Efficient staircase scheme with seamless channel transition mechanism

Video applications require large amount of bandwidth and also storage space. The Fast Broadcasting (FB) scheme is one of the simplest schemes to provide video services, but it requires considerably large buffer storage. This scheme assumes constant video popularity and thus has fixed amount of bandwidth requirement. The popularity of videos generally does not remain the same. It varies over a period of time and accordingly the bandwidth allocation should be adjusted. The variability in bandwidth requirement for videos based on popularity is overcome by incorporating seamless channel transition mechanism in a broadcasting scheme. After incorporating seamless channel transition mechanism, the scheme still delivers continuous video data to old and new users without jerks and hiccups. The FB scheme with seamless channel transition mechanism requires less buffer storage than the FB scheme. The staircase scheme also allocates a fixed amount of bandwidth to a video. The FB and staircase schemes divide a video into same number of segments; thus have same user’s waiting time. The basic difference between the FB and staircase schemes is that in the staircase scheme the segments are further divided into subsegments in order to reduce the buffer requirement. To consider variability of video popularity in the staircase scheme, seamless channel transition for staircase (SCTS) scheme has been discussed. The SCTS scheme performs better than the seamless Fast Broadcasting scheme as regard the buffer storage, while maintaining the same user’s waiting time. In this paper, we propose an efficient staircase scheme with seamless channel transition mechanism that performs better than the SCTS scheme. In the proposed scheme, the video (ESS scheme) data is downloaded at slower rate than that in the SCTS scheme without disrupting the user services and requiring less buffer storage.     

Content-Aware Distortion-Fair Video Streaming in Congested Networks

Internet is experiencing a substantial growth of video traffic. Given the limited network bandwidth resources, how to provide Internet users with good video playback quality-of-service (QoS) is a key problem. For video clips competing bandwidth, we propose an approach of Content-Aware distortion-Fair (CAF) video delivery scheme, which is aware of the characteristics of video frames and ensures max-min distortion-fair sharing among video flows. CAF leverages content-awareness to prioritize packet dropping during congestion. Different from bandwidth fair sharing, CAF targets end-to-end video playback quality fairness among users. The proposed CAF approach does not require rate-distortion modeling of the source, which is difficult to estimate. Instead, it exploits the temporal prediction structure of the video sequences along with a frame drop distortion metric to guide resource allocations and coordinations. Experimental results show that the proposed approach operates with limited overhead in computation and communication, and yields better QoS, especially when the network is congested.     

Geometrico-Harmonic Broadcasting Scheme With Continuous Redundancy

The harmonic broadcasting scheme has the best performance for the user latency. It, however, does not always provide the video data in time to the users. To provide the video data reliably, its two main variants - cautious and quasi-harmonic schemes have been proposed. They require more bandwidth than the harmonic scheme. The cautious and quasi-harmonic schemes need 0.50 b and 0.1771 b more bandwidth, respectively, than the harmonic scheme in limiting case. In this paper, a new broadcasting scheme: geometrico-harmonic scheme with continuous redundancy is proposed. This scheme provides the video data in time unlike the harmonic scheme, and its bandwidth requirement can be had as close to that of the harmonic scheme as we please. Moreover, the extra bandwidth required in this scheme can be evaluated at any point of time, that is, it can be estimated for a fractional size of a segment and/or subsegment. The bandwidth is a scarce resource and its requirement for any fractional size of segments (or subsegments) may be helpful while dealing with the variable bandwidth rate-encoded videos. In the proposed scheme, the user latency can be made arbitrarily close to that of the harmonic scheme. In comparison to the cautious and the quasi-harmonic schemes, it has better performance for the user latency as well as the buffer storage. For disk transfer rate, it performs better than the quasi-harmonic scheme and in comparison to the cautious harmonic scheme its performance is same     

