Shinya Kadono, Minoru Etoh, Naokazu Yokoya · Systems and Computers in Japan · 2002
Abstract This paper considers transcoding in which an MPEG stream is converted to a low‐bit‐rate MPEG stream, and proposes a method in which the transcoding error can be reduced by optimally selecting the quantization parameter for each macroblock. In transcoding with a low compression ratio, it is crucial to prohibit transcoding with a requantization parameter which is 1 to 2 times the quantization parameter of the input stream. Consequently, as the first step, an optimization method for the requantization parameter is proposed which cares for the error propagation effect by interframe prediction. Then, the proposed optimization method is extended so that the method can also be applied to the case of a high compression ratio in which the rate—distortion curve is approximated for each macroblock in the range of requantization parameters larger than 2 times the quantization parameter. It is verified by a simulation experiment that the PSNR is improved by 0.5 to 0.8 dB compared to the case in which a 6 Mbit/s MPEG stream is not optimized by twofold recompression. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(9): 21–30, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/scj.10096
Cited by 0
Xavier Seron, Michel Fayol · British Journal of Developmental Psychology · 1994
French‐speaking second‐grade children from France and Wallonia were asked to write down in the Arabic code, numbers orally presented at six successive one‐month‐spaced sessions. The evolution of the children's production (patterns of correct responses and errors) is analysed and tentatively interpreted through the model of number and calculation processing developed by McCloskey in adult neuropsychology. In order to evaluate their number production and comprehension mechanisms the children were furthermore submitted to other number processing tasks. It is tentatively concluded that the children's difficulties in the Arabic written task were localized at the level of the production of the Arabic sequences and that the regular pattern of errors some of them present is more easily explained by the lexical model of numbers processing recently proposed by Power & Dal Martello (1990), than by McCloskey's model (1992).
Cited by 137
K. H. Britton, R.P. Case, Andrew Citron et al. · IBM Systems Journal · 2001
The promise of e-business is coming true: both businesses and individuals are using the Web to buy products and services. Both want to extend the reach of e-business to new environments. Customers want to check accounts, access information, and make purchases with their cellular phones, pagers, and personal digital assistants (PDAs). Banks, airlines, and retailers are competing to provide the most ubiquitous, convenient service for their customers. Web applications designed to take advantage of the rich rendering capabilities of advanced desktop browsers on large displays do not generally render effectively on the small screens available on phones and PDAs. Some devices have little or no graphics capability, or they require different markup languages, such as Wireless Markup Language (WML), for text presentation. Transcoding is technology for adapting content to match constraints and preferences associated with specific environments. This paper compares and contrasts different approaches to content adapta tion, including authoring different versions to accommodate different environments, using application server technology such as JavaServer pages™ (JSP™) to create multiple versions of dynamic applications, and dynamically transcoding information generated by a single application. For dynamic transcoding, the paper describes several different transcoding methodologies employed by the IBM WebSphere™ Transcoding Publisher product, including HyperText Markup Language (HTML) simplification, Extensible Markup Language stylesheet selection and application, HTML conversion to WML, WML deck fragmentation, and image transcoding. The paper discusses how to decide whether transcoding should be performed at the content source or in a network intermediary. It also describes a means of identifying the device and network characteristics associated with a request and using that information to decide how to transcode the response. Finally, the paper discusses the need for new networking benchmarks to characterize the server load and performance characteristics for dynamic transcoding.
Cited by 52
Xie Xi, Kai Zhang, Li Zhang et al. · 2023
Video transcoding, which is a long-standing problem in video coding, can be used for a variety of applications including bit rate conversion, format conversion and video resolution conversion. In this paper, we present an effective transcoding solution from the popular previous generation video coding standard, High Efficiency Video Coding standard (HEVC), to Versatile Video Coding (VVC) which is the latest standard developed by JVET. VVC enjoys much better coding efficiency compared to its ancestors at the expense of higher encoding complexity. To facilitate the fast transcoding, we propose a low- complexity HEVC to VVC transcoding scheme. More specifically, the partition and motion information, which implies the intrinsic spatial and temporal characteristics of the video sequence, is inherited from HEVC for VVC encoding. The proposed scheme is tailored for HEVC to VVC conversion, and experimental results show the proposed method can achieve 31% encoding time saving with only 0.85%, 0.70% and 0.74% Bjøntegaard delta rate (BD- rate) loss on average for Y, Cb and Cr components, respectively, under random access configuration.
