Method and apparatus for reducing packet data mixer delay
View Patent ↗The present invention is directed to the reduction of delays introduced in connection with packet data mixing operations. In particular, in accordance with an embodiment of the present invention, communication endpoints providing packet data to a mixer are provided with packetization time adjustment information, in order to synchronize the arrival times of data from different communication endpoints. The packetization time adjustment information may be in the form of an amount of time or number of samples by which the endpoints packetization time should be shifted. The packetization time adjustment information may be provided as additional header information provided as part of a packet containing data transmitted to a communication endpoint from the mixer.
1. A method for minimizing packet data mixer delay, comprising:
receiving at a packet data mixer at least a first data packet sent from a first communication endpoint and a second data packet sent from a second communication endpoint;
determining a relative arrival time of the at least first and second data packets at the packet data mixer;
generating in the packet data mixer a signal;
sending the signal to the first communication endpoint, wherein the signal instructs the first communication endpoint to adjust a packetization time by a first amount, and wherein the first time amount is determined from the relative arrival times of the first and second data packets; and
in response to the signal, adjusting in the first communication endpoint the packetization time by the first amount, wherein as a result of adjusting in the first communication endpoint the packetization time the relative arrival time of a third data packet sent from the first communication endpoint and a fourth data packet sent from the second communication endpoint at the packet data mixer is changed as compared to the arrival time of the first and second data packets.
2. The method of claim 1 , wherein the step of generating and sending the signal comprises inserting within a data packet sent from said packet data mixer to the first communication endpoint an instruction to the first communication endpoint to adjust the packetization time.
3. The method of claim 1 , wherein the first and second data packets are received by the packet data mixer during a first packetization period.
4. The method of claim 1 , wherein the step of determining a relative arrival time comprises determining an amount of time between the receipt of the first data packet received within a first packetization period and the second data packet received during said first packetization period.
5. The method of claim 4 , wherein the second data packet comprises a last data packet received during the first packetization period.
6. The method of claim 4 , wherein the step of signaling comprises signaling the first communication endpoint to adjust a packetization time by an amount about equal to one-half the time between the receipt of the first data packet and the second data packet.
7. The method of claim 1 , wherein the step of signaling further comprises instructing the second communication endpoint to adjust a packetization time by a second amount.
8. The method of claim 1 , further comprising:
selecting a standard packetization time, wherein the step of signaling comprises instructing the first communication endpoint to adjust a packetization time by an amount about equal to a difference between the packetization time and an arrival time of a data packet received from the sending device.
9. The method of claim 8 , wherein the standard packetization time is selected as a mid-point between a time at which the first data packet is received during a packetization period and a time at which the second data packet is received during the packetization period, wherein the second data packet is a last data packet received during the packetization period.
10. The method of claim 9 , wherein the standard packetization time is selected as a time of arrival of an intermediate data packet, wherein the intermediate data packet is received after the first data packet and before the second data packet.
11. The method of claim 1 , wherein the first data packet is received as part of a super packet.
12. The method of claim 1 , wherein the first communication endpoint comprises a telephone.
13. The method of claim 1 , wherein the packet data mixer comprises at least one of a voice data conferencing device and a realtime transport protocol multiplexer.
14. The method of claim 2 , wherein the first communication endpoint and the second communication endpoint are sending data packets to one another as part of a real time communication, and wherein the data packet in which the packet data mixer inserts the signal is a data packet that includes data for transmission from the second communication endpoint to the first communication endpoint as part of the real time communication.
15. A method for synchronizing data packets, comprising:
receiving from a first communication endpoint a first received data packet;
receiving from a second communication endpoint a second received data packet;
determining a synchronized packetization time;
determining and generating at least a first packetization time adjustment instruction; and
sending a first sent data packet to the first communication endpoint, wherein the first sent data packet includes data from at least the second received data packet and the at least a first packetization time adjustment instruction, wherein in response to the packetization time adjustment instruction the first communication endpoint changes the time at which the first communication endpoint forms a data packet relative to a packetization period.
16. The method of claim 15 , wherein the step of determining at least a first packetization time adjustment instruction comprises calculating a difference between the synchronized packetization time and an actual arrival time of the first received data packet.
17. The method of claim 16 , wherein in response to a receipt of the first sent data packet, the first communication endpoint adjusts a first communication endpoint packetization time by an amount indicated by the at least a first packetization time adjustment instruction.
18. The method of claim 17 , wherein the first received data packet comprises a first quantity of data, and wherein a data packet formed by the first communication endpoint following the receipt of the first sent data packet contains a second quantity of data.
19. The method of claim 16 , further comprising:
sending a second sent data packet comprising data from the first received data packet and at least a second packetization time adjustment to the second communication endpoint, wherein the step of determining a packetization time adjustment instruction further comprises calculating a difference between the synchronized packetization time and an actual arrival time of said second received data packet.
20. The method of claim 15 , wherein the step of determining a synchronized packetization time comprises determining an average arrival time of the first and second received data packets.
21. The method of claim 15 , wherein the first packetization time adjustment instruction comprises an instruction to shift a packetization time by at least a first predetermined unit of time forward or by at least a first predetermined unit of time back.
22. An apparatus for mixing data packets, comprising:
a communication interface, operable to place the apparatus in communication with a plurality of communication devices; and
a processor operable to perform instructions, the instructions including instructions for:
determining within a first packetization period a relative time of arrival of data packets received from the plurality of communication devices;
forming a super packet containing some of the data packets;
generating an instruction to at least one of the communication devices to adjust a packetization time, wherein the instruction is included in the super packet; and
sending the super packet to the at least one of the communication devices to instruct the at least one communication device to adjust a relative packetization time.
23. The apparatus of claim 22 , wherein the apparatus comprises a router.
24. The apparatus of claim 22 , wherein said communication devices comprise telephony devices.
25. An apparatus for mixing data packets with reduced delay, comprising:
means for receiving data packets from at least first and second communication devices;
means for determining a relative arrival time of a first data packet received from said first communication device and a second data packet received from said second communication device; and
means for signaling to at least the first communication device a packetization time adjustment signal derived from the relative time of arrival of the first and second data packets, wherein in response to receiving the packetization time adjustment signal the first communication device adjusts a relative packetization time.
26. The apparatus of claim 25 , further comprising:
means for aggregating data received from a plurality of communication devices into a super packet, wherein said super packet includes said packetization time adjustment signal.
27. The apparatus of claim 26 , further comprising:
means for transmitting said super packet to at least the second communication device.