nils-herrmann/clean_scirepeval huggingface dataset:
Scheduled and Contention Access Transmission of Partitioned H.264 Video Over WLANs

Supporting Multimedia applications, such as video, over 802.11 wireless local area networks (WLAN) is a challenging task due to the inefficiency of the 802.11 MAC layer and the constant fluctuations in channel error rates. Therefore, specific measures must be taken in both application and delivery layers in order to achieve efficient and satisfactory quality for multimedia applications. Advanced video compression technologies, such as H.264, provide new data partitioning error resiliency feature that allows delivery of the video data in different streams with different levels of importance. There are several possible schemes for mapping these streams to the services of the IEEE 802.1 le MAC. In this article we examine the existing schemes and propose new mechanisms that improve the performance of the video communications system. We propose to use scheduled access schemes in MAC, along with aggregation of packets in the application layer to achieve the best results. We evaluate our proposed mechanisms using simulation experiments.
Effect of high frame rates on 3D video quality of experience

In this paper, we study the effect of 3D videos with increased frame rates on the viewers' quality of experience. We performed a series of subjective tests to seek the subjects' preferences among videos of the same scene at four different frame rates: 24, 30, 48, and 60 frames per second (fps). Results revealed that subjects clearly prefer higher frame rates. In particular, Mean Opinion Score (MOS) values associated with the 60 fps 3D videos were 55% greater than MOS values of the 24 fps 3D videos.
Delay-Aware Rate Control for Multi-User Scalable Video Streaming Over Mobile Wireless Networks

In this paper, we propose a delay and capacity constrained multi-user scalable video streaming scheme that improves the average end-to-end distortion of transmitted video streams compared to traditional streaming strategies. Wireless video streaming applications are characterized by their bandwidth-intensity, delay-sensitivity, and loss-tolerance. Our main contributions include: (i) an analytical expression for packet delay and play-out deadline of unequal erasure protection (UXP) protected scalable video, (ii) an analysis of the performance of delay-aware, capacity-aware rate allocation for optimized UXP streaming scenarios, (iii) proof that unequal error protection causes a rate-constrained optimization problem to be non-convex. Performance evaluations using a 3GPP network simulator show that, for different channel capacities and packet loss rates, delay- aware non-stationary rate-allocation delivers significant gains which range between 1.65 dB to 2 dB in average Y-PSNR of the received video streams over delay-unaware strategies. These gains come at a cost of increased off-line computation which is performed prior to the streaming session and therefore, do not affect the run-time performance of the streaming system. .
Online-Learning-Based Complexity Reduction Scheme for 3D-HEVC

3-D High Efficiency Video Coding (HEVC) is a new emerging video compression standard for multiview video applications. This standard utilizes advanced interview prediction characteristics in addition to the prediction features of the HEVC standard for efficient encoding of multiview video content. While using combined features improves the compression performance by utilizing the correlation between the views captured from slightly different angles of the same scene, they also increase coding complexity. The focus of this paper is on developing an efficient complexity reduction scheme for 3D-HEVC, with the intention to facilitate the adoption of this upcoming standard, especially for real-time applications. In this regard, first, we introduce two ways to decrease the complexity of the inter-/ intra-mode search process of the to-be-encoded blocks in the dependent texture views (${\mathrm {DV}}_{t}\text{s}$ ) of 3D-HEVC. Then, we propose a hybrid complexity reduction scheme that utilizes the two-mode prediction approaches, motion information of the base texture view (BVt), and the rate distortion cost of the already encoded blocks in the BVt and DVt. The performance of our proposed scheme is tested for the case with two views (i.e., base view + dependent view). The evaluations confirm that our proposed hybrid complexity reduction scheme reduces the 3D-HEVC codec complexity by 67.70% on average for the DVt compared with the unmodified 3D-HEVC encoder, while maintaining the overall video quality. Compared with the state-of-the-art method, it reduces complexity by 25.74% on average.
HEVC: The New Gold Standard for Video Compression: How Does HEVC Compare with H.264/AVC?