Cited by 1
Mokashi, Chaitanya Sudhir · D-Scholarship@Pitt (University of Pittsburgh) · 2022
All biological systems constantly receive, process and respond to external signals. Cells, although being the basic unit of life, show remarkable ability to decipher the environmental cues and produce appropriate responses. This signal transduction is achieved by intricate cascades of signaling molecules which carry out the calculations needed to encode, process, decode and transfer (i.e. ‘transcode’) the external signals to responses such as various cell fate decisions. Dysregulation of cellular signal transduction is therefore the underlying cause of many diseases. As it happens in real-time, the dynamics of both signals and the processing machinery play a crucial role in signal transduction. Microfluidic systems enable probing of signal transduction with dynamic stimuli but remain largely inaccessible. Particularly, such ability could prove useful in studying the signal processing in the NF-κB pathway, dynamics of which is pertinent to many disease pathologies. Computational approaches such as statistical and mechanistic modeling could help in formalizing the signal processing mechanisms and making useful predictions. The overarching theme of this dissertation is to study the signal processing and control mechanisms used by cells in the context of the NF-κB signaling pathway. This includes the mechanisms and functions of specific parts of the pathway as well as their dynamics, and how they fit together to achieve the final response output. First, we develop an accessible microfluidic system to study the cellular responses to dynamic stimuli. Second, we characterize the encoding and decoding of cytokine signals in the NF-κB pathway. Third, we alter the signal encoding by leveraging the microfluidic system to maximize NF-κB responses. Finally, we consolidate our findings and put forward a framework for a comprehensive model of the NF-κB pathway.
Cited by 0
Verhoeven, PHFM Richard, Jarnikov, DS Dmitri, Lukkien, JJ Johan · TU/e Research Portal (Eindhoven University of Technology) · 2008
A method is described to control a video transcoder based on the actual network conditions in a home network. A single TCP connection is used for transport, where the TCP protocol buffer of the sender provides feedback to the transcoder.
Cited by 0
LEE JUN WEI · National University of Singapore · 2007
Ph.D
Cited by 0
Gustavo Reyes, Amy R. Reibman, Justin C. Chuang et al. · 2015
We describe a method to maintain an acceptable quality for video transported over wireless networks under time-varying conditions. We use a transcoder to modify the resilience of the encoded bitstream by using source coding techniques to provide the appropriate level of resilience for the prevailing channel conditions. We develop a statistical model for image loss versus resilience and wireless conditions. Simulation results indicate that using a transcoder to adjust the resilience can improve video quality when errors occur without significantly sacrificing quality when there are no errors. Also, simulation results compare favorably to the analytical model. 1.
Cited by 0
Pavel Novotný, Avinash Ramachandran · 2024
The current scale of online video streaming requires hardware accelerated video transcoding solutions. Historically, hardware solutions have been excellent at offloading the computationally intensive tasks from CPUs, but often came with the penalty of being inflexible and not quickly adaptable to emerging market trends. We are presenting an architecture, which maintains all the benefits of hardware acceleration but also adds an unparalleled level of programmability and flexibility. This architecture supports a wide spectrum of markets ranging from ultra-low latency encoding all the way to high quality video on demand (VOD) markets with only firmware changes. These capabilities are achieved by a strategic combination of built-in hardware acceleration components and many embedded CPUs that have full control over the video encoding pipeline flow. This architecture not only provides deterministic timing, which is critical for ultra-low latency transcoding, but it also offers flexibility and programmability allowing robust product roadmaps through simple firmware updates.
