System and method for synchronizing channel handoff as among a plurality of devices

• US 7,668,964 B2
• Filed: 04/23/2005
• Issued: 02/23/2010
• Est. Priority Date: 04/23/2005
• Status: Active Grant

• Current Assignee: Sonos, Inc.
• Original Assignee: Sonos, Inc.
• Inventors: Millington, Nicholas A. J.
• Primary Examiner(s): Flynn; Nathan
• Assistant Examiner(s): Conaway; James E
• Application Number:
  US11/113,363
• Publication Number:
  US 20070022207A1
• Time in Patent Office: 1,767 Days
• Field of Search: 709/231, 709/248, 700/94, 725/74, 725 78- 85, 455436-444, 714799-824
• US Class Current: 709/231
• CPC Class Codes: H04L 65/1083 In-session procedures
• CPC Class Codes: H04L 65/80 Responding to QoS

Abstract

A system constructed comprises a plurality of devices interconnected to a network. At least two of the devices in the system can access streaming audio information over the network, and are capable of providing audio and rendering timing information to other devices in the system. One device, as the handed-off device, is configured to determine correspondences in connection with two information streams received from two information sources. That device comprises an information receiver module, a position identifier module, and a corresponding position utilization module. The information receiver module is configured to receive the two information streams. The position identifier module is configured to identify corresponding positions regarding corresponding sequences in the two information streams. The corresponding position utilization module is configured to utilize the identification of the corresponding positions in the two information streams.

Claims

1. A device for synchronizing two information streams, the device comprising:

an information receiver module configured to receive the two information streams, wherein the two information streams contain identical sequences of frames and the frames lack self-identifying information;

a position identifier module stored in memory and executable by a processor to identify corresponding frames in the two information streams by;

generating identifying information about the frames contained in the two information streams by calculating frame checksum values,

performing a comparison between a pair of frame checksum values series associated with the two information streams, and

controlling a frame pointer indicative of each pair of corresponding frames based on the comparison between the pair of frame checksum values series; and

a correspondence utilization module stored in memory and executable by a processor to utilize the frame pointers to synchronize the two information streams.

2. The device of claim 1, wherein the frame checksum values are calculated as the information streams are received.

3. The device of claim 1, wherein the position identifier module is executable to control a respective counter for each frame pointer to identify the number of frames in each sequence of frames, wherein controlling the frame pointer indicative of each pair of corresponding frames in further based on the counters.

4. The device of claim 1, wherein at least a minimum number of frames are identified as corresponding prior to execution of the correspondence utilization module to synchronize the two information streams.

5. The device of claim 1, wherein the information streams include digital media information.

6. The device of claim 5, wherein the information streams include digital audio information.

7. The device of claim 1, wherein each frame includes a selected number of digital media samples, and each frame checksum value is a function of the digital media samples in the respective frame.

8. A method for synchronizing two information streams, the method comprising:

receiving the two information streams wherein the two information streams contain identical sequences of frames and the frames lack self-identifying information;

executing instructions stored in memory to identify corresponding frames in the two information streams by;

generating identifying information about the frames contained in the two information streams by calculating frame checksum values,

performing a comparison between a pair of frame checksum values series associated with the two information streams, and

controlling a frame pointer indicative of each pair of corresponding frames based on the comparison between the pair of frame checksum values series; and

executing instructions stored in memory to utilize the frame pointers to synchronize the two information streams.

9. The method of claim 8, wherein the frame checksum values are calculated as the information streams are received.

10. The method of claim 8, wherein executing instructions stored in memory to identify the corresponding frames further includes controlling a respective counter for each frame pointer to identify the number of frames in each sequence of frames, wherein controlling the frame pointer indicative of each pair of corresponding frames is further based on the counters.

11. The method of claim 8, wherein at least a minimum number of frames are identified as corresponding prior to synchronizing the two information streams.

12. The method of claim 8, wherein the information streams include digital media information.

13. The method of claim 8, wherein the information streams include digital audio information.

14. The method of claim 8, wherein each frame includes a selected number of digital media samples, and each frame checksum value is a function of the digital media samples in the respective frame.

15. A computer readable storage medium having a program embodied thereon, the program executable by a processor to perform a method for synchronizing two information streams, the method comprising:

receiving the two information streams, wherein the two information streams contain identical sequences of frames and the frames lack self-identifying information;

identifying corresponding frames in the two information streams by;

generating identifying information about the frames contained in the two information streams by calculating frame checksum values,

performing a comparison between a pair of frame checksum values series associated with the two information streams, and

controlling a frame pointer indicative of each pair of corresponding frames based on the comparison between the pair of frame checksum values series; and

utilizing the frame pointers to synchronize the two information streams.

16. The computer readable storage medium of claim 15, wherein the frame checksum values are calculated as the information streams are received.

17. The computer readable storage medium of claim 15, wherein identifying the corresponding frames further includes controlling a respective counter for each frame pointer to identify the number of frames in each sequence of frames, wherein controlling the frame pointer indicative of each pair of corresponding frames is further based on the counters.

18. The computer readable storage medium of claim 15, wherein at least a minimum number of frames are identified as corresponding prior to synchronizing the two information streams.

19. The computer readable storage medium of claim 15, wherein the information streams include digital media information.

20. The computer readable storage medium of claim 15, wherein the information streams include digital audio information.

21. The computer readable storage medium of claim 15, wherein each frame includes a selected number of digital media samples, and each frame checksum value is a function of the digital media samples in the respective frame.