Synchronization of audio streams and sampling rate for wireless communication

Abstract

Disclosed herein, among other things, are methods and apparatus for providing a time-stamp based controller for synchronization of sink or source sampling rate with external packet rate. A method for wireless communications includes receiving a transmission of a packet using a wireless transceiver of an electronic device, and using a processor of the electronic device to read a first value of a system timer and store the first value as an arrival time-stamp. The packet is decoded and processed by the processor, and sent to an output. When the processed packet is sent, a second value of the system timer is read, adjusted and stored as a departure time-stamp. The arrival time-stamp and the departure time-stamp are used to calculate an adjustment stimulus for a sample rate actuator of the electronic device. The sample rate actuator is configured to maintain synchronization of sampling rate with an external packet rate.

What is claimed is: 
     
         1 . A method for wireless communications, comprising:
 receiving a transmission of a packet using a wireless transceiver of an electronic device;   using a processor of the electronic device to read a first value of a system timer and storing the first value as an arrival time-stamp;   decoding and processing the packet using the processor;   sending the processed packet to an output of the electronic device;   when the processed packet is sent, reading a second value of the system timer;   adjusting the second value and storing the adjusted second value as a departure time-stamp; and   using the arrival time-stamp and the departure time-stamp to calculate an adjustment stimulus for a sample rate actuator of the electronic device, the sample rate actuator configured to maintain synchronization of sampling rate with an external packet rate.   
     
     
         2 . The method of  claim 1 , wherein adjusting the second value includes using a multi-sample block direct memory access (DMA) transfer. 
     
     
         3 . The method of  claim 1 , wherein adjusting the second value includes using a fractional delay sampling rate converter (FD SRC) as the sample rate actuator. 
     
     
         4 . The method of  claim 3 , comprising calculating two phase increment values for sink and source FD SRC instances. 
     
     
         5 . The method of  claim 1 , further comprising synchronizing an audio stream in a relay device. 
     
     
         6 . The method of  claim 1 , further comprising tracking processing time and automatically reconfiguring a value of the device group delay in order to minimize total system throughput delay. 
     
     
         7 . The method of  claim 1 , wherein using a wireless transceiver of an electronic device includes using a wireless transceiver of a hearing device. 
     
     
         8 . The method of  claim 7 , wherein the hearing device includes a hearing assistance device. 
     
     
         9 . The method of  claim 8 , wherein the hearing assistance device includes a hearing aid. 
     
     
         10 . The method of  claim 8 , wherein the hearing assistance device includes a cochlear implant. 
     
     
         11 . A method for bidirectional wireless communications, comprising:
 receiving a transmission of a packet using a wireless transceiver of an electronic device;   calculating an incoming fractional delay (FD) using a FD sampling rate converter (SRC), the FD SRC configured to synchronize sample rate of the device with an external packet rate; and   using the incoming FD and current phase increment value of the FD SRC to calculate an outgoing FD, to provide a one-to-one relation between incoming and outgoing packets for the device.   
     
     
         12 . The method of  claim 11 , wherein calculating the incoming FD and the outgoing FD includes using a single FD SRC module. 
     
     
         13 . The method of  claim 11 , wherein using the incoming FD and current phase increment value of the FD SRC to calculate an outgoing FD prevents outgoing buffer overflow and underflow. 
     
     
         14 . The method of  claim 11 , wherein, if zero samples were copied from an incoming input buffer to a history buffer, an outgoing interpolator reads one sample from in outgoing input buffer to the history buffer of the outgoing interpolator, but does not produce any output samples. 
     
     
         15 . The method of  claim 14 , wherein, if more than one sample was copied, the outgoing interpolator reads one sample from the outgoing input buffer to the history buffer of the outgoing interpolator, and generates the same number of outgoing output samples. 
     
     
         16 . The method of  claim 11 , wherein a sample rate of an outgoing audio stream is synchronized with external packet rate and interpolator parameters for an incoming audio sample are calculated from the interpolator parameters for the outgoing audio stream. 
     
     
         17 . The method of  claim 11 , wherein using a wireless transceiver of an electronic device includes using a wireless transceiver of a hearing device. 
     
     
         18 . The method of  claim 17 , wherein the hearing device includes a hearing assistance device. 
     
     
         19 . The method of  claim 18 , wherein the hearing assistance device includes a hearing aid. 
     
     
         20 . The method of  claim 18 , wherein the hearing assistance device includes a cochlear implant.