System and method for voice Playout in an asynchronous packet network
First Claim
1. A System for Voice Playout in an Asynchronous Packet Network comprising:
- (a) a transmitting unit comprising a transmitting clock;
(b) a receiving unit comprising a receiving clock and a FIFO voice codeword storing device having a fill status; and
(c) an incoming packet sequence stream comprising the fill status of said FIFO voice codeword storing device which is transmitted from said transmitting unit to said receiving unit, wherein said incoming packet sequence stream synchronizes said transmitting unit'"'"'s transmitting clock with said receiving unit'"'"'s receiving clock by detecting said fill status.
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Accused Products
Abstract
A System for Voice Playout in an Unsynchronized Packet Network for use with isochronous and asynchronous data transmission over a communication network having at least one receiving unit and at least one transmitting unit each having independent clocks. A FIFO voice codeword storing device in the receiving unit removes timing jitter from incoming packets--and receives voice packets from a data network. A phase continuous packet clock thereafter removes packets from the FIFO voice codeword storing device which is synchronized to the incoming data rate using the fill status of the FIFO voice codeword storing device as a frequency control signal. A continuous phase resampler removes timing frequency offset without causing packet slips or loss of data. The transmitter inserts the contents of a free running packet counter into each transmitted packet, allowing the receiver to detect lost packets and to properly reproduce silence intervals during Playout. A receive sequence counter increments at the local packet rate to schedule Playouts for multiple voice segments. A clock frequency recovery is utilized where the receiver clock frequency differs from the transmitter clock frequency. When the receive clock is not available, such as voice over packet networks applications, the FIFO voice codeword storing device fill status can control the resampling rate.
152 Citations
20 Claims
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1. A System for Voice Playout in an Asynchronous Packet Network comprising:
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(a) a transmitting unit comprising a transmitting clock; (b) a receiving unit comprising a receiving clock and a FIFO voice codeword storing device having a fill status; and (c) an incoming packet sequence stream comprising the fill status of said FIFO voice codeword storing device which is transmitted from said transmitting unit to said receiving unit, wherein said incoming packet sequence stream synchronizes said transmitting unit'"'"'s transmitting clock with said receiving unit'"'"'s receiving clock by detecting said fill status. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of transmitting and recovering data in a System for Voice Playout in an Asynchronous Packet Network comprising:
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(a) inserting a sequence scheme into incoming packet sequence streams, wherein said incoming packet sequence streams have an incoming data rate; (b) transmitting said incoming packet sequence streams from a transmitting unit; (c) receiving said incoming packet sequence streams into a receiving unit; (d) analyzing said incoming packet sequence streams in said receiving unit; (e) removing timing jitter from said incoming packet sequence streams; (f) synchronizing said incoming packet sequence streams received in said receiving unit with said incoming packet sequence streams that were transmitted from said transmitting unit by using the fill status of a FIFO voice codeword storing device; and (g) playing said synchronized incoming packet sequence streams at playout. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method of transmitting and recovering data in a System for Voice Playout in an Asynchronous Packet Network comprising:
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(a) entering a wait for first segment state; (b) receiving an incoming packet sequence stream from a FIFO voice codeword storing device, having a fill status, an incoming data rate, and a sequence number; (c) entering a play segment, wherein the performance of a receiving unit'"'"'s clock frequency recovery rate is rendered in said play segment state by using the fill status of the FIFO voice codeword storing device; (d) emptying said incoming packet sequence stream from a voice codeword FIFO for synchronized data playout; and (e) entering a wait for next segment state to wait for a next incoming packet sequence stream. - View Dependent Claims (18, 19)
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20. A method of transmitting and recovering data in a System for Voice Playout in an Asynchronous Packet Network comprising:
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(a) an incoming packet sequence stream entering a D/A, said D/A having a frequency clocked at a local sample rate; (b) routing incoming packet sequence stream from said D/A to an echo canceler; (c) feeding said incoming packet sequence stream from said echo canceler into a voice encoder; (d) feeding said incoming packet sequence stream from said voice encoder into a data network; (e) receiving said incoming packet sequence stream from said data network into a voice sample FIFO, said voice sample FIFO having a frequency clocked at a far end sample rate; (f) removing said incoming packet sequence stream from said voice sample FIFO into a resampler; (g) synchronizing said incoming packet sequence stream in said sample local clock rate; (h) allowing said incoming packet sequence stream to enter said echo canceler at said sample local clock rate; and (i) permitting said incoming packet sequence stream to enter a D/A at said sample local clock rate for synchronized Playout.
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Specification