A2DP is used for streaming stereo music wirelessly to headphones or speakers over Bluetooth. Unlike other Bluetooth profiles (Headset and Handsfree), A2DP is one-way only and streams a stereo signal. The technical term “Advanced Audio Distribution Profile” – in short A2DP – refers to a transfer standard via a Bluetooth connection, for the wireless transfer of high quality audio signals. The transfer of audio signals between the devices of arbitrary manufacturers who support this standard is enabled by A2DP.
In general terms, the Low Complexity Subband Code – also referred to as the SBC Codec – is used in order to transfer stereo audio signals. It compresses the audio signals and always delivers these with a loss, although the high data transfer rate of up to 345 kilobits per second and the perfected algorithm ensure barely perceptible quality losses.
The Advanced Audio Distribution Profile is used between an A2DP source and a recipient. The audio signals, which are supplied by the source (e.g. a smartphone or MP3 player) via Bluetooth are decoded by the A2DP recipient (e.g. a Bluetooth-capable loudspeaker) and then reissued as an audio signal.
The Advanced Audio Distribution Profile Standard is supported by all the latest customary smartphone operating system versions (including amongst others iOS, Android and Windows Phone). This enables the playback of audio data on suitable devices. This technology is frequently found in the automotive sector in particular. Here, the smartphone is coupled with a hands-free kit or a car stereo via Bluetooth. If the connection is not being used for telephone calls then it is possible to play the music stored on the smartphone with a very high audio quality via the A2DP.
The Advanced Audio Distribution Profile is frequently also used in conjunction with the so-called AVRCP profile. This not only enables the transfer of pure audio data, but also of information for controlling devices. In this way it is also possible to remotely operate an audio player from a Bluetooth headset, for example.
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