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European Signal Processing Conference

作者： Ora Gendler Moshe Porat Department of Electrical Engineering Technion - Israel Institute of Technology

Real-time multimedia applications often require efficient bitrate reduction. This is mainly done by requantization, usually in the DCT domain. This work introduces theoretical rate-distortion analysis that allows for straightforward selection of the quantization step needed to achieve a given bit-rate. The analysis is based on the Laplace-like distribution of DCT coefficients in the transform domain and on the structure of the quantizers commonly used in video and image coding. We show that the proposed transcoding design achieves significant compression at relatively low distortion, while keeping the computational complexity very low, allowing for real-time implementation.

关键词： Videotapes Bit rate discrete cosine transforms DCT gene image coding rate-distortion analysis partition coefficients real-time multimedia low distortion Laplace quantizer transcoding

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Mobile Video Optimization at the Base Station: Adaptive Guaranteed Bit Rate for HTTP Adaptive Streaming

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BELL LABS TECHNICAL JOURNAL 2013年第2期18卷 159-174页

作者： Viswanathan, Harish De Vleeschauwer, Danny Beck, Andre Benno, Steven Miller, Raymond B. Li, Gang Clougherty, Mark M. Robinson, David C. Alcatel Lucent M2M & Wireless Networking Murray Hill NJ USA Bell Labs Murray Hill NJ USA Alcatel Lucent Murray Hill NJ USA Alcatel Lucent Bell Labs Antwerp Belgium Univ Ghent B-9000 Ghent Belgium Univ Ghent Telecommun & Informat Proc Dept TELIN B-9000 Ghent Belgium Alcatel Lucent Bell Labs Video & Mobile Packet Networking Res Dept Murray Hill NJ USA Alcatel Lucent Corp Chief Technol Off CTO Murray Hill NJ USA Alcatel Lucent Network & Platforms Core Div Maidenhead Berks England Digital Equipment Corp Maynard MA USA

Video is expected to be the dominant application by traffic volume over mobile networks in the near future. Mobile network operators are deploying video optimization techniques to enhance the user experience and network utilization for video delivery. Video optimization is typically out-of-network and includes techniques such as transcoding, transrating, time shifting and pacing that are implemented outside of mobile radio access and core networks. However, such techniques cannot easily exploit information about real time cell congestion and radio conditions for the video terminals because it is difficult to obtain such information from the radio access network. We propose a novel in-network video optimization technique, named Adaptive Guaranteed Bit Rate (AGBR), for HTTP-based Adaptive Streaming (HAS) video. This optimization technique is implemented at the base station and can thus exploit knowledge of the radio and congestion conditions. With only limited knowledge of the video stream properties or content, AGBR works by adjusting the throughput delivered to the different HAS clients that in turn adjust the video quality they request. The optimization algorithm maximizes aggregate quality across multiple video flows served by the base station without starving data clients, thereby improving the overall quality of experience. We demonstrate through extensive analytical modeling and simulations that AGBR can adapt to changing network conditions to support more video sessions at an acceptable quality than alternative algorithms, while enforcing fairness among all users competing for resources within a sector. (c) 2013 Alcatel-Lucent.

关键词： Streaming media Bit rate Video communication Base stations Telecommunication traffic transcoding Bandwidth Mobile communication

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Impact of video transcoding artifacts on the subjective quality

Impact of video transcoding artifacts on the subjective qual...

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International Workshop on Quality of Multimedia Experience, QoMEx

作者： Lutz Goldmann Francesca De Simone Frederic Dufaux Touradj Ebrahimi Rudolf Tanner Mauro Lattuada EPFL/STI/IEL/GR-EB Ecole Palytechnique Federale de Lausanne Lausanne Switzerland Abilis Systems Sarl Plan-Les-Ouates Switzerland

Video transcoding is an important step to enable interoperability between different networks, terminals, applications, and services for video communication. This paper studies the influence of typical video transcoding artifacts due to frame rate reduction and drift error on the subjective quality. Given a realistic dataset for a DVB-T to DVB-H transcoding scenario, the subjective quality before and after the transcoding is compared against each other. In order to quantify the influence of both artifacts, a pixel domain and an open loop transcoding solution have been considered. Since the strength of both artifacts depends largely on the initial encoding parameters, additional experiments have been conducted to quantify the influence of the distance between I frames and the number of consecutive B frames on the subjective quality.