Digital video has become ubiquitous in our everyday lives; everywhere we look, there are devices that can display, capture, and transmit video. The recent advances in technology have made it possible to capture and display video material with ultrahigh definition (UHD) resolution. Now is the time when the current Internet and broadcasting networks do not even have sufficient capacity to transmit large amounts of HD content-Let alone UHD. The need for an improved transmission system is more pronounced in the mobile sector because of the introduction of lightweight HD resolutions (such as 720 pixel) for mobile applications. The limitations of current technologies prompted the International Standards Organization/International Electrotechnical Commission Moving Picture Experts Group (MPEG) and International Telecommunication Union-Telecommunication Standardization Sector Video Coding Experts Group (VCEG) to establish the Joint Collaborative Team on Video Coding (JCT-VC), with the objective to develop a new high-performance video coding standard.
An improved scalar quantization-based digital video watermarking scheme for H.264/AVC

Digital video watermarking has attracted a great deal of research interest in the past few years in applications such as digital fingerprinting and owner identification. H.264/AVC is the latest and most advanced video coding standard, but to this date, there are very few watermarking schemes designed for it. This is mainly due to its complexity and compression efficiency which presents a major challenge for any video watermarking approach. We developed a quantization-based video watermarking scheme, which is designed to work with H.264/AVC. Our scheme offers constant robustness at all compression rates without affecting the overall bite rate and quality of the video stream. Experimental results show that compared to existing methods, our scheme significantly outperforms existing methods under compression, transcoding, filtering, scaling, rotation and collusion attacks
A new prediction structure for multiview video coding

A new prediction structure for coding multi-view video streams is presented. In general, for Free viewpoint TV (FTV) applications, it is necessary that multi-view videos are efficiently compressed before transmission. Our algorithm synthesizes extra video streams and uses them as extra references when coding the original views. These streams are synthesized based on the already encoded frames from neighboring views, without requiring the scene's depth information. The proposed scheme utilizes both motion and disparity compensation methods to exploit temporal and inter-view correlation within each view sequence and among views, respectively. To guarantee the best bitrate performance, our algorithm adaptively re-sorts the reference frame list, such that minimum number of bits is used for coding reference frame indices. Performance evaluations show that our proposed coding method outperforms the recent multiview coding standard by up to 1 dB PSNR and enhances the compression ratio by 22.97%.
Perceptual distortion measurement in the coding unit mode selection for 3D-HEVC

3D-HEVC achieves higher compression efficiency compared with the simulcast HEVC or disparity-compensated multi-view video coding (MVC). Improved compression efficiency is highly desirable in the transmission of 3D video and its storage. The coding efficiency gain is the result of the new coding tools introduced in 3D-HEVC such as inter-view motion prediction and inter-view residual prediction. We propose to integrate a perceptual video quality metric inside the rate distortion optimization process of the 3D-HEVC. Specifically, in the coding unit (CU) mode selection process, PSNR-HVS is used as a measure for distortion. PSNR-HVS is based on the characteristics of the human visual system (HVS). Results show that the proposed approach improves the compression efficiency of the 3D-HEVC and achieves higher video quality compared with 3D-HEVC.
Motion vector prediction for improving one bit transform based motion estimation

One bit transforms (1BT) have been proposed for lowering the complexity of motion estimation (ME) in video coding. These transforms generate a one bit representation of each pixel in the video that is used in the motion search. This approach can greatly reduce the silicon area and power required for hardware based video encoding. However 1BT methods under-perform traditional Sum of absolute differences (SAD) based motion estimation, particularly for smaller block sizes. In this paper, it is proposed to improve 1BT based ME by predicting the motion vector for each block based on the vectors from previous blocks and modifying the cost function to favor motion vectors close to the predicted one. This takes advantage of the spatial correlation between motion vectors and produces a more uniform motion field. Simulation results show the proposed method can improve the PSNR of frames reconstructed through motion compensation by up to 1 dB and substantially improve the subjective video quality by reducing blocking artifacts.
Perceptually-friendly rate distortion optimization in high efficiency video coding

We propose the employment of a perceptual video quality metric in measuring the distortion in the High Efficiency Video Coding (HEVC) Standard. The mean square error presently used as quality metric is not a good measure to use, as it poorly correlates with human perception. Integration of a video quality metric based on the characteristics of the Human Visual System (HVS) inside the rate distortion optimization procedure is expected to improve the compression efficiency of the video coding. In this paper, the PSNR-HVS measure is used in the rate distortion optimization process. The compression efficiency of the proposed approach is compared to that used by HEVC, the recent video coding standard. Simulations prove that the proposed approach yields higher compression efficiency and provides better visual quality.
Optimizing the Lagrange multiplier in perceptually-friendly high efficiency video coding for mobile applications

In mobile applications, the amount of memory and bandwidth is restricted. Efficient compression of video is essential to provide better quality streaming on a mobile device. High efficiency video coding (HEVC) standard provide substantial bitrate savings compared with the previous standards. The compression efficiency of HEVC has been improved by integration of a perceptual video quality metric inside the encoder. In the rate distortion optimization process, PSNR-HVS has been used to measure distortion for the coding unit mode selection. In this paper, we find the optimal Lagrange multiplier based on the quantization parameter. Experimental results for various test sequences show the compression efficiency of the perceptual HEVC will be improved by finding the optimal Lagrange multiplier.
New interactive services for digital TV

