Audio switch Certification Guidelines

Preparation for Certification

• Prepare test devices.
  • You will need 5 Android devices.
    • These devices must include:
      • At least one Android T (13) and one Android V (15).
      • At least one Samsung and one Pixel.
      • For example:
        • 1 OnePlus (Android 10).
        • 3 Samsung (Android 11, 12, 13).
        • 1 Pixel (Android 15).
  • One device without Audio switch:
    • Any iPhone, PC, Bluetooth (BT)-enabled laptop, or an Android phone which Audio switch disabled.
      • You can turn off Audio switch from Bluetooth device detail setting.
    • Multipoint (MP) Test case 2.8 needs a device without Audio switch in addition to the 5 test phones.

• Join the Audio switch test group with your test accounts in order to show debug notifications on test phones.

  • This also enables Google to collect test data through Google Analytics.

Classic with A2DP+HFP

• Ensure all Android devices have GmsCore version 23.xx.xx or later installed.

BLE with LE Audio

• At least two of the reference phones must support LE Audio.
  • For example, one Samsung phone and one Pixel phone that support LE Audio.
• Ensure all Android devices have GmsCore version 24.33.xx or later installed.

Certification Criteria

• Target Switching success rate must exceed 95% in all test cases.

• In tests requiring a switch, the profile connection and switch active state must complete within 3 seconds after triggering audio events in at least 75% of cases.

Classic with A2DP+HFP

Self-Tests must be performed in the following combinations:

• Phone A=Android S (12) + Phone B=Android T (13)
• Phone A=Android T (13) + Phone B=Android S (12)

BLE with LE Audio

Self-Tests must be performed in the following combinations:

• Phone A: BT Classic, Phone B: BT Classic
• Phone A: LE Audio, Phone B: BT Classic
• Phone A: BT Classic, Phone B: LE Audio

Optionally, Providers that support Dual LE Audio connections should test:

• Phone A: LE Audio, Phone B: LE Audio

Testing Guide

Device Under Test (DUT) Preparation

• Verify that the BT device hasn't previously been paired with any phone logged-in to the testing Google Account.
  • If the device has been paired to the testing Google Account, do the following to clear the pairing:
    • In the paired devices:
      • Navigate to the Bluetooth settings.
      • Choose "Forget Device".
      • Toggle Airplane mode on and off.
  • Ensure "Automatically save devices" is ON.
    • This switch is OFF by default.
    • You can find this option in Settings > Google > Devices > Saved devices (one per DUT).
  • Put the Bluetooth device in Pairing Mode.
  • Pair the initial Bluetooth device (A).
  • Pair subsequent Bluetooth devices with other devices (B, C, D, etc.).

Scope

• All Headsets run tests from the various tabs in either the BT Classic or BT LE Audio Self-Test report.
• Headsets supporting only SinglePoint (SP) mode run the following:
  • The Generic_test tab.
• Headsets supporting MP mode run the following:
  • The Generic_test tab.
  • The Multipoint_only tab.
• MP headsets that can be toggled into SP mode run the following:
  • The Generic_test tab with MP off.
  • The Generic_test tab with MP on.
  • The Multipoint_only tab with MP on.

Completing Self-Rest and the Self-Test Report

• Make a copy of either the BT Classic or BT LE Audio Self-Test Reports.
• Run all test cases at least twice.

• Tests should be executed in the following form:

Classic with A2DP+HFP

• Device B will be the main DUT.
  • Enter Device B's details into the "Phone" and "OS" fields on the top of the template.

An example test case:

• Test phones:

  • Device 1: Samsung (Android 13)
  • Device 2: Pixel (Android 12 or 13) and others.

• Executed tests:

  • Run 1. Device A=Samsung S10+ (12), Device B=Pixel 7 pro (13) column D: Phone=Pixel 7 pro, OS=Android 13
  • Run 2. Device A=Pixel 7 pro (13), Device B=Pixel 6(12) column E: Phone=Pixel 6, OS=Android 12

An example of a completed test in the self-test template:

BLE with LE Audio

1. Device A=Android V (15) + Device B=Android T (13)
2. Device A=Android T (13) + Device B=Android V (15)
3. Device A=Android T (13) + Device B=Android S (12)
4. Device A=Android T (15) + Device B=Android V (15)
5. Device B will be the main DUT.
   • Enter Device B's details into the "Phone" and "OS" fields on the top of the template.

