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1.
Large scale video streaming over the Internet requires a large amount of resources such as server I/O bandwidth and network
bandwidth. A number of video delivery techniques can be used to lower these requirements. Periodic broadcast by a central
server combined with proxy caching offers a significant reduction of the aggregate network and server I/O bandwidth usage.
However, the resources available to a single server are still limited. In this paper we propose a system with multiple geographically distributed servers. The problem of multiple servers for periodic broadcast is quite different from the problem of object location for multiple
web servers. Multiple servers offer increased amount of resources and service availability and may potentially allow a further
reduction of network bandwidth usage. On the other hand, the benefit of periodic broadcast mostly comes from high demand videos.
With multiple servers holding a video, the demand of the video at each server is reduced. Therefore, it is a challenge to
use multiple servers efficiently. We first analyze the dependence of the resource requirements on the number and locations
of the servers. Based on the character of the function describing such a dependence, we formulate and solve the problem of
video location and delivery, in a way that minimizes resource usage. We explore a trade-off between network and I/O bandwidth
requirements. We evaluate our proposed solutions through a number of tests.
相似文献
David H. C. DuEmail: |
2.
Applying video smoothing techniques to real-time video transmission can significantly reduce the peak rate and rate variability
of compressed video streams. Moreover, statistical multiplexing of the smoothed traffic can substantially improve network
utilization. In this paper we propose a new smoothing scheme, which exploits statistical multiplexing gain that can be obtained
after smoothing of individual video streams. We present a new bandwidth allocation algorithm that allows for responsive interactivity.
The local re-smoothing algorithm is carried out using an iterative process. In the proposed scheme the smoothed video streams
are divided into fixed intervals and then a new transmission schedule for each interval is calculated. The problem of applying
an optimal transmission schedule for aggregated smoothing video streams is shown to be NP-hard problem. Partitioning the whole
stream into sections enables parallel processing of the smoothing algorithm in real-time before transmission. This approach
allows partial transmission of the multiplexed stream while smoothing other intervals. The simulation results show a significant
reduction in peak rate and rate variability of the aggregated stream, compared to the non-smoothing case. Therefore the proposed
scheme allows us to increase the number of simultanusally-served video streams.
相似文献
Shlomo GreenbergEmail: |
3.
An important research issue in video streaming is how to efficiently utilize the network resources to provide clients instant
access to multiple video objects. Caching strategy and transmission scheme are the two essential points inside the video streaming
framework. Recent research efforts on them are not sufficient due to their inflexible support for scalable encoded video streams
and heterogeneous requests from clients. In this paper, we propose an optimized caching strategy (OCS) and a scalable transmission
scheme (STS) for scalable coded video streaming. By exploring the characteristics of video streaming workload and system design
objectives, OCS and STS work efficiently to minimize both network bandwidth cost and user access latency. Firstly, we analyze
the caching problem for the proxy-assisted video streaming system and derive a maneuverable caching scenario. Secondly, we
develop an efficient transmission scheme for scalable coded videos. Thirdly, we formulate a multi-objective optimization model
with closed-form expressions to obtain the optimized caching strategy. Finally, with designed algorithms, an excellent compromise
between two competing objectives (minimizing the bandwidth cost and the access latency) is achieved. We start our evaluation
by studying the optimized caching strategy for a single video object. Then we apply the strategy to multiple video objects
and illustrate the tradeoff between the optimization objectives. Our evaluation results show that compared with other caching
strategies, the proposed optimized scalable caching strategy can achieve a significant reduction in bandwidth cost with even
a small proxy cache size. Meanwhile, the best performance (in terms of bandwidth cost) is obtained together with the proposed
scalable batch-patching transmission scheme.
相似文献
Kenneth OngEmail: |
4.
A survey on peer-to-peer video streaming systems 总被引:2,自引:1,他引:2
Video-over-IP applications have recently attracted a large number of users on the Internet. Traditional client-server based
video streaming solutions incur expensive bandwidth provision cost on the server. Peer-to-Peer (P2P) networking is a new paradigm
to build distributed network applications. Recently, several P2P streaming systems have been deployed to provide live and
on-demand video streaming services on the Internet at low server cost. In this paper, we provide a survey on the existing
P2P solutions for live and on-demand video streaming. Representative P2P streaming systems, including tree, multi-tree and
mesh based systems are introduced. We describe the challenges and solutions of providing live and on-demand video streaming
in P2P environment. Open research issues on P2P video streaming are also discussed.
