Adaptively selecting timeouts for streaming media

• US 7,991,905 B1
• Filed: 02/12/2003
• Issued: 08/02/2011
• Est. Priority Date: 02/12/2003
• Status: Active Grant

• Current Assignee: NetApp, Inc.
• Original Assignee: NetApp, Inc.
• Inventors: Endo, Yasuhiro, Yadav, Sandeep, Roussos, Konstantinos
• Primary Examiner(s): Follansbee; John
• Assistant Examiner(s): Chou; Alan S
• Application Number:
  US10/365,074
• Time in Patent Office: 3,093 Days
• Field of Search: 709/231
• US Class Current: 709/231
• CPC Class Codes: H04L 65/65 Network streaming protocols, e.g. real-time transport protocol [RTP] or real-time control protocol [RTCP]
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols

Abstract

The present invention provides a streaming media cache configured to select a timing interval, chosen from a set of one or more predetermined timing intervals, for each client that requests a data stream from the streaming media cache. Illustratively, clients requesting data streams below a predetermined bit rate (“bandwidth”) are assigned longer timing intervals than clients requesting data streams above the predetermined bit rate. More specifically, because the server can accommodate a larger number of relatively low-bandwidth clients than relatively high-bandwidth clients, the server selects timing intervals of longer duration for the relatively low-bandwidth clients so it may have more time to schedule send times for their requested packets.

Claims

1. A method for operating an intermediate network cache, the method comprising:

(A) receiving a request from a client computer system to transmit a sequence of a plurality of data packets at a specified bit rate, wherein the specified bit rate is a rate requested by the client computer system for receiving the plurality of data packets, and wherein the request is formatted according to an RTSP or a MMS protocol;

(B) comparing the specified bit rate requested by the client computer system with a predetermined bit rate associated with the intermediate network cache to determine a selected timing interval, wherein the predetermined bit rate indicates a bandwidth value of the intermediate network cache;

in the event that the specified bit rate is greater than the predetermined bit rate, pacing transmission of the data packets with a first timing interval as the selected timing interval;

in the event that the specified bit rate is less than the predetermined rate, pacing transmission of the data packets with a second timing interval as the selected timing interval;

(C) determining, in response to the pacing transmission of the data packets, a send time that defines when the server transmits to the client system a first data packet in the sequence of one or more data packets, wherein the send time includes a predetermined random time offset that has been assigned to the client system to control pacing of the transmission of the data packets to the client system;

(D) rounding the send time to align with the selected timing interval;

(E) transmitting the first data packet after the rounded send time has elapsed; and

(F) repeating steps (B) through (E) for each data packet in the sequence of one or more data packets, wherein the timing interval in step (B) is selected to optimize the intermediate network cache'"'"'s allocation of resources when determining the send time in step (C).

2. The method according to claim 1, wherein step (C) further comprises:

selecting a first timing interval from the set of one or more predetermined timing intervals if the client-requested bit rate is greater than a predetermined bit rate, otherwise selecting a second timing interval from the set of one or more predetermined timing intervals.

3. The method according to claim 2, wherein the second timing interval is a longer duration interval than the first timing interval.

4. The method according to claim 1, wherein step (B) further comprises:

waiting a predetermined timeout period if the first data packet is not resident in the intermediate network cache; and

determining whether the first data packet was received by the intermediate network cache during the predetermined timeout period.

5. An intermediate network cache comprising:

a processor and memory;

a network adapter configured to send and receive data packets over a computer network;

a network protocol engine configured to receive requests from the client system and configured to transmit data packets in a sequence of a plurality of data packets to the client system;

a streaming media protocol engine configured to determine, in response to a request received by the network protocol engine, a specified bit rate to transmit a plurality of data packets to the client system, wherein the specified bit rate is a rate requested by the client system for receiving the plurality of data packets, and wherein the request is formatted according to an RTSP or a MMS protocol;

an operating system to compare the specified bit rate requested by the client system with a predetermined bit rate associated with the intermediate network cache to determine a selected timing interval, wherein the predetermined bit rate indicates a bandwidth value of the intermediate network cache;

in the event that the specified bit rate is greater than the predetermined bit rate, pacing transmission of the data packets with a first timing interval as a selected timing interval;

in the event that the specified bit rate is less than the predetermined rate, pacing transmission of the data packets with a second timing interval as the selected timing interval; and

a packet pacing sub-system configured (i) to receive a send time from the streaming media protocol engine, wherein the send time includes a predetermined random time offset that has been assigned to the client system to control pacing of the transmission of the data packets to the client system, (ii) to round the received send time to align with the selected timing interval, and (iii) to forward a data packet in the sequence of a plurality of data packets to the network protocol engine at the rounded send time.

6. The intermediate network cache according to claim 5, wherein at least one request received by the network protocol engine indicates a client-requested bit rate that is used by the packet pacing sub-system to select the timing interval from a set of one or more predetermined timing intervals.

7. The intermediate network cache according to claim 6, wherein the packet pacing sub-system selects a first timing interval from a set of one or more predetermined timing intervals if the client-requested bit rate is greater than a predetermined bit rate, otherwise the packet pacing sub-system selects a second timing interval from the set of one or more predetermined timing intervals.

