共查询到20条相似文献,搜索用时 31 毫秒
1.
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: |
2.
Providing scalable video services in a peer-to-peer (P2P) environment is challenging. Since videos are typically large and
require high communication bandwidth for delivery, many peers may be unwilling to cache them in whole to serve others. In
this paper, we address two fundamental research problems in providing scalable P2P video services: (1) how a host can find
enough video pieces, which may scatter among the whole system, to assemble a complete video; and (2) given a limited buffer
size, what part of a video a host should cache and what existing data should be expunged to make necessary space. We address
these problems with two new ideas: Cell caching collaboration and Controlled Inverse Proportional (CIP) cache allocation. The Cell concept allows cost-effective caching collaboration in a fully distributed environment and
can dramatically reduce video lookup cost. On the other hand, CIP cache allocation challenges the conventional caching wisdom
by caching unpopular videos in higher priority. Our approach allows the system to retain many copies of popular videos to
avoid creating hot spots and at the same time, prevent unpopular videos from being quickly evicted from the system. We have
implemented a Gnutella-like simulation network and use it as a testbed to evaluate the proposed technique. Our extensive study
shows convincingly the performance advantage of the new scheme.
相似文献
Wallapak TavanapongEmail: |
3.
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: |
4.
A survey on peer-to-peer video streaming systems 总被引:3,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.
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: |
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.
Meng-Yen Hsieh Yueh-Min Huang Tzu-Chinag Chiang 《Multimedia Tools and Applications》2007,34(2):155-177
Mobile ad hoc networks without centralized infrastructure change their topology rapidly because of node mobility, making multimedia
applications difficult to run across wireless networks. Moreover, video transmission over ad hoc networks causes frequent
transmission loss of video packets owing to end-to-end transmission with a number of wireless links, and requires essential
bandwidth and restricted delay to provide quality-guaranteed display. This paper presents an architecture supporting transmission
of multiple video streams in ad hoc networks by establishing multiple routing paths to provide extra video coding and transport
schemes. This study also proposes an on-demand multicast routing protocol to transport layered video streams. The multicast
routing protocol transmits layered video streaming based on a weight criterion, which is derived according to the number of
receivers, delay and expiration time of a route. A simulation is performed herein to indicate the viability and performance
of the proposed approach. The simulation results demonstrate that the proposed transport scheme is more effective than other
video transport schemes with single or multiple paths.
相似文献
Tzu-Chinag ChiangEmail: |
8.
A video streaming proxy server needs to handle hundreds of simultaneous connections between media servers and clients. Inside,
every video arrived at the server and delivered from it follows a specific arrival and delivery schedule. While arrival schedules
compete for incoming network bandwidth, delivery schedules compete for outgoing network bandwidth. As a result, a proxy server
has to provide sufficient buffer and disk cache for storage, together with memory space, disk space and disk bandwidth. In
order to optimize the throughput, a proxy server has to govern the usage of these resources. In this paper, we first analyze
the property of a traditional smoothing algorithm and a video staging algorithm. Then we develop, based on the smoothing algorithm,
a video staging algorithm for video streaming proxy servers. This algorithm allows us to devise an arrival schedule based
on the delivery schedule. Under this arrival and delivery schedule pair, we can achieve a better resource utilization rate
gracefully between different parameter sets. It is also interesting to note that the usage of the resources such as network
bandwidth, disk bandwidth and memory space becomes interchangeable. It provides the basis for inter-resource scheduling to
further improve the throughput of a video streaming proxy server system.
相似文献
Daniel P. K. LunEmail: |
9.
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: |
10.
Streaming of scalable h.264 videos over the Internet 总被引:1,自引:0,他引:1
Aylin Kantarcı 《Multimedia Tools and Applications》2008,36(3):303-324
To investigate the benefits of scalable codecs in the case of rate adaptation problem, a streaming system for scalable H.264
videos has been implemented. The system considers congestion level in the network and buffer status at the client during adaptation
process. The rate adaptation algorithm is content adaptive. It selects an appropriate substream from the video file by taking
into account the motion dynamics of video. The performance of the system has been tested under congestion-free and congestion
scenarios. The performance results indicate that the system reacts to congestion properly and can be used for Internet video
streaming where losses occur unpredictably.
相似文献
Aylin KantarcıEmail: |
11.
Leonardo Bidese de Pinho Claudio Luis de Amorim 《Journal of Network and Systems Management》2008,16(2):183-200
The growing need for ubiquitous access to video on demand (VoD) applications by large audiences has driven researches to build
new scalable VoD systems that can guarantee Quality of Service (QoS) over wireless networks. In this paper, we propose and
evaluate a novel system-level design that guarantees QoS by eliminating the service latency for short videos over IEEE 802.11
networks. Furthermore, our VoD system attains scalable performance by employing collocated access points (APs) coupled with
an efficient association management of clients to the APs using a generic least-loaded-first heuristic on non-overlapping
channels. Simulated results of our VoD system demonstrated that it achieved scalable performance due to its effective use
of available bandwidth of the APs while supporting a low blockage rate for short videos up to 360 s. These results suggest
that our VoD system can be an attractive solution for several classes of scalable VoD applications that require QoS guarantee
such as movie trailers, news, video clips, and commercials.
相似文献
Claudio Luis de AmorimEmail: |
12.
