Multi-App Audio

An Android app that sets each app's volume, from 0 to 100%, right from the notification shade. It also lets several apps play at the same time and stops Android Auto from pausing YouTube. For Pixels and other phones running stock Android 12 or newer. No root: a one-time setup over ADB unlocks it, and from then on everything happens in the app.

Features

• Per-app volume. Turn YouTube down to 40% while Spotify stays at 100%. Pull down the notification shade and the App volume notification lists what's playing right now:

  • expand it for - / + buttons (1% per tap, or 2, 5, 10, 20 or 25%),
  • tap it for sliders that open over whatever app you're using, with - / + beside each,
  • or use the App volume Quick Settings tile.

  Each app's level is remembered and applies whenever it plays. Need more than 100%? Turn on Allow boost above 100% for up to 200%, with a limiter so it can't clip.

• Several apps at once (Samsung-style multi-app audio). Music and videos stop pausing each other. Calls, alarms and navigation prompts still interrupt.

• Android Auto fix. Android Auto can't pause YouTube or swap in YouTube Music, and YouTube plays alongside your other audio in the car. Pick more apps in the app.

• Mute any app completely. Pick the apps in the app.

• Pause and resume around calls. Media picks up again when a call ends, which Android doesn't do on its own when several apps play at once.

Everything survives reboots and updates. The app has no internet permission.

Install

You need a computer with adb and your phone with USB debugging on (first-time ADB setup). Plug the phone in and run these once:

# Download and install the app
curl -LO https://github.com/channelramble/multiAPPaudio/releases/latest/download/MultiAppAudio.apk
adb install -r MultiAppAudio.apk

# One-time setup for the app
adb shell pm grant io.github.channelramble.multiappaudio android.permission.POST_NOTIFICATIONS
adb shell pm grant io.github.channelramble.multiappaudio android.permission.DUMP
adb shell cmd notification allow_listener io.github.channelramble.multiappaudio/io.github.channelramble.multiappaudio.MediaListener
adb shell cmd statusbar add-tile io.github.channelramble.multiappaudio/.MixerTileService
adb shell cmd appops set com.google.android.youtube TAKE_AUDIO_FOCUS ignore
adb shell settings put system multi_audio_focus_enabled 1
adb reboot

After the reboot, pull down the notification shade and start something playing. That's the whole setup. The next section explains each line, and the app's Setup card shows what's granted.

Windows: in PowerShell, type curl.exe instead of curl. Or download MultiAppAudio.apk in a browser and run the rest from the same folder.

Updating: install the new APK the same way (adb install -r MultiAppAudio.apk), or open it on the phone. The setup commands don't need to be run again.

What the setup commands do

Command	What it's for
pm grant … android.permission.POST_NOTIFICATIONS	Lets the App volume notification show. The app also asks for this the first time you open it.
pm grant … android.permission.DUMP	Lets the app read Android's list of audio streams, so it knows which app is playing each one. Per-app volume needs it.
cmd notification allow_listener …	Lets the app pause and resume media players, for the call and Android Auto helpers. It never reads your notifications.
cmd statusbar add-tile …	Adds the App volume tile to Quick Settings. You can also add it from the app.
cmd appops set com.google.android.youtube TAKE_AUDIO_FOCUS ignore	The Android Auto fix for YouTube: it never takes audio focus, so it can't be paused or swapped out, and it plays alongside other apps. Skip it if you don't want that.
settings put system multi_audio_focus_enabled 1 + reboot	Turns on Android's own multi-app audio mode, so media apps stop pausing each other.

Android stores each of these and re-applies it at every boot.

First-time ADB setup

1. On the phone: Settings > About phone, tap Build number 7 times. Then Settings > System > Developer options and turn on USB debugging.
2. On the computer, install ADB (Android's platform tools):
   • macOS: brew install android-platform-tools
   • Windows: winget install Google.PlatformTools
   • Linux: sudo apt install adb (or your distro's package)
   • Or download platform-tools.
3. Plug the phone in, run adb devices, and tap Allow on the phone.

Using the app

App volume. Pull down the notification shade:

• The collapsed App volume notification shows each playing app and its level, like YouTube 40% · Spotify 100%.
• Expand it for - and + on each app.
• Tap it for sliders, with - and + beside each for fine steps; hold one for 2 seconds and it keeps going by 1% every half second. Tap an app's speaker icon to mute it, or its percentage to reset it to 100%.
• The Quick Settings tile opens the same sliders.

