Gateway with voice
In one aspect of the present invention, a network gateway is configured to facilitate on line and off line bi-directional communication between a number of near end data and telephony devices with far end data termination devices via a hybrid fiber coaxial network and a cable modem termination system. The described network gateway combines a QAM receiver, a transmitter, a DOCSIS MAC, a CPU, a voice and audio processor, an Ethernet MAC, and a USB controller to provide high performance and robust operation.
1. An apparatus for synchronizing voice data, comprising:
a first voice queue configured to store samples of the voice data to provide a first stored voice sample;
a voice synchronizer configured to up-sample the first stored voice sample from the first voice queue by a ratio of a first count to a second count when the first count is greater than the second count, and to down-sample the first stored voice sample by a second ratio of the second count to the first count when the first count is less than or equal to the second count to provide a re-sampled voice sample;
a second voice queue configured to store the re-sampled voice sample as a second stored voice sample; and
a digital to analog converter (DAC) configured to convert the second stored voice sample from the second voice queue from a digital representation to an analog representation,
wherein the apparatus is configured such that a rate at which the DAC removes the second stored voice sample is substantially equivalent to a rate at which the second stored voice sample is inserted into the second voice queue.
2. The apparatus of claim 1 , wherein the voice synchronizer is configured to compensate for a delay.
3. The apparatus of claim 1 , wherein the voice synchronizer is further configured to compensate for a lost voice sample using synthesized voice.
4. The apparatus of claim 1 , wherein the voice synchronizer is further configured to insert synthesized voice if a data underflow condition occurs.
5. The apparatus of claim 4 , wherein the data underflow condition occurs when the rate at which the DAC removes the second stored sample is substantially greater than a second rate at which the first voice sample is inserted into the first voice queue.
6. The apparatus of claim 1 , wherein the voice synchronizer is further configured to delete a sample of the voice data if a data overflow condition occurs.
7. The apparatus of claim 6 , wherein the data overflow condition occurs when the rate at which the DAC removes the second stored sample is substantially less than a second rate at which the first voice sample is inserted into the first voice queue.
8. The apparatus of claim 1 , wherein the voice synchronizer is further configured to re-sample the first stored voice sample by fractionally decimating the first stored voice sample if a data overflow condition occurs.
9. The apparatus of claim 1 , wherein the voice synchronizer is further configured to re-sample the first stored voice sample by fractionally interpolating the first stored voice sample if a data underflow condition occurs.
10. A method for synchronizing digital audio data, the method comprising:
storing a first plurality of digital audio samples in a first queue, wherein the first plurality of digital audio samples are characterized as being associated with a first rate;
sampling the first plurality of digital audio samples from the first voice queue to provide a second plurality of digital audio samples, the second plurality of digital audio samples being characterized as being associated with a second rate, the sampling including:
up-sampling the first plurality of digital audio samples from the first voice queue by a ratio of the first rate to the second rate when the first rate is greater than the second rate; and
down-sampling the first plurality of digital audio samples by a second ratio of the second rate to the first rate when the first rate is less than or equal to the second rate;
storing the second plurality of digital audio samples in a second queue; and
converting the second plurality of digital audio samples to an analog audio signal at the second rate.
11. The method of claim 10 , wherein the sampling further includes:
compensating for a delay.
12. The method of claim 10 , wherein the sampling further includes:
compensating for a lost audio sample using a synthesized audio sample.
13. The method of claim 10 , wherein the sampling further includes:
inserting a synthesized audio sample if a data underflow condition occurs.
14. The method of claim 13 , wherein the data underflow condition occurs when the second rate is greater than the first rate.
15. The method of claim 10 , wherein the sampling further includes:
deleting digital audio samples in the first plurality of digital audio samples if a data overflow condition occurs.
16. The method of claim 15 , wherein the data overflow condition occurs when the second rate is less than the first rate.
17. The method of claim 10 , wherein the sampling further includes:
fractionally decimating the first plurality of digital audio samples during a data overflow condition.
18. The method of claim 10 , wherein the sampling further includes:
fractionally interpolating the first plurality of digital audio samples during a data underflow condition.