相似文献
Chao LiangEmail: |
5.
Minh Tran Wallapak Tavanapong Wanida Putthividhya 《Multimedia Tools and Applications》2007,34(1):25-56
Video streaming is vital for many important applications such as distance learning, digital video libraries, and movie-on-demand.
Since video streaming requires significant server and networking resources, caching has been used to reduce the demand on
these resources. In this paper, we propose a novel collaboration scheme for video caching on overlay networks, called Overlay Caching Scheme (OCS), to further minimize service delays and loads placed on an overlay network for video streaming applications. OCS is not a
centralized nor a hierarchical collaborative scheme. Despite its design simplicity, OCS effectively uses an aggregate storage
space and capability of distributed overlay nodes to cache popular videos and serve nearby clients. Moreover, OCS is light-weight
and adaptive to clients’ locations and request patterns. We also investigate other video caching techniques for overlay networks
including both collaborative and non-collaborative ones. Compared with these techniques on topologies inspired from actual
networks, OCS offers extremely low average service delays and approximately half the server load. OCS also offers smaller
network load in most cases in our study.
相似文献
Wanida PutthividhyaEmail: |
6.
Service replication is an effective way to address resource requirements and resource availability problem. Dynamic service
selection enables clients to choose a server offering the best performance. Proper server selection is especially important
for video streaming over the Internet due to its high bandwidth requirements. However, given the length of a typical video
transmission, the server priorly selected may no longer be an optimal one for the duration of the entire transmission. More
importantly, a server may fail during the transmission of a video. In this paper we examine the possibility of switching to
another server during an on-going transmission for Periodic Broadcast schemes. Due to the timing requirements typical for
Periodic Broadcast the server switch may cause playback disruptions. We analyze the magnitude of the problem and propose an
easy to implement solution. We define the criteria, additional to the bandwidth availability for example, according to which
a new server should be selected. The client is also required to delay its playback by the amount of time bounded by the server
transmission offset. In addition, we propose an alternative method to ensure uninterrupted playback that relies on proxy caching.
Simulation results show that our approach can significantly reduce the likelihood of playback disruptions.
相似文献
David H. C. DuEmail: |
7.
Periodic broadcast is a cost-effective solution for large-scale distribution of popular videos. Regardless of the number of
video requests, this strategy guarantees a constant worst service latency to all clients, making it possible to serve a large
community with a minimal amount of broadcast bandwidth. Although many efficient periodic broadcast techniques have been proposed,
most of them impose rigid requirements on client receiving bandwidth. They either demand clients to have the same bandwidth
as the video server, or limit them to receive no more than two video streams at any one time. In our previous work, we addressed
this problem with a Client-Centric Approach (CCA). This scheme takes into consideration both server broadcast bandwidth and client receiving bandwidth and allows clients
to use all their receiving capability for prefetching broadcast data. As a result, given a fixed broadcast bandwidth, a shorter
broadcast period can be achieved with an improved client communication capability. In this paper, we present an enhanced version
of CCA to further leverage client bandwidth for more efficient video broadcast. The new scheme reduces the broadcast latency
up to 50% as compared to CCA. We prove the correctness of this new technique and provide an analytical evaluation to show
its performance advantage as compared with some existing techniques.
相似文献
Johnny WongEmail: |
8.
This work investigates the modeling of aggregate available bandwidth in multi-sender network applications. Unlike the well-established
client–server model, where there is only one server sending the requested data, the available bandwidth of multiple senders
when combined together does exhibit consistent properties and thus can be modeled and estimated. Through extensive experiments
conducted in the Internet this work proposed to model the aggregate available bandwidth using a normal distribution and then
illustrates its application through a hybrid download-streaming algorithm and a playback-adaptive streaming algorithm for
video delivery under different bandwidth availability scenarios. This new multi-source bandwidth model opens a new way to
provide probabilistic performance guarantee in best-effort networks such as the Internet, and is particularly suitable for
the emerging peer-to-peer applications, where having multiple sources is the norm rather than the exception.
