Method for streaming multimedia information over public networks

Claim 2

In a network having a content server which hosts a plurality of streaming multimedia (SM) objects which comprise a plurality of time-ordered packets for distribution over said network through a plurality of helper servers (HS) to a plurality of clients, a method of reducing latency associated with distributing said plurality of SM objects from said content server and said plurality of helper servers HSs to said plurality of clients, said method comprising: servicing a first request received from one of said plurality of clients, including a requested starting position of said SM object, for one of said plurality of SM objects by allocating a first ring buffer in a memory associated with said one of said plurality of HSs for storing data representing a first portion of one of said plurality of SM objects, wherein said first portion includes a packet having an associated time-stamp approximately equal to the requested starting position; maintaining the first ring buffer in the memory as a sliding window by replacing stored data with data representing successive portions of said one of said plurality of SM objects; and allocating a second ring buffer to service a further request for said one of said plurality of SM objects received at said one of said plurality of helper servers, if it is determined that said further request cannot be serviced from said first ring buffer, otherwise servicing said further request from said first ring buffer.

Claim 3

The method according to claim 1 , wherein said further request is determined not to be serviceable from said first ring buffer by performing the following steps: calculating a temporal distance between said first request and said further request; comparing the calculated temporal distance with a buffer temporal distance associated with said first ring buffer; and determining that the calculated temporal distance is greater than the buffer temporal distance.

Claim 4

The method according to claim 2 , wherein said temporal distance is calculated as: Δ( r 1 ,r 2 )═( t 2 −p 2 )−( t 1 −p 1)−( p 2 −p 1 ) where r 1 is said first request for said one of said plurality of SM objects; r 2 is said further request for said one of said plurality of SM objects; t 1 is the request time associated with the first request; t 2 is a request time associated with the further request; P 1 is a requested starting position of said one of said plurality of SM objects, in seconds, associated with the first request; and P 2 is a requested starting position of said one of said plurality of SM objects, in seconds, associated with the further request.

Claim 5

The method according to claim 2 , wherein the temporal distance is a function of the request time and the requested starting position for said one of said plurality of SM objects.

Claim 6

The method according to claim 1 , wherein said further request is determined not to be serviceable from said first ring buffer by determining that said requested starting time is not contained in a range between a largest timestamp associated with a packet stored in the buffer and a smallest time-stamp associated a packet stored in the buffer.

Claim 7

The method according to claim 2 , wherein the buffer temporal distance is a measure of the allocated buffer size in units of time.

Claim 8

The method according to claim 1 , wherein said stored data comprises a plurality of data segments, wherein each of said plurality of data segments is sourced from one of said content server and/or said plurality of HSs.

Claim 9

The method according to claim 1 , wherein a further ring buffer associated with said one of said plurality of SM objects is allocated in the memory, if it is determined that a previously allocated ring buffer associated with said one of said plurality of SM objects cannot service a current request for said one of said plurality of SM objects.

Claim 10

The method of claim 8 , wherein the number of ring buffers capable of being allocated in memory is dependent upon the size of the memory.

Claim 11

The method according to claim 1 , further including the step of replacing stored data with data representing successive portions of said one of said plurality of SM objects, wherein said step further comprises the steps of: a) determining that said first ring buffer is full; b) initiating a garbage collector event including the steps of: i) determining that a stored packet having the lowest associated time-stamp is less than the current position associated with a most recently received request and wherein said stored packet having the associated lowest time-stamp value is less than the difference between the stored packet having an associated highest time-stamp value and the buffer temporal distance; ii) removing said stored packet from said first ring buffer, if determination step (i) is true; iii) repeating steps(i) through (ii), until determination step (i) is no longer true, iv) de-initiating said garbage collector event, until it is determined that step (a) is true again and returning to step (b).

Claim 12

The method according to claim 1 , wherein said first ring buffer is de-allocated from the memory upon removing all stored packets from said first ring buffer.

Claim 13

The method according to claim 1 , wherein said time-ordered packets are RTP packets.

