输特性,常需将已压缩的视频码流进行转换编码,以实现网络间资源共享。主要介绍了对已有的压缩视频流根据目标的要求如何进行相应的变换,如通过改变量化参数获得码率的变换;通过下变换获得缩小的图像,实现空间分辨率的变换,以及跳帧获得时间分辨率的变换。对不同变换器结构形式进行了分析,以获得结构复杂性和图像质量的均衡,并重点剖析了转换编码器核心技术——运动矢量的确定。 相似文献
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Ikeda M. Kondo T. Nitta K. Suguri K. Yoshitome T. Minami T. Iwasaki H. Ochiai K. Naganuma J. Endo M. Tashiro Y. Watanabe H. Kobayashi N. Okubo T. Kasai R. 《Micro, IEEE》1999,19(4):56-65
Thanks to increased market acceptance of applications such as digital versatile disks (DVDs), HDTV, and digital satellite broadcasting, the MPEG-2 (Moving Picture Experts Group-2) standard is becoming widely used. The MPEG-2 video standard, established in 1934, provides for a high-quality video compression format that, through high bit rates and frame rates, yields high-resolution video images. Emerging multimedia applications, such as digital versatile disk and high-definition television, demand higher quality video than ever before. In response, our MPEG-2 video encoder chip supports multiple profiles and levels 相似文献
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A first approach to speeding-up the inter mode selection in MPEG-2/H.264 transcoders using machine learning 总被引:1,自引:0,他引:1
Gerardo Fernández-Escribano Hari Kalva Pedro Cuenca Luis Orozco-Barbosa 《Multimedia Tools and Applications》2007,35(2):225-240
The H.264 standard achieves much higher coding efficiency than the MPEG-2 standard, due to its improved inter and intra prediction
modes which come with a cost of higher computation complexity. Transcoding MPEG-2 video to H.264 is important to enable gradual
migration to H.264. However, given the significant differences between the MPEG-2 and the H.264 coding algorithms, transcoding
is much more complex and new approaches to transcoding are necessary. In this paper, we introduce and evaluate a low complexity
macroblock partition mode decision algorithm, to be used as part of a high-efficient inter-frame prediction in MPEG-2 to H.264
transcoder. The proposed tools are used to compute an optimal MB coding mode decision with significantly reduced computational
complexity. Specifically, we achieve the computational savings by using the following MB information coming from MPEG-2: the
MB coding modes, the coded block pattern (CBPC) in MPEG-2, and the mean and variance of the 16 4 × 4 sub blocks of the MPEG-2
residual MBs. We use data mining algorithms to develop a decision tree for H.264 coding mode decisions. The decision trees
are built using RD optimized mode decisions and result in highly efficient mode decisions, with significantly reduced computational
complexity. The proposed transcoder is 35% faster than the RD optimized H.264 reference transcoder without a significant PSNR
degradation (0.05 dB on average). The proposed transcoder performs over 0.4 dB better on average than the SAE cost based H.264
transcoding.
相似文献
Luis Orozco-BarbosaEmail: |
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在结合RTP/RTCP协议和MPEG-4视频标准基础上,提出了一种适用于MPEG-4视频流网络传输系统的解决方案,重点介绍了MPEG-4数据的RTP协议封装技术,并对网络传输的相关编程实现做了详细的讨论. 相似文献
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An efficient method for splitting an 8×8 2-D DCT block into four 4×4, two 8×4 (or 4×8) 2-D DCT blocks is presented in this paper. The reverse direction (the “merge” case) also can be realized by inverse transposing the given matrix operations in the “split” case. The computational complexity of the proposed methods is lower than that of the direct approach and other known efficient converting approaches. Due to its efficiency, the proposed DCT splitter/merger will play an important role in realizing the transcoding between the latest video coding standard, AVC/H.264, and the older ones, such as MPEG-1, MPEG-2, and MPEG-4 part 2. 相似文献
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One of the fundamental challenges in deploying multimedia systems, such as telemedicine, education, space endeavors, marketing, crisis management, transportation, and military, is to deliver smooth and uninterruptible flow of audio-visual information, anytime and anywhere. A multimedia system may consist of various devices (PCs, laptops, PDAs, smart phones, etc.) interconnected via heterogeneous wireline and wireless networks. In such systems, multimedia content originally authored and compressed with a certain format may need bit rate adjustment and format conversion in order to allow access by receiving devices with diverse capabilities (display, memory, processing, decoder). Thus, a transcoding mechanism is required to make the content adaptive to the capabilities of diverse networks and client devices. A video transcoder can perform several additional functions. For example, if the bandwidth required for a particular video is fluctuating due to congestion or other causes, a transcoder can provide fine and dynamic adjustments in the bit rate of the video bitstream in the compressed domain without imposing additional functional requirements in the decoder. In addition, a video transcoder can change the coding parameters of the compressed video, adjust spatial and temporal resolution, and modify the video content and/or the coding standard used. This paper provides an overview of several video transcoding techniques and some of the related research issues. We introduce some of the basic concepts of video transcoding, and then review and contrast various approaches while highlighting critical research issues. We propose solutions to some of these research issues, and identify possible research directions. 相似文献
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可分级编码是解决Internet流视频应用中网络带宽不断波动的一种有效方法,所以MPEG-4标准中采用了FGS(fine granularity scalability)编码方法来获得精细颗粒可分级能力,但其代价是编码效率的下降。为解决此问题,现提出在增强层中采用运动补偿的MC加FGS(motion compensation加FGS)结构,用于去除FGS方案中增强层在时域上的冗余,以提高FGS方案编码效率的双环和单环两种方法。在比较了两种结构各自的优缺点后,选定了一种复杂度小、实现简单、效率高的单环结构,并提出了对单环结构的缺陷进行改善的方法。实验结果表明,该方法的编码性能优于MPEG-4 FGS方法。 相似文献
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The paper investigates efficient bandwidth allocation schemes for the transmission of MPEG-2 video traffic on high-speed
networks. To this end we performed an extensive analysis of the traffic generated by an MPEG-2 encoder. Specifically, we encoded
“The Sheltering Sky” movie according to the MPEG-2 standard. By the analysis of the generated traffic it results that a constant-quality
transmission can be performed with a poor bandwidth utilization. In the paper we identified that the low bandwidth utilization
is caused by rare high-rate periods in the codec bitstream. Hence, we identified the source scalability as a promising approach
to achieve a “quasi-constant” quality transmission and an efficient bandwidth utilization. The effectiveness of this approach
is evaluated in the paper via simulation. Specifically, by defining a Markovian model for an MPEG-2 scalable source we performed
a set of simulation experiments which indicate that the source scalability approach significantly increases the utilization,
while maintaining the quality of the video signal at the highest value for most of the time, e.g., a 50% of the network utilization
with the highest quality for the 99.7% of the time. 相似文献
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MPEG-4标准是目前视频监控应用中最先进的压缩方法。本文在对MPEG-4编码原理进行研究后,提出了一种基于MPEG-4标准的视频处理芯片AT2401的嵌入式视频监控系统的实现方法,并详细介绍了该嵌入式视频监控系统的主要功能、硬件设计和软件设计流程。该系统完全由硬件进行视频的实时压缩,通过网络可实现多路视频的远程监控。经实际应用证明,该系统稳定可靠,可满足视频监控的需求。 相似文献