Abstract:
A method for loading a buffer of a consumer node operable in a system for streaming multimedia content. The method includes dividing the buffer to sections each section being filled with multimedia data during a different time interval; loading a first section of the buffer by accessing at least one resource node of the multimedia content during a first time interval; and loading a second section of the buffer by accessing at least one reliable node of the multimedia content during a second time interval; wherein the buffer continuously delivers the multimedia content to a display of the consumer node and wherein the at least one reliable node is adapted to guarantee delivery of multimedia content to connected nodes.

Description:
TECHNICAL FIELD 
     The present invention relates generally to the field of network communication and media distribution in a peer-to-peer (P2P) network, and more specifically to buffering techniques to ensure continued quality of a video display at a node. 
     BACKGROUND OF THE INVENTION 
     The ubiquity of the Internet enables new techniques adaptation to enable direct distribution of multimedia files and real-time media streaming to end-users in an electronic format. The advantages associated with electronic distribution allow media content providers to establish global distribution systems for digital content. Furthermore, new compression algorithms, designed specifically for multimedia data, dramatically reduce the bandwidth and storage space required for the electronic distribution of multimedia data. This, together with the availability of broadband communication, encourages content providers to adopt the Internet as an alternate distribution system complementing the conventional distribution systems (e.g., cable or satellite TV). 
     Peer-to-peer (P2P) or grid networks enable the distribution of media between users without using server centric solutions. As an example, P2P file sharing systems are well known in the industry and use a very efficient technology to deliver media. Examples for such P2P systems are BitTorrent® and Gnutella. However, these systems do not distribute the content in real-time. Rather, a user can download the content (files) and view it only when the download has completed, i.e., a user cannot view the file (e.g., a movie) while downloading it. 
     Recently, new systems for real-time streaming over P2P networks have been developed. Examples for such systems may be found in “A Data Driver Overlay Network for Efficient Live Media Streaming” by Zhang, et al. and in “Peer-to-Peer Media Streaming Using CollectCast”, by Hefeeda, et al., both of which are incorporated herein by reference merely for the useful understanding of the background of the invention. Real-time streaming systems fail to fully utilize the network&#39;s resources, as they do not consider the asymmetric nature of the nodes (peers) in a typical Internet protocol (IP) network. 
     Generally, such systems consider the upload bandwidth of nodes as equal to the download bandwidth. This is rarely the case in IP networks, such as asymmetric digital subscriber line (ADSL) and cable based networks, as in most cases a node&#39;s upload bandwidth is half or less of the bandwidth of the download. Another type of real-time P2P network for distributing media can be found in PCT application number PCT/IL2007/000392 entitled “Realtime Media Distribution in a P2P Network”, by Omer Luzzatti, et al (hereinafter “Luzzatti”) which is assigned to common assignee and incorporated herein by reference merely for the useful understanding of the background of the invention. Luzzatti discloses a real-time P2P network where nodes in the network can act in the role of ‘amplifiers’ to increase the total available bandwidth made available in the network and thus to improve the quality of the media consumed by the viewers. 
     In such systems, where the video delivery to an accepting node is from one or more donating nodes, it is essential to maintain the quality of the video content. That is, it is important to make sure that video streams continue to be pleasurable to the eye and ear. A common approach to address this requirement is to have a buffer that buffers a few seconds of the data stream delivered to the accepting node. However, due to changes in network traffic patterns, or the availability of a donating node to provide data to the accepting node, such phenomenon occurs and results in undesirable visual or audio appearance. 
     It would be therefore advantageous to provide a solution for managing the loading of a buffer utilized in a multimedia delivery system to enable high quality reception of both video and audio contents. 
     SUMMARY OF THE INVENTION 
     Certain embodiments of the invention include a system for streaming multimedia content. The system comprises at least one resource node for delivering multimedia content; at least one reliable node for reliably delivering multimedia content, wherein the at least one reliable node is guaranteed to provide multimedia content to connected nodes; and at least a consumer node for receiving the multimedia content distributed by the at least one resource node and the at least one reliable node over a network; wherein the consumer node includes a buffer being filled with multimedia content by the at least one resource node for a first time interval, and then by the at least one reliable node for a second time interval, the second time interval being subsequent to the first time interval. 
