Synchronizing data streams

• US 20060031556A1
• Filed: 08/29/2005
• Published: 02/09/2006
• 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 7,480,728 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 system comprising:

one or more processors;

one or more computer-readable media;

computer-readable instructions on the one or more computer-readable media which, when executed by the one or more processors, cause the one or more processors to;

query one or more filters configured to process timestamped data streams for each filter'"'"'s input timestamp-to-output timestamp mapping;

receive responses from the queried filters;

extrapolate one or more lines characterizing an individual mapping to a selected input timestamp value;

calculate a skip value for one or more of the lines, a skip value representing a value by which the output timestamps for a given filter are to be corrected; and

provide instructions to one or more of the filters to adjust their output timestamps in accordance with an associated skip value.

2. The system of claim 1, wherein the instructions cause the one or more processors to query the one or more filters for each filter'"'"'s data stream playback rate.

3. The system of claim 1, wherein the instructions cause the one or more processors to query one or more decoders filters.

4. The system of claim 1, wherein the instructions cause the one or more processors to linearly extrapolate the one or more lines.

5. The system of claim 1, wherein the selected input timestamp value comprises a current input timestamp value for one of the filters.

6. The system of claim 1, wherein the selected input timestamp value comprises a future input timestamp value.

7. A system comprising:

means for querying one or more filters configured to process timestamped data streams for each filter'"'"'s input timestamp-to-output timestamp mapping;

means for receiving responses from the queried filters;

means for extrapolating one or more lines characterizing an individual mapping to a selected input timestamp value;

means for calculating a skip value for one or more of the lines, a skip value representing a value by which the output timestamps for a given filter are to be corrected; and

means for providing instructions to one or more of the filters to adjust their output timestamps in accordance with an associated skip value.

8. The system of claim 7, wherein the means for querying queries the one or more filters for each filter'"'"'s data stream playback rate.

9. The system of claim 7, wherein the means for querying queries one or more decoders filters.

10. The system of claim 7, wherein the means for extrapolating comprises means for linearly extrapolating the one or more lines.

11. The system of claim 7, wherein the selected input timestamp value comprises a current input timestamp value for one of the filters.

12. The system of claim 7, wherein the selected input timestamp value comprises a future input timestamp value.

13. A computer-implemented method comprising:

querying one or more filters configured to process timestamped data streams for each filter'"'"'s input timestamp-to-output timestamp mapping;

receiving responses from the queried filters;

extrapolating one or more lines characterizing an individual mapping to a selected input timestamp value;

calculating a skip value for one or more of the lines, a skip value representing a value by which the output timestamps for a given filter are to be corrected; and

providing instructions to one or more of the filters to adjust their output timestamps in accordance with an associated skip value.

14. The method of claim 13, wherein said querying queries the one or more filters for each filter'"'"'s data stream playback rate.

15. The method of claim 13, wherein said querying queries one or more decoders filters.

16. The method of claim 13, wherein said extrapolating linearly extrapolates the one or more lines.

17. The method of claim 13, wherein the selected input timestamp value comprises a current input timestamp value for one of the filters.

18. The method of claim 13, wherein the selected input timestamp value comprises a future input timestamp value.