Methods and systems for distributing multimedia data over heterogeneous networks

• US 20020150053A1
• Filed: 04/17/2001
• Published: 10/17/2002
• Est. Priority Date: 04/17/2001
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Atkinson, Robert G., Valavi, Anand, Blank, Tom, Gray, Donald M. III
• Granted Patent: US 6,970,481 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04N 21/43632 involving a wired protocol, e.g. IEEE 1394 high-speed IEEE 1394 serial bus H04L12/40052
• CPC Class Codes: H04N 21/64707 for transferring content from a first network to a second network, e.g. between IP and wireless

Abstract

Real-time communication of multimedia data over heterogeneous networks that may include constant delay networks, variable delay networks that have a common reckoning of time, and variable delay networks that do not have a common reckoning of time. If there are any variable delay networks in which there is no common reckoning of time in the heterogeneous networks, a common reckoning of time is established in each of those networks. Then, a constant delay network is emulated for each variable delay network using the specific common time reckoning present in each variable delay network.

Claims

1. In a network system that includes a multimedia source and a multimedia sink, the multimedia source transmitting a stream of multimedia packets to the multimedia sink over a plurality of heterogeneous networks, the heterogeneous networks including a plurality of variable delay networks, a method of performing constant delay communication of the stream of multimedia packets from the multimedia source over the heterogeneous networks to the multimedia sink even though one or more of the variable delay networks do not themselves provide for a common reckoning of time in the variable delay network, the method comprising the following:

establishing a common time reckoning in all of the variable delay networks that do not themselves provide for a common time reckoning;

emulating the plurality of variable delay networks as one or more constant delay networks using the specific common time reckonings present in the plurality of variable delay networks, wherein the heterogeneous networks as a whole emulates a constant delay network; and

transmitting a multimedia packet over the heterogeneous networks.

2. A method in accordance with claim 1, further comprising the following:

receiving the multimedia packet from a previous network in the heterogeneous networks;

as the multimedia packet transitions from the previous network to a next network in the heterogeneous networks, configuring the multimedia packet if necessary to conform with the requirements of the next network if the multimedia packet does not already conform with the requirements of the next network; and

transmitting the reconfigured multimedia packet onto the next network.

3. A method in accordance with claim 2, further comprising:

repeating the act of receiving the multimedia packet from a previous network, the act of configuring the multimedia packet if necessary, and the act of transmitting the reconfigured multimedia packet onto the next network for each network transition as the multimedia packet traverses the heterogeneous networks from the multimedia source to the multimedia sink.

4. The method in accordance with claim 2, wherein the next network is a variable delay network, wherein the act of configuring the multimedia packet if necessary comprises the following:

generate a time stamp that represents a time in accordance with a common time reckoning of the variable delay network; and

including the time stamp in the multimedia packet.

5. The method in accordance with claim 4, wherein the act of including the time stamp in the multimedia packet is performed by the link layer.

6. The method in accordance with claim 4, wherein the act of including the time stamp in the multimedia packet comprises the following:

including the time stamp in the multimedia packet before control of the multimedia packet transfers to the link layer associated with the next network.

7. The method in accordance with claim 6, wherein the act of including the time stamp in the multimedia packet before control of the multimedia packet transfers to the link layer comprises the following:

an application layer including the time stamp in the multimedia packet.

8. In a variable delay network that includes a transmitter and a receiver, a transmitter application associated with the transmitter configured to transmit a stream of multimedia packets through a transmitter link layer controller, over the variable delay network, through a receiver link layer controller to a receiver application associated with the receiver, the transmitter link layer controller having an undedicated variable delay interface with the transmitter application, the transmitter link layer controller and the receiver link layer controller being substantially synchronized in accordance with a common network time base, a method of the transmitter link layer controller emulating a constant delay network over the variable delay network despite the undedicated variable delay interface, the method comprising the following:

receiving a first multimedia packet from the transmitter application, the first multimedia packet including a first transmitter application time stamp, which represents the relative time that the information in the first multimedia packet should be rendered by the receiver application in accordance with a transmitter application time base;

including in the first multimedia packet a first network time stamp, which represents the relative time that the information in the first multimedia packet should be rendered by the receiver application in accordance with the common network time base;

receiving data representing a frequency of the transmitter application time base;

receiving a second multimedia packet from the transmitter application, the second multimedia packet including a second transmitter application time stamp, which represents the relative time that the information in the second multimedia packet should be rendered by the receiver application in accordance with the transmitter application time base;

calculating a second network time stamp representing the relative time that the information in the second multimedia packet should be rendered by the receiver application in accordance with the common network time base, the calculation based on the first transmitter application time stamp, the second transmitter application time stamp, the frequency, and the first network time stamp;

including the second network time stamp in the second multimedia packet; and

dispatching the second multimedia packet to the receiver application.