P-chaining: a practical VoD service scheme autonomically handling interactive operations 总被引:1,自引:1,他引:0
Providing scalable VoD streaming services has recently become a hot issue, and many approaches have been proposed. Because
video streaming services through the Internet are widely used, the need to support VCR operations also increases. However,
there are few approaches to supporting VCR operations on the Internet. We propose a service scheme based on chaining, in which
clients as well as the server provide streaming services. In the proposed scheme, services are provided by unicast and managed
locally using node lists. In addition, our scheme can support frequent VCR operations without incurring significant overhead
in the server workload. We have evaluated our scheme through simulation with real traces from a content distribution network
(CDN) company and with various parameters. The results show that the proposed scheme reduces server workload significantly.
The results also verify that frequent VCR operations can be served smoothly without causing too much overhead.
相似文献
Heon Y. YeomEmail: |
13.
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: |
14.
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: |
15.
In this paper, the problem of caching continuous media data in a (main) memory and disk caching system is addressed. Caching
schemes can significantly reduce the load on the network as well as on the servers, also the retrieval of documents from the
cache requires short response time. In interval-level caching algorithms, an interval of data between two adjacent streams
is the basic caching entity. In this paper, we design a novel algorithm, referred to as variable bit rate caching (VBRC) algorithm, which belongs to the interval-level caching algorithms. The proposed VBRC algorithm can be used in the
system for memory caching or disk caching. VBRC can handle variable retrieval bandwidth as well as constant retrieval bandwidth
. In designing the VBRC algorithm, we propose the strategies of reducing the number of switching operation, which will probably
cause discontinuity of retrieving data. Also, we propose a just-in-time scheme for resource allocation in our VBRC algorithm and show that the caching performance in comparison with the reservation scheme
adopted in the resource-based caching (RBC) algorithm is significantly improved. Our simulation study compares the recent
and most popular generalized interval caching, RBC, and VBRC, on several influencing factors such as cache space size, cache
I/O bandwidth, request arrival rate, and percentage of requests for large documents, with respect to the byte hit ratio and the number of switching operations. The simulation result confirms our analysis.
相似文献
Bharadwaj VeeravalliEmail: URL: http://cnds.ece.nus.edu.sg |
16.
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: |
17.
Francesco Palmieri Ugo Fiore Sergio Ricciardi 《Journal of Network and Systems Management》2008,16(4):421-448
Advances in optical technologies have enabled the deployment of wavelength division-multiplexed (WDM) transmission systems
capable of providing huge amounts of bandwidth across long distances. In this scenario, dynamic routing for direct provisioning
of optical paths at the WDM layer becomes a challenging problem. Any distributed algorithm for routing dynamic traffic demands
on optical transport infrastructures should be simple, flexible, efficient and scalable. The contribution of this paper is
a novel integrated routing and grooming scheme for setting-up bandwidth guaranteed paths on hybrid wavelength and label switched
networks. Our proposal exploits and refines the minimum interference routing idea according to an improved and re-optimized
resource and traffic-aware approach, where critical links are detected and weighted according to a low complexity all-pairs
minimum cut strategy that substantially reduce the overall number of calculations and hence the computational cost. The valuable
results achieved in the comparison against other well-known reference techniques clearly demonstrate that our algorithm is
very time-efficient while performing better in terms of blocking probability.
相似文献
Sergio RicciardiEmail: |
18.
A structured P2P network based on the small world phenomenon 总被引:1,自引:0,他引:1
In this paper, we propose a new structured P2P overlay network, named SW-Uinta(small-world). In order to reduce the routing
latency, we firstly construct the Uinta network in which both physical characteristics of network and data semantic are considered.
Furthermore, based on Uinta, a nondeterministic caching strategy is employed to allow for poly-logarithmic search time while
having only a constant cache size. Compared with the deterministic caching strategy proposed by previous P2P systems, the
nondeterministic caching strategy can reduce communication overhead for maintaining the routing cache table. Cache entries
in the cache table of peer nodes can be updated by subsequent queries rather than only by running stabilization periodically.
In the following, a novel cache replacement scheme, named the SW cache replacement scheme, is used to improve lookup performance,
which has proved to satisfy the small-world principle. So we call this network SW-Uinta(small-world). After that, according
to the theoretical analysis, it can be proved that SW-Uinta(small-world) can get O((log 2
N)/k) search time with O(k) cache size. Lastly, the performance of SW-Uinta(small-world) is compared with those of other structured P2P networks such
as Chord and Uinta. It shows that SW-Uinta(small-world) can achieve improved object lookup performance and reduce maintenance
cost.
相似文献
Hai Jin (Corresponding author)Email: |
19.
In conventional motion compensated temporal filtering based wavelet coding scheme, where the group of picture structure and
low-pass frame position are fixed, variations in motion activities of video sequences are not considered. In this paper, we
propose an adaptive group of picture structure selection scheme, which the group of picture size and low-pass frame position
are selected based on mutual information. Furthermore, the temporal decomposition process is determined adaptively according
to the selected group of picture structure. A large amount of experimental work is carried out to compare the compression
performance of proposed method with the conventional motion compensated temporal filtering encoding scheme and adaptive group
of picture structure in standard scalable video coding model. The proposed low-pass frame selection can improve the compression
quality by about 0.3–0.5 dB comparing to the conventional scheme in video sequences with high motion activities. In the scenes
with un-even variation of motion activities, e.g. frequent shot cuts, the proposed adaptive group of picture size can achieve
a better compression capability than conventional scheme. When comparing to adaptive group of picture in standard scalable
video coding model, the proposed group of picture structure scheme can lead to about 0.2~0.8 dB improvements in sequences
with high motion activities or shot cut.
相似文献
Zhao-Guang LiuEmail: |
20.
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: |