Data streaming system and method

• US 8,135,852 B2
• Filed: 03/27/2003
• Issued: 03/13/2012
• 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: Nilsson, Michael E, Jebb, Timothy R
• Primary Examiner(s): Moise, Emmanuel L
• Assistant Examiner(s): Kim, Edward
• Application Number:
  US10/507,826
• Publication Number:
  US 20050172028A1
• Time in Patent Office: 3,274 Days
• Field of Search: 709230-236
• 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 typically use a server arranged to stream one of a plurality of encoded data streams to a client. Each of the plurality of data streams may be an independent representation of a common data source encoded at a different resolution to the other of the plurality of data streams. The server can include a transmitter and a first buffer. The transmitter can be arranged to transmit data packets of the encoded data stream to the client via the first buffer. The transmitter can be arranged to monitor the content of the first buffer and switch to transmit another of the plurality of data streams in the event that predetermined criteria are detected from the first buffer.

Claims

1. A data streaming system comprising:

a server arranged to stream one of a plurality of encoded data streams to a client, each of the plurality of data streams being a representation of a common data source encoded at a different resolution from the other(s) of the plurality of data streams;

the server comprising a transmitter and a first buffer, the transmitter being arranged to transmit data packets of the encoded data stream to the client via the first buffer and to remove a data packet from the first buffer upon acknowledgement by the client of receipt of the packet, wherein the transmitter includes means arranged to estimate the playing duration represented by the contents of data buffered at the client and switch to transmit another of the plurality of data streams in the event that the estimated playing duration meets predetermined criteria;

wherein the transmitter monitors the content of the first buffer and the estimate of playing duration is determined in dependence on the contents of the first buffer and on an estimation, made by the transmitter, of the number of packets decoded by the client.

2. A system according to claim 1, wherein the first buffer includes a minor buffer storing data on packets in the first buffer, the transmitter being arranged to monitor the content of the first buffer using the data in the mirror buffer.

3. A system according to claim 1, further comprising a plurality of transmitters, each communicating with a respective client via a respective first buffer to transmit one of the plurality of data streams determined in dependence on respective predetermined criteria.

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

5. A system according to claim 4, wherein the transmitter is arranged to multiplex audio packets and video packets within the transmission of data packets.

6. A system according to claim 5, wherein neighboring audio and video packets represent audio and video information representing audio and video events occurring at the same time.

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

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

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

10. A system according to claim 9, further comprising a plurality of buffers, wherein the encoder is arranged to output each encoded data stream into a respective one of the plurality of buffers, the transmitter being arranged to obtain data packets for a respective data stream from its respective one of the plurality of buffers.

11. A system according to claim 1, wherein the server includes a file source storing the plurality of encoded data streams.

12. A data streaming system according to claim 1, further comprising a client with a receiving buffer, wherein the client is arranged to store received data packets in the receiving buffer and to acknowledge receipt to the server.

13. A system according to claim 12, wherein the packets include packet sequence data, the client being arranged to request retransmission of non-received packets based on the sequence data, the server being arranged to retransmit a packet from the first buffer upon receipt of a retransmission request.

14. A method of streaming one of a plurality of encoded data streams to a client, each of the plurality of data streams being a representation of a common data source encoded at a different resolution from the other(s) of the plurality of data streams, the method comprising:

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

removing a data packet from the first buffer upon acknowledgment by the client of receipt of the packet;

estimating, at the transmitter, the playing duration represented by the contents of data buffered at the client, in dependence on the contents of the first buffer and on an estimation, made by the transmitter, of the number of packets decoded by the client, and

switching to transmit another of the plurality of data streams in the event that the estimated playing duration meets predetermined criteria.

15. A method according to claim 14, 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.

16. A method according to claim 14, wherein the predetermined criteria include an amount of data determined to be buffered at client.

17. A method according to claim 14 wherein the predetermined criteria include one or more network throughput thresholds.

18. A method according to claim 17, wherein network throughput is calculated by:

counting the number of bytes passed to the first buffer;

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

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

19. A method according to claim 18, further comprising the step of measuring network throughput over more than one interval to determine throughput variation.

20. A method according to claim 18, wherein the predetermined criteria include determination of network throughput sufficient to sustain another of the plurality of the data streams.

21. A method according to claim 18, further comprising 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.

22. A method according to claim 14, 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 quantized source access pictures interspersed at predetermined periods in the picture series, and wherein the method of encoding the quantized source access pictures includes:

encoding picture as a predicted picture; and

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

24. A method according to claim 14 wherein the data stream is encoded video data.

25. A method according to claim 24, wherein the transmitter multiplexes audio packets and video packets within the transmission of data packets.

26. A method according to claim 25, wherein neighboring audio and video packets represent audio and video information representing audio and video events occurring at the same time.

23. A tangible non-transitory computer program storage medium containing computer program code which, when executed by a computer, performs the steps of streaming one of a plurality of encoded data streams to a client, each of the plurality of data streams being a representation of a common data source encoded at a different resolution from the other(s) of the plurality of data streams, the steps comprising:

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

removing a data packet from the first buffer upon acknowledgement by the client of the receipt of the packet;

estimating, at the transmitter, the playing duration represented by the contents of data buffered at the client, in dependence on the contents of the first buffer and on an estimation, made by the transmitter, of the number of packets decoded by the client, and

switching to transmit another of the plurality of data streams in the event that the estimated playing duration meets predetermined criteria.