     Certain embodiments of the invention also include a consumer node operable in a system for streaming multimedia content. The consumer node comprises an interface to a network enabling communication with at least one resource node adapted to deliver multimedia content and at least one reliable node adapted to guarantee the reliable delivery of multimedia content; and a buffer for buffing the multimedia content; wherein the buffer is filled with multimedia content by having the consumer node first access the at least one resource node for a first time interval, and then the at least one reliable node for a second time interval, the second time interval being subsequent to the first time interval. 
     Certain embodiments of the invention further include a method for loading a buffer of a consumer node operable in a system for streaming multimedia content. The method comprises dividing the buffer to sections each section being filled with multimedia data during a different time interval; loading a first section of the buffer by accessing at least one resource node of the multimedia content during a first time interval; and loading a second section of the buffer by accessing at least one reliable node of the multimedia content during a second time interval; wherein the buffer continuously delivers the multimedia content to a display of the consumer node and wherein the at least one reliable node is adapted to guarantee delivery of multimedia content to connected nodes. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The subject matter that is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings. 
         FIG. 1  is a diagram of a P2P network used to describe the principles of the present invention. 
         FIG. 2  is a diagram of communication between a consumer node and both resource nodes and a reliable node. 
         FIG. 3  is a flowchart demonstrating the principles of operation of buffer loading of a consumer node by both resource nodes and a reliable node implemented in accordance with an embodiment of the invention. 
         FIG. 4  is a timing diagram describing sources for packets provided in accordance with the invention. 
         FIG. 5  is a data connectivity diagram describing the connections between the nodes provided in accordance with the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     It is important to note that the embodiments disclosed by the invention are only examples of the many advantageous uses of the innovative teachings herein. In general, statements made in the specification of the present application do not necessarily limit any of the various claimed inventions. Moreover, some statements may apply to some inventive features but not to others. In general, unless otherwise indicated, singular elements may be in plural and vice versa with no loss of generality. In the drawings, like numerals refer to like parts through several views. 
     Certain embodiments of the invention a method for management loading of a buffer with multimedia (e.g., video and audio) contents, where the buffer is part of a node receiving video swarms in a peer-to-peer (P2P) network. Nodes in the network are connected to other nodes that are providers of portions of the video content as well as to one or more reliable nodes of the P2P network. In order to ensure good quality of video display, the buffer first retrieves initial data from a reliable node, then from other nodes to which the receiving node is connected, and then, the last portion, typically measure in time, of the buffer is filled again from a reliable node. A reliable node is a node that is guaranteed to provide multimedia data to other nodes connected to the reliable node. This approach balances loads between nodes as well as provides assurance against jitters. 
       FIG. 1  shows a non-limiting and exemplary block diagram of a P2P network  100  used to describe the principles of the invention. The P2P network  100  includes a plurality of nodes (peers)  120 - 1  through  120 -N (collectivity referred to as nodes  120 ), reliable nodes  130 - 1  through  130 -M (collectivity referred to as nodes  130 ), and a broadcaster  140 , all of which communicate with each other over an Internet protocol (IP) network  150 . The P2P network  100  may further include a centralized management server  110 . The P2P network  100  is utilized to distribute content in several parallel (and alternative) “channels”. For example, the P2P network  100  may distribute several unrelated channels (e.g., TV-like channels) of real-time streaming media, with viewers who can choose to view one particular stream at a time. In a preferable implementation there will be at least two reliable nodes  130 . 
     The nodes  120  and reliable nodes  130 , distributing the content of a particular channel, constitute a “channel swarm”. The nodes  120  may be, but are not limited to, personal computers, servers, portable media devices, media control devices, set-up boxes, or any other device capable of exchanging data with other nodes connected to it. A node may also refer to a module of a software system such as a media player application. Each node  120  can act as a consumer-node and/or a resource-node. Typically, reliable nodes  130  are used only for the purpose of providing content and such nodes receive content from a broadcaster  140 . In a typical embodiment of the invention reliable nodes  130  are placed at central points of the network  150  that are considered to be valuable for the distribution of data. For example, a certain geographical area, for example, a town may have one or two reliable nodes  130  in general network proximity to the nodes  120  it may serve. A reliable node may be relied to provide a consistent bandwidth and be generally available to the nodes it serves, unlike the other resource nodes, as explained below, which may be available or unavailable, or change bandwidth, over relatively short periods of time. 
