Function Introduction：
1. The Advance Audio Distribution Profile protocol specifies the use of bluetooth asynchronous transmission channels and the protocol stack software and methods for transferring high-quality music file data. Based on this protocol, high-quality stereo music can be transmitted via Bluetooth.
Note:
1. As long as both parties support A2DP protocol, both parties can transmit audio signals at a quality of 16 bits, 44.1kHz.
2. If one party doesn't support A2DP, the audio signal can only be transmitted in an 8 bits, 8kHz quality transmission mode, and the sound quality will be much worse.
3. Take Bluetooth headset as an example: Not all headset is bluetooth stereo headset that supports A2DP, stereo realization of the basic requirements is double channel, so mono bluetooth headset can not achieve stereo.