Message Synchronization Over A Stochastic Network

• US 20100118888A1
• Filed: 01/25/2010
• Published: 05/13/2010
• Est. Priority Date: 08/30/2004
• Status: Active Grant

• Current Assignee: Harmonic Incorporated
• Original Assignee: Harmonic Incorporated
• Inventors: KOREN, NOAM, PICCO, MARTIN RAPTIS
• Granted Patent: US 8,396,159 B2
• Time in Patent Office: Days
• US Class Current: 370/468
• CPC Class Codes: H04J 3/0632 Synchronisation of packets and cells, e.g. transmission of voice via a packet network, circuit emulation service [CES] queuing arrangements in packet switching elements H04L49/90; synchronising systems for the synchronous transmission of a pulse code modulated video signal with one or more other pulse code modulated signals H04N7/56
• CPC Class Codes: H04J 3/0682 by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/263 Rate modification at the source after receiving feedback
• CPC Class Codes: H04L 47/28 in relation to timing considerations
• CPC Class Codes: H04L 47/43 Assembling or disassembling of packets, e.g. segmentation and reassembly [SAR]

Abstract

Methods and apparatus to communicate between a local component and a remote component, where the local component is connected to the remote component using a non-deterministic communication link. A local clock is synchronized with a remote clock to within a maximum offset. A rate message from the remote component is received at the local component, where the rate message includes a first time stamp. A data rate is adjusted using the rate message when the time of the local clock substantially matches a time determined using the first time stamp. A data message is sent to the remote component using the adjusted data rate, where the data message includes a second time stamp for use in processing data in the data message. In some implementations, the time determined using the first time stamp is also determined using information about a communication link delay and/or a clock offset.

Claims

1. A method comprising:

sending an encoded message associated with an input signal from a first device to a second device;

receiving a time-stamped message containing recommended encoding information from and timing information associated with the second device in response to the encoded message; and

adjusting a data rate associated with the input signal based on the timing information and the recommended encoding information.

2. The method of claim 1, where receiving the time-stamped message includes receiving new bitrate information as the recommended encoding information for adjusting the data rate associated with the input signal;

and

where adjusting the data rate associated with the input signal includes adjusting the data rate using the new bitrate information.

3. The method of claim 1, where adjusting the data rate includes adjusting a level of compression applied to the input signal

4. The method of claim 1, where sending the encoded message includes sending a complexity message containing an identification number associated with the first device and information associated with a last time-stamped message received from the second device before sending the encoded message.

5. The method of claim 4, where sending the complexity message further includes sending the complexity message containing a minimum rate and a maximum bitrate at which the first device encodes the input signal.

6. The method of claim 1, where sending the encoded message includes sending a complexity message containing information indicative of a bitrate or number of bits required to encode the input signal at a given level of quality.

7. The method of claim 1, where sending the encoded message includes sending a complexity message containing timing information indicative of a time at which the complexity message is sent by the first device or a time at which the complexity message is to be processed by the second device.

8. The method of claim 7, where sending the complexity message further includes sending the complexity message containing at least one of a maximum network delay associated with a network connecting the first device to the second device and a maximum negative offset indicative of a time value associated with a local time of the first device being behind a local time of the second device.

9. The method of claim 1, further comprising sending the input signal with the adjusted data rate in a new encoded message to the second device if a time at which the new encoded message as received by the second device is equal to or less than a time indicated by the timing information associated with the second device.

10. The method of claim 1, where receiving the time-stamped message includes receiving the recommended encoding information having been determined using historical data associated with prior encoded messages sent by the first device.

11. The method of claim 1, where receiving the time-stamped message includes receiving the timing information indicative of a time at which the time-stamped message is transmitted by the second device or a time at which the time-stamped message is to be processed by the first device.

12. The method of claim 11, where receiving the time-stamped message further includes receiving the time-stamped message containing at least one of a maximum network delay associated with a network connecting the first device to the second device and a maximum positive offset indicative of a time value associated with a local time of the first device being ahead of a local time of the second device.

13. The method of claim 1, where adjusting the data rate associated with the input signal is performed only if a time at which the time-stamped message as received by the first device is equal to or less than a time indicated by the timing information associated with the second device.

14. The method of claim 1, where receiving the time-stamped message includes receiving the time-stamped message containing an identification number associated with the first device, and a message number associated with the time-stamped message.

15. The method of claim 1, where adjusting the data rate associated with the input signal is performed after a buffer period.

16. The method of claim 15, where adjusting the data rate associated with the input signal after the buffer period includes adjusting the data rate when local timing information associated with the first device matches the timing information associated with the second device to allow the input signal with the adjusted data rate to be received by the second device in time for output processing.

17. The method of claim 1, further comprising:

queuing the recommended encoding information; and

applying the queued recommended encoding information for a future input signal.

18. The method of claim 1, where sending the encoded message includes sending the encoded message that corresponds to a first segment of the input signal;

and

where receiving the time-stamped message includes receiving the time-stamped message corresponding to the first segment of the input signal.

19. The method of claim 18, further comprising processing a remaining segment of the input signal including sending a new encoded message that corresponds to the remaining segment of the input signal to the second device while waiting for the time-stamped message corresponding to the first segment to be received from the second device.

20. The method of claim 1, where adjusting the data rate associated with the input signal is performed only at a time as indicated in the timing information associated with the second device.

21. A method comprising:

sending a message including timing information from a processing device to an encoding device;

receiving a data message including a time stamp from the encoding device; and

processing data included in the data message based on the time stamp including determining when to place the data in an output stream.

22. The method of claim 21, where receiving the data message includes receiving an encoded message encoded using an adjusted data rate determined based on the timing information.

23. The method of claim 21, where receiving the data message includes receiving the time stamp indicative of a time at which the data message is sent by the encoding device.

24. The method of claim 23, where determining when to place the data in the output stream includes determining when to place the data in the output stream based on the time at which the data message is sent and at least one of a network delay and an offset associated with a timing difference between a local time of the encoding device and a local time of the processing device.

25. The method of claim 21, where sending the message includes sending a broadcast message to a plurality of encoding devices including the encoding device, the broadcast message including a time stamp and one of an individual bitrate for each encoding device or a single bitrate to be implemented by the plurality of encoding devices.

26. The method of claim 25, where receiving the data message includes receiving a plurality of data messages from the plurality of encoding devices including the encoding device at the individual bitrate or single bitrate, the method further comprising:

combining data in the plurality of data messages into a multiplexed output stream.

27. A system comprising:

one or more encoding devices for processing data using one or more bitrates; and

a multiplexer in communication with the one or more encoding devices using one or more messages, the one or more messages containing a time stamp and transmission characteristic information that allows the one or more encoders to adjust the one or more bitrates for encoding the data such that data encoded with the one or more adjusted bitrates by the one or more respective encoding devices arrive in time to be placed in an output stream within a time limit as determined based on the time stamp.