Distributed playback architecture

• US 9,781,485 B2
• Filed: 09/15/2016
• Issued: 10/03/2017
• Est. Priority Date: 10/15/2010
• Status: Active Grant

• Current Assignee: Cinemo Gmbh
• Original Assignee: Cinemo Gmbh
• Inventors: Russell, Ivan
• Primary Examiner(s): Lonsberry, Hunter B
• Application Number:
  US15/266,882
• Publication Number:
  US 20170006352A1
• Time in Patent Office: 383 Days
• Field of Search: 725 93- 95, 725133
• CPC Class Codes: H04N 21/4122 additional display device, e.g. video projector digital output for controlling a plurality of local displays G06F3/1423
• CPC Class Codes: H04N 21/41407 embedded in a portable device, e.g. video client on a mobile phone, PDA, laptop constructional details of equipment or arrangements specially adapted for portable computer application G06F1/1626; arrangements specially adapted for mobile receivers in broadcast systems H04H20/57
• 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 21/43615 Interfacing a Home Network, e.g. for connecting the client to a plurality of peripherals home Audio Video Interoperability [HAVI] data switching networks H04L12/2805
• CPC Class Codes: H04N 21/44227 Monitoring of local network, e.g. connection or bandwidth variations; Detecting new devices in the local network configuring of peripheral devices in general G06F9/4411; monitoring connectivity in data switched networks H04L43/0811
• CPC Class Codes: H04N 21/6332 directed to client

Abstract

Master element for a distributed playback architecture for a media data, having: a payload data source for providing payload data packets; a beacon packet creator for creating beacon packets useable for synchronizing a playback process of the payload data packets at, at least one, slave element in the distributed playback architecture; and a network interface for transmitting an interleaved packet stream to the at least one slave element, the interleaved packet stream having the payload data packets provided by the payload data source and the beacon packets created by the beacon packet creator. A corresponding slave element, the distributed playback architecture, a method, and a computer program product are also disclosed.

Claims

1. A master element for a distributed playback architecture for media data, comprising:

a payload data source for providing payload data packets;

a beacon packet creator for creating beacon packets useable for synchronizing a playback process of the payload data packets at at least one slave element in the distributed playback architecture;

a network interface for transmitting an interleaved packet stream to the at least one slave element, the interleaved packet stream comprising the payload data packets provided by the payload data source and the beacon packets created by the beacon packet creator;

a response packet evaluator for evaluating response packets issued by the at least one slave element in response to the beacon packet by determining a network latency between a first time instant at which a particular beacon packet was transmitted by the master element and a second time instant at which the particular beacon packet was received by the slave element, wherein the response packet evaluator is adapted to measure a total roundtrip time between the first time instant and a third time instant at which a corresponding response packet was received at the master element; and

wherein the response packet evaluator is further adapted to determine the network latency on the basis of the measured total roundtrip time;

wherein the beacon packet creator is adapted to comprise the determined network latency for the at least one slave element in a subsequent beacon packet,

wherein the payload data packets represent the media data,

wherein the beacon packets comprise a respective reference clock time being the respective time on a clock of the master element when the respective beacon packet is transmitted by the master element,

wherein a particular response packet issued in response to a particular beacon packet as an acknowledgement comprises the reference clock time of the particular beacon packet and a unique identifier identifying the at least one slave element having issued the particular response packet,

wherein the response packet evaluator is adapted to measure a total roundtrip time for the at least one slave element identified by the unique identifier between a first time instant being the reference clock time included in the particular response packet and a third time instant at which the particular response packet was received at the master element, and

wherein the response packet evaluator is further adapted to determine a network latency for the at least one slave element identified by the unique identifier between the first time instant and a second time instant at which the particular beacon packet was received by the slave element on the basis of the measured total roundtrip time.

2. The master element according to claim 1, wherein the response packet evaluator is adapted to extract an arrival time indication from the response packet, the arrival time indication indicating the second time instant and having been added to the response packet by the slave element.

3. The master element according to claim 1, wherein the response packet evaluator is further arranged to establish a list indicating the slave elements that have sent response packets during a preceding, predetermined time span period.

4. The master element according to claim 3, wherein the list further indicates a network latency for at least one of the plurality of slave elements mentioned in the list, and wherein the beacon packet creator is arranged for comprising the list in a subsequent beacon packet.

5. The master element according to claim 1, further comprising a presentation time scheduler adapted to determine an earliest possible presentation instant for the at least one slave element and a particular payload data packet.

6. The master element according to claim 5, wherein the determination of the earliest possible presentation instant is based on a maximal network latency for the at least one slave element or for a plurality of slave elements.

7. The master element according to claim 1, wherein the beacon packet creator is arranged to create beacon packets at regular time intervals.

