Redundant Media Packet Streams

• US 20090274149A1
• Filed: 05/17/2007
• Published: 11/05/2009
• Est. Priority Date: 05/17/2006
• Status: Active Grant

• Current Assignee: Audinate Holdings Pty Limited
• Original Assignee: Audinate Pty Ltd (Audinate Group Ltd.)
• Inventors: Williams, Aidan, White, Andrew
• Granted Patent: US 7,978,696 B2
• Time in Patent Office: Days
• US Class Current: 370/389
• CPC Class Codes: H04L 47/50 Queue scheduling
• CPC Class Codes: H04L 47/564 Attaching a deadline to packets, e.g. earliest due date first
• CPC Class Codes: H04L 49/90 Buffering arrangements
• CPC Class Codes: H04L 49/901 using storage descriptor, e.g. read or write pointers
• CPC Class Codes: H04L 65/60 Network streaming of media packets
• CPC Class Codes: H04L 65/611 for multicast or broadcast systems for broadcast or conference H04L12/18; arrangements for broadcast or distribution combined with broadcast H04H20/00; arrangements for broadcast applications with a direct linkage to broadcast information or to broadcast space-time H04H60/00; selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS], H04W4/06
• CPC Class Codes: H04L 65/613 for the control of the source by the destination control signals issued by the client directed to the server or network components specially adapted for selective content distribution H04N21/637
• CPC Class Codes: H04L 65/762 at the source reformatting of additional data in video distribution servers H04N21/2355
• CPC Class Codes: H04L 65/764 at the destination reformatting of additional data in video clients H04N21/4355
• CPC Class Codes: H04L 69/14 Multichannel or multilink protocols
• CPC Class Codes: H04N 21/4392 involving audio buffer management

Abstract

This invention concerns the transmitting and receiving of digital media packets, such as audio and video channels and lighting instructions. In particular, the invention concerns the transmitting and receiving of redundant media packet streams. Samples are extracted (556) from a first (904) and second (906) media packet stream. The extracted samples are written to a buffer (910) based on the output time of each sample (556). Extracted samples having the same output time are written to the same location in the buffer. Both media packet streams are simply processed all the way to the buffer without any particular knowledge that one of the packet streams is actually redundant. This simplifies the management of the redundant packet streams, such as eliminating the need for a “fail-over” switch and the concept of an “active stream”. The location is the storage space allocated to store one sample. The extracted sample written to the location may be written over another extracted sample from a different packet stream previously written to the location. These extracted samples written to the same location may be identical.

Claims

1. A receiver device for receiving media packet streams from a data network, the receiver device comprising:

a first data interface to receive a first media packet stream containing samples of a media channel;

a second data interface to receive a second media packet stream containing the samples of the media channel;

a processor to extract samples from the first and second media packet streams and to determine an output time for the extracted samples;

a buffer to temporarily store the extracted samples for output; and

wherein the processor operates to cause the extracted samples to be written to the buffer based on the respective output time, such that extracted samples having the same output time are written to the same location in the buffer.

2. A receiver device according to claim 1, wherein the buffer is able to temporarily store a predetermined maximum number of extracted samples.

3. A receiver device according to claim 1, wherein the buffer is able to temporarily store the extracted samples in sequential order according to their respective output time.

4. A receiver device according to claim 1, wherein the output time is the playout time.

5. A receiver device according to claim 1, wherein the location is the storage space allocated to store one sample.

6. A receiver device according to claim 1, wherein a first extracted sample written to the location is written over a second extracted sample from a different packet stream previously written to the location.

7. A receiver device according to claim 1, wherein the first and second extracted samples are identical.

8. A receiver device according to claim 1, wherein the buffer is associated with one output channel and each media packet stream is directed to the same output channel.

9. A receiver device according to claim 1, wherein the receiver device further comprises a third data interface to receive a third media packet stream containing the samples of the media channel, wherein the processor further operates to extract samples from the third media packet stream and to determine an output time for the extracted samples, and to cause the extracted samples to be written to the buffer based on the respective output time.

10. A receiver device according to claim 1, wherein the processor further operates to detect samples that are corrupted and to prevent these corrupted samples from being written to the buffer.

11. A receiver device according to claim 1, wherein all the samples contained in one media packet of the first media packet stream are not all contained in any single media packet of the second media packet stream.

12. A receiver device according to claim 1, wherein the first and second media packet streams are received from different data interfaces of a transmitter device connected to the data network.

13. A receiver device according to claim 1, where the samples of the media channel each have an associated timestamp and the processor operates to determine the output time for the extracted samples based on the respective timestamps.

14. A method of receiving media packet streams from a data network, the method comprising the steps of:

receiving a first media packet stream containing samples of a media channel;

receiving a second media packet stream containing the samples of the media channel;

extracting samples from the first and second media packet streams;

determining an output time for the extracted samples;

based on the respective output time of the extracted sample, writing each extracted sample to a buffer for output, such that extracted samples having the same output time are written to the same location in the buffer.

15. A method according to claim 14, wherein the step of writing each extracted sample to a buffer comprises writing the extracted samples in sequential order according to the respective output time of each extracted sample.

16. A method according to claim 14, wherein the output time is a playout time.

17. A method according to claim 14, wherein the location is the storage space allocated to store one sample.

18. A method according to claim 14, wherein the step of writing each extracted sample to a buffer comprises writing a first extracted sample to a location and then writing a second extracted sample from a different packet stream over the first extracted sample at the location.

19. A method according to claim 14, wherein the first and second extracted samples are identical.

20. A method according to claim 14, wherein the buffer is associated with one output channel and each media packet stream is directed to the same output channel.

21. A method according to claim 14, wherein the method further comprises the step of receiving a third media packet stream containing the samples of the media channel and extracting samples from the third media packet stream.

22. A method according to claim 14, wherein the method further comprises the step of detecting samples that are corrupted and causing these corrupted samples not to be written to the buffer.

23. A method according to claim 14, wherein all the samples contained in one media packet of the first media packet stream are not all contained in any single media packet of the second media packet stream.

24. A method according to claim 14, wherein the samples of the media channel each have an associated timestamp and the step of determining the output time for the extracted samples is based on the respective timestamps.

25. A method according to claim 14, wherein the step of receiving the first media packet stream is from a first data interface of a transmitter device connected to the data network and the step of receiving the second media packet streams is from the first or a second data interface of the transmitter device connected to the data network.

26. A method according to claim 14, wherein the method further comprises sending one message to request that the first and second media packet streams be received.

27. Computer software to operate a receiver device to perform the method of claim 14.

28. A transmitter device for transmitting media packet streams on a data network to a receiver device, the transmitter device comprising:

one or more data interfaces to transmit a first media packet stream and a second media packet stream to the receiver device, the media streams containing one or more media channels;

based on a request from the receiver device, a processor to packetize media channels to create media packet streams for transmission from the data interfaces; and

a controller cause the processor to create two independent media packet streams containing the same media channels to be transmitted to the receiver device.

29. A data network comprising:

a transmitter device according to claim 28;

a receiver device comprising;

a first data interface to receive a first media packet stream containing samples of a media channel;

a second data interface to receive a second media packet stream containing the samples of the media channel;

a processor to extract samples from the first and second media packet streams and to determine an output time for the extracted samples; and

a buffer to temporarily store the extracted samples for output; and

communication means to allow media packet streams to be sent from the transmitter device to the receiver device.