Resynchronizing media during streaming

• US 20020010917A1
• Filed: 04/06/2001
• Published: 01/24/2002
• Est. Priority Date: 04/08/2000
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Proctor, Seth, Shafer, Matthew, Srikantan, Geetha, Narasimhan, Aravind, Brittenson, Jan, Sergent, Jonathan S.
• Granted Patent: US 6,857,130 B2
• Time in Patent Office: Days
• US Class Current: 725/1
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/65 Network streaming protocols, e.g. real-time transport protocol [RTP] or real-time control protocol [RTCP]
• CPC Class Codes: H04L 65/70 Media network packetisation
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04N 21/2381 Adapting the multiplex stream to a specific network, e.g. an Internet Protocol [IP] network transmission of MPEG streams over ATM H04L12/5601
• CPC Class Codes: H04N 21/242 Synchronization processes, e.g. processing of PCR [Program Clock References] arrangements for synchronising broadcast or distribution via plural systems in broadcast distribution systems H04H20/18
• CPC Class Codes: H04N 21/4363 Adapting the video stream to a specific local network, e.g. a Bluetooth® network
• CPC Class Codes: H04N 21/4381 Recovering the multiplex stream from a specific network, e.g. recovering MPEG packets from ATM cells transmission of MPEG streams over ATM H04L12/5601
• CPC Class Codes: H04N 21/6437 Real-time Transport Protocol [RTP]

Abstract

A system and method are provided for resynchronizing a media stream. A media streaming server receives live or pre-recorded media for streaming to clients. When media is not received or available for streaming at the appropriate media time index, the media stream is deemed to be out of synchronization. The server selects a future time index at which to resynchronize the stream and may discard intervening media. Media corresponding to the new time index is requested or retrieved and, if available at the new time index, media streaming resumes in synchronization. If media corresponding to the new time index is not available, the server may select another future time index and try again to resynchronize. Resynchronization may be attempted a configurable number of times and, if unsuccessful, the server may terminate the stream.

Claims

1. A method of synchronizing a media stream, comprising:

streaming media from a media program to a client;

detecting a loss of synchronization in said media stream at a current media time index;

selecting a second time index later in said media than said first media time index; and

attempting to synchronize said media at said second media time index.

2. The method of claim 1, if said attempting to synchronize is unsuccessful, repeating said selecting and said attempting a predetermined number of times.

3. The method of claim 2, further comprising terminating said media stream if each of said predetermined number of attempts to synchronize is unsuccessful.

4. The method of claim 1, wherein said detecting comprises:

identifying a current time index of the media program, wherein said current time index corresponds to media that should be streamed at said current time index; and

comparing said current time index to a time index of said media actually being streamed.

5. The method of claim 4, wherein said selecting a second time index comprises adding a predetermined amount of time to said current time index.

6. The method of claim 4, wherein said selecting a second time index comprises adding a predetermined amount of time to said time index of said media actually being streamed.

7. The method of claim 4, wherein said attempting to synchronize comprises:

determining whether a portion of the media program corresponding to said second time index is available for streaming at said second time index; and

if said media program portion is available for streaming, resuming streaming of the media program at said second time index.

8. A method of resynchronizing a media program streamed to a client from a media server, the method comprising:

(a) requesting a first portion of a media program to be streamed to the client, said first media portion corresponding to a first time index of the media program; and

(b) if said first media portion is unavailable for streaming at said first time index, attempting to resynchronize the media program by;

(c) selecting a second time index of said media program later than said first time index;

(d) requesting a second portion of the media program corresponding to said second time index;

(e) halting streaming of the media program until said second time index; and

(f) if said second media portion is available at said second time index, commencing streaming the media program from said second time index.

9. The method of claim 8, further comprising:

(g) if said second media portion is unavailable at said second time index, repeating (b)-(f) for a later time index and another media portion corresponding to said later time index.

10. The method of claim 9, wherein said (b)-(f) are repeated a predetermined number of times and, if said resynchronization attempts are unsuccessful each of said predetermined number of times, terminating said streaming.

11. The method of claim 8, wherein the media program is a pre-recorded media program and said requesting comprises scheduling retrieval of o portion of the media program from a storage device.

12. The method of claim 8, wherein said selecting comprises, for a first resynchronization attempt:

determining a current media time index; and

adding a predetermined time increment to said current media time index.

13. The method of claim 12, wherein said selecting comprises, for a subsequent resynchronization attempt:

determining a second current media time index; and

adding a multiple of said predetermined time increment to said second current media time index.

14. The method of claim 8, wherein said halting comprises discarding media data corresponding to a time index prior to said second time index.

15. The method of claim 8, wherein said streaming the media program from said second time index comprises transmitting to the client media from multiple tracks of the media program, wherein said transmitted media corresponds to said second time index.

16. A computer readable storage medium storing instructions that, when executed by a computer, cause the computer to perform a method of synchronizing a media stream, the method comprising:

streaming media from a media program to a client;

detecting a loss of synchronization in said media stream at a current media time index;

selecting a second time index later in said media than said first media time index; and

attempting to resynchronize said media at said second media time index.

17. A computer readable storage medium storing instructions that, when executed by a computer, cause the computer to perform a method of resynchronizing a media program streamed to a client from a media server, the method comprising:

(a) requesting a first portion of a media program to be streamed to the client, said first media portion corresponding to a first time index of the media program; and

(b) if said first media portion is unavailable for streaming at said first time index, attempting to resynchronize the media program by;

(c) selecting a second time index of said media program later than said first time index;

(d) requesting a second portion of the media program corresponding to said second time index;

(e) halting streaming of the media program until said second time index; and

(f) if said second media portion is available at said second time index, commencing streaming the media program from said second time index.

18. An apparatus for synchronizing a stream of media to a client, comprising:

a stream module configured to control the streaming of a media program to a client;

a media time index configured to identify a current time index of the media program, wherein for each said time index a corresponding portion of the media program should be streamed; and

a first track stream module configured to retrieve media for a first track of the media program from a media source;

wherein if a first portion of the media program is unavailable for streaming at a first current time index, said stream module;

advances said media time index from said current time index to a future time index;

requests said portion of the media program corresponding to said future time index; and

resumes said streaming at said future time index if said requested media program portion is available for streaming at said future time index.

19. An apparatus for synchronizing a media stream to a client, comprising:

a first track of a media program stored on a first storage device;

a first track stream module configured to retrieve media from said first media track, wherein the media comprises multiple media portions corresponding to successive time indices at which said corresponding media portions should be played; and

a stream module configured to control streaming of the media to a client by transmitting to the client media corresponding to a current media program time index; and

a synchronization module configured to synchronize said media streaming when a portion of the media corresponding to a first current media program time index is not available for streaming at said first current media program time index.

20. The apparatus of claim 19, wherein said synchronization comprises:

selecting a second current media program time index that is later than said first current media program time index;

requesting a portion of the media corresponding to said second current media time index;

suspending said media streaming until said second current media time index; and

if said requested media portion if available for streaming at said second current media time index, resuming said media streaming.