Synchronization of one or more data streams

• US 5,664,164 A
• Filed: 02/24/1995
• Issued: 09/02/1997
• Est. Priority Date: 02/24/1995
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Riddle, Guy Gregory
• Primary Examiner(s): Heckler, Thomas M.
• Assistant Examiner(s): BUTLER, DENNIS
• Application Number:
  US08/394,089
• Time in Patent Office: 921 Days
• Field of Search: 395/550, 395/650, 395/154, 395/700, 395/200.04, 395/2, 395/2.2, 395/2.44, 395/2.76, 395/878, 348/500, 348/508, 348/510, 348/512, 348/515
• US Class Current: 713/400
• CPC Class Codes: H04N 21/2187 Live feed
• CPC Class Codes: H04N 21/23113 involving housekeeping operations for stored content, e.g. prioritizing content for deletion because of storage space restrictions storage management, e.g. defragmentation G06F3/0604; snloading stored programs G06F9/445; housekeeping operations in file systems, e.g. deletion policies G06F16/10; buffering arrangements in a network node or in an end terminal in packet networks H04L49/90
• CPC Class Codes: H04N 21/43072 of multiple content streams on the same device
• CPC Class Codes: H04N 21/4788 communicating with other users, e.g. chatting arrangements for providing for computer conferences, e.g. chat rooms, to substation in data switching networks H04L12/1813; distributed application using peer-to-peer [P2P] networks H04L67/104

Abstract

Synchronization of one or more data streams comprising an electronic data connection. The synchronization of one or more data streams having inherent temporal qualities or relationships is maintained on playback so as to retain the value of these temporal relationships established at capture time.

Claims

1. In a computer system having a central processing unit;

an input unit for receiving a data stream associated with a data type, said data stream including a set of data segments, each data segment having a time stamp; and

, an output unit, a data stream synchronization method comprising;

a) handling housekeeping chores of incoming data of said data stream to said input unit, said housekeeping chores handling step including the steps of;

1) determining a processing time associated with a data player used to process said data type;

2) reducing said time stamp for each data segment in said set of data segments by said processing time; and

,

3) placing each data segment in a queue;

b) handling status of said data stream and adjusting a clock for said data stream with said central processing unit; and

,

c) utilizing said data stream with said output unit.

2. The data stream synchronization method of claim 1, wherein said queue is configured for holding data of said data type.

3. The data stream synchronization method of claim 1, wherein said placing step includes the step of assigning a wait state to each data segment.

4. The data stream synchronization method of claim 1, wherein said status handling step comprises the steps of:

determining a minimum time and a maximum time of each data segment in said queue;

adding an amount of time equal to an elapsed time since said status handling step was last invoked to an idle time period;

examining each data segment to determine a particular state assigned to each data segment; and

,

processing each data segment in accordance with said particular state.

5. The data stream synchronization method of claim 4, wherein said particular state is a waiting state and said processing step comprises the steps of:

comparing an idle time period to an idle time threshold;

resetting a clock to a current time if said idle time is greater than said idle time threshold;

resetting said idle time period to zero;

comparing a first data segment time stamp of a first data segment of said set of data segments with said clock; and

,

assigning a ready state to said first data segment and noting a time when said first data segment was assigned said ready state if said first data segment time stamp is less than or equal to said clock.

6. The data stream synchronization method of claim 5, further comprising the steps of:

comparing a discard time threshold to a difference between said first data segment time stamp and said clock time; and

,

assigning a discard state to said first data segment if said difference is greater than said discard time threshold.

7. The data stream synchronization method of claim 6, further comprising the steps of:

comparing said first data segment time stamp with said clock; and

;

if said first data segment time stamp is less than said clock, setting said clock in accordance to the following formula;

space="preserve" listing-type="equation">new clock time=old clock time-((old clock time-data segment time stamp)×

adjustment factor).

8. The data stream synchronization method of claim 4, wherein said particular state is a ready state and said processing step comprises the steps of:

comparing a first data segment time stamp of a first data segment of said set of data segments with twice the value of a discard time threshold; and

,

assigning a discard state to said first data segment if said first data segment time stamp is greater than or equal to two times the value of said discard time threshold.

9. The data stream synchronization method of claim 4, wherein said particular state is a played state and said processing step comprises the steps of:

removing a first data segment of said set of data segments from said queue;

calculating a play duration value according to the following formula;

space="preserve" listing-type="equation">play duration=(finish time-start time);

and,

resetting the playing time according to the following formula;

space="preserve" listing-type="equation">new playing time=((old playing time+play duration)/2).

10. The data stream synchronization method of claim 4, further including the steps of:

checking a first data segment of said set of data segments for an error condition; and

dividing a playing time by two if said first data segment contains an error condition.

11. The data stream synchronization method of claim 4, further including the steps of:

examining said queue to determining a number of data segments which are in a waiting state;

multiplying said number with the difference between said maximum time and said minimum time; and

,

adding 1/100th of said number to said clock.

12. The data stream synchronization method of claim 1, wherein said data stream utilizing step comprises the steps of:

checking for a maximum time limit; and

,

examining said queue for any data segments having a ready state and processing those data segments using said data player if said maximum time limit has not been reached.

13. In a computer system having a central processing unit;

an input unit for receiving a data stream associated with a data type, said data stream including a set of data segments, each data segment having a time stamp; and

an output unit, a data stream synchronization apparatus comprising;

a) means for handling housekeeping chores of incoming data of said data stream to said input unit, said housekeeping chores handling means having;

1) means for determining a processing time associated with a data player used to process said data type;

2) means for reducing said time stamp for each data segment in said set of data segments by said processing time; and

,

3) means for placing each data segment in a queue;

b) means for handling status of said data stream and for adjusting a clock for said data stream with said central processing unit; and

,

c) means for utilizing said data stream with said output unit.

14. An apparatus comprising:

a processor;

a memory coupled to said processor;

an input unit coupled to said processor, said input unit receiving a data stream associated with a data type, said data stream including a set of data segments, each data segment having a time stamp;

an output unit coupled to said processor;

said memory configured to cause said processor to;

a) handle housekeeping chores of incoming data of said data stream to said input unit, said housekeeping chores handling step includes the steps of;

1) determining a processing time associated with a data player used to process said data type;

2) reducing said time stamp for each data segment in said set of data segments by said processing time; and

,

3) placing each data segment in a queue;

b) handle status of said data stream data and adjusting a clock for said data stream with said central processing unit; and

,

c) utilize said data stream data with said output unit.