8. The intermediate network cache according to claim 7, wherein the second timing interval is a longer duration interval than the first timing interval.

9. The intermediate network cache according to claim 5, wherein the streaming media protocol engine includes a protocol-client thread for communicating with the client system, and the packet pacing sub-system includes a client-memory thread for managing when data packets in the sequence of a plurality of data packets are forwarded to the network protocol engine.

10. The intermediate network cache according to claim 9, wherein the client-memory thread receives send times from the streaming media protocol engine, rounds the received send times to align with the timing interval, and forwards data packets in the sequence of one or more data packets to the network protocol engine based on the rounded send times.

11. An intermediate network cache comprising:

a processor;

a network adapter configured to send and receive data packets over a computer network;

a memory including a buffer cache that stores a sequence of one or more data packets, at least a portion of the memory being configured to store a sequence of instructions executable by the processor for;

(A) receiving a request from a client computer system to transmit a sequence of a plurality of data packets at a specified bit rate, wherein the specified bit rate is a rate requested by the client computer system for receiving the plurality of data packets, and wherein the request is formatted according to an RTSP or a MMS protocol;

(B) comparing the specified bit rate requested by the client computer system with a predetermined bit rate associated with the intermediate network cache to determine a selected timing interval, wherein the predetermined bit rate indicates a bandwidth value of the intermediate network cache, and

in the event that the specified bit rate is greater than the predetermined bit rate, pacing transmission of the data packets with a first timing interval as the selected timing interval;

in the event that the specified bit rate is less than the predetermined rate, pacing transmission of the data packets with a second timing interval as the selected timing interval;

(C) determining, in response to the pacing transmission of the data packets, a send time that defines when the computer system transmits to the client system a first data packet in the sequence of one or more data packets, wherein the send time includes a predetermined random time offset that has been assigned to the client system to control pacing of the transmission of the data packets to the client system;

(D) rounding the send time to align with the selected timing interval;

(E) transmitting the first data packet after the rounded send time has elapsed; and

(F) repeating steps (B) through (E) for each data packet in the sequence of one or more data packets, wherein the timing interval in step (B) is selected to optimize the computer system'"'"'s allocation of resources when determining the send time in step (C).

12. The intermediate network cache according to claim 11, wherein the network adapter receives at least one of the data packets in the sequence of a plurality of data packets from an origin server in communication with the intermediate network cache over the network.

13. The intermediate network cache according to claim 11, wherein step (C) further comprises:

selecting a first timing interval from a set of one or more predetermined timing intervals if the client-requested bit rate is greater than a predetermined bit rate, otherwise selecting a second timing interval from the set of one or more predetermined timing intervals.

14. The intermediate network cache according to claim 13, wherein the second timing interval is a longer duration interval than the first timing interval.

15. An intermediate network cache comprising:

means for receiving a request from a client computer system to transmit a sequence of a plurality of data packets at a specified bit rate, wherein the specified bit rate is a rate requested by the client computer system for receiving the plurality of data packets, and wherein the request is formatted according to an RTSP or a MMS protocol;

means for comparing the specified bit rate requested by the client computer system with a predetermined bit rate associated with the intermediate network cache to determine a selected timing interval, wherein the predetermined bit rate indicates a bandwidth value of the intermediate network cache;

in the event that the specified bit rate is greater than the predetermined bit rate, pacing transmission of the data packets with a first timing interval as the selected timing interval;

in the event that the specified bit rate is less than the predetermined rate, pacing transmission of the data packets with a second timing interval as the selected timing interval;

means for determining, in response to the selected timing interval, a send time that defines when the apparatus transmits to the client system a data packet in the sequence of one or more data packets, wherein the send time includes a predetermined random time offset that has been assigned to the client system to control pacing of the transmission of the data packets to the client system;

means for rounding the send time to align with the selected timing interval; and

means for transmitting the data packet after the rounded send time has elapsed.

16. The intermediate network cache according to claim 15, further comprising:

means for selecting a first timing interval from a set of one or more predetermined timing intervals if the client-requested bit rate is greater than a predetermined bit rate, otherwise selecting a second timing interval from the set of one or more predetermined timing intervals.

17. The intermediate network cache according to claim 16, wherein the second timing interval is a longer duration interval than the first timing interval.

18. A computer-readable non-transitory media comprising instructions for execution in a processor for the practice of a method of operating an intermediate network cache comprising:

(A) receiving a request from a client computer system to transmit a sequence of a plurality of data packets at a specified bit rate, wherein the specified bit rate is a rate requested by the client computer system for receiving the plurality of data packets, and wherein the request is formatted according to an RTSP or a MMS protocol;

(B) comparing the specified bit rate requested by the client computer system with a predetermined bit rate associated with the intermediate network cache to determine a selected timing interval, wherein the predetermined bit rate indicates a bandwidth value of the intermediate network cache,

in the event that the specified bit rate is greater than the predetermined bit rate, pacing transmission of the data packets with a first timing interval as the selected timing interval;

in the event that the specified bit rate is less than the predetermined rate, pacing transmission of the data packets with a second timing interval as the selected timing interval;

(C) determining, in response to the selected timing interval, a send time that defines when the server transmits to the client system a first data packet in the sequence of one or more data packets, wherein the send time includes a predetermined random time offset that has been assigned to the client system to control pacing of the transmission of the data packets to the client system;

(D) rounding the send time to align with the selected timing interval;

(E) transmitting the first data packet after the rounded send time has elapsed; and

(F) repeating steps (B) through (E) for each data packet in the sequence of one or more data packets, wherein the timing interval in step (B) is selected to optimize the intermediate network cache'"'"'s allocation of resources when determining the send time in step (C).