8. The master element according to claim 1, further comprising an arbitrator for arbitrating a plurality of playback control commands issued by the at least one slave element.

9. A distributed playback architecture comprising a master element and a slave element, the master element comprising

a payload data source for providing payload data packets;

a beacon packet creator for creating beacon packets useable for synchronizing a playback process of the payload data packets at at least one slave element in the distributed playback architecture; and

a network interface for transmitting an interleaved packet stream to the at least one slave element, the interleaved packet stream comprising the payload data packets provided by the payload data source and the beacon packets created by the beacon packet creator;

a response packet evaluator for evaluating response packets issued by the at least one slave element in response to the beacon packet by determining a network latency between a first time instant at which a particular beacon packet was transmitted by the master element and a second time instant at which the particular beacon packet was received by the slave element, wherein the response packet evaluator is adapted to measure a total roundtrip time between the first time instant and a third time instant at which a corresponding response packet was received at the master element; and

wherein the response packet evaluator is further adapted to determine the network latency on the basis of the measured total roundtrip time;

wherein the beacon packet creator is adapted to comprise the determined network latency for the at least one slave element in a subsequent beacon packet

the slave element comprising;

a network interface for receiving an interleaved data stream comprising payload data packets and beacon packets transmitted from a master element of the distributed playback architecture;

a beacon packet extractor for extracting the beacon packets from the interleaved datastream; and

a beacon packet evaluator for evaluating a transmission time indication within the beacon packet, the transmission time indication being indicative of a first time instant at which a particular beacon packet comprising the transmission time indication was transmitted by the master element, and for determining a network latency between the master element and the slave element on the basis of the transmission time indication by extracting the network latency indication from the beacon packet indicative of an approximate network latency between the master element and the slave element corresponding to a roundtrip time of a preceding beacon packet and a corresponding preceding response packet, wherein the beacon packet evaluator is further adapted to adjust a presentation time instant for a payload packet on the basis of the network latency indication;

a response packet creator for creating a response packet;

wherein the network interface is arranged to transmit the response packet to the master element in response to the particular beacon packet,

wherein the payload data packets represent the media data,

wherein the beacon packets comprise a respective reference clock time being the respective time on a clock of the master element when the respective beacon packet is transmitted by the master element,

wherein a particular response packet issued in response to a particular beacon packet as an acknowledgement comprises the reference clock time of the particular beacon packet and a unique identifier identifying the at least one slave element having issued the particular response packet,

wherein the response packet evaluator is adapted to measure a total roundtrip time for the at least one slave element identified by the unique identifier between a first time instant being the reference clock time (321) included in the particular response packet and a third time instant at which the particular response packet was received at the master element, and

wherein the response packet evaluator is further adapted to determine a network latency for the at least one slave element identified by the unique identifier between the first time instant and a second time instant at which the particular beacon packet was received by the slave element on the basis of the measured total roundtrip time.

10. A method for synchronized playback in a distributed playback architecture comprising a master element and at least one slave element, the method comprising:

providing a plurality of payload data packets from a payload data source;

creating at least one beacon packet useable for synchronizing the synchronized playback of the plurality of payload packets at the at least one slave element;

interleaving the at least one beacon packet with the plurality of payload packets to form an interleaved datastream;

transmitting the interleaved datastream over a network to the at least one slave element

receiving the interleaved datastream at the at least one slave element;

extracting the at least one beacon packet from the interleaved datastream;

sending a response packet from the at least one slave element to the master element in response to the beacon packet;

determining, at the master element, a network latency between the master element and the slave element on the basis of the transmission time indication by measuring a total roundtrip time between the first time instant and a third time instant at which the corresponding response packet was received at the master element;

comprising the determined network latency for the at least one slave element in a subsequent beacon packet,

wherein the payload data packets represent the media data,

wherein the beacon packets comprise a respective reference clock time being the respective time on a clock of the master element when the respective beacon packet is transmitted by the master element,

wherein a particular response packet issued in response to a particular beacon packet as an acknowledgement comprises the reference clock time of the particular beacon packet and a unique identifier identifying the at least one slave element having issued the particular response packet,

wherein a total roundtrip time for the at least one slave element identified by the unique identifier between a first time instant being the reference clock time included in the particular response packet and a third time instant at which the particular response packet was received at the master element is measured by the master element, and

wherein a network latency for the at least one slave element identified by the unique identifier between the first time instant and a second time instant at which the particular beacon packet was received by the slave element is determined by the master element on the basis of the measured total roundtrip time.