     A consumer-node, also referred to as an acceptor or viewer, is a node  120 - c  (where c is an integer greater than or equal to 1) that belongs to an end-user who wants to watch a channel (i.e., to consume the real-time content). Each consumer-node is constrained to join one or more channel-swarms as determined by the end-user, and must receive a complete, consumable stream of the real-time content. An end-user can view media content broadcasted in a channel on a display connected to the consumer-node. This includes, but is not limited to, a TV screen connected to a set-up box, a monitor connected to a personal computer, a portable multimedia device, and the like. It should be noted that a consumer node may operate also a resource node, or a donor, to another node  120  of the network  150 . 
     A resource-node is a node  120 - r  (where r is an integer greater than or equal to 1) with an available upload bandwidth that can be contributed to the one or more channel-swarms. In accordance with one embodiment a resource-node may be a dedicated network device that shares its bandwidth, but does not consume the media. Such devices are typically installed by service providers, but may also be nodes that are otherwise consumer nodes bit are presently not used for viewing of video swarms. A resource-node may be also an amplifier as described in greater detail in Luzzatti. It should be noted that different resource-nodes may have different capabilities, and in particular may be differently capable of providing resources to different consumer-nodes. The allocation of particular resource-nodes to a channel should be chosen to guarantee a certain quality of service, while minimizing the overhead associated with joining a channel swarm. 
       FIG. 2  shows an exemplary and non-limiting diagram  200  of communication between a consumer node and both resource nodes and at least one reliable node. In accordance with the principles of the invention the consumer node  120 - i  includes a buffer  125 - i  which requests content which it receives from three resources. Two resources are the resource nodes  120 - j  and  120 - k . The other resource is the reliable node  130 - p . As all are part of the P2P network  100  they are able to communicate and operate to provide the necessary content. Portions of the content may be provided by one node and other portions by another node. However, according to the principles of the disclosed invention a particular order must be adhered to in order to maintain the quality of the video stream provided to the consumer node  120 - i.    
     A buffer in a consumer node  120  may be viewed as comprising three time intervals: a lead time interval, a middle time interval, and a trailing time interval. For example, the buffer  125 - i  may be able to contain a total of five seconds of content. In one embodiment the lead time interval of the buffer will contain a period of one second and so will the trailing time interval which will also be one second. The middle time interval will therefore consist of a period of three seconds. To provide content for both the lead time interval and the trailing time interval the node  120 - i  will receive data preferably from the reliable node  130 - p  while the data for the middle time interval is to be provided from the nodes  120 - j  and  120 - k , as well as from reliable node  130 - p  if it is also available to do so. Each consumer node is always directed to use specific reliable nodes  130 . In one embodiment the consumer node  120 - i  is further directed to a preference list between reliable nodes  130 , such that one such node may be more preferable for use by the node  120 - i  over another reliable node. Furthermore, in a typical application, consumer node  120 - i  periodically checks to which resource nodes  120  it is connected as well as to the reliable nodes  130  and determines if any changes are to be made. 
       FIG. 3  shows an exemplary and non-limiting flowchart  300  demonstrating the principles of operation of the buffer loading of a consumer node by both resource nodes and reliable nodes implemented in accordance with an embodiment of the invention. In S 310  the resource nodes, to be used by the consumer node, are determined from a list of potential consumer nodes. In S 320  the reliable nodes, to be used by the consumer node, are determined from a list of potential reliable nodes. In one embodiment of the disclosed invention S 320  is optional. Typically, at least two reliable nodes will be used. In S 330  the consumer node loads the leading time zone of its buffer with data from selected reliable nodes. In S 340  the consumer node loads the middle time zone of its buffer with data from selected resource nodes. In S 350  the consumer node loads the trailing time zone of its buffer with data from selected reliable nodes. In one embodiment of the disclosed invention any missing data not provided for in the buffer&#39;s middle time zone is also requested from the reliable nodes so as to enable smooth video transfer. 