An example test case:

• Test phones:

  • Device 1: Samsung (Android 13)
  • Device 2: Pixel (Android 15) and others.

• Executed tests:

  • [LEA+BT]: Device A= Pixel 8 (15), Device B=Pixel 7 pro (13) column D: Phone=Pixel 7 pro, OS=Android 13
  • [BT+LEA]: Device A=Pixel 7 (13), Device B=Pixel 8 (Android 15) column E: Phone=Pixel 8, OS=Android 15
  • [BT+BT]: Device A=Pixel 7 pro (13), Device B=Samsung S10+ (12) column E: Phone=Samsung S10+, OS=Android 12
  • [LEA+LEA]: Device A=Pixel 8 (15), Device B=Pixel 8(15) column E: Phone=Pixel 8, OS=Android 15

An example of a completed test in the self-test template:

Audio Events:

• The 4 types of tested audio events and recommended testing apps are:

  1. Call:
     1. The built-in phone app.
  2. VoIP: Any VoIP App will work, such as:
     1. The Audio switch test app.
     2. FB Messenger.
     3. Line.
     4. WhatsApp.
     5. Google Meet.
     6. Google Meet.
  3. Media: Any audio player will work, such as:
     1. The Audio switch test app.
     2. Youtube Music.
     3. Apple Music.
     4. Spotify.
     5. Google Podcasts.
  4. Game:
     1. The Audio switch test app.

Note: Refer to the Audio switch test app section for more details.

Debug Information:

• Notifications are enabled after joining the fp-sass-partner-test group. Here are some examples:

  • Latest state notification:

  

  • No switch notification:

  

  Note: 'Latest State' is the connection state when the audio event happens, NOT the current latest event.
  • Switch latency notification:

  

Latency Measurement

Note: "Seeker" means the phone or tablet you use to connect with headset in test, also known as device A, B, C, D, or E in the test cases.

• There are two kinds of switch latency:
  1. Connecting a Bluetooth profile to a disconnected Seeker.
     • This include all SinglePoint cases, and some MP cases whose target Seeker (device B) is disconnected.
  2. Switching the active connected Seeker.
     • This includes some MP cases which the target Seeker (device B) is already connected.
• There are two ways to retrieve latency info:
  1. All latency can be dumped by adb command.
     • Refer to the dump latency section for details.
     • This command can provide and record latency after finishing at least one test case.
  2. Using the Audio switch test app.
     • The App running on the target Seeker will display latency after switching.
     • If there was no switch, the app will display the 'no switch' reason.

Audio switch Test App:

• Using the app to trigger VoIP/Media/Game audio events during a self test will simplify test setup and reduce the Seeker's event latency.
  • The latest version can be downloaded here.
  • The LE Audio VoIP test needs a policy to be manually enabled: > adb root > adb shell settings put global hidden_api_policy 1 > adb reboot

Note: You will need a Google Account to request access to the download link. Being granted access is a manual process and may take several days.

• App Installation:
  • Copy the apk to your test phone and open it.
  • Alternatively, use adb install audio_test_app.apk.

Warning: Allow all permissions when opening the app for the first time.

• If you see a dialog asking for notification access:
  1. click "OK"
  2. Choose "FP SASS test" in the app list
  3. Allow notification access.

App Overview:

• Target provider

  • This button will show a list of paired Bluetooth devices when clicked. Select the one you want to test.
  • The Connect and Disconnect buttons works like the one in the Bluetooth settings' device detail.

• Current state

  • This field shows the last connection state the Seeker received from a Provider using BLE advertising or event stream.
  • Audio switch debug notifications are also shown here.

• Seeker type

  • This option is used to switch the device between audio streams.