相似文献
Jack Y. B. LeeEmail: |
9.
Pradeep K. Atrey Wei-Qi Yan Mohan S. Kankanhalli 《Multimedia Tools and Applications》2007,34(1):107-135
This paper addresses the problem of ensuring the integrity of a digital video and presents a scalable signature scheme for
video authentication based on cryptographic secret sharing. The proposed method detects spatial cropping and temporal jittering
in a video, yet is robust against frame dropping in the streaming video scenario. In our scheme, the authentication signature
is compact and independent of the size of the video. Given a video, we identify the key frames based on differential energy
between the frames. Considering video frames as shares, we compute the corresponding secret at three hierarchical levels.
The master secret is used as digital signature to authenticate the video. The proposed signature scheme is scalable to three
hierarchical levels of signature computation based on the needs of different scenarios. We provide extensive experimental
results to show the utility of our technique in three different scenarios—streaming video, video identification and face tampering.
相似文献
Mohan S. KankanhalliEmail: |
10.
R. Venkatesh Babu Andrew Perkis Odd Inge Hillestad 《Multimedia Tools and Applications》2008,37(2):211-231
This paper deals with monitoring user perception of multimedia presentations in a Universal Multimedia Access (UMA) enabled
system using objective no-reference (NR) metrics. These NR metrics are designed for an UMA-enabled system, in a novel architecture,
for a multimedia viewer. The first metric measures block-edge impairments in a video frame at the receiver end, based on the
observation that they occur in regions with low spatial activity. The second metric evaluates the quality of the reconstructed
video frame in the event of packet loss. Here, the structure of the artifact is itself exploited for the evaluation. Both
the metrics involve low computational complexity and are feasible for real-time monitoring of streaming video in a multimedia
communication scenario. Further, in rate-adaptive streaming of video, these metrics could serve as feedback parameters to
dynamically adapt the bit rates based on network congestion.
相似文献
Odd Inge HillestadEmail: |
11.
In this paper, we study the bandwidth allocation problem for serving video requests in a mobile real-time video player system.
One of the main issues to maintain the quality of services (QoS) in mobile video playback is to ensure sufficient number of
video frames available at the client side while a video is being played. However, due to the limited bandwidth of a mobile
network and variable workload streaming video, this is not easy to achieve in practice. In addition, the communication link
between mobile clients and a video server is subject to frequent errors and temporary disconnection. In this paper, we propose
to use the notion of buffered bandwidth in addition to the network bandwidth to support real-time playback of videos at mobile clients. Based on this, we designed
a bandwidth allocation scheme called Cooperative Pre-Fetching (CP) in which the amount of bandwidth to be allocated to serve a video request depends on the current buffer level of the
video at the client relative to the target buffer level of the client. In determining the target buffer level, we consider
the errors in communication to the client as well as the other clients who are concurrently served by the system. The buffered
video frames at the clients are then used to minimize the impact of error in communications on the overall QoS of video playbacks
in the whole system.
相似文献
Kam-Yiu Lam (Corresponding author)Email: |
12.
In the paper, we try to find a method that can service more users in a video-on-demand (VoD) system, based on MPEG-4 object
streams. The characteristics of object segmentation made on MPEG-4 videos can be utilized to reduce re-transmission of the
same objects, and then the saved bandwidth can be used to service more users. However, some thresholds must be analyzed first
to maintain the acceptable quality of services (QoS) requested by users, when reducing unnecessary object transmission on
one side. Thus, according to the defined thresholds, we propose a dynamically adjusting algorithm to coordinate the object
streams between the server and clients. The server not only allocates network bandwidth, but also adjusts ever-allocated QoS
appropriately using a degrading and upgrading strategy, based on the current network status. Lastly, through the simulation,
we found that our method has better performance than the other three methods owing to its flexibility to the network status.
相似文献
Yin-Fu HuangEmail: |
13.
Dynamic video summarization using two-level redundancy detection 总被引:1,自引:0,他引:1
The mushroom growth of video information, consequently, necessitates the progress of content-based video analysis techniques.
