A heuristic approach of bandwidth management for video sources in ATM networks

One of the most important properties in the ATM network is that the resource of the network, including buffer and bandwidth, can be flexibly managed according to different demands of various applications. The network bandwidth can be effectively allocated and utilized if the data volume of the arrival traffic can be predicted precisely. In this paper, we study the bandwidth management schemes for variable bit rate (VBR) pre‐coded MPEG video sources. The proposed bandwidth allocation method, which predicts the bandwidth by the frame correlation, demonstrates a quite good performance when comparing with a previous scheme, especially for the video scenes with the combination of intraframes and interframes. Bandwidth allocation of a multiplexer connected to several video sources is also studied by using heuristic information. The experimental results show that the proposed method is much better than that of the fixed bandwidth allocation and is suitable for the application of MPEG video services. Copyright © 2000 John Wiley & Sons, Ltd.     

Best packetisation scheme for H.263 Internet video communication

The H.263 codec is an efficient way to stream variable bit-rate video sequences. It is proposed that, for equivalent bandwidth and frame rate, a two-slice packetisation scheme results in superior peak signal-to-noise ratio, rather than the conventional one-slice scheme, and that constant inter-packet gap rather than 'bursty' delivery is preferable.     

Hybrid Multicast and Segment‐Based Caching for VoD Services in LTE Networks

This paper proposes a novel video delivery scheme that reduces the bandwidth consumption cost from a video server to terminals in Long‐Term Evolution networks. This proposed scheme combines optimized hybrid multicast with a segment‐based caching strategy for use in environments where the maximum number of multicast channels is limited. The optimized hybrid multicast, allocation of multicast channels, and cache allocation are determined on the basis of a video's request rate, the related video's length, and the variable cost per unit size of a segment belonging to the related video. Performance evaluation results show that the proposed scheme reduces a video's delivery costs. This work is applicable to on‐demand TV services that feature asynchronous video content requests.     

Efficient channel utilization for real-time video in OVSF-CDMA systems with QoS assurance

In this paper, the utilization of real-time video service in the downlink of an orthogonal variable spreading factor code division multiple access (OVSF-CDMA) system is studied. By modeling the video traffic and wireless channel as a joint Markov modulated process, and properly partitioning the states of the Markov process, an adaptive rate allocation scheme is proposed for real-time video transmission with quality of service provisioning while achieving high channel utilization. The scheme is applicable for packet switching and frame-by-frame real-time video transmission, and incorporates both the physical layer and network layer characteristics. For QoS provisions, the closed form expressions of packet delay and loss probability are derived based on the Markov model. Analytical and simulation results demonstrate that the proposed scheme can significantly improve the channel utilization over the commonly used effective bandwidth approach.     

Transporting compressed video over ATM networks with explicit-ratefeedback control

We propose a scheme for transmission of variable bit rate (VBR) compressed video for interactive applications using the explicit-rate congestion-control mechanisms proposed for the available bit rate (ABR) service in asynchronous transfer mode networks. Compressed video is inherently bursty, with rate fluctuations over both short and long time scales. This source behavior can be accommodated by the ABR service, since the explicit-rate scheme allows sources to request varying amounts of bandwidth over time. Moreover, when the bandwidth demand cannot be met, the network provides feedback indicating the bandwidth currently available to a connection. In our scheme, the video source rate is matched to the available bandwidth by modifying the quantization level used during compression. We use trace-driven simulations to examine how effective the enhanced explicit-rate scheme is in “rate matching” between the network and the source and the effect on end-to-end delay. We also look at the sensitivity of the proposed scheme to the estimates of the network round-trip times and to inaccuracies in the rate requests made by sources     

A retransmission‐based scheme for video streaming over wireless channels

Efficient resource allocation is a key factor to improve the efficiency of video transmission over wireless channels. To increase the number of correctly received video frames at the decoder, it is desirable to reduce the video source rate while increasing error protection when the wireless channel is anticipated to be bad or when the receiver buffer is approaching starvation. In this study, we introduce a retransmission‐based adaptive source‐channel rate control scheme for video transmission over wireless packet networks. In this scheme, the level of adaptiveness is optimized to reduce the bandwidth requirement while guaranteeing delay and loss bounds. The proposed scheme has the advantage of providing closed‐form expressions of the near‐optimum parameters of the proposed model, which are then fed back to the transmitter to scale both the source and channel rates adaptively. Simulation and numerical investigations are carried out to verify the adequacy of the analysis and study the impact of the adaptive process on the continuity of the video playback process. Copyright © 2009 John Wiley & Sons, Ltd.     

