Video distribution synchronization

1. A method in a distribution network, the distribution network including a central master node for distributing a received media stream including packets of a first type over the distribution network to a plurality of client devices, the method comprising:

providing a common master-client shared time reference T ref ; and

at the central master node,

determining a mean intermediate arrival time for received packets of the first type,

determining respective first playout times for the packets of the first type based on the mean intermediate arrival time and the time reference T ref ,

time stamping the packets of the first type with the respective first playout times, and

distributing the media stream to the plurality of client devices.

2. The method according to claim 1 , wherein

the received media stream further includes packets of a second type, and

the method further includes time stamping the packets of the second type with respective second playout times, based on a predetermined ratio between number of packets of the first type and a number of packets of the second type.

3. The method according to claim 2 , wherein

the first type is associated with full picture video data, and

the second type is associated with delta picture video data.

4. The method according to claim 1 , wherein

the time reference T ref is based on Coordinated Universal Time, UTC, or NTP, or

the time reference T ref is derived from a mobile network or from GPS.

5. The method according to claim 1 , further comprising:

inserting time stamps of the time reference T ref into the media stream and into a back reporting stream, and

extracting the time stamps of the time reference T ref in the plurality of client devices for providing a coordinated local time of the plurality of client devices.

6. The method according to claim 1 , wherein each respective first playout time includes a playout delay Δ.

7. The method according to claim 6 , wherein the playout delay Δ is predetermined or set by the central master node.

8. The method according to claim 7 , wherein the playout delay Δ is selected to correspond to at least a maximum transport delay of the media stream to a client device of the plurality of client devices through the distribution network.

9. The method according to claim 7 , further comprising:

at the central master node, inserting the playout delay Δ into the media stream.

10. The method according to claim 6 , wherein the playout delay Δ is selected to correspond to at least a maximum transport delay of the media stream to a client device of the plurality of client devices through the distribution network.

11. The method according to claim 10 , further comprising:

at the central master node, inserting the playout delay Δ into the media stream.

12. The method according to claim 6 , further comprising:

at the central master node, inserting the playout delay Δ into the media stream.

13. A node in a distribution network, the node comprising:

means for performing the method according to claim 1 .

14. A device, comprising:

a memory storing a program of instructions; and

a processor configured to execute the program of instructions to perform the method according to claim 1 .

15. A client side method in a distribution network, the distribution network including a central master node for distributing a media stream over the distribution network to a plurality of client devices, the method comprising:

receiving a common master-client shared time reference T ref ;

receiving the media stream;

determining, based on first playout time information extracted from the media stream, a respective first playout time of each packet of a first type of the media stream, wherein the respective first playout time of each packet of the first type is based on a mean intermediate time arrival for received packets of the first type of the media stream at the central master node; and

playing each packet at the respective first playout time, thereby providing synchronized playout of the media stream at the plurality of client devices.

16. The client side method according to claim 15 , wherein

the media stream further includes packets of a second type, and

the method further includes

determining, based on time information extracted from the media stream and on a predetermined ratio between a number of packets of the first type and a separate number of packets of the second type, a respective second playout time of each packet of the second type of the media stream.

17. The client side method according to claim 16 , further comprising:

adding a playout delay on each first playout time and/or each second playout time.

18. The client side method according to claim 15 , further comprising:

extracting time stamps of the time reference T ref from the media stream to provide a local time reference.