Schemes capable of synchronizing native clocks and audio codec clocks of audio playing for bluetooth wireless devices

Abstract

A method utilized in a wireless device used to wirelessly receive and play audio information includes: receiving a data packet stream transmitted from an audio source; monitoring a data amount of at least one buffer of a memory of the wireless device; and tuning an audio clock frequency dedicated for playing audio samples if the data amount of the at least one buffer deviates from a specific data amount level.

What is claimed is: 
     
         1 . A method utilized in a wireless device used to wirelessly receive and play audio information, comprising:
 receiving a data packet stream transmitted from an audio source;   monitoring a data amount of at least one buffer of a memory of the wireless device; and   tuning an audio clock frequency dedicated for playing audio samples if the data amount of the at least one buffer deviates from a specific data amount level.   
     
     
         2 . The method of  claim 1 , wherein the wireless device is used as a primary Bluetooth device to be wirelessly connected to the audio source and can be used to be wireless connected to a secondary Bluetooth device, and the method further comprises:
 sending audio clock trimming information from the primary Bluetooth device to the secondary Bluetooth device to control both of the primary Bluetooth device and the secondary Bluetooth device to adjust corresponding audio clock frequencies to a target audio clock frequency, before tuning the audio clock frequency of the primary Bluetooth device.   
     
     
         3 . The method of  claim 1 , wherein the memory comprises an audio codec buffer, and the monitoring step comprises:
 monitoring an audio sample amount of the audio codec buffer;   increasing the audio clock frequency if a value of the monitored audio sample amount is higher than a specific audio sample amount level; and   decreasing the audio clock frequency if the value of the monitored audio sample amount is lower than the specific audio sample amount level.   
     
     
         4 . The method of  claim 1 , wherein the memory comprises an audio packet buffer for storing audio packet(s), and the monitoring step comprises:
 monitoring a data amount of the audio packet buffer to calculate a first average value of a first data amount in a first time period;   monitoring the data amount of the audio packet buffer to calculate a second average value of a second data amount level in a second time period later than the first time period; and   tuning the audio clock frequency by comparing the first average value with the second average value.   
     
     
         5 . The method of  claim 4 , wherein the tuning step comprises:
 deriving a difference value between the first average value and the second average value;   increasing the audio clock frequency if the difference value indicates that an absolute value of the difference value is higher than a threshold value as well as the second average value is higher than the first average value; and   decreasing the audio clock frequency if the difference value indicates that the absolute value of the difference value is higher than the threshold value as well as the second average value is lower than the first average value.   
     
     
         6 . The method of  claim 1 , further comprising:
 tuning a clock frequency generated from an oscillator of the wireless device according to at least one of a frequency offset generated from a receiver circuit of the wireless device and a reception time offset of the receiver circuit of the wireless device.   
     
     
         7 . A method utilized in a wireless device to be used as a slave device to be wirelessly connected to a master device in a piconet, comprising:
 using a receiver circuit of the wireless device to receive a data packet stream transmitted from an audio source; and   tuning a clock frequency generated from an oscillator of the wireless device according to at least one of a frequency offset generated from the receiver circuit of the wireless device and a reception time offset of the receiver circuit of the wireless device.   
     
     
         8 . The method of  claim 7 , further comprising:
 generating the frequency offset by comparing a frequency count number of the receiver circuit of the wireless device with a specified frequency count number transmitted from the master device.   
     
     
         9 . The method of  claim 7 , further comprising:
 generating the reception time offset by comparing a reception timing of the receiver circuit of the wireless device with a specified reception timing transmitted from the master device.   
     
     
         10 . A Bluetooth wireless device used to wirelessly receive and play audio information, the Bluetooth wireless device to be used as a slave device to be wirelessly connected to a master device in a piconet, and the Bluetooth wireless device comprises:
 a receiver circuit, used for receiving a data packet stream transmitted from an audio source;   a controlling circuit, coupled to the receiver circuit, used for monitoring a data amount of at least one buffer of a memory of the Bluetooth wireless device and tuning an audio clock frequency dedicated for playing audio samples if the data amount of the at least one buffer deviates from a specific data amount level.   
     
     
         11 . The Bluetooth wireless device of  claim 10 , wherein the Bluetooth wireless device is used as a primary Bluetooth device to be wirelessly connected to the master device which is a mobile device used as the audio source and can be used to be wireless connected to a secondary Bluetooth device; and, the controlling circuit is arranged for sending audio clock trimming information from the primary Bluetooth device to the secondary Bluetooth device to control both of the primary Bluetooth device and the secondary Bluetooth device to adjust corresponding audio clock frequencies to a target audio clock frequency at a specific time slot, before tuning the audio clock frequency of the primary Bluetooth device. 
     
     
         12 . The Bluetooth wireless device of  claim 10 , wherein the at least one buffer comprises an audio codec buffer, and the controlling circuit is arranged for monitoring an audio sample amount of the audio codec buffer, increasing the audio clock frequency if a value of the monitored audio sample amount is higher than a specific audio sample amount level, and decreasing the audio clock frequency if the value of the monitored audio sample amount is lower than the specific audio sample amount level. 
     
     
         13 . The Bluetooth wireless device of  claim 10 , wherein the at least one buffer comprises an audio packet buffer for storing audio packet(s), and the controlling circuit is arranged for monitoring a data amount of the audio packet buffer to calculate a first average value of a first data amount in a first time period, monitoring the data amount of the audio packet buffer to calculate a second average value of a second data amount level in a second time period later than the first time period, and tuning the audio clock frequency by comparing the first average value with the second average value. 
     
     
         14 . The Bluetooth wireless device of  claim 13 , wherein the controlling circuit is arranged for:
 deriving a difference value between the first average value and the second average value;   increasing the audio clock frequency if the difference value indicates that an absolute value of the difference value is higher than a threshold value as well as the second average value is higher than the first average value; and   decreasing the audio clock frequency if the difference value indicates that the absolute value of the difference value is higher than the threshold value as well as the second average value is lower than the first average value.   
     
     
         15 . The Bluetooth wireless device of  claim 10 , wherein the controlling circuit is arranged for tuning a clock frequency generated from an oscillator of the Bluetooth wireless device according to at least one of a frequency offset generated from a receiver circuit of the Bluetooth wireless device and a reception time offset of the receiver circuit of the Bluetooth wireless device. 
     
     
         16 . A Bluetooth wireless device used as a slave device to be wirelessly connected to a master device in a piconet, comprising:
 a receiver circuit, used for receiving a data packet stream transmitted from an audio source; and   a controlling circuit, coupled to the receiver circuit, used for tuning a clock frequency generated from an oscillator of the Bluetooth wireless device according to at least one of a frequency offset generated from the receiver circuit of the Bluetooth wireless device and a reception time offset of the receiver circuit of the Bluetooth wireless device.   
     
     
         17 . The Bluetooth wireless device of  claim 16 , wherein the controlling circuit is used for generating the frequency offset by comparing a frequency count number of the receiver circuit of the Bluetooth wireless device with a specified frequency count number transmitted from the master device. 
     
     
         18 . The Bluetooth wireless device of  claim 16 , wherein the controlling circuit is used for generating the reception time offset by comparing a reception timing of the receiver circuit of the Bluetooth wireless device with a specified reception timing transmitted from the master device.