Methods and systems for synchronizing data streams

• US 7,202,803 B2
• Filed: 02/22/2005
• Issued: 04/10/2007
• Est. Priority Date: 01/15/2002
• Status: Expired due to Term

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Evans, Glenn F.
• Primary Examiner(s): Williams; Howard L.
• Application Number:
  US11/062,666
• Publication Number:
  US 20050146448A1
• Time in Patent Office: 777 Days
• Field of Search: 341/61, 370/503, 370/507, 375/240.28, 709/248, 713/400, 713/600
• US Class Current: 341/50
• CPC Class Codes: H04N 21/2368 Multiplexing of audio and video streams
• CPC Class Codes: H04N 21/4143 embedded in a Personal Computer [PC]
• CPC Class Codes: H04N 21/4305 Synchronising client clock from received content stream, e.g. locking decoder clock with encoder clock, extraction of the PCR packets arrangements for synchronising receiver with transmitter by comparing receiver clock with transmitter clock H04L7/0012; arrangements for synchronising receiver with transmitter wherein the receiver takes measures against momentary loss of synchronisation H04L7/0083
• CPC Class Codes: H04N 21/43072 of multiple content streams on the same device
• CPC Class Codes: H04N 21/4341 Demultiplexing of audio and video streams
• CPC Class Codes: H04N 21/4344 Remultiplexing of multiplex streams, e.g. by modifying time stamps or remapping the packet identifiers

Abstract

Methods and systems are provided for synchronizing various time-stamped data streams. The data streams can be synchronized to another data stream or to a point of reference such as a reference clock. In one embodiment, synchronization processing takes place in association with a filter graph comprising multiple filters. The filter graph is configured to process multiple timestamped data streams for rendering the data streams in accordance with data stream timestamps. A synchronization module is provided and is associated with the filter graph queries individual filters of the filter graph to ascertain input timestamp-to-output timestamp mappings. The module computes adjustments that are to be made to output time stamps in order to synchronize the data streams, and then instructs queried filters to adjust their output timestamps in accordance with its adjustment computations.

Claims

1. A method comprising:

providing, in a filter graph, at least one time-stamped data stream that is to be rendered in accordance with data stream timestamps; and

synchronizing said at least one time-stamped data stream relative to an internal time-stamped data stream being processed by the filter graph by adjusting one or more timestamps of said at least one time-stamped data stream wherein, the act of synchronizing utilizes extrapolation based processing to synchronize said at least one time-stamped data stream relative to the internal time-stamped data stream.

2. The method of claim 1, wherein the act of synchronizing comprises doing so periodically.

3. The method of claim 1, wherein the act of synchronizing comprises determining whether said at least one time-stamped data stream is within a defined tolerance and, if not, performing said act of synchronizing.

4. The method of claim 1, wherein said at least one time-stamped data stream comprises a video stream.

5. The method of claim 1, wherein said at least one time-stamped data stream comprises an audio stream.

6. The method of claim 1, wherein said at least one time-stamped data stream comprises a video stream and an audio stream.

7. A method comprising:

providing a filter graph comprising multiple filters, the filter graph being configured to process multiple timestamped data streams for rendering the data streams in accordance with data stream timestamps; and

synchronizing at least one time-stamped data stream relative to a reference by adjusting one or more timestamps of said at least one lime-stamped data stream wherein, the act of synchronizing can be performed by querying filters of the filter graph upstream of a rendering filter, and wherein the act of synchronizing comprises instructing one or more of the filters upstream of the rendering filter to adjust at least one timestamp associated with at least one data sample of one or more of the data streams.

8. The method of claim 7, wherein the act of instructing comprises instructing one or more decoder filters to adjust at least one timestamp associated with at least one data sample.

9. The method of claim 7, wherein the reference comprises another time-stamped data stream.

10. The method of claim 7, wherein the reference comprises a reference clock.

11. The method of claim 7, wherein the act of synchronizing comprises doing so periodically.

12. The method of claim 7, wherein the act of synchronizing comprises determining whether said at least one time-stamped data stream is within a defined tolerance and, if not, performing said act of synchronizing.

13. One or more computer-readable media comprising instructions which, when executed by one or more processors, cause the one or more processors to implement the method of claim 7.