What is Bluetooth ?
Bluetooth wireless technology is a short-range communications technology intended to replace the cables connecting portable and/or fixed devices while maintaining high levels of security. The key features of Bluetooth technology are robustness, low power, and low cost. The Bluetooth specification defines a uniform structure for a wide range of devices to connect and communicate with each other.
What is A2DP ?
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 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 Headset (HSP), Hands-Free (HFP) and Audio/Video Remote Control (AVRCP) profiles.
A2DP is designed to transfer a uni-directional 2-channel stereo audio stream, like music from an MP3 player, to a headset or car radio.[2] This profile relies on AVDTP and GAVDP. It includes mandatory support for the low complexity SBC codec and supports optionally: MPEG-1(usually include MP3), MPEG-2, MPEG-4, AAC, and ATRAC, and is extensible to support manufacturer-defined codecs. Most bluetooth stacks implement the SCMS-T digital rights management (DRM) scheme. In these cases it is possible to connect the A2DP headphones for high quality audio.
What is AVRCP ?
This profile is designed to provide a standard interface to control TVs, Hi-fi equipment, etc. to allow a single remote control (or other device) to control all of the A/V equipment to which a user has access. It may be used in concert with A2DP or VDP. It has the possibility for vendor-dependent extensions. Additionally, with the version 1.3 release of the specification, there is now capability to transmit information on the status of the music source (playing, stopped, etc), including information on the track itself (artist, track name, etc).