19. The computer-readable media according to claim 18, wherein step (C) further comprises:

selecting a first timing interval from a set of one or more predetermined timing intervals if the client-requested bit rate is greater than a predetermined bit rate, otherwise selecting a second timing interval from the set of one or more predetermined timing intervals.

20. The computer-readable media according to claim 19, wherein the second timing interval is a longer duration interval than the first timing interval.

21. An intermediate network cache comprising:

a memory configured to store a sequence of instructions executable by a processor for;

(A) receiving a request from a client computer system to transmit a sequence of a plurality of data packets at a specified bit rate, wherein the specified bit rate is a rate requested by the client computer system for receiving the plurality of data packets, and wherein the request is formatted according to an RTSP or a MMS protocol;

(B) comparing the specified bit rate requested by the client computer system with a predetermined bit rate associated with the intermediate network cache to determine a selected timing interval, wherein the predetermined bit rate indicates a bandwidth value of the intermediate network cache;

in the event that the specified bit rate is greater than the predetermined bit rate, pacing transmission of the data packets with a first timing interval as the selected timing interval;

in the event that the specified bit rate is less than the predetermined rate, pacing transmission of the data packets with a second timing interval as the selected timing interval;

(C) determining, in response to the selected timing interval, a send time that defines when the server transmits to the client system a first data packet in the sequence of one or more data packets, wherein the send time includes a predetermined random time offset that has been assigned to the client system to control pacing of the transmission of the data packets to the client system;

(D) transmitting the first data packet to the client system in accordance with the send time; and

(E) repeating steps (B) through (D) for each data packet in the sequence of one or more data packets, wherein the timing interval in step (B) is selected to optimize the intermediate network cache'"'"'s allocation of resources when determining the send time in step (C).

22. The intermediate network cache according to claim 21, wherein the sequence of instructions further comprises instructions for rounding the send time to align with the selected timing interval.

23. The intermediate network cache according to claim 21, wherein step (C) further comprises:

selecting a first timing interval from a set of one or more predetermined timing intervals if the client-requested bit rate is greater than a predetermined bit rate, otherwise selecting a second timing interval from the set of one or more predetermined timing intervals.

24. The server according to claim 23, wherein the second timing interval is a longer duration interval than the first timing interval.

25. A method for operating an intermediate network cache, the method comprising:

receiving a request from a client computer system to transmit a sequence of a plurality of data packets at a specified bit rate, wherein the specified bit rate is a rate requested by the client computer system for receiving the plurality of data packets, and wherein the request is formatted according to an RTSP or a MMS protocol;

comparing the specified bit rate requested by the client computer system with a predetermined bit rate associated with the intermediate network cache to determine a selected timing interval, wherein the predetermined bit rate indicates a bandwidth value of the intermediate network cache;

in the event that the specified bit rate is greater than the predetermined bit rate, pacing transmission of the data packets with a first timing interval as the selected timing interval;

in the event that the specified bit rate is less than the predetermined rate, pacing transmission of the data packets with a second timing interval as the selected timing interval;

determining, in response to the selected timing interval, a send time, wherein the send time includes a predetermined random time offset that has been assigned to the client computer system to control pacing of the transmission of the data packets to the client system;

rounding the send time to correspond with the selected timing interval to generate a rounded send time; and

transmitting a data packet at the rounded send time.

26. A computer-readable non-transitory media comprising instructions for execution in a processor for the practice of a method of operating an intermediate network cache that transmits a sequence of a plurality of data packets to a client system, the method comprising:

receiving a request from a client computer system to transmit a sequence of a plurality of data packets at a specified bit rate, wherein the specified bit rate is a rate requested by the client computer system for receiving the plurality of data packets, and wherein the request is formatted according to an RTSP or a MMS protocol;

comparing the specified bit rate requested by the client computer system with a predetermined bit rate associated with the intermediate network cache to determine a selected timing interval, wherein the predetermined bit rate indicates a bandwidth value of the intermediate network cache,

in the event that the specified bit rate is greater than the predetermined bit rate, pacing transmission of the data packets with a first timing interval as the selected timing interval;

in the event that the specified bit rate is less than the predetermined rate, pacing transmission of the data packets with a second timing interval as the selected timing interval;

determining a send time in response to identifying the client, wherein the send time includes a predetermined random time offset that has been assigned to the client system to control pacing of the transmission of the data packets to the client system;

rounding the send time to correspond with the selected timing interval to generate a rounded send time; and

transmitting a data packet at the rounded send time.