11. Non-transitory storage medium comprising stored thereon a computer program comprising a program code for performing, when running on a computer, a method for synchronized playback in a distributed playback architecture comprising a master element and at least one slave element, the method comprising:

providing a plurality of payload data packets from a payload data source;

creating at least one beacon packet useable for synchronizing the synchronized playback of the plurality of payload packets at the at least one slave element;

interleaving the at least one beacon packet with the plurality of payload packets to form an interleaved datastream;

transmitting the interleaved datastream over a network to the at least one slave element receiving the interleaved datastream at the at least one slave element;

extracting the at least one beacon packet from the interleaved datastream;

sending a response packet from the at least one slave element to the master element in response to the beacon packet;

determining, at the master element, a network latency between the master element and the slave element on the basis of the transmission time indication by measuring a total roundtrip time between the first time instant and a third time instant at which the corresponding response packet was received at the master element;

comprising the determined network latency for the at least one slave element in a subsequent beacon packet,

wherein the payload data packets represent the media data,

wherein the beacon packets comprise a respective reference clock time being the respective time on a clock of the master element when the respective beacon packet is transmitted by the master element,

wherein a particular response packet issued in response to a particular beacon packet as an acknowledgement comprises the reference clock time of the particular beacon packet and a unique identifier identifying the at least one slave element having issued the particular response packet,

wherein a total roundtrip time for the at least one slave element identified by the unique identifier between a first time instant being the reference clock time included in the particular response packet and a third time instant at which the particular response packet was received at the master element is measured by the master element, and

wherein a network latency for the at least one slave element identified by the unique identifier between the first time instant and a second time instant at which the particular beacon packet was received by the slave element is determined by the master element on the basis of the measured total roundtrip time.

12. Method of operating a master element for a distributed playback architecture for media data, comprising:

providing payload data packets;

creating beacon packets useable for synchronizing a playback process of the payload data packets at at least one slave element in the distributed playback architecture;

transmitting an interleaved packet stream to the at least one slave element, the interleaved packet stream comprising the payload data packets provided by the payload data source and the beacon packets created by the beacon packet creator;

evaluating response packets issued by the at least one slave element in response to the beacon packet by determining a network latency between a first time instant at which a particular beacon packet was transmitted by the master element and a second time instant at which the particular beacon packet was received by the slave element, wherein the evaluating comprises measuring a total roundtrip time between the first time instant and a third time instant at which a corresponding response packet was received at the master element; and

wherein evaluating further comprises determining the network latency on the basis of the measured total roundtrip time; and

wherein the creating comprises introducing the determined network latency for the at least one slave element in a subsequent beacon packet,

wherein the payload data packets represent the media data,

wherein the beacon packets comprise a respective reference clock time being the respective time on a clock of the master element when the respective beacon packet is transmitted by the master element,

wherein a particular response packet issued in response to a particular beacon packet as an acknowledgement comprises the reference clock time of the particular beacon packet and a unique identifier identifying the at least one slave element having issued the particular response packet,

wherein a total roundtrip time for the at least one slave element identified by the unique identifier between a first time instant being the reference clock time included in the particular response packet and a third time instant at which the particular response packet was received at the master element is measured by the master element, and

wherein a network latency for the at least one slave element identified by the unique identifier between the first time instant and a second time instant at which the particular beacon packet was received by the slave element is determined by the master element on the basis of the measured total roundtrip time.

13. Non-transitory storage medium comprising stored thereon a computer program comprising a program code for performing, when running on a computer, a method of operating a master element for a distributed playback architecture for media data, the method comprising:

providing payload data packets;

creating beacon packets useable for synchronizing a playback process of the payload data packets at at least one slave element in the distributed playback architecture;

transmitting an interleaved packet stream to the at least one slave element, the interleaved packet stream comprising the payload data packets provided by the payload data source and the beacon packets created by the beacon packet creator;

evaluating response packets issued by the at least one slave element in response to the beacon packet by determining a network latency between a first time instant at which a particular beacon packet was transmitted by the master element and a second time instant at which the particular beacon packet was received by the slave element, wherein the evaluating comprises measuring a total roundtrip time between the first time instant and a third time instant at which a corresponding response packet was received at the master element; and

wherein evaluating further comprises determining the network latency on the basis of the measured total roundtrip time;

wherein the creating comprises introducing the determined network latency for the at least one slave element in a subsequent beacon packet,

wherein the payload data packets represent the media data,

wherein the beacon packets comprise a respective reference clock time being the respective time on a clock of the master element when the respective beacon packet is transmitted by the master element,

wherein a particular response packet issued in response to a particular beacon packet as an acknowledgement comprises the reference clock time of the particular beacon packet and a unique identifier identifying the at least one slave element having issued the particular response packet,

wherein a total roundtrip time for the at least one slave element identified by the unique identifier between a first time instant being the reference clock time included in the particular response packet and a third time instant at which the particular response packet was received at the master element is measured by the master element, and

wherein a network latency for the at least one slave element identified by the unique identifier between the first time instant and a second time instant at which the particular beacon packet was received by the slave element is determined by the master element on the basis of the measured total roundtrip time.