Real time variable bit rate video traffic prediction

Real time variable bit rate (VBR) video traffic prediction plays an important role in dynamic bandwidth allocation schemes by providing an accurate estimation of the instantaneous bandwidth requirement of VBR video traffic and it has been widely used in dynamic bandwidth allocation. A number of prediction algorithms were proposed in the literature and they can be broadly classified into two categories: time domain approaches and wavelet domain approaches. In this paper, we first present a survey of the existing algorithms in the literature. On the basis of the survey, new algorithms are proposed in the time domain and in the wavelet domain, respectively. Simulations using real VBR video traces are conducted which show that the proposed algorithms achieve better performance than those in the literature. Copyright © 2006 John Wiley & Sons, Ltd.     

Supporting multi-user real-time VBR video service using dynamic bandwidth management based on prediction

Real-time variable bit rate (VBR) video is expected to take a significant portion of multimedia applications. However, plentiful challenges to VBR video service provision have been raised for its characteristic of high traffic abruptness. To support multi-user real-time VBR video transmission with high bandwidth utilization and satisfied quality of service (QoS), this article proposes a practical dynamic bandwidth management scheme. This scheme forecasts future media rate of VBR video by employing time-domain adaptive linear predictor and using media delivery index (MDI) as both QoS measurement and complementary management reference. In addition, to support multi-user application, an adjustment priorities classified strategy is also put forward. Finally, a test-bed based on this management scheme is established. The experimental results demonstrate that the scheme proposed in this article is efficient with bandwidth utilization increased by 20%-60% compared to a fixed service rate and QoS guaranteed.     

Radio Resource Allocation for Scalable Video Services Over Wireless Cellular Networks

Good quality video services always require higher bandwidth. Hence, to provide the video services e.g., multicast/broadcast services (MBSs) and unicast services along with the existing voice, internet, and other background traffic services over the wireless cellular networks, it is required to efficiently manage the wireless resources in order to reduce the overall forced call termination probability, to maximize the overall service quality, and to maximize the revenue. Fixed bandwidth allocation for the MBS sessions either reduces the quality of the MBS videos and bandwidth utilization or increases the overall forced call termination probability and of course the handover call dropping probability as well. Scalable video coding (SVC) technique allows the variable bit rate allocation for the video services. In this paper, we propose a bandwidth allocation scheme that efficiently allocates bandwidth among the MBS sessions and the non-MBS traffic calls (e.g., voice, unicast, internet, and other background traffic). The proposed scheme reduces the bandwidth allocation for the MBS sessions during the congested traffic condition only to accommodate more calls in the system. Instead of allocating fixed bandwidths for the MBS sessions and the non-MBS traffic, our scheme allocates variable bandwidths for them. However, the minimum quality of the videos is guaranteed by allocating minimum bandwidth for them. Using the mathematical and numerical analyses, we show that the proposed scheme maximizes the bandwidth utilization and significantly reduces the overall forced call termination probability as well as the handover call dropping probability.     

A new resource allocation scheme based on a PSNR criterion forwireless video transmission to stationary receivers over Gaussianchannels

A new resource allocation scheme is proposed for video service over a Gaussian channel. For video quality rating, we introduce a suitable metric: the average peak signal-to-noise ratio (PSNR) or the average channel-induced PSNR degradation. Then, we model the end-to-end distortion considering the error propagation effect caused by motion compensation. On the basis of this model, we propose an efficient resource allocation scheme for real video service. Unlike conventional schemes, the new scheme satisfies the PSNR requirement of each video user by adjusting the bit-error rate level with the changes of image characteristics. Simulation results show that the proposed scheme utilizes the bandwidth more efficiently than conventional schemes     

Dynamic bandwidth allocation and buffer dimensioning under equal segment scheme to support video‐on‐demand services

