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| <head> |
| <title>Bluetooth Services</title> |
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| <body> |
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| Copyright 2017 The Android Open Source Project |
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| Licensed under the Apache License, Version 2.0 (the "License"); |
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| |
| <p> |
| Over Bluetooth, devices can transmit data that can be used for |
| interactive services such as audio, messaging, and telephony. The |
| Bluetooth profiles used for different services can be found in |
| <code><a href="https://android.googlesource.com/platform/system/bt/+/master/include/hardware/bluetooth.h"> |
| include/hardware/bluetooth.h</a></code>. |
| </p> |
| |
| <h2 id="audio">Audio</h2> |
| |
| <aside class="note"><strong>Note</strong>: Currently only |
| Classic Bluetooth supports any type of audio streaming. |
| </aside> |
| |
| <p> |
| A Bluetooth connection lets users stream audio on Bluetooth-enabled |
| devices. For most audio use cases, the Android device is the source, |
| and the rendering device, such as a speaker or a headset, is the sink. |
| </p> |
| |
| <h3 id="absolute-volume-control">Absolute volume control</h3> |
| |
| <p> |
| In Android 6.0 and later, the Android Bluetooth stack lets a |
| source set an absolute volume, giving users accurate control over |
| audio volume. The source device sends un-attenuated audio and volume |
| information to the sink. The sink then amplifies the audio according |
| to the volume information, so users hear accurate playback volume. |
| </p> |
| |
| <p> |
| The source device can also register volume notifications. When |
| volume changes are made with controls on the sink, the sink sends a |
| notification to the source. This lets the source accurately display |
| volume information on a user interface. |
| </p> |
| |
| <p> |
| Absolute volume control is on by default. To disable absolute |
| volume control, users can go to <strong>Settings</strong> > |
| <strong>System</strong> > <strong>Developer options</strong> |
| and select the toggle for <strong>Disable absolute volume</strong>. |
| </p> |
| |
| <h3 id="advanced-audio-codecs">Advanced audio codecs</h3> |
| |
| <p> |
| In Android 8.0, devices that use the Advanced Audio Distribution |
| Profile (A2DP) can support additional audio codecs. The Bluetooth |
| stack supports audio codec negotiation for when devices connect to |
| a remote audio sink. This negotiation selects the best codec |
| supported by both the sender and the sink to provide high-quality |
| audio. After selection, all audio is routed through the selected |
| encoder and then sent to the sink. |
| </p> |
| |
| <h4 id="implementation">Implementation</h4> |
| |
| <p> |
| Devices running Android 8.0 that support A2DP automatically |
| gain the additional codec support. Device manufacturers may need |
| to obtain separate licenses and binary blobs for some |
| proprietary audio codecs. In addition to SBC, Android 8.0 |
| supports the following codecs: |
| </p> |
| |
| <ul> |
| <li>AAC</li> |
| <li>aptX</li> |
| <li>aptX HD</li> |
| <li>LDAC</li> |
| </ul> |
| |
| <p> |
| Device manufacturers can choose which codecs their devices |
| attempt to use first. Set the codec priorities by changing the |
| following values in <code><a href="https://android.googlesource.com/platform/packages/apps/Bluetooth/+/master/res/values/config.xml"> |
| res/values/config.xml</a></code>: |
| </p> |
| |
| <pre class="prettyprint"> |
| <!-- Configuring priorities of A2DP source codecs. Larger value means |
| higher priority. Value -1 means the codec is disabled. |
| Value 0 is reserved and should not be used here. Enabled codecs |
| should have priorities in the interval [1, 999999], and each |
| priority value should be unique. --> |
| <integer name="a2dp_source_codec_priority_sbc">1001</integer> |
| <integer name="a2dp_source_codec_priority_aac">2001</integer> |
