Audio Switch Certification Guidelines

AI-generated Key Takeaways

outlined_flag

• This guide outlines the preparation, criteria, and testing procedures for Audio Switch Certification on Android devices.

• Achieving a 95% switching success rate and a switch completion time within 3 seconds in 75% of cases are key certification criteria.

• The testing process involves using a variety of Android devices, specific GmsCore versions, and the Audio Switch test app for simulating audio events and measuring latency.

• Debug information and detailed test reports are essential for identifying and resolving potential issues during certification.

• Headsets are categorized as SinglePoint or Multipoint, with specific test tabs and procedures for each type within the Audio Switch test app.

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.

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.

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:

• 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.

Debug Information:

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

  • Latest state notification:

  

  • No switch notification:

  

  • Switch latency notification:

  

Latency Measurement

• 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

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

• 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

• 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.