Video summarization, aiming to provide a short video summary of the original video document, has drawn much attention these
years. In this paper, we propose an algorithm for video summarization with a two-level redundancy detection procedure. By
video segmentation and cast indexing, the algorithm first constructs story boards to let users know main scenes and cast (when
this is a video with cast) in the video. Then it removes redundant video content using hierarchical agglomerative clustering
in the key frame level. The impact factors of scenes and key frames are defined, and parts of key frames are selected to generate
the initial video summary. Finally, a repetitive frame segment detection procedure is designed to remove redundant information
in the initial video summary. Results of experimental applications on TV series, movies and cartoons are given to illustrate
the proposed algorithm.
相似文献
Wei-Bo Wang |
14.
In this paper, an adaptive framework for video streaming over the Internet is presented. The framework is a joint design of
packet scheduling and rate control with optimal bandwidth resource allocation. The transmission rate is dynamically adjusted
to obtain maximal utilization of the client buffer and minimal allocation of the bandwidth. Under the constraint of the transmission
rate, a prioritized packet scheduling is designed to provide a better visual quality of video frames. The packet scheduling
is a refined bandwidth allocation which takes into account of varying importance of the different packets in a compressed
video stream. Moreover, the proposed approach is scalable with increasing multimedia flows in the distributed Internet environment.
Comparisons are made with the most current streaming approaches to evaluate the performance of the framework using the H.264
video codec. The extensive simulation results show that the average Peak Signal to Noise Ratio (PSNR) increases in our proposed
approach. It provides a better quality of the decoded frames, and the quality of the decoded frames changes more smoothly.
The achieved video quality among different users also has a lower fluctuation, which indicates a fair sharing of network resources.
相似文献
Shu-Ching ChenEmail: |
15.
With the recent advances in network technology, the number of high-speed networked homes increases rapidly and the enhanced services such as on-demand video services become feasible in terms of market maturity. Another trend is that storage systems become network-accessible. One of the leading network-attached storage systems is the Fiber Channel Arbitrated Loop (FC-AL). As a residential service gateway, the FC-AL-based servers can stably provide high quality video (e.g., DVD quality MPEG-2 stream) with thousands of clients between external service providers and local clients. In addition, in densely populated areas such as New York City, they can be much more cost efficient. Using our end-to-end simulation experiments to combine all the components, we have observed that FC-AL-based streaming servers perform better than SCSI-based systems, but there is still room for performance improvement. We are motivated by the fact that, unlike in SCSI-based systems, all the disks in FC-AL-based severs utilize only a small portion of their caches to a similar degree due to FC-AL fairness arbitration algorithm. Thus, we propose an effective prefetching scheme to improve the performance by further utilizing the disk cache. We show how the proposed scheme can determine the maximum number of prefetched blocks depending on the disk block and cache size. It is also shown how to find the optimal number of blocks transmitted to the FC-AL from the disk cache per FC-AL arbitration. In addition, we describe the cache replacement policy to take full advantage of the sequential access pattern of video files, and explain how to support multiple loops. By analysis and simulation experiments, we show that our prefetching scheme is not able to only increase the total number of concurrent streams significantly by reducing the disk seek time, but it can also further utilize the FC-AL by reducing the overhead of arbitration.
相似文献
Jonathan C. L. LiuEmail: |
16.
Efficient video encryption scheme based on advanced video coding 总被引:1,自引:0,他引:1
Shiguo Lian Jinsheng Sun Guangjie Liu Zhiquan Wang 《Multimedia Tools and Applications》2008,38(1):75-89
A video encryption scheme combining with advanced video coding (AVC) is presented and analyzed in this paper, which is different
from the ones used in MPEG1/2 video encryption. In the proposed scheme, the intra-prediction mode and motion vector difference
are encrypted with the length-kept encryption algorithm (LKE) in order to keep the format compliance, and the residue data
of the macroblocks are encrypted with the residue data encryption algorithm (RDE) in order to keep low cost. Additionally,
a key distribution scheme is proposed to keep the robustness to transmission errors, which assigns sub-keys to different frames
or slices independently. The encryption scheme’s security, time efficiency and error robustness are analyzed in detail. Experimental
results show that the encryption scheme keeps file format unchanged, is secure against replacement attacks, is efficient in
computing, and is robust to some transmission errors. These properties make it a suitable choice for real-time applications,
such as secure IPTV, secure videoconference or mobile/wireless multimedia, etc.