一种新的视频点播方案——扩展幂级方案

提出一种适合于热门节目的分块广播(partition broadcasting)方案——扩展幂级方案，分析了该方案的资源需求包括服务器信道、用户端缓存、用户端I／O带宽等，并根据方案的周期性分析了用户点播时间与缓存空间及用户端I／O带宽的关系．结论表明它比现有的许多其它同类方案有着更好的兼容性，能很好地权衡用户端的I／O带宽及缓存空间，而且更易于实现。     

Dual-plan bandwidth smoothing for layer-encoded video

Traditional bandwidth smoothing techniques can be naturally supported by the renegotiated constant bit rate (RCBR) service model, but renegotiation failure in RCBR may cause buffer underflow and interrupt the playback of video. To address this concern, a novel dual-plan bandwidth smoothing (DBS) scheme is proposed in this paper by taking advantage of the SNR scalability of layer-encoded video. Upon renegotiation failure, the proposed scheme can adaptively discard certain enhancement layers to guarantee continuous video playback at the original frame rate. Experiments are carried out to demonstrate the validity of the proposed scheme. The impacts of renegotiation interval, granularity of enhancement layers, and playback buffer size on resulted video quality are also studied. From the simulation results, it is shown that the performance of the RCBR-based DBS scheme can be improved by 1) reducing the minimum time gap of renegotiation interval; 2) employing multilayer video encoding with finer granularity; and/or 3) increasing the playback buffer size.     

Low cost pre-stored video transmission across networks

This paper proposes a simple, practical and low-cost dynamic segmentation and bandwidth allocation scheme, called middle point, to transmit pre-stored video from source to playback destination across networks. The proposed scheme is based on two concepts, playback tunnel and bandwidth tunnel, to determine the segmentation boundary and transmission bandwidth with the objective of reducing transmission cost while guaranteeing the playback buffer neither underflows nor overflows. The performance of the proposed scheme is evaluated by a set of real-life MPEG video traces and also compared with the well-known optimal smoothing scheme. The obtained results show that the proposed scheme can be easily implemented with low complexity and low transmission cost.     

Adaptive bandwidth allocation based on playback tunnel to support video on demand service over ATM networks

This paper focuses on adaptive bandwidth allocation (ABA) for transporting pre-stored VBR compressed video data across networks in support of video-on-demand (VoD) service. Two key issues are addressed. Firstly, a simplified dynamic programming method based on playback tunnel is proposed to predict the bandwidth which can be dynamically allocated for transporting video segment to guarantee that the playback buffer neither underflows nor overflows. Secondly, ABA schemes with different criteria including middle-tunnel ABA (MT-ABA) and reduced-bandwidth-variability ABA (RBV-ABA) are investigated. The proposed ABA schemes are evaluated by a set of real-life MPEG video traces. The obtained results show that the RBV-ABA scheme outperforms MT-ABA scheme in terms of peak rate, traffic burstiness and bandwidth variability. On the other hand, the MT-ABA scheme is more significant for avoiding the playback buffer overflow or underflow than that of RBV-ABA.     

Improvement of the client-centric approach for broadcasting popular videos

Periodic broadcast is a cost-effective solution for large-scale distribution of popular videos. Regardless of the number of video requests, this strategy guarantees constant worst service latency to all clients. An essential periodic broadcast method is the client-centric approach (CCA), which allows clients to use smaller receiving bandwidth to download broadcast data. An enhanced version, namely CCA+, was proposed to yield a shorter waiting time. This work further improves CCA+ by leveraging client bandwidth for more efficient video broadcast. The new scheme reduces the broadcast latency by as much as 39?% when compared to CCA+ and 78?% when compared to CCA. We prove the applicability of this new scheme and provide an analytical evaluation to demonstrate the performance advantage, as compared with particular schemes.     