Current interactive TV services are limited. They mainly consist of accessing the World Wide Web. These services basically display a Web page beside a TV program that is related to the contents of TV program. We define new interactive services for digital TV, which can be used in many attractive applications such as parental management, multilingual audio and video in video. These services have also the advantages that they do not require an Internet return path and that they preserve the compatibility of the transmitted stream with conventional TV systems and receivers. In this paper we evaluate the feasibility of the proposed interactive services for digital TV and specify the challenges and problems in implementing these services. We present methods for overcoming these problems. We also specify the minimum decoder buffer required and the average random access delay for multilingual support in a typical standard definition TV program.
Channel Aware Multiuser Scalable Video Streaming Over Lossy Under-Provisioned Channels: Modeling and Analysis

In this paper, we analyze the performance of media-aware multiuser video streaming strategies in capacity limited wireless channels suffering from latency problems and packet losses. Wireless video streaming applications are characterized by their bandwidth-intensity, delay-sensitivity, and loss-tolerance. Our main contributions include (i) a rate-minimized unequal erasure protection (UXP) scheme, (ii) an analytical expression for packet delay and play-out deadline of UXP protected scalable video, (iii) a loss-distortion model for hierarchical predictive video coders with picture copy concealment, (iv) an analysis of the performance and complexity of delay-aware, capacity-aware, and optimized UXP streaming scenarios, and (v) we show that the use of unequal error protection causes a rate-constrained optimization problem to be nonconvex. Performance evaluations using a 3GPP network simulator show that, for different channel capacities and packet loss rates, delay-aware nonstationary rate-allocation streaming policies deliver significant gains which range between 1.65 dB to 2 dB in average Y-PSNR of the received video streams over delay-unaware strategies. These gains come at a cost of increased offline computation which is performed prior to the start of the streaming session or in batches during transmission and therefore, do not affect the run-time performance of the streaming system.
Efficient motion vector re-estimation for MPEG-2 TO H.264/AVC transcoding with arbitrary down-sizing ratios

As for down-sizing MPEG-2 to H.264/AVC transcoding, an efficient algorithm of estimating initial H.264/AVC motion vectors is proposed. By using the estimated initial motion vectors, only a small range of motion vector refinement is sufficient to find the final motion vector for each partition. Experimental results show that our proposed algorithm achieves average 0.08 dB improvement (maximum 0.24 dB) in the picture quality compared to the other state-of-art method. At the same time, the computational complexity of estimating the initial motion vectors is less than that of the other state-of-art technique (average 36% reduction).
A hybrid coding method for digital HDTV

Digitally transmitted video images suffer from sudden degradation in picture quality at high channel noise levels. This is due to the variable length coding and the large synchronization blocks used. To remedy that, we propose encoding the DCT coefficients by a hybrid fixed and variable length coding compression scheme. This method improves the compression ratio by approximately 20% and increases the system's resistance to channel errors. To fortify the transmitted bits against channel noise we then use a synchronization method which restricts the effects of an error to a 32/spl times/16 pixel picture block. The resulting combined scheme (1) significantly improves the error resistance characteristic of the system, (2) eliminates the abrupt picture degradation, and (3) does not alter the original data transmission rate.
A stereo matching data cost robust to blurring

Most modern stereo matching algorithms involve solving an optimization problem where the objective function includes a data cost term and a smoothness term. The data cost term measures how well corresponding pixels match between the left and right images. In this paper a new stereo matching data cost is proposed which is robust to variations in blurring between the images caused by camera focus. In our method, each image is blurred once with a large filter. By comparing the original and blurred versions of each image we obtain a range of possible values each pixel could take on for different levels of blurring. Based on this range we construct a blur robust data cost for comparing pixels between two images. Experimental results show our proposed method greatly improves stereo matching accuracy when the left and right images in a stereo pair are focused differently.
A Cross Layer Optimization Mechanism to Improve H.264 Video Transmission over WLANs

Supporting video applications over 802.11 wireless local area networks is a challenging task due to the constant fluctuations in channel error rates and the inefficiency of the MAC layer. New video compression technologies, such as H.264, provide a network adaptation layer for adapting the output of the video encoder to the characteristics of the underlying transport network. In this article we demonstrate that it is possible to improve the performance of H.264 video applications over 802.11 WLANs through a cross-layer design that optimizes the encoded H.264 packet sizes. We propose the use of aggregation and fragmentation mechanisms to create the optimal frame lengths. We also investigate several application layer error
An efficient H.264 based fine-granular-scalable video coding system

