Redundant media packet streams
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 from a first and second media packet stream. The extracted samples are written to a buffer based on the output time of each sample. 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.
1. A transmitter device for transmitting media packet streams on a data network to a receiver device, the transmitter device comprising:
a transmitter 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;
a processor to packetize the one or more media channels, based on a request from the receiver device, to create media packet streams for transmission from the data interfaces; and
a controller to cause the processor to create two independent media packet streams to be transmitted to the receiver device, wherein one of the two independent media packet streams contains data corresponding to the packetized one or more media channels and the other of the two independent media packet streams contains a copy of the data corresponding to the packetized one or more media channels;
wherein the packets in the two independent media streams include identifying information for causing data from corresponding packets from the two independent media streams to be written to the same buffer location.
2. The transmitter device according to claim 1 , comprising a first data interface to transmit the first media packet stream and a second data interface to transmit the second media packet stream.
3. The transmitter device according to claim 1 , wherein the data network comprises a first data sub-network and a second data sub-network.
4. The transmitter device according to claim 3 , wherein the controller causes the first media packet stream to be transmitted on the first data sub-network and the second media packet stream to be transmitted on the second data sub-network.
5. The transmitter device according to claim 4 , wherein the first and the second data sub-networks have different transmission protocols.
6. The transmitter device according to claim 1 , wherein the transmitter device is configured to continually process a primary media packet stream.
7. The transmitter device according to claim 1 , wherein the one or more data interfaces transmit the media streams using a unicast protocol.
8. The transmitter device according to claim 1 , wherein the one or more data interfaces transmit the media streams using a multicast protocol.
9. The transmitter device according to claim 1 , wherein the media streams contain one or more media channels in samples, each sample having an associated timestamp.
10. A method for transmitting media packet streams on a data network to a receiver device, the method comprising the steps of:
packetizing one or more media channels;
creating a first media packet stream and a second media packet stream containing one or more channels;
transmitting the first media packet stream to the receiver device; and
transmitting the second media packet stream to the receiver device,
wherein the first and the second media packet streams are independent and contain the same media channels;
wherein the first media packet stream contains data corresponding to the one or more channels and the second media packet stream contains a copy of the data corresponding to the one or more media channels; and
wherein the packets in the two independent media streams include identifying information for causing data from corresponding packets from the two independent media streams to be written to the same buffer location.
11. The method according to claim 10 , wherein the step of transmitting the first media packet stream is from a first data interface of a transmitter device connected to the data network and the step of transmitting the second media packet stream is from the first or a second data interface of the transmitter device connected to the data network.
12. The method according to claim 10 , wherein the method further comprises receiving a message from the receiver device requesting that the first and second media packet streams be transmitted.