     In S 360  it is checked whether additional data is to be provided, and if so execution continues with S 310 ; otherwise, execution terminates. The result of this implementation is a balanced loading between “volunteer” resource nodes which is the typical operation of nodes  120  and the reliable nodes  130  that kick-in to provide the refinement of the performance of the overall video delivery but relying on the resource nodes  120  to provide the bulk of the content. 
     To further comprehend the method of operation in accordance with the invention reference is now made to  FIG. 4  where an exemplary and non-limiting timing diagram  400  describing sources for packets provided in accordance with an embodiment of the invention is shown. The operation is generally divided between two time periods, one being a push period and the other being a pull period. During the push period packets are pushed from a source node(s) to a destination node(s) while in the pull period, during time interval T t    430 , packets are specifically requested by a destination node from a source node(s) to account for specific packets determined to be missing for the purpose of smooth reproduction of video swarms. The push period has two separate time intervals, T l    410  and T m    420 . In time interval  410  the leading packets, i.e., those packets which should be used first for the video swarm, are pushed from one or more reliable nodes  130 . The length of time of such time interval is determined by the characteristics of the network and at a minimum may be zero, but typically would account for at least one second of the buffer (e.g., buffer  125 - i ) content, when the buffer holds 5 seconds of multimedia content. 
     During time interval  420  packets are received by the destination node from other nodes in the network, typically nodes  120 . These nodes may be one of two types of nodes, one is referred to as an amplifier node, i.e., a node which is currently used for the transfer of data but no viewing is actively occurring on that node, or from a viewer node, i.e., a node that both provides bandwidth for transferring of video swarm packets but at the same time its user is using some of the bandwidth for the purpose of viewing one or more video swarms. In one embodiment the time interval  420  is divided into two time intervals, one time interval  424  where packets are received from amplifiers, and a subsequent time interval  426  where the packets are received from viewers. Typically, in a 5-second buffer  125 - i , time interval  424  amounts to 2 seconds while time interval  426  amounts to 1 second. The reason for using such a scheme and identifying the nodes as amplifier nodes and viewer nodes for this purpose, is to enable to ensure the quality of service (QoS) for all the users of the system  100 . 
     For the last time interval  430 , i.e., filling up the last portion of the buffer  125 , typically a 1 second period, packets are requested from a reliable node  130 , to ensure that all the necessary packets for smooth viewing of a video swarm are actually available. In one embodiment of the invention, the ratios between the various time periods discussed hereinabove are programmable may be dynamically changed responsive to changes in network bandwidth availability, availability of amplifier nodes, availability of viewer nodes, and availability of reliable nodes. 
       FIG. 5  provides an exemplary and non-limiting data connectivity diagram describing the connections between the nodes in accordance with the invention. A broadcaster  140  is connected to one or more primary reliable nodes  130 , each primary reliable node  130  connected optionally to one or more secondary reliable nodes  130 . Using this kind of option configuration of primary and secondary reliable nodes may improve the QoS. Consumer nodes  120  connects to other consumer-nodes  120 , to resource nodes  120  (i.e., nodes which are at least not currently used in a viewing mode), and to secondary reliable nodes  130 , if those exist, or otherwise, directly to primary reliable nodes  130 . The timeslots during which a viewer either receives (in push mode) or demands (in pull mode) was described in more detail hereinabove with respect to  FIG. 4 . 
     The principles of the invention may be implemented in hardware, firmware, software or any combination thereof. Moreover, the software is preferably implemented as an application program tangibly embodied on a program storage unit or computer readable medium. The application program may be uploaded to, and executed by, a machine comprising any suitable architecture. Preferably, the machine is implemented on a computer platform having hardware such as one or more central processing units (“CPUs”), a memory, and input/output interfaces. The computer platform may also include an operating system and microinstruction code. The various processes and functions described herein may be either part of the microinstruction code or part of the application program, or any combination thereof, which may be executed by a CPU, whether or not such computer or processor is explicitly shown. In addition, various other peripheral units may be connected to the computer platform such as an additional data storage unit and a printing unit. 
     The foregoing detailed description has set forth a few of the many forms that the invention can take. It is intended that the foregoing detailed description be understood as an illustration of selected forms that the invention can take and not as a limitation to the definition of the invention. It is only the claims, including all equivalents that are intended to define the scope of this invention.