H.264, with its superior coding efficiency and network friendly design, has emerged as the newest international video standard and is expected to become the preferred codec for video broadcasting. Presently, there is an effort to add scalability to H.264, in order to offer a solution to network congestion and bandwidth variations. Proposals range from scalable subband extension to introduction of FGS to the H.264 standard. We propose a novel structure for the FGS layer that uses 4/spl times/4 integer transform, instead of 8/spl times/8 discrete cosine transform (DCT), so that the same transform is used for both layers. We also propose a novel hierarchical algorithm to code macroblock header of FGS layer that uses less bits than the standard FGS algorithm and significantly increases the coding efficiency. When compared with the original FGS structure, the proposed structure uses 70% less bits for macroblock headers, has less complexity and has an increased PSNR of 0.7 dB on average.
A high quality VBR MPEG system for Internet and broadcasting applications

A high quality variable bit rate (VBR) MPEG-2 encoding scheme that offers optimum video quality and bandwidth allocation is presented. This scheme utilizes a real-time bit redistribution method, insertion of I frames at scene changes and large GOP (group of pictures) size to produce high picture quality. An encoders-bank with predetermined sets of "nominal-long-term", minimum and maximum bit rates in combination with a sophisticated picture quality control process allows a bit rate selector to choose the optimum bit stream from a set of encoders, thus resulting in a high quality VBR video stream. The proposed scheme is very easy to implement and offers an efficient real-time VBR solution for broadcasting applications that involve multiplexed distribution of multiple video sources.
Online identification of hidden semiMarkov models

Hidden Markov models (HMM) are a powerful tool in signal modelling. In an HMM, the probability that signal leaves a state is constant, and hence the duration that signal stays in each state has an exponential distribution. However, this exponential density is not appropriate for a large class of physical signals. Hence, a more sophisticated model, called hidden semiMarkov models (HSMM), are used where the state durations are modelled in some form. This paper presents new signal model for hidden semiMarkov models. This model is based on state duration dependant transition probabilities, where the state duration densities are modelled with parametric distribution functions. An adaptive algorithm for online identification of HSMMs based on our signal model is presented. This algorithm is based on the 'recursive prediction error' technique, where the parameter estimates are updated adaptively in a direction that maximizes the likelihood of parameter estimates. From the numerical results it is shown that the proposed algorithms can successfully estimate the true value of parameters. These results also show that our algorithm can adaptively track the parameter's changes in time.
An Mpeg2-to-atm Converter To Optimize Performance Of Vbr Video Broadcast Over Atm Networks

This paper presents a novel MPEG2-to-ATM converter for VBR video broadcast over ATM networks. It functions as an external post-coding source rate controller between any MPEG2 source and an ATM network. Dynamic break points are employed to shape and partition the video data into high priority ATM cells which conform to the prevailing usage parameter control contract with the network, and nonconforming low priority cells which minimize the effects of cell loss due to network congestion on the subjective quality of the received video. Both high and low priority cells are transmitted over a common ATM virtual connection. Performance evaluations of actual VBR MPEG2 streams transmitted over a simulated converter and ATM network are presented to demonstrate the effectiveness of the proposed method.
Compensation of Requantization and Interpolation Errors in MPEG-2 to H.264 Transcoding

Implementing MPEG-2 to H.264 transcoding schemes in the pixel domain introduces a high degree of computational complexity. In the transform domain, this transcoding is more computationally efficient, and several methods have been developed to address that approach. However, incompatibilities between the two standards, such as the mismatches between the MPEG-2 and H.264 motion compensation processes, cause several distortions that may affect the overall picture quality. In this study, we address the main distortions that result from requantization errors: luminance half-pixel and chrominance quarter/three-quarter interpolation errors. Then, we propose algorithms that compensate for these errors. The traditional requantization error compensation algorithm for DCT coefficients is updated so that it can be applied to the H.264 integer transform coefficients. Equations that compensate for the luminance half-pixel and chrominance quarter/three-quarter pixel interpolation errors are derived. To remove the interpolation errors, the previous H.264 frame is needed. Thus, the compensation scheme includes a closed-loop H.264 motion compensation process, which is implemented in the pixel domain. To evaluate the performance of the proposed compensation algorithms in terms of picture quality, our scheme is compared with two different cascaded pixel-domain transcoding structures. The first structure reuses the MPEG-2 motion vectors, and the other implements plusmn2 pixels motion vector refinement, but each one has an H.264 deblocking filter. The experimental results show that the proposed compensation algorithms achieve 5-dB quality improvement over the open-loop transform-domain-based transcoding and almost the same picture quality (0.3-0.6 dB) as the cascaded structures. An additional advantage is the reduction in computational complexity that ranges from 13% to 69% compared with the two cascaded methods.