Only apps playing right now are listed. An app drops off a few seconds after it stops, and its level comes back when it plays again.

In the Multi-App Audio app:

• App volume: Allow boost above 100% (up to 200%), Each - / + tap changes volume by (1, 2, 5, 10, 20 or 25%; 1% by default), Keep the App volume notification, and Reset all to 100%.
• Multi-app audio: shows whether it's on, and Resume media after calls.
• Android Auto: Choose apps to add more pass-through apps besides YouTube, plus Undo automatic source switches and Pause pass-through apps during calls.
• Mute apps: Choose apps to silence completely.
• Setup and Diagnostics: what's granted, and Copy report if something doesn't work.

Adding pass-through or muted apps is the one thing Android only allows over ADB. The app gives you a ready-to-copy command for each app you pick; run it once, like the setup.

Things to know

• Some apps can't be adjusted. Games with low-latency audio can't take the volume effect. If an app shows Can't adjust, close and reopen it.
• Music stays quieter after a navigation prompt. This is an Android 16/17 bug in multi-app audio mode; pause and play to fix it. The app's Multi-app audio > Read more has Google's own fix, a flag you can try.
• A pass-through app won't start. Some players refuse to start without audio focus. The app's Android Auto > Read more has the command to undo it for that app.
• Which apps the Android Auto fix covers. On Android 16 it only applies to apps targeting Android 15 or newer; on Android 17 it covers almost everything. Also worth doing once: in Android Auto's settings, turn off starting media automatically, and in YouTube Music, turn off letting external devices start playback.
• Media control from Settings. Instead of the allow_listener command you can turn on notification access in Settings. Sideloaded apps may first need Allow restricted settings on the app's info page.

Tested on a Pixel 10 Pro Fold (Android 17) and on the Android 14 and 17 emulators. If something doesn't behave, send Diagnostics > Copy report in an issue.

Uninstall

In the app, tap Reset all to 100% first: Android keeps the volume effect on an app that's playing at that moment until that app closes its audio. Then undo the setup and remove the app:

adb shell settings put system multi_audio_focus_enabled 0
adb shell cmd appops set com.google.android.youtube TAKE_AUDIO_FOCUS default
adb uninstall io.github.channelramble.multiappaudio
adb reboot

If you added pass-through or muted apps, the app's Read more sections list their undo commands; run those before uninstalling.

Verify the download

Releases are signed with the project's release key. Its certificate SHA-256 is:

3bf35b33f7ec1bb42634e2dfa4fb144447701f2a5f57801f218b780324a86ee0

The same value is in .github/signing-cert.sha256, and the release workflow refuses to publish an APK signed with any other key. To check a download, run apksigner verify --print-certs MultiAppAudio.apk, or use an app such as AppVerifier.

How it works

• Per-app volume works like an equalizer app: it attaches Android's DynamicsProcessing effect to each app's audio session and sets its gain. The DUMP grant lets it read which app owns each session. That's dumpsys audio up to Android 16, and AudioFlinger's track list on Android 17, which locks the former away from apps.
• Multi-app audio, pass-through and mute are Android's own settings and app-ops. They're set over ADB because Android doesn't let apps change them, and the app shows their state.
• The helper is a small foreground service, and its notification is the App volume control. It restarts after reboots and updates.

The details, with AOSP source references, are in docs/RESEARCH.md.

Building from source: ./gradlew assembleRelease with JDK 17 or 21 and the Android SDK. app/ is a plain Android app with no dependencies:

• core/AudioDump.kt reads the audio stream list (dumpsys audio, or media.audio_flinger on Android 17).
• core/AppVolumes.kt attaches DynamicsProcessing to other apps' audio sessions.
• core/ActiveApps.kt works out which apps are playing right now.
• MixerNotification.kt, MixerActivity.kt and MixerTileService.kt are the App volume notification, slider panel and Quick Settings tile.
• core/CarWatcher.kt, core/SessionWatcher.kt and core/AutoSwitchGuard.kt are the Android Auto and call helpers.
• AudioControlService.kt is the foreground service that hosts all of the above.