Media stream synchronization using device and host clocks

• US 8,239,748 B1
• Filed: 02/19/2010
• Issued: 08/07/2012
• Est. Priority Date: 01/30/2004
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Moore, Jeff, Berthoud, Jean-Michel, Cherna, Tim
• Primary Examiner(s): Hutton, Jr., Doug
• Assistant Examiner(s): DYER, ANDREW R
• Application Number:
  US12/709,317
• Time in Patent Office: 900 Days
• Field of Search: 715/201, 715/202, 715/203
• US Class Current: 715/201
• CPC Class Codes: G06F 16/4393 Multimedia presentations, e.g. slide shows, multimedia albums

Abstract

A synchronization manager synchronizes multiple media streams. The synchronization manager queries a media stream output device associated with each media stream to synchronize, and in response receives the current device clock time of each device, each device'"'"'s next available media stream output time, and each device'"'"'s delta between available media stream output times. The synchronization manager uses this timing information to determine an earliest available media stream output time common to each media stream output device, and synchronizes the output of the media streams by providing each stream to its associated output device at the earliest available common output time.

Claims

1. A computer system for synchronizing multiple media streams, the computer system comprising:

a processor;

a computer readable storage medium storing computer-executable program instructions, the program instructions when executed by one or more processing units cause the one or more processing units to perform steps comprising;

initiating queries to a plurality of media stream output devices;

receiving a) current time of each queried media stream output device according to its device clock, b) next available media stream output time of each queried media stream output device according to its device clock and c) a delta between available media stream output times;

determining an earliest available media stream output time common to each media stream output device based on data received responsive to the queries; and

providing each media stream an associated media stream output device at the earliest available common media stream output time for synchronizing output of the plurality of media streams.

2. The computer system of claim 1, wherein the program instruction when executed further cause the one or more processing units to perform steps comprising:

defining one media stream of the plurality as a master media stream; and

slaving at least one additional media stream of the plurality off the master media stream.

3. The computer system of claim 1 wherein the plurality of media streams comprises at least a video stream and an audio stream.

4. The computer system of claim 1 wherein at least one of the plurality of media streams comprises a video stream.

5. The computer system of claim 1 wherein at least one of the plurality of media streams comprises a audio stream.

6. The computer system of claim 1 wherein at least one of the plurality of media streams comprises a closed captioning data stream.

7. The computer system of claim 1 wherein at least one of the plurality of media streams comprises a stream of MIDI events.

8. The computer system of claim 1 wherein at least one of the plurality of media streams comprises a stream of text to Braille data.

9. The computer system of claim 1 wherein at least one of the plurality of media streams comprises a stream of side band data.

10. The computer system of claim 1, wherein the program instructions when executed further cause the one or more processing units to perform steps comprising:

correlating each received device clock time to a common host clock time; and

referencing events on the plurality of media stream output devices based on the common host clock time.