This profile defines how high quality audio (stereo or mono) can be streamed from one device to another over a Bluetooth connection[1] - for example, music streamed from a mobile phone to a wireless headset.

A2DP was initially used in conjunction with an intermediate Bluetooth transceiver that connects to a standard output audio jack, encodes the incoming audio to a Bluetooth-friendly format, and sends the signal wirelessly to Bluetooth headphones that decode and play the audio. However, many Bluetooth 1.1, 1.2, and 2.0 mobile phones and portable media players do not natively support A2DP, while some newer Bluetooth 2.0 headphones do support it.

Bluetooth headphones, especially the more advanced models, often come with a microphone and support for the Audio/Video Remote Control (AVRCP), Headset (HSP) and Hands-Free (HFP) profiles.

A2DP[2] is designed to transfer a 2-channel stereo audio stream, like music from an MP3 player, to a headset or car radio. This profile relies on AVDTP and GAVDP. It includes mandatory support for low complexity Sub Band Codec (SBC) and supports optionally: MPEG-1,2 Audio, MPEG-2,4 AAC and ATRAC, and is extensible to support manufacturer-defined codecs. Most bluetooth stacks implement the SCMS-T DRM (digital rights management) scheme. In these cases it is not possible to connect the A2DP headphones for high quality audio. E.g. the Motorola HT820 can be used for high quality audio only with certain versions of the Toshiba bluetooth stack.


http://en.wikipedia.org/wiki/Bluetooth_pro...file_.28A2DP.29