Synchronizing data streams

• US 20050228898A1
• Filed: 06/08/2005
• Published: 10/13/2005
• Est. Priority Date: 01/15/2002
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Evans, Glenn F.
• Granted Patent: US 7,248,187 B2
• Time in Patent Office: Days
• US Class Current: 709/231
• 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 timestamps 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 computer-implemented method comprising:

defining a skip value tolerance that can be used to ascertain when synchronization processing of multiple data streams should take place;

ascertaining whether any input timestamp-to-output timestamp mappings associated with any of the multiple data streams meet or exceed the skip value tolerance; and

synchronizing the multiple data streams if any input timestamp-to-output timestamp mappings meet or exceed the skip value tolerance.

2. The computer-implemented method of claim 1, wherein said synchronizing comprises synchronizing to a common data stream.

3. The computer-implemented method of claim 1, wherein said synchronizing comprises synchronizing to a reference clock.

4. The computer-implemented method of claim 1, wherein one of the multiple data streams comprises a video stream.

5. The computer-implemented method of claim 1, wherein one of the multiple data streams comprises an audio stream.

6. The computer-implemented method of claim 1, wherein one of the multiple data streams comprises a video stream and another of the multiple data streams comprises a video stream.

7. A system comprising:

means for defining a skip value tolerance that can be used to ascertain when synchronization processing of multiple data streams should take place;

means for ascertaining whether any input timestamp-to-output timestamp mappings associated with any of the multiple data streams meet or exceed the skip value tolerance; and

means for synchronizing the multiple data streams if any input timestamp-to-output timestamp mappings meet or exceed the skip value tolerance.

8. The system of claim 7, wherein said means for synchronizing comprises means for synchronizing to a common data stream.

9. The system of claim 7, wherein said means for synchronizing comprises means for synchronizing to a reference clock.

10. The system of claim 7, wherein one of the multiple data streams comprises a video stream.

11. The system of claim 7, wherein one of the multiple data streams comprises an audio stream.

12. The system of claim 7, wherein one of the multiple data streams comprises a video stream and another of the multiple data streams comprises a video stream.