Table of Contents
What is a2dp hardware offload
A2DP, or audio-binaurally duplicating profile, is a standard for smartphones and digital media players to transmit two-channel digital audio streams that the user can play back through headphones. A2DP devices are able to send stereo audio to compatible headphones in a predictable manner. This makes them an excellent solution for streaming high quality audio to headphones wirelessly.
A2DP is a pair of Bluetooth profiles developed by the Bluetooth Special Interest Group (SIG). These profiles are used by audio devices to transmit stereo audio from one device to another. The A2DP usage model also allows for multiple simultaneous connections, making it suitable for point-to-point applications like wireless headsets.
As well as the profile specifications, the A2DP framework also provides additional services that enable efficient management of audio sessions between devices. These include:
Bluetooth specification version 2.1+EDR and higher allow for greater than two channels (e.g. 5.1 surround sound).
How does it work
A2DP allows for high quality audio to be transmitted in asynchronous method using the Bluetooth 2.1 specification. Streaming of compressed audio from a source, such as a smartphone or tablet, to a pair of compatible headphones occurs in much the same way as it would when transmitting data files across Bluetooth. The difference is that the A2DP profile enables two-way communication between the source and headphones. This allows for audio to be streamed from the source to the headset, or vice versa.
A2DP streams are generally sent in the same way as traditional Bluetooth data: unidirectionally from the source to the target. Once a connection has been established, the control channel will carry SBC audio at a 48 kbit/s bit rate, using 20 ms packets. Any other A2DP device within range can receive and make use of the audio stream by connecting to the same source device through its control channel. Determining whether an A2DP connection is available may require user intervention.
Although A2DP is a legacy protocol, there are several benefits to using it. It allows for higher quality audio because a lossless format is used. Without A2DP, the compressed audio would have to be converted to analog format, which may degrade the audio quality. Furthermore, A2DP connections are generally easier to establish than Bluetooth connections between the same devices.
What are the benefits of a2dp hardware offload
Wireless communication of audio offers many benefits to both the end user and the developer. The most obvious advantage is freedom of mobility. Using Bluetooth to stream audio allows the user to move around freely, to exercise, or even just walk around the house, without being tethered to the source device. Because Bluetooth is a standardized technology, any Bluetooth A2DP headset is compatible with any device that supports the A2DP profile. This means that an iPhone user can use the same headset and playlists as an Android user and vice versa. This increased compatibility between devices increases the utility of the technology. A2DP hardware offload enables this by allowing a Bluetooth device to both discover and play audio directly from the device’s memory.
The benefits go beyond just mobility and compatibility between devices. The standard allows for the streaming of higher quality audio. A2DP supports a “fast lane” that allows data to be transferred at speeds that are faster than the service rate (i.e., 2Mbps). A2DP also supports a “low latency” mode that lowers the latency of audio delivery. This is particularly useful for gaming applications where “ping times” must be as low as possible to provide a competitive advantage. A2dp hardware offload allows the audio to be streamed directly from the device’s memory. This eliminates the latency caused by buffering audio on the device, which can degrade both audio quality and competitive advantage in an online game.
How can you enable a2dp hardware offload on your device
The Bluetooth stack is the software and hardware that allows for Bluetooth communication. The A2DP profile is supported in most modern versions of Android. To enable it on your Android device, you must have a compatible Bluetooth chip with integrated A2DP support. Most Android smartphones made after 2010 should have this capability. However, a2dp hardware offload is enabled by default on newer devices, so you may need to enable it manually. There are also options in Android to allow for manual Bluetooth pairing and custom profiles. To do this, you must be rooted. For instructions on enabling A2DP hardware offload, see this online tutorial or this forum post.
While you can enable hardware offload for a2dp, this does not mean that all applications will use it. Some music apps allow you to select which audio stream is used, while others may use the default Android audio stream. You can still enable a2dp hardware offload and select one of the Bluetooth audio sources in your music app’s settings menu. Some applications do not have this option available to you, so you may need to look for an alternative application that supports your particular device.
Examples of devices that support a2dp hardware offload
A variety of devices support A2DP hardware offload. Phones from HTC, Sony, Nvidia and Samsung are just a few examples of devices that support the standard. Many MP3 players also support this feature. This in many cases makes using headphones with a phone easier than using a traditional wired connection to connect to the phone. With a2dp hardware offload, all you need is a compatible headset, such as the Sony MDR-RF925RK RF Wireless Headset, which uses the A2DP profile to connect wirelessly to your phone for high quality audio.
A2DP, or advanced audio distribution profile, is an audio profile standard used to send stereo audio over a wireless network. Because devices that support A2DP hardware offload can send high quality sound without any loss of fidelity, this standard has become much more popular as wireless networks have gotten faster. A2DP does have a few other benefits as well, such as the ability to transfer multiple pieces of information simultaneously over the same connection.
Although Bluetooth 2.0 is the standard used most often for A2DP offloading, some newer technology is emerging that can increase the quality of wireless audio. Qualcomm’s aptX technology is being incorporated into some upcoming phones to make A2DP calls with greater fidelity. In addition, other technologies such as Near Field Communication (NFC) may also be able to support A2DP offloading in the near future.