相似文献
Shiguo LianEmail: |
17.
The paper presents an automatic video summarization technique based on graph theory methodology and the dominant sets clustering
algorithm. The large size of the video data set is handled by exploiting the connectivity information of prototype frames
that are extracted from a down-sampled version of the original video sequence. The connectivity information for the prototypes
which is obtained from the whole set of data improves video representation and reveals its structure. Automatic selection
of the optimal number of clusters and hereafter keyframes is accomplished at a next step through the dominant set clustering
algorithm. The method is free of user-specified modeling parameters and is evaluated in terms of several metrics that quantify
its content representational ability. Comparison of the proposed summarization technique to the Open Video storyboard, the
Adaptive clustering algorithm and the Delaunay clustering approach, is provided.
相似文献
D. BesirisEmail: |
18.
Gerardo Fernández-Escribano Pedro Cuenca Luis Orozco-Barbosa Antonio Garrido Hari Kalva 《Multimedia Tools and Applications》2008,38(1):1-25
Recent developments have given birth to H.264/AVC: a video coding standard offering better bandwidth to video quality ratios
than MPEG-2. It is expected that the H.264/AVC will take over the digital video market, replacing the use of MPEG-2 in most
digital video applications. The complete migration to the new video-coding algorithm will take several years given the wide
scale use of MPEG-2 in the market place today. This creates an important need for MPEG-2/H264 transcoding technologies. However,
given the significant differences between both encoding algorithms, the transcoding process of such systems is much more complex
to other heterogeneous video transcoding processes. In this work, we start by analyzing the methods defined in the H.264 video
coding standard for the intra prediction: a central element of every H.264 encoder. We then introduce and evaluate six fast
intra mode decision algorithms which should enable the development of MPEG-2 to H.264 transcoders. Having evaluated all the
proposed methods, we have come out with a high-efficient method, namely DC-ABS pixel. Our results show that our algorithm
considerable reduces the complexity involved in the intra prediction with respect the mode decision algorithms used in H.264
JM reference software, while exhibiting a slight degradation on the RD function.. Finally, we analyze a comparative study
with two of the most prominent fast intra prediction methods presented in the literature. The results show that the proposed
DC-ABS pixel method achieves the best results for video transcoding applications.
相似文献
Hari KalvaEmail: |
19.
Combining the advantages of Peer-to-Peer (P2P) content distribution concept and metadata driven adaptation of videos in compressed
domain, in this paper, we propose a simple but scalable design of distributed adaptation and overlay streaming using MPEG-21
gBSD, called DAg-stream. The objective is not only to shift the bandwidth burden to end participating peers, but also to move
the computation load for adapting video contents away from dedicated media-streaming/adaptation servers. It is an initiative
to merge the adaptation operations and the P2P streaming basics to support the expansion of context-aware mobile P2P systems.
DAg-stream organizes mobile and heterogeneous peers into overlays. For each video, a separate overlay is formed. No control
message is exchanged among peers for overlay maintenance. We present a combination of infrastructure-centric and application
end-point architecture. The infrastructure-centric architecture refers to a tree controller, named DAg-master, which is responsible
for tree/overlay administering and maintenance. The application end-point architecture refers to video sharing, streaming
and adaptation by the participating resourceful peers. The motivation for this work is based on the experiences and lessons
learned so far about developing a video adaptation system for heterogeneous devices. In this article, we present our architecture
and some experimental evaluations supporting the design concept for overlay video streaming and online adaptation.
