SYSTEM AND METHOD FOR SYNCHRONIZING MEDIA PRESENTATION AT MULTIPLE RECIPIENTS

• US 20140244863A1
• Filed: 01/29/2014
• Published: 08/28/2014
• Est. Priority Date: 06/04/2004
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Bradley, Bob, Newberry, Robert Dale Jr.
• Granted Patent: US 9,729,630 B2
• Time in Patent Office: Days
• US Class Current: 709/248
• CPC Class Codes: H04L 12/18 for broadcast or conference , e.g. multicast
• CPC Class Codes: H04L 12/1881 with schedule organisation, e.g. priority, sequence management
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/75 Media network packet handling
• CPC Class Codes: H04L 65/756 adapting media to device capabilities
• CPC Class Codes: H04L 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes
• 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 21/4305 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 21/8547 involving timestamps for synchronizing content

Abstract

A network media delivery system includes client devices and a host device. Each client device has a network interface, an engine for processing media data, and a media interface. The host device, which can be a computer, establishes network communication links with the client devices, which can be networked media stations, and sends media data to the client devices. The media data can be sent wirelessly as packets of media data transmitted at intervals to each client device. In one embodiment, the host device controls processing of media data such that processed media is delivered in a synchronized manner at each of the client devices. In another embodiment, the host device controls processing of media data such that processed media is delivered in a synchronized manner at the host device and at least one client device.

Claims

1. A host device, comprising:

a network interface for communicating with a first client device;

a reference clock; and

a processing component operatively coupled to the network interface and the reference clock, the processing component synchronizing a first local clock of the first client device with the reference clock and generating a first presentation time line for media data based on the reference clock, the first presentation time line specifying when to present the media data at the first client device, the processing component sending the media data and the first presentation time line to the first client device via the network interface and controlling presentation of the sent media data at the first client device with the first presentation timeline.

2. The host device of claim 1, wherein to send the media data and the first presentation timeline to the first client device, the processing component sends a unicast stream of first packets containing the media data to the first client device, each of the first packets having a timestamp specifying when to present the media data associated with the first packet.

3. The host device of claim 2, wherein the first packets comprise Real-Time Transport Protocol encapsulated in User Datagram Protocol packets.

4. The host device of claim 2, wherein the timestamps in the first packets comprise an adjustment based on a presentation latency associated with the first client device.

5. The host device of claim 1, wherein to synchronize the first local clock of the first client device with the reference clock, the processing component sends second packets to the first client device via the network interface in response to requests from the first client device, the second packets having time information to correlate the first local clock with the reference clock.

6. The host device of claim 5, wherein the second packets comprise Network Time Protocol (NTP) encapsulated in Real-Time Transport Control Protocol (RTCP) packets.

7. The host device of claim 1, wherein the processing component synchronizes a second local clock of a second client device with the reference clock and generates a second presentation time line for the media data based on the reference clock, the second presentation timeline specifying when to present the media data at the second client device such that the media data is presented in a synchronized manner at both the first and second client devices, the processing component sending the media data and the second presentation time line to the second client device via the network interface and controlling presentation of the sent media data at the second client device with the second presentation time line.

8. A host device, comprising:

a network interface for communicating with a plurality of client devices; and

a processing component operatively coupled to the network interface, the processing component sending media data to the client devices via the network interface and controlling processing of the sent media data at the client devices such that the processed media data is presented in a synchronized manner at each of the client devices.

9. The host device of claim 8, wherein to send the media data to each of the client devices via the network interface, the processing components sends a separate unicast stream of first packets containing the media data to each of the client devices, each of the first packets having a timestamp specifying when to present the media data associated with the first packet.

10. The host device of claim 9, wherein the timestamps in the first packets for a given one of the client devices comprise an adjustment based on a presentation latency associated with the given client device.

11. The host device of claim 8, wherein the host device comprises a reference clock, and wherein the processing component synchronizes each local clock of the client devices with the reference clock.

12. The host device of claim 11, wherein to synchronize each of the local clocks with the reference clock, the processing component sends second packets to each of the client devices in response to requests from each of the client devices, the second packets having time information to correlate the local clocks with the reference clock.

13. The host device of claim 8, further comprising:

an engine for processing the media data into processed media; and

a media interface for presenting the processed media data, wherein the processing component is operatively coupled to the engine and the media interface,

the processing component controlling processing of the media data with the engine such that the media interface presents the processed media data in a synchronized manner commensurate with the plurality of client devices.

14. A client device, comprising:

a network interface for network communication;

a media interface for presenting processed media data;

a local clock; and

a processing component operatively coupled the network interface, the media interface, and the local clock, the processing component receiving media data and synchronized timing information via the network interface, the processing component processing the media data for output with the media interface according to the synchronized timing information.

15. The client device of claim 14, wherein to receive the media data and the synchronized timing information, the processing component receives a unicast stream of first packets containing the media data via the network interface, each of the first packets having a timestamp and a sequence number, the timestamps specifying when to process the media data associated with the first packets.

16. The client device of claim 15, wherein the processing component synchronizes the timestamps to the local clock when processing the media data in the first packets for output with the media interface.

17. The client device of claim 15, wherein the processing component queues the first packets for processing based on the sequence numbers.

18. The client device of claim 17, wherein the processing component determines whether a given first packet is missing from the queue based on a missing sequence number and sends a request for retransmission of the missing first packet.

19. The client device of claim 14, wherein the processing component synchronizes the local clock to an external reference clock.

20. The client device of claim 19, wherein to synchronize the local clock to the external reference clock, the processing component sends requests for time information and receive responses to the requests, the responses having second packets containing time information to correlate the local clock to the external reference clock.