Software based audio timing and synchronization
Synchronization of plural outputs of data transported by a wireless network is facilitated by bandlimiting a sample clock signal controlling a rate at which data is processed by the network's devices and/or bandlimiting wall time data controlling the real time for presenting a datum.
1. An audio system comprising:
(a) a first listener including:
(i) a wall clock maintaining a wall time for occurrence of an event, said wall time updated by data transmitted by a master clock and received by said first listener;
(ii) a sample clock recoverer retrieving a sample clock from data received by said first listener from a talker, said sample clock regulating a processing rate for a datum included in said data received from said talker; and
(iii) a frequency filter bandlimiting said sample clock output by said sample clock recoverer, wherein said frequency filter comprises an estimator connected to receive said sample clock output by said sample clock recoverer; and
(iv) a transmitter transmitting said bandlimited sample clock; and
(b) a second listener arranged to receive said transmitted bandlimited sample clock and use said bandlimited sample clock to regulate processing data received from said talker.
2. The audio system of claim 1 wherein the first listener further comprises a frequency filter attenuating a frequency of said updating data received from said master clock.
3. The audio system of claim 2 wherein said updating data received from said master clock comprises a timing synchronization function datum.
4. The audio system of claim 2 wherein said updating datum received from said master clock comprises a precision time protocol datum.
5. An audio system comprising:
(a) a first listener including:
(i) a wall clock maintaining a wall time for occurrence of an event, said wall time updated by a data transmitted by a master clock and received by said first listener;
(ii) a frequency filter bandlimiting said updating data received from said master clock and said wall time, wherein said frequency filter comprises an estimator connected to receive said updating data by said sample clock recoverer; and
(iii) a sample clock recoverer retrieving a sample clock from data received by said first listener from a talker, said sample clock regulating a processing rate for a datum included in said data received from said talker; and
(iv) a transmitter transmitting said bandlimited wall time; and
(b) a second listener arranged to receive said bandlimited wall time and to use said bandlimited wall time to recover a sample clock from data received from said talker.
6. The audio system of claim 5 wherein said updating data received from said master clock comprises a timing synchronization function datum.
7. The audio system of claim 5 wherein said updating datum received from said master clock comprises a precision time protocol datum.
8. A method of recovering audio timing in a network, the method comprising the steps of:
(a) bandlimiting a raw wall time signal about a mean frequency of the raw wall time signal by estimating the frequency and delay of the raw wall time signal to a talker transmitter audio clock; and
(b) including timing datum in a data packet about the mean frequency of said timing signal from the estimate of the frequency and delay of said timing signal and an audio playtime at the transmitter; and
(c) bandlimiting said raw wall time signal about the mean frequency of said raw wall time signal by estimating the frequency and delay of said raw wall time signal to a listener receiver audio clock; and
(d) combining both wall time estimation and received timing datum estimation from a packet to generate audio play time at the receiver; and
(e) using the playtime to generate coefficients for a polynomial interpolator that resamples the audio to the receiver audio clock.
9. A method of recovering audio timing in a network, the method comprising the steps of:
(a) bandlimiting a raw wall time signal about a mean frequency of the raw wall time signal by estimating the frequency and delay of the raw wall time signal to the listener receiver audio clock;
(b) estimating the frequency and delay of this wall time signal to the transmitter audio clock by the talker transmitter requesting a copy of the wall time signal from the receiver and bandlimiting about a mean frequency of this wall time signal by;
(c) including timing datum in a data packet about the mean frequency of said timing signal from the estimate of the frequency and delay of said timing signal and an audio playtime at the transmitter; and
(d) combining both wall time estimation and received timing datum estimation from a packet to generate audio play time at the receiver; and
(e) using the playtime to generate coefficients for a polynomial interpolator that resamples the audio to the receiver audio clock.
10. A method of recovering audio timing in a network, the method comprising the steps of:
(a) bandlimiting a raw wall time signal about a mean frequency of the raw wall time signal by estimating the frequency and delay of the raw wall time signal to the talker transmitter audio clock;
(b) including timing datum in a data packet about the mean frequency of said timing signal from the estimate of the frequency and delay of said timing signal and an audio playtime at the transmitter;
(c) estimating the frequency and delay of this wall time signal to the receiver audio clock by the listener receiver requesting a copy of the wall time signal from the transmitter and bandlimiting about a mean frequency of this wall time signal; and
(d) combining both wall time estimation and received timing datum estimation from a packet to generate audio play time at the receiver; and
(e) using the playtime to generate coefficients for a polynomial interpolator that resamples the audio to the receiver audio clock.
11. A method of recovering audio timing in a network, the method comprising the steps of:
(a) bandlimiting a raw wall time signal about a mean frequency of the raw wall time signal by estimating the frequency and delay of the raw wall time signal to a talker transmitter audio clock; and
(b) including timing datum in a data packet about the mean frequency of said timing signal from the estimate of the frequency and delay of said timing signal and an audio playtime at the transmitter; and
(c) bandlimiting said raw wall time signal about the mean frequency of said raw wall time signal by estimating the frequency and delay of said raw wall time signal to a listener receiver audio clock; and
(d) combining both wall time estimation and received timing datum estimation from a packet to generate audio play time at the receiver; and
(e) using the playtime to generate coefficients for a fractional delay filter that resamples the audio to the receiver audio clock.
12. A method of recovering audio timing in a network, the method comprising the steps of:
(a) bandlimiting a raw wall time signal about a mean frequency of the raw wall time signal by estimating the frequency and delay of the raw wall time signal to the listener receiver audio clock;
(b) estimating the frequency and delay of this wall time signal to the transmitter audio clock by the talker transmitter requesting a copy of the wall time signal from the receiver and bandlimiting about a mean frequency of this wall time signal by;
(c) including timing datum in a data packet about the mean frequency of said timing signal from the estimate of the frequency and delay of said timing signal and an audio playtime at the transmitter; and
(d) combining both wall time estimation and received timing datum estimation from a packet to generate audio play time at the receiver; and
(e) using the playtime to generate coefficients for a fractional delay filter that resamples the audio to the receiver audio clock.
13. A method of recovering audio timing in a network, the method comprising the steps of:
(a) bandlimiting a raw wall time signal about a mean frequency of the raw wall time signal by estimating the frequency and delay of the raw wall time signal to the talker transmitter audio clock;
(b) including timing datum in a data packet about the mean frequency of said timing signal from the estimate of the frequency and delay of said timing signal and an audio playtime at the transmitter;
(c) estimating the frequency and delay of this wall time signal to the receiver audio clock by the listener receiver requesting a copy of the wall time signal from the transmitter and bandlimiting about a mean frequency of this wall time signal; and
(d) combining both wall time estimation and received timing datum estimation from a packet to generate audio play time at the receiver; and
(e) using the playtime to generate coefficients for a fractional delay filter that resamples the audio to the receiver audio clock.