Razib Iqbal is pursuing his Ph.D. degree in Computer Science at the University of Ottawa (uOttawa), Canada. His current research interests include — Distributed and online video adaptation, and video watermaking. Mr. Iqbal received his Masters and Bachelors degree, both in Computer Science, from uOttawa in 2006 and North South University, Bangladesh in 2003 respectively. He is a recipient of the uOttawa International Admission Scholarship for both his Masters and Ph.D. studies. Shervin Shirmohammadi Associate Professor at the School of Information Technology and Engineering, University of Ottawa, Canada, joined the University as an Assistant Professor in 2004, after 4 years of industry experience as a Senior Software Architect and Project Manager that followed his Ph.D. degree in Electrical Engineering from the same University in 2000. His current research interests include Massively Multiuser Online Gaming (MMOG) and Virtual Environments, Application Layer Multicasting and Overlay Networks, Adaptive P2P Audio/Video Streaming, and Multimedia Assisted Rehabilitation Engineering. In addition to his academic publications, which include two Best Paper Awards, he has over a dozen technology transfers to the private sector. He is Editor-in-Chief of the International Journal of Advanced Media and Communications, Associate Editor of ACM Transactions on Multimedia Computing, Communications, and Applications, Associate Editor of Springer's Journal of Multimedia Tools and Applications, and also chairs or serves on the program committee of a number of conferences in multimedia, virtual environments and games, and medical applications. Dr. Shirmohammadi is a University of Ottawa Gold Medalist, a licensed Professional Engineer in Ontario, a Senior Member of the IEEE, and a Professional Member of the ACM. 相似文献
Shervin ShirmohammadiEmail: |
Razib Iqbal is pursuing his Ph.D. degree in Computer Science at the University of Ottawa (uOttawa), Canada. His current research interests include — Distributed and online video adaptation, and video watermaking. Mr. Iqbal received his Masters and Bachelors degree, both in Computer Science, from uOttawa in 2006 and North South University, Bangladesh in 2003 respectively. He is a recipient of the uOttawa International Admission Scholarship for both his Masters and Ph.D. studies. Shervin Shirmohammadi Associate Professor at the School of Information Technology and Engineering, University of Ottawa, Canada, joined the University as an Assistant Professor in 2004, after 4 years of industry experience as a Senior Software Architect and Project Manager that followed his Ph.D. degree in Electrical Engineering from the same University in 2000. His current research interests include Massively Multiuser Online Gaming (MMOG) and Virtual Environments, Application Layer Multicasting and Overlay Networks, Adaptive P2P Audio/Video Streaming, and Multimedia Assisted Rehabilitation Engineering. In addition to his academic publications, which include two Best Paper Awards, he has over a dozen technology transfers to the private sector. He is Editor-in-Chief of the International Journal of Advanced Media and Communications, Associate Editor of ACM Transactions on Multimedia Computing, Communications, and Applications, Associate Editor of Springer's Journal of Multimedia Tools and Applications, and also chairs or serves on the program committee of a number of conferences in multimedia, virtual environments and games, and medical applications. Dr. Shirmohammadi is a University of Ottawa Gold Medalist, a licensed Professional Engineer in Ontario, a Senior Member of the IEEE, and a Professional Member of the ACM. 相似文献
20.
Peer to peer video streaming in Bluetooth overlays 总被引:2,自引:2,他引:0
As Bluetooth is available in most personal and portable terminals (eg, cellular phone, PDA, videocamera, laptop, etc) Peer-to-peer
video streaming through Bluetooth networks is now a reality. Camera equipped Bluetooth phones capture video and broadcast
it to other Bluetooth devices and to the infrastructure. Tra ditionally, large scale Bluetooth networks were designed using
scatternet concepts. However, many Bluetooth devices do not support Scatternet connections and, even if they support it, they
provide only very limited features suitable mostly for static environments. In high mobility situations, a traditional Scatternet
design is not useful because of frequent disconnections and reconnections. To overcome these problems, we propose overlaid
Bluetooth Piconets (OBP) and simplified overlaid Bluetooth Piconets (SOBP) that interconnect Piconets forming virtual Scatternets.
In OBP, every Piconet dynamically reconfigures to collect metadata from neighboring Piconets. If metadata shows the existence
of useful data to transfer, an inter-Piconet connection is made to carry out the transfer. SOBP can be used instead of OBP
once neighbor Piconets have already discovered each other. In this paper, we compare via analysis and simulation the throughput
and efficiency of OBP, SOBP and Scatternet for video applications. We demonstrate the feasibility of video over OBP and SOBP
for a representative application.
相似文献
Mario GerlaEmail: |