关键词： transcoding Digital video broadcasting Video compression Streaming media Spatial resolution Bit rate Encoding MPEG 4 Standard Decoding Mobile handsets

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Fast block-size partitioning using empirical rate-distortion models for MPEG-2 to H.264/AVC transcoding

Fast block-size partitioning using empirical rate-distortion...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： Qiang Tang Panos Nasiopoulos Rabab Ward University of British Columbia Vancouver BC Canada

We present an efficient H.264/AVC block-size partitioning prediction method, which is based on our proposed empirical rate and distortion models. Compared to other state-of-the-art transcoding methods, and for the same rate-distortion performance, our proposed algorithm requires the least computational complexity, reaching a 73% reduction in variable block-size motion estimation for SDTV sequences, and 71% reduction for CIF sequences.

关键词： Rate-distortion Automatic voltage control transcoding Partitioning algorithms Computational complexity Encoding Lagrangian functions Predictive models Motion estimation Video compression

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Temporal transcoding of H.264/AVC video to the scalable format

Temporal transcoding of H.264/AVC video to the scalable form...

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Workshops on Image Processing Theory, Tools and Applications, IPTA

作者： Hussain Al-Muscati Fabrice Labeau Department of Electrical and Computer Engineering McGill University Montreal Canada

In this work, a novel implementation of a video transcoder that converts a video sequence encoded with the H.264/AVC standard to a temporally scalable H.264/SVC stream is achieved with the use of a pixel-domain heterogeneous architecture. The input H.264/AVC stream is fully decoded by the transcoder. Macroblock coding modes are extracted from the input stream and are reused to encode the output stream. A set of new motion vectors is computed from the input stream coded motion vectors, and are mapped to either the hierarchical B-frame or zero-delay referencing structures employed by H.264/SVC. These new motion vectors are further subjected to a 3 pixel refinement. As a result, a significant decrease in computational complexity is achieved, while maintaining a close to optimum compression efficiency.

关键词： Static VAr compensators Automatic voltage control Streaming media Pixel transcoding PSNR

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Perceptually optimized error resilient transcoding using attention-based intra refresh

Perceptually optimized error resilient transcoding using att...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： Viet-Anh Nguyen Zhenzhong Chen Yap-Peng Tan School of Electrical & Electronic Engineering Nanyang Technological University Singapore

While deployment of wireless channels has become widespread and fast-growing for mobile applications, transmitting data over these existing error-prone networks can be very unreliable and challenging due to time-varying interference and channel errors. Many error-resilient algorithms have been proposed to provide adequate resilient features in order to protect video data from channel errors. However, these algorithms often aim to achieve the optimal decoded video quality in terms of mean square error without any consideration for the visual quality. In this paper, we present a perceptually error-resilient method for video transcoding based on the attention-based intra refresh technique and the characteristics of the human visual system to enhance the perceptual performance of the transcoded video. Specifically, the foveated just noticeable distortion and visual attention models are employed to estimate the perceptual loss impact due to error propagation for allocating intra-refreshed macroblocks in the transcoded video. Experimental results show that the proposed method can achieve a much better performance than the existing methods in terms of both the visual quality and perceptual quality measure.

关键词： transcoding Humans Propagation losses Video compression Interference Protection Decoding Mean square error methods Visual system Streaming media

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A System for Real-Time transcoding and Delivery of Video to Smartphones

A System for Real-Time Transcoding and Delivery of Video to ...

