Method for synchronously accessing audio data and audio playback system using the same

An audio playback system, comprising:

• a first device;
• a second device electrically connected to the first device through an interface, wherein the second device comprises:
• an audio output device;
• an audio memory, wherein when the second device performs an audio playback, the first device transmits an audio data through the interface to the audio memory of the second device;
• and
• a control circuit coupled to the audio memory and the audio output device;
• wherein when the first device transmits the audio data to the second device, the first device writes the audio memory, the control circuit of the second device reads the audio memory and performs a playback through the audio output device;
• wherein when a difference between a read address value of the second device and a write address value of the first device is different from a predetermined difference, the control circuit of the second device performs an interpolation operation;
• wherein the control circuit judges whether the difference between the read address value of the second device and the write address value of the first device is greater than the predetermined difference, a point deleting operation is performed when the difference between the read address value of the second device and the write address value of the first device is greater than the predetermined difference, and a point interpolating operation is performed when the difference between the read address value of the second device and the write address value of the first device is smaller than the predetermined difference;
• wherein the audio data comprises multiple sampling point data, the control circuit determines a specific sampling point data from the sampling point data to perform the point interpolating operation, the control circuit performs a digital filter computation according to neighboring M sampling point data of the specific sampling point data and generates (M+1) new sampling point data, where M is a natural number.