This paper focuses on the optimization of network bandwidth allocation and buffer dimensioning to transport pre‐stored MPEG video data from source to playback destination across ATM networks. This is one of the most important issues in the support of video‐on‐demand (VoD) service. This paper provides a novel scheme in the dynamic allocation of bandwidth to segments of video using ABR mode. The dynamic bandwidth allocation is based on a new concept, called playback tunnel which is obtained from the traffic characteristics of the pre‐stored MPEG video trace to determine the optimum of transmission bandwidth as well as the buffer capacity to ensure that the playback buffer neither underflows nor overflows. The proposed scheme is tested with real‐life MPEG video traces. The obtained results have shown its significant performance improvement in terms of the capacity of playback buffer, the start‐up playback delay, the size of video segment and the network multiplexing gain. Copyright © 2001 John Wiley & Sons, Ltd.     

针对移动视频终端的基于感兴趣区域的快速转换编码

提出一种针对移动终端,基于感兴趣区域(ROI)的快速转换编码方案.首先,根据移动终端的显示尺寸,在视频服务器端利用视觉关注度模型从H.264视频流自动地检测出ROI.然后,在代理服务器端根据ROI转换编码生成适合于移动终端的视频流.此外,针对此转码体系提出了一种快速模式选择算法.仿真实验结果表明,本方案可在降低网络占用带宽的情况下,获得较好的主观视觉效果,并且计算量小.     

Smoothing transcoded MPEG-1 video streams for Internet transmission

An efficient smoothing scheme for the real-time transmission of MPEG-1 transcoded video over 'best-effort' IP networks is presented. The scheme uses intelligent partitioning and multiplexing of the packetised bit stream. Bit-rate smoothing is achieved by partitioning packets according to their picture type (I, P or B). Subsequently, the partitioned packets are multiplexed in such a way that each packet from an anchor (I and P) picture is followed by two packets from B-pictures. The proposed scheme smooths the bit rate of the encoded video, making it more suitable for adaptive video streaming applications. In such applications, the transmission bit rate is varied so as to adapt to the available network bandwidth. The scheme reorganises the transmission order of the packets, spreading the less important packets from the B-pictures into the more important packets from the anchor pictures. This indicates a reduction in the likelihood of losing more important anchor packets as the bandwidth bottleneck increases, implying an improvement in the quality of transmitted video. A variety of simulations results are presented to demonstrate these points.     

Optimal video stream multiplexing through linear programming

This paper presents a new optimal multiplexing scheme for compressed video streams based on their individual e-PCRTT transmission schedules. A linear programming algorithm is proffered, which takes into account the different constraints of each client. The algorithm simultaneously finds the optimum total multiplexed and individual stream schedules that minimize the peak transmission rate. Since the problem is formulated as a linear program it is bounded in polynomial time. It is shown that the algorithm succeeds in obtaining maximum bandwidth utilization with Quality of Service (QoS) guarantees. Simulation results using 10 real MPEG-1 video sequences are presented. The optimal multiplexing linear programming results are compared to the e-PCRTT and Join-the-Shortest-Queue (JSQ) procedures in terms of peak transmission bandwidth, P-loss performance and standard deviation. For several client buffer sizes, the rate obtained by our LP solution when compared to a previous e-PCRTT and JSQ methods resulted in reductions of 47% and 56%, respectively. This implies for a fixed rate problem that the proposed scheme can allow an increase in the number of simultaneously served video streams.     

Aggregate bandwidth estimation in stored video distribution systems

Multimedia applications like video on demand, distance learning, internet video broadcast, etc. will play a fundamental role in future broadband networks. A common aspect of such applications is the transmission of video streams that require a sustained relatively high bandwidth with stringent requirements of quality of service. In this paper various original algorithms for evaluating, in a video distribution system, a statistical estimation of aggregate bandwidth needed by a given number of smoothed video streams are proposed and discussed. The variable bit rate traffic generated by each video stream is characterized by its marginal distribution and by conditional probabilities between rates of temporary closed streams. The developed iterative algorithms evaluate an upper and lower bound of needed bandwidth for guaranteeing a given loss probability. The obtained results are compared with simulations and with other results, based on similar assumptions, already presented in the literature. Some considerations on the developed algorithms are made, in order to evaluate the effectiveness of the proposed methods. Copyright © 2002 John Wiley & Sons, Ltd.     

