Data streaming system and method

• US 20050172028A1
• Filed: 03/27/2003
• Published: 08/04/2005
• Est. Priority Date: 03/27/2002
• Status: Active Grant

• Current Assignee: British Telecommunications PLC (BT Group PLC)
• Original Assignee: British Telecommunications PLC (BT Group PLC)
• Inventors: Jebb, Timothy R., Nilsson, Michael E.
• Granted Patent: US 8,135,852 B2
• Time in Patent Office: Days
• US Class Current: 709/231
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/70 Media network packetisation
• CPC Class Codes: H04L 65/752 adapting media to network capabilities
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: H04N 19/30 using hierarchical techniques, e.g. scalability H04N19/63 takes precedence
• CPC Class Codes: H04N 19/503 involving temporal prediction adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109
• CPC Class Codes: H04N 21/23406 involving management of server-side video buffer
• CPC Class Codes: H04N 21/23424 involving splicing one content stream with another content stream, e.g. for inserting or substituting an advertisement
• CPC Class Codes: H04N 21/23439 for generating different versions
• CPC Class Codes: H04N 21/2402 Monitoring of the downstream path of the transmission network, e.g. bandwidth available traffic monitoring in data switching networks H04L43/00; monitoring data switching networks utilization H04L43/0876
• CPC Class Codes: H04N 21/2662 Controlling the complexity of the video stream, e.g. by scaling the resolution or bitrate of the video stream based on the client capabilities
• CPC Class Codes: H04N 21/44004 involving video buffer management, e.g. video decoder buffer or video display buffer
• CPC Class Codes: H04N 21/44016 involving splicing one content stream with another content stream, e.g. for substituting a video clip
• CPC Class Codes: H04N 21/8455 involving pointers to the content, e.g. pointers to the I-frames of the video stream

Abstract

A data streaming system and method are described. A server (10) is arranged to stream one of a plurality of encoded data streams to a client (40, 50, 60). Each of the plurality of data streams is an independent representation of a common data source encoded at a different resolution to the other of the plurality of data streams. The server (10) comprises a transmitter (100) and a first buffer (120). The transmitter is arranged to transmit data packets of the encoded data stream to the client (40, 50, 60) via the first buffer (120). The transmitter (100) is arranged to monitor the content of the first buffer (120) and switch to transmit another of the plurality of data streams in the event that predetermined criteria are detected from the first buffer (120).

Claims

1. A data streaming system comprising a server (10) arranged to stream one of a plurality of encoded data streams to a client (40, 50, 60), each of the plurality of data streams being an independent representation of a common data source encoded at a different resolution to the other of the plurality of data streams, the server (10) comprising a transmitter (100) and a first buffer (120), the transmitter (100) being arranged to transmit data packets of the encoded data stream to the client (40, 50, 60) via the first buffer (120), wherein the transmitter (100) is arranged to monitor the content of the first buffer (120) and switch to transmit another of the plurality of data streams in the event that predetermined criteria are detected from the first buffer (120).

2. A system according to claim 1, wherein the transmitter (100) is arranged to determine the amount of data buffered at the client (40, 50, 60) from the content of the first buffer (120), wherein the predetermined criteria include a predetermined level of data determined to be buffered at the client.

3. A system according to claim 2, wherein a data packet is removed from the first buffer (120) upon acknowledgement by the client (40, 50, 60) of receipt of the packet.

4. A system according to claim 3, wherein the transmitter (100) is arranged to determine the amount of data buffered at the client (40, 50, 60) in dependence on the latest data packet removed from the first buffer (120) and on an estimation of number of packets decoded by the client (40, 50, 60).

5. A system according to claim 1, wherein the first buffer (120) includes a mirror buffer (120a) storing data on packets in the first buffer (120), the transmitter (100) being arranged to monitor the content of the first buffer (120) using the data in the mirror buffer (120A).

6. A system according to claim 1, wherein data packets are transmitted to the client (40, 50, 60) using an extended TPKT protocol, the data packets including a header containing a decoding timestamp and a data stream identifier.

7. A system according to claim 1, further comprising a plurality of transmitters (100), each communicating with a respective client (40, 50, 60) via a respective first buffer (120) to transmit one of the plurality of data streams determined in dependence on respective predetermined criteria.