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International Conference on Information Visualisation (IV)

作者： Lior D. Shefer Francis T. Marchese Computer Science Department Pace University NY USA

This paper presents a report of a system that delivers customized video content to mobile devices. Constructed from open source components, it can stream transcoded video to mobile devices in real-time. In addition, it allows publishers to add content into their video streams on-the-fly. As a demonstration of this system's capabilities, an application was designed to deliver transcoded Adobe Flash content to Apple iPhones in real-time with the insertion of randomly selected commercial content.

关键词： Streaming media Smart phones Web services transcoding Real time systems

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Efficient motion re-estimation for H.264 B- and P-frame transcoding by using maximun likelihood

Efficient motion re-estimation for H.264 B- and P-frame tran...

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International Conference on Electronics And Information Engineering (ICEIE)

作者： Shian-Chu Huang Ching-Ting Hsu Mei-Juan Chen Department of Electrical Engineering National Dong Hwa University Hualien Taiwan Department of Computer Science and Information Engineering Cheng Shiu University Kaohsiung Taiwan

Efficient motion re-estimation schemes for H.264 Band P-frame transcoding are proposed in this paper. The proposed methods compose new motion vectors for out-going video bitstream from the pre-coded bitstream by utilizing Maximum Likelihood. The experimental results show that the proposed method can improve the performance and efficiency compared to previous approaches.

关键词： transcoding Containers Bit rate Transform coding Motion estimation Automatic voltage control Monitoring

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Temporal scalable mobile video communications based on an improved WZ-to-SVC transcoder

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EURASIP JOURNAL ON ADVANCES IN SIGNAL PROCESSING 2013年第1期2013卷 1页

作者： Corrales-Garcia, Alberto Luis Martinez, Jose Fernandez-Escribano, Gerardo Jose Quiles, Francisco Univ Castilla La Mancha Inst Invest Informat Albacete Albacete 02071 Spain

Wyner-Ziv (WZ) to scalable video coding (SVC) transcoding can offer a suitable framework to support scalable video communications between low-cost devices. In addition, the video delivery provided by SVC covers the needs of a wide range of homogeneous networks and different devices. Despite the advantages of the video transcoding framework, the transcoder accumulates high complexity and it must be reduced in order to avoid excessive delays in communication. In this article, an approach for WZ to SVC transcoding is presented. The information generated during the first stage is reused during the second one, and as a consequence the time taken by the transcoding is reduced by around 77.77%, with a negligible rate-distortion penalty.

关键词： transcoding Scalable video coding Wyner-Ziv coding Temporal scalability

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Low-Complexity Heterogeneous Video transcoding by Motion Vector Clustering

Low-Complexity Heterogeneous Video Transcoding by Motion Vec...

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International Conference on Information Science and Applications (ICISA)

作者： Yoonjeong Shin Namrye Son Nguyen Dinh Toan Gueesang Lee Department of Computer Engineering Gwangju University Gwangju South Korea Primary Research Center Mokpo National University Muan South Korea School of Electronics and Computer Engineering Chonnam National University Gwangju South Korea

ISBN: (纸本)9781424459421

The recently developed video compression standard, H.264/AVC surpasses the performance of previous video standards, such as MPEG-2, MPEG-4(part2), and H.263 and is therefore expected to be selected as the video standard for most digital video applications. The widely distributed infrastructure, however, continues to use the previous standards. Heterogeneous video transcoding offers a significant key to the resolution of this problem. This paper suggests a new algorithm for H.264/AVC to MPEG-2 transcoding that uses motion vector clustering to reduce the computation time with no loss of quality. Such a clustering method can reduce the number of candidate motion vectors that are gathered during the H.264 decoding stage. These candidate motion vectors consider the correlation between the direction and distance of the motion vectors in the variable blocks in H.264/AVC. The candidate motion vector that has the least distortion is then selected in the MPEG-2 encoder. The MPEG-2 encoder can therefore use the best motion vector without carrying out computations for motion estimation. The experimental results show that the proposed method can maintain a good level of video quality while reducing the computational complexity by a considerable 64%, on average, compared to a cascade transcoder.

关键词： transcoding Video compression Standards development Automatic voltage control Transform coding Clustering algorithms Clustering methods Decoding Motion estimation Computational complexity

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