| <integer name="a2dp_source_codec_priority_aptx">3001</integer> |
| <integer name="a2dp_source_codec_priority_aptx_hd">4001</integer> |
| <integer name="a2dp_source_codec_priority_ldac">5001</integer> |
| </pre> |
| |
| <h4 id="ldac-certification">LDAC certification</h4> |
| |
| <p> |
| The Android Open Source Project includes Sony's LDAC codec, so a |
| separate license or blob is not needed for it. To integrate the |
| LDAC codec into your device, register with Sony and follow the |
| <a href="https://www.sony.net/Products/LDAC/aosp/"> |
| LDAC certification process</a>. |
| </p> |
| |
| <p> |
| The LDAC certification website has documentation about LDAC, |
| such as specification and operation handbooks. The LDAC site also |
| provides validation and interoperability tests for mobile and |
| tablet devices. Send passing test results to Sony to complete LDAC |
| certification. |
| </p> |
| |
| <h4 id="ui-features">UI features</h4> |
| |
| <p> |
| Along with additional codec support, Android 8.0 provides a |
| user-facing setting to disable high-definition (HD) Bluetooth |
| audio codecs. |
| </p> |
| |
| <ol> |
| <li>Navigate to <strong>Settings</strong> > |
| <strong>Connected devices</strong> > |
| <strong>Bluetooth</strong>.</li> |
| <li>Tap on the gear icon next to the sink you want to disable codecs |
| for.</li> |
| <li>Uncheck the <strong>HD Audio</strong> checkbox.</li> |
| </ol> |
| |
| <p> |
| Device manufacturers that customize Settings should implement a |
| way for users to disable HD codecs. |
| </p> |
| |
| <h2 id="messaging">Messaging</h2> |
| |
| <p> |
| Messaging over Bluetooth lets users read, browse, and compose SMS |
| messages from a remote device. This capability is often used when |
| connecting a phone to an in-vehicle infotainment system. |
| </p> |
| |
| <aside class="note"><strong>Note</strong>: Bluetooth messaging services |
| currently only support SMS. Email and instant messages are not |
| supported. |
| </aside> |
| |
| <h2 id="telephony">Telephony</h2> |
| |
| <p> |
| Bluetooth telephony services lets users stream calls and sync |
| contacts from a phone to another Bluetooth device. These features are |
| often used for hands-free calls when driving. |
| </p> |
| |
| <p> |
| In Android 8.0, Bluetooth supports in-band ringtone. When a phone |
| connected over Bluetooth receives an incoming call, the ringtone will |
| play on the sink. Enable in-band ringtone in <strong>Settings</strong> |
| > <strong>System</strong> > <strong>Developer options</strong> by |
| selecting the toggle for <strong>Enable in-band ringing</strong>. |
| </p> |
| |
| <h2>Bluetooth features</h2> |
| <p> To implement the Bluetooth services, the Bluetooth stack supports a |
| variety of profiles and features. |
| </p> |
| |
| <h3 id="bluetooth-profiles">Bluetooth profiles</h3> |
| |
| <p> |
| These profiles are available for Bluetooth: |
| </p> |
| |
| <table> |
| <tr> |
| <th colspan="2" >Feature</th> |
| <th colspan="5" >Android version</th> |
| </tr> |
| <tr> |
| <th>Name</th> |
| <th>Description</th> |
| <th>6.0</th> |
| <th>7.0</th> |
| <th>7.1</th> |
| <th>7.1.2</th> |
| <th>8.0</th> |
| </tr> |
| <tr> |
| <td><strong>SAP</strong></td> |
| <td>SIM Access Profile</td> |
| <td>1.1</td> |
| <td>1.1</td> |
| <td>1.1</td> |
| <td>1.1</td> |
| <td>1.1</td> |
| </tr> |
| <tr> |
| <td><strong>MAP</strong></td> |
| <td>Message Access Profile for SMS</td> |
| <td>1.2</td> |
| <td>1.2</td> |
| <td>1.2</td> |
| <td>1.2</td> |
| <td>1.2</td> |
| </tr> |
| <tr> |
| <td><strong>OPP</strong></td> |
| <td>Object Push Profile</td> |
| <td>1.1</td> |
| <td>1.1</td> |
| <td>1.1</td> |
| <td>1.1</td> |
| <td>1.2</td> |
| </tr> |
| <tr> |
| <td><strong>OBEX over L2CAP</strong></td> |
| <td>OBject EXchange over Logical Link Control and Adaptation |
| Protocol</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| </tr> |
| <tr> |
| <td><strong>HFP Audio Gateway</strong></td> |
| <td>Hands-Free Profile</td> |
| <td>1.6</td> |
| <td>1.6</td> |
| <td>1.7</td> |
| <td>1.7</td> |
| <td>1.7</td> |
| </tr> |
| <tr> |
| <td><strong>HSP</strong></td> |