Optimal adaptive channel scheduling for scalable video broadcasting over MIMO wireless networks

Video broadcasting is an efficient way to deliver video content to multiple receivers. However, due to heterogeneous channel conditions in MIMO wireless networks, it is challenging for video broadcasting to map scalable video layers to proper MIMO transmit antennas to minimize the average overall video transmission distortion. In this paper, we investigate the channel scheduling problem for broadcasting scalable video content over MIMO wireless networks. An adaptive channel scheduling based unequal error protection (UEP) video broadcasting scheme is proposed. In the scheme, video layers are protected unequally by being mapped to appropriate antennas, and the average overall distortion of all receivers is minimized. We formulate this scheme into a non-linear combinatorial optimization problem. It is not practical to solve the problem by an exhaustive search method with heavy computational complexity. Instead, an efficient branch-and-bound based channel scheduling algorithm, named TBCS, is developed. TBCS finds the global optimal solution with much lower complexity. The complexity is further reduced by relaxing the termination condition of TBCS, which produces a (1 − ε)-optimal solution. Experimental results demonstrate both the effectiveness and efficiency of our proposed scheme and algorithm. As compared with some existing channel scheduling methods, TBCS improves the quality of video broadcasting across all receivers significantly.     

Efficient schemes for broadcasting popular videos

We provide a formal framework for studying broadcasting schemes and design a family of schemes for broadcasting popular videos, the greedy disk-conserving broadcasting (GDB) family. We analyze the resource requirements for GDB, i.e., the number of server broadcast channels, the client storage space, and the client I/O bandwidth required by GDB. Our analysis shows that all of our proposed broadcasting schemes are within a small factor of the optimal scheme in terms of the server bandwidth requirement. Furthermore, GDB exhibits a tradeoff between any two of the three resources. We compare our scheme with a recently proposed broadcasting scheme, skyscraper broadcasting (SB). With GDB, we can reduce the client storage space by as much as 50% or the number of server channels by as much as 30% at the cost of a small additional increase in the amount of client I/O bandwidth. If we require the client I/O bandwidth of GDB to be identical to that of SB, GDB needs only 70% of the client storage space required by SB or one less server channel than SB does. In addition, we show that with small client I/O bandwidth, the resource requirements of GDB are close to the minimum achievable by any disk-conserving broadcasting scheme.     

Design and analysis of permutation-based pyramid broadcasting

Periodic broadcasting can be used to support near-video-on-demand for popular videos. For a given bandwidth allocation, pyramid broadcasting schemes substantially reduce the viewer latency (waiting) time compared to conventional broadcasting schemes. Nevertheless, such pyramid schemes typically have substantial storage requirements at the client end, and this results in set-top boxes needing disks with high transfer rate capabilities. In this paper, we present a permutation-based pyramid scheme in which the storage requirements and disk transfer rates are greatly reduced, and yet the viewer latency is also smaller. Under the proposed approach, each video is partitioned into contiguous segments of geometrically increasing sizes, and each segment is further divided into blocks, where a block is the basic unit of transmission. As in the original pyramid scheme, frequencies of transmission for the different segments of a video vary in a manner inversely proportional to their size. Instead of transmitting the blocks in each segment in sequential order, the proposed scheme transmits these blocks in a prespecified cyclic permutation to save on storage requirements in the client end. Performance analyses are provided to quantify the benefits of the new scheme.     

Interlayer Jitter Index for the Transmission of Layered Video Stream over the Internet

A novel scheme of dynamic bandwidth allocation and buffer dimensioning based on the video playback tunnel and the jitter_index tunnel is proposed to guarantee the synchronization between the basic layer video stream and the enhancement layer video streams in the transmission of layered video streams over the Internet. The performance of the proposed scheme is evaluated using a set of real-life video traces with the focus on the effects of bandwidth, traffic burstiness and network traffic loading on the statistics of jitter_index between the basic layer and enhancement layers. The numerical results show that the proposed dynamic bandwidth allocation and buffer dimensioning scheme is able to significantly reduce the effect of interlayer jitters in the transmission of multiple layer-coded video streams over the Internet.     