Audio type

Classic with A2DP+HFP

• VoIP
  • Selecting this mode will change the audio mode to AudioManager.MODE_IN_COMMUNICATION and call AudioManager.startBluetoothSco, then play audio with USAGE_VOICE_COMMUNICATION.
  • The stream type is STREAM_VOICE_CALL.
  • The provider connection state should switch to CONNECTED_HFP within 5 seconds.
• Media
  • Selecting this mode will play audio supporting AVRCP. The audio usage type is: USAGE_MEDIA.
  • The provider connection state should switch to CONNECTED_A2DP_WITH_AVRCP within 5 seconds.
  • The connection state may briefly switch to CONNECTED_A2DP_ONLY when started or stopped.
• Game
  • Selecting this mode plays audio which doesn't support AVRCP. The audio usage type is: USAGE_GAME.
  • The provider connection state should switch to CONNECTED_A2DP_ONLY within 5 seconds.

BLE with LE Audio

• VoIP

  • Selecting this mode will change the audio mode to AudioManager.MODE_IN_COMMUNICATION and play audio with USAGE_VOICE_COMMUNICATION.
  Note: For Android versions earlier than Tiramisu (Android 13), the test app calls AudioManager.startBluetoothSco to start a bluetooth SCO audio connection. Otherwise, the test app calls AudioManager.setCommunicationDevice to select the audio device used for communication.
  • The stream type is STREAM_VOICE_CALL.
  • The provider connection state should switch to CONNECTED_LE_AUDIO_CALL within 5 seconds.

• Media

  • Selecting this mode will play audio with stream type as STREAM_MUSIC. The audio usage type is: USAGE_MEDIA.
  • The provider connection state should switch to CONNECTED_LE_AUDIO_MEDIA_WITH_CONTROL within 5 seconds.
  • The connection state may briefly switch to CONNECTED_LE_AUDIO_MEDIA_WITHOUT_CONTROL when started or stopped.

• Game

  • Selecting this mode plays audio which the user doesn't have direct control over. The audio usage type is: USAGE_GAME.
  • The provider connection state should switch to CONNECTED_LE_AUDIO_MEDIA_WITHOUT_CONTROL within 5 seconds.

• Play and Stop buttons

  • The PLAY and STOP buttons start or stop the audio.

• Switch result

  • This field displays the Connect and Switch active latency. It also displays the reason for denying a switch if an audio event was triggered but the switch didn't happen.
  • Latency is measured in milliseconds (ms).
  • In general, latency is measured from the start of the Audio switch trigger to the receipt of a BT profile connected or Notify multipoint-switch event.
  • Provider-triggered switches measure latency from audio start.

Dump Latency

• The following command allows a user to capture latency measurements when running manual tests: adb shell dumpsys activity service com.google.android.gms/.nearby.discovery.service.DiscoveryService
  • Latency measurements are shown under NearbyDeviceManager's SwitchHistory section:

            NearbyDeviceManager
              Nearby Sass device count: 1
                Sass device - address:XX:XX:XX:XX:XX:XX, name:Googler's Pixel Buds, accountKey:XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX, modelId:6edaf7
                  SwitchHistory
                    15:30:21:166 - 15:30:25:201, latency 3035ms, Succeed, SASS_TRIGGERED_CONNECT, SASS switch, A2DP
                    15:34:58:568 - 15:34:58:568, latency 0ms, Succeed, SWITCH_ACTIVE_TO_SELF, SASS switch, HFP
                    15:36:26:615 - 15:36:31:603, latency 1988ms, Succeed, SASS_TRIGGERED_CONNECT, SASS switch, A2DP
                    15:37:56:108 - 15:37:56:250, latency 142ms, Succeed, SWITCH_ACTIVE_TO_SELF, SASS switch, A2DP"

• Any switch that GmsCore cannot measure (e.g. active switch for HFP) will be recorded as 0ms latency.

Reference of log patterns:

Known Issues:

The following are known bugs caused by the Seeker:

1. Incorrect game audio switching.
   • Samsung phones will set the connection state to CONNECTED_A2DP_WITH_AVRCP, instead of CONNECTED_A2DP_ONLY when playing games.
   • Some games (such as Candy crush) may replay background music and trigger a new audio event without user input. The connected phones may constantly switch audio on every phone that opens the game.