Region-of-interest based rate control for UAV video coding

To meet the requirement of high-quality transmission of videos captured by unmanned aerial vehicles (UAV) with low bandwidth, a novel rate control (RC) scheme based on region-of-interest (ROI) is proposed. First, the ROI information is sent to the encoder with the latest high efficient video coding (HEVC) standard to generate an ROI map. Then, by using the ROI map, bit allocation methods are developed at frame level and large coding unit (LCU) level, to avoid inaccurate bit allocation produced by camera movement. At last, by using a better robustness R-λ model, the quantization parameter (QP) for each LCU is calculated. The experimental results show that the proposed RC method can get a lower bitrate error and a higher quality for reconstructed video by choosing appropriate pixel weight on the HEVC platform.     

Bandwidth renegotiation for VBR video over ATM networks

A scheme for delivery or variable bit-rate (VBR) video over asynchronous transfer mode (ATM) networks where bandwidth can be renegotiated during the duration of a call between the video source and the network is considered. Renegotiation can be initiated by either the video source or the network. The video bandwidth requirement is characterized by a usage parameter control (UPC) consisting, in general, of peak rate, burst length, and sustained rate. A baseline design is outlined where rate-control adjusts the source's rate while a new UPC is requested from the network. When granted, the new UPC allows the source to maintain its target quantization and delay requirements. Rate control epochs may be extended when the network blocks UPC requests or sets a lower UPC value to temporally deal with congestion. Simulation results are presented for VBR MPEG video. The results show that with a moderate renegotiation rate the scheme tracks the bandwidth requirements of the source. As a result, the video quality and bandwidth efficiency can be maintained     

一种基于立体视觉显著性的多视点视频比特分配方法

针对多视点立体视频压缩编码,提出了一种基于立 体视觉显著性的比 特分配方法。研究综合利用多视点立体视频数据中场景的运动、深度以及深度边缘信息提取 人眼感兴趣区 域(ROI)的方法;然后根据ROI的划分结果优化区域比特分配。实验结果表 明,本文提出的算法能有效提 高ROI区域的编码性能,同时整体视频的率失真性能有一定程度的提高。     

视频对象分割与两种面向对象的视频编码器

在基于对象的视频编码中,视频对象的分割是重要的任务.本文研究一种利用位移帧差(DFD)的高阶统计特性和数学形态学算子的视频对象自动分割方法.这种方法首先根据一组转移帧差的高阶矩来得到一个大体覆盖运动对象的区域(模板),接着用形态学的腐蚀算子从模板的边沿向内腐蚀,直到对象的边沿.提出一种简单而高效的基于查找人头肩像轮廓最大转折点的头肩分离算法.在分割的基础上,用软件实现了一种基于MPEG-4的视频编码系统.提出一种面向对象分配带宽(OOBA——object-oriented bandwidth allocation)的极低比特率视频编码器.该编码器与传统基于帧的视频编码器相比,在低比特率环境下,PSNR略为下降,但图像的主观视觉质量得到提高.     

Optimal quality adaptation for scalable encoded video

The dynamic behavior of the Internet's transmission resources makes it difficult to provide perceptually good quality streaming video. Scalable video encoding techniques have been proposed to deal with this problem. However, an encoded video generally exhibits significant data rate variability to provide consistent visual quality. We are, therefore, faced with the problem of accommodating the mismatch between the available bandwidth variability and the encoded video variability. We investigate quality adaptation algorithms for scalable encoded variable bit-rate video over the Internet. Our goal is to develop a quality adaptation scheme that maximizes perceptual video quality by minimizing quality variation, while at the same time increasing the usage of available bandwidth. We propose an optimal adaptation algorithm and a real-time adaptation algorithm based on whether the network conditions are known a priori. Experimental results show that the real-time adaptation as well as the optimal adaptation algorithm provide consistent video quality when used over both TCP-friendly rate control (TFRC) and transmission control protocol (TCP).