Claim 14

In a network having a content server which hosts streaming multimedia (SM) objects, each of said SM objects comprising a plurality of time-ordered packets for distribution over said network through a plurality of HSs to a plurality of clients, a method of reducing latency associated with distributing said SM objects from said content server and said plurality of helpers (HS) to said plurality of clients, said method comprising: receiving a first request for an SM object, including a requested starting position, received from one of said plurality of clients at one of said plurality of HSs; allocating a first ring buffer in a memory associated with said one of said plurality of HSs upon receiving said first request; retrieving said SM object comprising said plurality of time-ordered packets from at least one of said plurality of HSs including said one of said plurality of HSs and said content server; sequentially storing said plurality of time-ordered packets from said retrieved SM object in said first ring buffer by replacing lower time-ordered packets with higher time-ordered packets; servicing a second request for said SM object from said first ring buffer, if it is determined that said subsequent request includes a starting request position within a range between a largest timestamp associated with a packet stored in the buffer and a smallest time-stamp associated a packet stored in the buffer; and allocating a second ring buffer in the memory, if it is determined at the servicing step that said second request cannot be serviced from said first ring buffer.

Claim 15

In a network having a content server which hosts streaming multimedia (SM) objects, each of said SM objects comprising a plurality of time-ordered packets for distribution over said network through a plurality of HSs to a plurality of clients, a method of reducing latency associated with distributing said SM objects from said content server and said plurality of helpers (HS) to said plurality of clients, said method comprising: receiving a first request for an SM object, including a requested starting position, received from one of said plurality of clients at one of said plurality of HSs; allocating a first ring buffer in a memory associated with said one of said plurality of HSs upon receiving said first request; retrieving said SM object comprising said plurality of time-ordered packets from at least one of said plurality of HSs including said one of said plurality of HSs and said content server; sequentially storing said plurality of time-ordered packets from said retrieved SM object in said first ring buffer by replacing lower time-ordered packets with higher time-ordered packets; servicing a second request for said SM object from said first ring buffer, if it is determined that said subsequent request includes a starting request position within a range between a largest timestamp associated with a packet stored in the buffer and a smallest time-stamp associated a packet stored in the buffer; and allocating a second ring buffer in the memory, if it is determined at the servicing step that said second request cannot be serviced from said first ring buffer.

Claim 16

The method according to claim 13 , wherein at said retrieving step, said data is retrieved from said one of said plurality of HSs, if said data is it determined to reside at said one of said plurality of HSs.

Claim 17

The method according to claim 14 , wherein said method further comprises the steps of, if it is determined a first portion of said requested SM object is not stored at said one of said plurality of HSs: forwarding said first request for said SM object from said one of said plurality of HSs to said content server; and receiving at least said first portion of said requested SM object at said one of said plurality of HSs from said content server in response to said forwarded first request.

Claim 20

A network of interconnected helper servers (HSs), each of said interconnected helpers comprising means for receiving and processing real-time streaming protocol (RTSP) requests from clients; means for forwarding client requests to a content server; means for streaming data to a plurality of clients using the real-time (RTP) protocol; means for managing available memory in the form of a buffer pool, each buffer in said buffer pool being associated with an SM object identified by a uniform resource locator (URL); means for mapping URLs identifying said objects received as a parameter along with an SM object request to local filenames; means for managing the disk space allocated for caching by implementing a cache replacement policy; means for recording data onto said cache and reading data from said cache; and scheduler means for managing data producer, data consumer, and garbage collector events, wherein said data producer events are events which source at least a portion of said SM object to said one of said plurality of helper servers to be stored in one of said buffers in said buffer pool, said data consumer events are RTSP requests from clients, and garbage collector events are events associated with removing a portion of said SM objects stored in said buffer pool to free the available memory.

Claim 21

A network of interconnected helper servers (HSs), each of said interconnected helpers comprising means for receiving and processing real-time streaming protocol (RTSP) requests from clients; means for forwarding client requests to a content server; means for streaming data to a plurality of clients using the real-time (RTP) protocol; means for managing available memory in the form of a buffer pool, each buffer in said buffer pool being associated with an SM object identified by a uniform resource locator (URL); means for mapping URLs identifying said objects received as a parameter along with an SM object request to local filenames; means for managing the disk space allocated for caching by implementing a cache replacement policy; means for recording data onto said cache and reading data from said cache; and scheduler means for managing data producer, data consumer, and garbage collector events, wherein said data producer events are events which source at least a portion of said SM object to said one of said plurality of helper servers to be stored in one of said buffers in said buffer pool, said data consumer events are RTSP requests from clients, and garbage collector events are events associated with removing a portion of said SM objects stored in said buffer pool to free the available memory.