9. A method in accordance with claim 8, where the variable delay network is an IEEE 1394 compliant network, the transmitter link layer controller comprises an OHCI link layer controller, and the undedicated variable delay interface comprises a PCI interface.

10. A method in accordance with claim 8, wherein including the second network time stamp in the second multimedia packet is performed in accordance with the IEC 61883 protocol.

11. A computer program product for use in a variable delay network that includes a transmitter and a receiver, a transmitter application associated with the transmitter configured to transmit a stream of multimedia packets through a transmitter link layer controller, over the variable delay network, through a receiver link layer controller to a receiver application associated with the receiver, the transmitter link layer controller having an undedicated variable delay interface with the transmitter application, the transmitter link layer controller and the receiver link layer controller being substantially synchronized in accordance with a common network time base, the computer program product for implementing a method of the transmitter link layer controller emulating a constant delay network over the variable delay network despite the undedicated variable delay interface, the computer program product comprising computer-readable medium having stored thereon computer-executable instructions that, when executed by one or more processor, cause the transmitter link layer controller to perform the following:

detecting the receipt of a first multimedia packet from the transmitter application, the first multimedia packet including a first transmitter application time stamp, which represents the relative time that the information in the first multimedia packet should be rendered by the receiver application in accordance with a transmitter application time base;

including in the first multimedia packet a first network time stamp, which represents the relative time that the information in the first multimedia packet should be rendered by the receiver application in accordance with the common network time base;

detecting the receipt of data representing a frequency of the transmitter application time base;

detecting the receipt of a second multimedia packet from the transmitter application, the second multimedia packet including a second transmitter application time stamp, which represents the relative time that the information in the second multimedia packet should be rendered by the receiver application in accordance with the transmitter application time base;

calculating a second network time stamp representing the relative time that the information in the second multimedia packet should be rendered by the receiver application in accordance with the common network time base, the calculation based on the first transmitter application time stamp, the second transmitter application time stamp, the frequency, and the first network time stamp;

including the second network time stamp in the second multimedia packet; and

causing the second multimedia packet to be dispatched to the receiver application.

12. A computer program product in accordance with claim 11, wherein the computer-readable medium is one or more physical storage media.

13. A computer program product in accordance with claim 11, wherein the variable delay network is an IEEE 1394 compliant network, the transmitter link layer controller comprises an OHCI link layer controller, and the undedicated variable delay interface comprises a PCI interface.

14. A computer program product in accordance with claim 11, wherein the computer-executable instructions for including the second network time stamp in the second multimedia packet is executed in accordance with the IEC 61883-x protocol.

16. The method in accordance with claim 15, wherein the variable delay network is an IEEE 802.11 compliant network.

18. A computer program product in accordance with claim 17, wherein the computer-readable medium is one or more physical storage media.

19. A computer program product in accordance with claim 17, wherein the variable delay network is an IEEE 802.11 compliant network.

15. In a variable delay network that includes a transmitter and a receiver, a transmitter application associated with the transmitter configured to transmit a stream of multimedia packets through a transmitter link layer controller, over the variable delay network, through a receiver link layer controller to a receiver application associated with the receiver, a method of the transmitter emulating a constant delay network over the variable delay network, the method comprising the following:

storing a transmitter application time base in a register;

periodically transmitting the transmitter application time base to one or more other devices in the variable delay network;

including a transmitter application time stamp in a multimedia packet, the transmitter application time stamp representing the relative time that the information in the multimedia packet should be rendered by the receiver application; and

dispatching the multimedia packet to the receiver application.

17. A computer program product for use in a variable delay network that includes a transmitter and a receiver, a transmitter application associated with the transmitter configured to transmit a stream of multimedia packets through a transmitter link layer controller, over the variable delay network, through a receiver link layer controller to a receiver application associated with the receiver, the computer program product for implementing a method of the transmitter emulating a constant delay network over the variable delay network, the computer program product comprising a computer readable medium having stored thereon computer-executable instructions for performing the following:

causing a transmitter application time base to be stored in a register;

periodically transmitting the transmitter application time base to one or more other devices in the variable delay network;

including a transmitter application time stamp in a multimedia packet, the transmitter application time stamp representing the relative time that the information in the multimedia packet should be rendered by the receiver application; and

causing the multimedia packet to be dispatched to the receiver application.