Data transmission
First Claim
1. A method of operating a data transmission system comprising:
- transmitting data packets from a first media device to a second media device using a first transfer mode, wherein said first transfer mode employs an unreliable data transfer protocol;
identifying missing data packet(s) which do not arrive at the second media device;
sending a message or messages containing the identity of the missing data packet(s) from the second media device to the first media device, wherein, upon completion of the transmission of data packets using said first transfer mode the first media device transmits data packet(s) identified as missing to the second media device using a second transfer mode, wherein said second transfer mode employs a reliable data transfer protocol.
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Accused Products
Abstract
The invention involves a refinement to conventional data transmission over packet networks (e.g. IP). Conventionally, multimedia streaming systems use either a reliable protocol (e.g. TCP) or an unreliable protocol (e.g. UDP) for the media transmission. Each method has its own benefits. Using a reliable protocol ensures that all the packets arrive at the receiver, but this does require more bandwidth due to protocol overheads and it introduces more delay. An unreliable protocol is lightweight and faster although the data stream may be subjected to packet loss. In the present invention a combination of both protocols is used, where an unreliable protocol is employed initially followed by a reliable protocol at the end of the media clip. The unreliable protocol is used for the low delay transmission of packets while the reliable protocol at the end is used for the transmission of packets that were initially lost.
158 Citations
18 Claims
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1. A method of operating a data transmission system comprising:
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transmitting data packets from a first media device to a second media device using a first transfer mode, wherein said first transfer mode employs an unreliable data transfer protocol;
identifying missing data packet(s) which do not arrive at the second media device;
sending a message or messages containing the identity of the missing data packet(s) from the second media device to the first media device, wherein, upon completion of the transmission of data packets using said first transfer mode the first media device transmits data packet(s) identified as missing to the second media device using a second transfer mode, wherein said second transfer mode employs a reliable data transfer protocol. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 18)
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12. A method of operating a media transmission device comprising;
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transmitting data packets from the media transmission device to a receiver using a first transfer mode, wherein the first transfer mode employs an unreliable data transfer protocol, receiving a message or messages containing the identity of missing data packet(s) which do not arrive at the receiver, wherein, when the transmission of data packets is complete the media transmission device transmits data packet(s) identified as missing to the receiver using a second transfer mode, wherein said second transfer mode employs a reliable data transfer protocol.
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13. A method of operating a media reception device comprising;
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receiving data packets from a transmitter which have been transmitted in a first transfer mode, wherein the first transfer mode employs an unreliable data transfer protocol, identifying data packet(s) which were expected but are missing, sending a message or messages to the transmitter wherein said message or messages contain the identity of the missing data packet(s), receiving, from the transmitter, the data packet(s) which were identified in the message or messages, wherein said data packet(s) are received in a second transfer mode which employs a reliable data transfer protocol.
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14. A media transmission device comprising;
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transmission means for transmitting data packets from the media transmission device to a receiver using a first transfer mode, wherein said first transfer mode employs an unreliable data transfer protocol, receiving means for receiving a message or messages containing the identity of missing data packet(s) which do not arrive at the receiver, wherein, the device further comprises;
control means arranged such that, upon completion of the transmission of data packets using said first mode the media transmission device transmits data packet(s) identified as missing to the receiver using a second transfer mode, wherein said second transfer mode employs a reliable data transfer protocol. - View Dependent Claims (16, 17)
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15. A media reception device comprising;
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receiving means for receiving data packets from a transmitter which have been transmitted in a first transfer mode, wherein the first transfer mode employs an unreliable data transfer protocol, identifying means for identifying data packet(s) which were expected but are missing, sending means for sending a message or messages to the transmitter wherein said message or messages contain the identity of the missing data packet(s), receiving means for receiving, from the transmitter, the data packet(s) which were identified in the message or messages, wherein said data packet(s) are received in a second transfer mode which employs a reliable data transfer protocol.
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Specification