Smooth workload adaptive broadcast

The high-bandwidth requirements and long-lived characteristics of digital video make transmission bandwidth usage a key limiting factor in the widespread streaming of such content over the Internet. A challenging problem is to develop bandwidth-efficient techniques for delivering popular videos to a large, asynchronous client population with time-varying demand characteristics. In this paper, we propose smooth workload adaptive broadcast to address the above issues. A key component of our scheme is Flexible Periodic Broadcast (FPB). By introducing a feedback control loop into FPB, and enhancing FPB using techniques such as parsimonious transmission, smooth workload adaptive broadcast provides instantaneous or near-instantaneous playback services and can smoothly adapt to workload changes. Furthermore, FPB, as proposed in this paper, is bandwidth efficient and exhibits the periodic smooth channel transition property.     

Scalable playback rate control in P2P live streaming systems

Current commercial live video streaming systems are based either on a typical client–server (cloud) or on a peer-to-peer (P2P) architecture. The former architecture is preferred for stability and QoS, provided that the system is not stretched beyond its bandwidth capacity, while the latter is scalable with small bandwidth and management cost. In this paper, we propose a P2P live streaming architecture in which by adapting dynamically the playback rate we guarantee that peers receive the stream even in cases where the total upload bandwidth changes very abruptly. In order to achieve this we develop a scalable mechanism that by probing only a small subset of peers monitors dynamically the total available bandwidth resources and a playback rate control mechanism that dynamically adapts playback rate to the aforementioned resources. We model analytically the relationship between the playback rate and the available bandwidth resources by using difference equations and in this way we are able to apply a control theoretical approach. We also quantify monitoring inaccuracies and dynamic bandwidth changes and we calculate dynamically, as a function of these, the maximum playback rate for which the proposed system able to guarantee the uninterrupted and complete distribution of the stream. Finally, we evaluate the control strategy and the theoretical model in a packet level simulator of a complete P2P live streaming system that we designed in OPNET Modeler. Our evaluation results show the uninterrupted and complete stream delivery (every peer receives more than 99 % of video blocks in every scenario) even in very adverse bandwidth changes.     

端到端MPEG-4 FGS视频TCP友好的平滑传输

着重研究了Internet上MPEG-4 FGS(fine grained scalable)视频流的自适应平滑传输,其主要目的在于,在网络带宽变化的情况下,提供稳定的视频回放质量.提出了一种新的基于TFRC(TCP-friendly rate control)的MPEG-4 FGS端到端视频流传输系统框架,在此框架的基础上,首先假设完整的可用带宽变化已知,并且提出了一种离线的自适应平滑算法.此后,给出一种基于改进的ARAR(autoregressive autoregressive)预测技术的在线自适应平滑算法.最后,以NS-2为实验平台进行了模拟实验.模拟实验表明,提出的离线和在线自适应平滑算法可以充分利用可用网络带宽,并且能够在可用网络带宽持续波动的情况下保证接收方的回放尽可能地平稳,从而达到获得最佳视觉效果的目的.     

Joint Video Coding and Statistical Multiplexing for Broadcasting Over DVB-H Channels

A novel joint video encoding and statistical multiplexing (StatMux) method for broadcasting over digital video broadcasting for handhelds (DVB-H) channels is proposed to improve the quality of encoded video and to decrease the end-to-end delay in a broadcast system. The main parts of end-to-end delay in a DVB-H system result from a time-sliced transmission scheme that is used in DVB-H and from the bit rate variations of service bit streams. The time-sliced transmission scheme is utilized in DVB-H to reduce the power consumption of DVB-H receivers. Variable bit rate (VBR) video bit streams are used in DVB-H to improve the video quality and compression performance. The time-sliced transmission scheme has increased the channel switching delay, i.e., switching to a new audio-visual service, in DVB-H. The used VBR bit streams increase the required buffering delays in the whole system. The different parts of end-to-end delay in a DVB-H system can be affected by the used video encoding and multiplexing methods. Different scenarios for encoding and StatMux of video sources for DVB-H application are studied in this paper. Moreover, a new method for jointly encoding and StatMux of video sources is proposed that not only decreases the end-to-end delay but also improves the average quality of compressed video by dynamically distributing available bandwidth between the video sources according to their relative complexity. Performance of the proposed method is validated by simulation results.      