Cited by 0
Rare & Special e-Zone (The Hong Kong University of Science and Technology) · 2015
Cited by 0
Olof Werner · IEEE Transactions on Image Processing · 1999
An investigation on requantization for transcoding of video signals is carried out. Specifically, MPEG-2 compatible discrete cosine transform (DCT) intraframe coding is addressed. The aim of this work is twofold: first, to provide a theoretical analysis of the transcoding problem, and second, to derive quantization methods for efficient transcoding based on the results of the analysis. The mean squared error (MSE) cost function is proposed for designing a quantizer with minimum distortion resulting in up to 1.3 dB gain compared with the quantizer used in the MPEG-2 reference coder TM5. However, the MSE quantizer leads in general to a larger bit rate and may therefore only be applied locally to blocks of sensitive image content. A better rate-distortion performance can be provided by the maximum a posteriori (MAP) cost function. In critical cases, the MAP quantizer gives a 0.4 dB larger signal-to-noise-ratio (SNR) at the same bit rate compared with the TM5 quantizer. The results are not limited to MPEG-2 and can be adapted to other coding schemes such as H.263 or JPEG.
Cited by 86
Boris G. Sokolov, Maria Gourieva · Vestnik of Saint Petersburg State University of Culture · 2018
Cited by 1
Srinivas Gudumasu, Yuwen He, Yan Ye et al. · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2015
This paper proposes an efficient Scalable High efficiency Video Coding (SHVC) to High Efficiency Video Coding (HEVC) transcoder, which can reduce the transcoding complexity significantly, and provide a desired trade-off between the transcoding complexity and the transcoded video quality. To reduce the transcoding complexity, some of coding information, such as coding unit (CU) depth, prediction mode, merge mode, motion vector information, intra direction information and transform unit (TU) depth information, in the SHVC bitstream are mapped and transcoded to single layer HEVC bitstream. One major difficulty in transcoding arises when trying to reuse the motion information from SHVC bitstream since motion vectors referring to inter-layer reference (ILR) pictures cannot be reused directly in transcoding. Reusing motion information obtained from ILR pictures for those prediction units (PUs) will reduce the complexity of the SHVC transcoder greatly but a significant reduction in the quality of the picture is observed. Pictures corresponding to the intra refresh pictures in the base layer (BL) will be coded as P pictures in enhancement layer (EL) in the SHVC bitstream; and directly reusing the intra information from the BL for transcoding will not get a good coding efficiency. To solve these problems, various transcoding technologies are proposed. The proposed technologies offer different trade-offs between transcoding speed and transcoding quality. They are implemented on the basis of reference software SHM-6.0 and HM-14.0 for the two layer spatial scalability configuration. Simulations show that the proposed SHVC software transcoder reduces the transcoding complexity by up to 98-99% using low complexity transcoding mode when compared with cascaded re-encoding method. The transcoder performance at various bitrates with different transcoding modes are compared in terms of transcoding speed and transcoded video quality.
Cited by 1
Hong-Goo Kang, Hong Kook Kim, R.V. Cox · IEEE Transactions on Multimedia · 2003
With the trend of merging various communication networks, a need arises to provide transcoding between different speech coding formats. Presently this means a cross tandem between the two coders in each case. This results in both quality loss and extra delay. A possible alternative is using a bitstream mapping approach that directly converts parameter values. For several standard coders having a similar coding structure, it should be possible to generate comparable or better quality without adding much delay or complexity. This paper proposes a bitstream mapping method between ITU-T Recommendation G.729 and TIA IS-641. Informal listening tests and the perceptual subjective quality measure (PSQM) scores show that the proposed method has better quality than the cross tandem method, while it has at least 5 ms less delay and six times less computation.