| <td>Headset Profile</td> |
| <td>1.2</td> |
| <td>1.2</td> |
| <td>1.2</td> |
| <td>1.2</td> |
| <td>1.2</td> |
| </tr> |
| <tr> |
| <td><strong>A2DP</strong></td> |
| <td>Advanced Audio Distribution Profile</td> |
| <td>1.2</td> |
| <td>1.2</td> |
| <td>1.2</td> |
| <td>1.2</td> |
| <td>1.2</td> |
| </tr> |
| <tr> |
| <td><strong>AVRCP</strong></td> |
| <td>Audio/Video Remote Control Profile</td> |
| <td>1.3</td> |
| <td>1.3</td> |
| <td>1.3</td> |
| <td>1.3</td> |
| <td>1.4</td> |
| </tr> |
| <tr> |
| <td><strong>HID</strong></td> |
| <td>Human Interface Device Profile</td> |
| <td>1.0</td> |
| <td>1.0</td> |
| <td>1.0</td> |
| <td>1.0</td> |
| <td>1.0</td> |
| </tr> |
| <tr> |
| <td><strong>PBAP</strong></td> |
| <td>Phone Book Access Profile</td> |
| <td>1.1.1</td> |
| <td>1.1.1</td> |
| <td>1.1.1</td> |
| <td>1.1.1</td> |
| <td>1.2</td> |
| </tr> |
| <tr> |
| <td><strong>HDP</strong></td> |
| <td>Health Device Profile</td> |
| <td>1.0</td> |
| <td>1.0</td> |
| <td>1.1</td> |
| <td>1.1</td> |
| <td>1.1</td> |
| </tr> |
| <tr> |
| <td><strong>SPP</strong></td> |
| <td>Serial Port Profile</td> |
| <td>1.2</td> |
| <td>1.2</td> |
| <td>1.2</td> |
| <td>1.2</td> |
| <td>1.2</td> |
| </tr> |
| <tr> |
| <td><strong>PAN / BNEP</strong></td> |
| <td>Personal Area Networking Profile / Bluetooth Network |
| Encapsulation Protocol</td> |
| <td>1.0</td> |
| <td>1.0</td> |
| <td>1.0</td> |
| <td>1.0</td> |
| <td>1.0</td> |
| </tr> |
| <tr> |
| <td><strong>DIP</strong></td> |
| <td>Device ID Profile</td> |
| <td>1.3</td> |
| <td>1.3</td> |
| <td>1.3</td> |
| <td>1.3</td> |
| <td>1.3</td> |
| </tr> |
| <tr> |
| <td><strong>HOGP 1.0</strong></td> |
| <td>HID over GATT</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| </tr> |
| <tr> |
| <td><strong>HD Audio</strong><sup id="fnref1"><a href="#fn1" |
| rel="footnote">1</a></sup></td> |
| <td>See "Advanced audio codecs" above</td> |
| <td>No</td> |
| <td>No</td> |
| <td>No</td> |
| <td>No</td> |
| <td>Yes</td> |
| </tr> |
| </table> |
| |
| <p> |
| <sup id="fn1">1</sup> Implementing HD Audio depends on device |
| capabilities, both on the source and the sink. |
| </p> |
| |
| <h3 id="bluetooth-low-energy-features">Bluetooth Low Energy features</h3> |
| |
| <p> |
| These features are available for BLE: |
| </p> |
| |
| <table> |
| <tr> |
| <th>Feature</th> |
| <th colspan="5" >Android version</th> |
| </tr> |
| <tr> |
| <th>Name</th> |
| <th>6.0</th> |
| <th>7.0</th> |
| <th>7.1</th> |
| <th>7.1.2</th> |
| <th>8.0</th> |
| </tr> |
| <tr> |
| <td><strong>BR/EDR secure connections</strong></td> |
| <td>4.1</td> |
| <td>4.1</td> |
| <td>4.1</td> |
| <td>4.1</td> |
| <td>5.0</td> |
| </tr> |
| <tr> |
| <td><strong>LE Privacy</strong></td> |
| <td>4.2</td> |
| <td>4.2</td> |
| <td>4.2</td> |
| <td>4.2</td> |
| <td>5.0</td> |
| </tr> |
| <tr> |
| <td><strong>LE secure connections</strong></td> |
| <td>4.2</td> |
| <td>4.2</td> |
| <td>4.2</td> |
| <td>4.2</td> |
| <td>5.0</td> |
| </tr> |
| <tr> |
| <td><strong>Data Packet Extensions</strong></td> |
| <td>4.2</td> |
| <td>4.2</td> |
| <td>4.2</td> |
| <td>4.2</td> |
| <td>5.0</td> |
| </tr> |
| <tr> |
| <td><strong>32-bit UUIDs</strong></td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| </tr> |
| <tr> |
| <td><strong>Dual Mode LE Central/Peripheral</strong></td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| </tr> |
| <tr> |
| <td><strong>LE Peripheral Mode</strong></td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| </tr> |
| <tr> |
| <td><strong>Google HCI Requirements</strong></td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| <td>Yes</td> |
| </tr> |
| <tr> |
| <td><strong>LE Connection-Oriented Channels</strong></td> |
| <td>No</td> |
| <td>No</td> |
| <td>No</td> |
| <td>No</td> |
| <td>Yes<sup id="fnref2"><a href="#fn2" rel="footnote">2</a></sup> |
| </td> |
| </tr> |
| </table> |
| |
| <p> |
| <sup id="fn2">2</sup> Implementing LE Connection-Oriented Channels |
| depends on device capabilities, both on the source and the sink. |
| </p> |
| </body> |
| </html> |