A scalable cost-effective video broadcasting system for on-demand video services

Recent years have seen intensive investigations of Periodic Broadcast, an attractive paradigm for broadcasting popular videos. In this paradigm, the server simply broadcasts segments of a popular video periodically on a number of communication channels. A large number of clients can be served simultaneously by tuning into these channels to receive segments of the requested video. A playback can begin as soon as a client can access the first segment. Periodic Broadcast guarantees a small maximum service delay regardless of the number of concurrent clients. Existing periodic broadcast techniques are typically evaluated through analytical assessment. While these results are good performance indicators, they cannot demonstrate subtle implementation difficulty that can prohibit these techniques from practical deployment. In this paper, we present the design and implementation of a video broadcasting system based on our periodic broadcast scheme called Striping Broadcast. Our experience with the system confirms that the system offers a low service delay close to its analytical guaranteed delay while requiring small storage space and low download bandwidth at a client.     

An early split and skip algorithm for fast intra CU selection in HEVC

The rapid development and increase of multimedia applications, as well as the demand for higher video-quality services at restricted resources such as storage capacity, transmission bandwidth and power consumption, has brought the urgent need for more efficient video compression techniques. The new video coding standard high efficiency video coding (HEVC) has a significant superiority over its predecessor advanced video coding (AVC). HEVC is reported to halve the bit rate with the same visual quality, or a better quality with the same bit rate when compared with AVC. Beside other improvements, HEVC significantly gets its power from the use of dynamic hierarchical quad-tree structure by partitioning the frames into smaller regions called coding units (CU), by means of a rate–distortion optimization process. However, this improvement yields to a dramatic increase of high computational complexity and increased encoding time, which primarily restricts its adaptation in real-time applications. In this paper, we proposed an early CU determination algorithm for fast encoder realization to reduce the encoding time which is the most important part of the standard standing for development. The experimental results show that the proposed algorithm has approximately 45 % encoding time saving with a 4.6 % bit-rate increment, on average.     

Design and Implementation of the Stony Brook Video Server

The system architecture of the Stony Brook Video Server (SBVS), which guarantees end-to-end real-time video playback in a client-server setting, is presented. SBVS employs a real-time network access protocol, RETHER, to use existing Ethernet hardware as the underlying communications media. The video server tightly integrates the bandwidth guarantee mechanisms for network transport and disk I/O. SBVS's stream-by-stream disk scheduling scheme optimizes the effective disk bandwidth without incurring significant scheduling overhead. To demonstrate the feasibility of the proposed architecture, we have implemented a prototype called SBVS-1, which can support five concurrent MPEG-1 video streams on an Intel 486DX2/EISA PC. To our knowledge, this system is the first video server that provides an end-to-end performance guarantee from the server's disks to the each user's display over standard Ethernet. This paper describes the implementation details of integrating network and I/O bandwidth guarantee mechanisms, and the performance measurements that drive and/or validate our design decisions. © 1997 by John Wiley & Sons, Ltd.     

Generalized Sequence-Based and Reverse Sequence-Based Models for Broadcasting Hot Videos

It has been well recognized as an efficient approach for broadcasting popular videos by partitioning a video data stream into multiple segments and launching each segment through an individual channel simultaneously and periodically. Based on the design premises, some recent studies, including skyscraper broadcasting (SkB), client-centric approach (CCA), greedy disk-conserving broadcasting (GDB), and reverse fast broadcasting (RFB) schemes, etc., have been reported. To study the client segment downloading process, this paper first introduces an applicable sequence-based broadcasting model that can be used to minimize the required buffer size. By extending RFB, this paper further proposes a reverse sequence-based broadcasting model, which can generally improve the existing schemes such as SkB, CCA, GDB, and FB in terms of the relaxed client buffer size. To have a deeper understanding on the proposed reverse model, the upper bound of the client buffer requirement is obtained through a comprehensive analysis, which is proved to be much smaller than the conventional sequence model by 25% to 50%. Based on the proposed reverse model, a reverse sequence-based broadcasting scheme is developed for achieving smaller delay than CCA and GDB.