Cited by 19
禹讚溢, 申仁澈 · 2002
Cited by 0
Zhenan Lin, Qi Zhang, Keji Chen et al. · 2016
The arbitrary ratio transcoding usually introduces coding block grid misalignment, which results in difficulties to utilize the decoding information in coding blocks of source videos during the encoding phase. To reduce the large computation load of HEVC downscale transcoding in such situation, we propose an efficient transcoding method that we refer the decoded coding unit (CU) partitioning to accelerate partition decision, which takes up the most complexity in the encoding phase as well as the whole transcoding. First, we predict CU depth in pixel level according to decoded partitioning of source videos. Then, we propose adaptive rules to determine CU partitioning of target videos based on the prediction, so that we can make early CU splitting or pruning decision without complex recursive search. Experiments demonstrate that the proposed method achieves about 74% time reduction on average with acceptable BD-rate increase in the encoding phase compared to the encoder in reference software HM13.0.
Cited by 6
Gissette Reyes, Amy R. Reibman, J.C.-I. Chuang et al. · 2002
We describe a method to maintain an acceptable quality for video transported over wireless networks under time-varying conditions. We use a transcoder to modify the resilience of the encoded bitstream by using source coding techniques to provide the appropriate level of resilience for the prevailing channel conditions. We develop a statistical model for image loss versus resilience and wireless conditions. Simulation results indicate that using a transcoder to adjust the resilience can improve video quality when errors occur without significantly sacrificing quality when there are no errors. Also, simulation results compare favorably to the analytical model.
Cited by 6
Zhijun Lei · uO Research (University of Ottawa) · 2004
The transmission of compressed video over channels with different capacities may require a reduction in bit rate if the transmission channel has a lower capacity than the capacity required by the video bit-stream, or when the channel capacity is changing over time. The process of converting a compressed video format into another compressed format is known as transcoding. This thesis addresses the specific transcoding problem of dynamic bit-rate adaptation for transmission over low bandwidth wireless channels. Transmitting compressed video over lower bandwidth wireless channels require accurate and efficient rate-control schemes. In this thesis, we propose several techniques to improve transcoding performance. Based on our experimental results, we present an approximate linear bit allocation model and macroblock layer rate-control algorithm, which can achieve accurate transcoding bit-rate. By reusing useful statistics information from the incoming compressed video, the bit-rate of the transcoded video can be determined according to the video scene context. Considering a specific bursty error wireless channel, we propose a solution which combines video transcoding and an ARQ protocol to transmit compressed video over this channel. In order to make sure that the end decoder can decode and play the transcoded video within the required end-to-end delay, we analyze the rate and buffer constraints of the transcoder and derive the conditions that have to be met by the transcoder. In order to test the proposed solution, we use a statistical channel model to simulate the wireless channel and use this model and channel observation to estimate the effective channel bandwidth, which will be fed back to the transcoder for better rate control. In this thesis, we discuss two applications. For real time video communication over wireless channel, we propose an algorithm that determines the transcoding scaling factor considering end-to-end delay, buffer fullness and effective channel bandwidth. For pre-encoded video distribution over wireless channels, we propose an algorithm which can determine the transcoding bit budget based on end-to-end delay, effective bandwidth, and original video bit profile. The proposed algorithm outperforms H.263 TMN8 in terms of video quality and buffer behavior with the same computational requirements.
Cited by 1Open access
Kitchen, Kris · Figshare · 2015
Early work on possible theory of Black Mirror Rejection Membrane: Transcoding information machine to maintain causality and void the information paradox. Note due to not being able to locate any works similar to this there was not much to cite.
Cited by 0Open access
Robert Clausecker, Daniel Lemire · Software Practice and Experience · 2023
Abstract Intel includes in its recent processors a powerful set of instructions capable of processing 512‐bit registers with a single instruction (AVX‐512). Some of these instructions have no equivalent in earlier instruction sets. We leverage these instructions to efficiently transcode strings between the most common formats: UTF‐8 and UTF‐16. With our novel algorithms, we are often twice as fast as the previous best solutions. For example, we transcode Chinese text from UTF‐8 to UTF‐16 at more than 5 GiB using fewer than 2 CPU instructions per character. To ensure reproducibility, we make our software freely available as an open‐source library. Our library is part of the popular Node.js JavaScript runtime.
Cited by 1Open access