8. A system according to claim 1, wherein the data stream is encoded video data.

9. A system according to claim 8, wherein the transmitter (100) is arranged to multiplex audio packets and video packets within the transmission of data packets.

10. A system according to claim 9, wherein neighbouring audio and video packets represent audio and video information that is intended for representation at substantially the same time.

11. A system according to claim 1, wherein the data stream is encoded audio data.

12. A system according to claim 1, wherein the resolution is an encoding bit rate of the data.

13. A system according to claim 1, wherein the server (10) includes an encoder (20) arranged to accept a data feed and encode the data feed into the plurality of encoded data streams.

14. A system according to claim 13, further comprising a plurality of buffers (70, 80, 90), wherein the encoder (20) is arranged to output each encoded data stream into a respective one of the plurality of buffers (70, 80, 90), the transmitter (100) being arranged to obtain data packets for a respective data stream from its respective one of the plurality of buffers.

15. A system according to claim 1, wherein the server (10) includes a file source (30) storing the plurality of encoded data streams.

16. A data streaming system comprising a client and a server, the server (10) being arranged to stream one of a plurality of encoded data streams to the client (40, 50, 60), each of the plurality of data streams being an independent representation of a common data source encoded at a different resolution to the other of the plurality of data streams, the server (10) comprising a transmitter (100) and a first buffer (120) and the client (40, 50, 60) including a receiving buffer (130), wherein the transmitter (100) is arranged to transmit data packets of the encoded data stream to the client (40, 50, 60) via the first buffer (120), wherein the client (40, 50, 60) is arranged to store received data packets in the receiving buffer (130) and to acknowledge receipt to the server (10), wherein the transmitter (100) is arranged to delete packets from the first buffer (120) when an acknowledgement receipt is received, the transmitter (100) being arranged to switch to another of the plurality of data streams in the event that predetermined criteria are satisfied, the predetermined criteria comprising analysis on content of the first buffer (120).

17. A system according to claim 16, wherein the packets include packet sequence data, the client (40, 50, 60) being arranged to request retransmission of non-received packets based on the sequence data, the server (10) being arranged to retransmit a packet from the first buffer (120) upon receipt of a retransmission request.

27. A computer program comprising computer program code means for executing the steps claim 17 when run on a computer.

28. A computer program as claimed in claim 27 embodied on a computer readable medium.

18. A method of streaming one of a plurality of encoded data streams to a client, each of the plurality of data streams being an independent representation of a common data source encoded at a different resolution to the other of the plurality of data streams, the method comprising the steps of:

transmitting data packets of the encoded data stream to the client via a first buffer;

monitoring the content of the first buffer; and

, switching to transmit another of the plurality of data streams in the event that predetermined criteria are detected from the first buffer.

19. A method according to claim 18, wherein the plurality of data streams are each encoded at a different bit rate, the method further comprising the step of initially transmitting data packets of the lowest bit rate data stream.

20. A method according to claim 18, wherein the predetermined criteria includes an amount of data determined to be buffered at client.

21. A method according to claim 18, wherein the predetermined criteria include one or more network throughput thresholds.

22. A method according to claim 21, wherein network throughput is calculated by the steps of:

counting the number of bytes passed to the first buffer;

subtracting the counted number of bytes from the size of the first buffer; and

, dividing the result by the time since the start of transmission.

23. A method according to claim 22, further comprising the step of measuring network throughput over more than one interval to determine throughput variation.

24. A method according to claim 22, wherein the predetermined criteria include determination of network throughput sufficient to sustain the other of the plurality of the data streams.

25. A method according to claim 22, further comprising the step transmitting data at a maximum rate irrespective of an amount of data buffered at the client, wherein the predetermined criteria include network throughput determined at the maximum rate.

26. A method according to claim 18, wherein the data streams are encoded as a series of pictures predictively encoded in dependence on the previous pictures in the data stream, the data streams including quantised source access pictures interspersed at predetermined periods in the picture series, wherein the method of encoding the quantised source access pictures including the steps of :

encoding picture as a predicted picture; and

, if no information about an area of a picture is indicated in the encoded predicted picture, setting the quantiser index to a fine quantisation value when encoding as a quantised source access picture.