← HY Studio home日本語
LunaMixer

Every app.
Your volume.

Control each app’s volume. All in one place.

One-time setup, so every app that is playing gets its own volume. No computer, no cable — just Wi-Fi for the first run, all on this phone.

No computer No root No extra app Wi-Fi first run only Network only for billing
Screenshot of the LunaMixer mixer on a phone, taken mid-navigation. YouTube, Maps and LINE each have their own volume slider.

What this app does

The usual per-app volume apps switch the whole device volume to match whichever app is in front. LunaMixer sets a separate volume for each app that is playing, all at the same time.

!

If you have a Galaxy

On Galaxy (Samsung) phones, the built-in "Sound Assistant" may already do this. Trying that first is probably quicker. This app is for phones without an equivalent.

Why does it need a special setup?
The volume controls this app uses cannot be reached through ordinary Android settings, so the first connection is made over wireless debugging. Leaving USB debugging on afterwards keeps that connection alive even with no Wi-Fi around. Everything used here is a standard part of Android, and the only network traffic is Google Play's billing system checking your purchase. What you listen to and which apps you have are never sent.
0

Install from Google Play

Google Play → LunaMixer
ImportantTap Allow when it asks about notifications. Later on, the six-digit code is typed into this app's notification.
  1. Get LunaMixer from Google Play.
  2. Open the app and tap Start.
  3. Tap Allow when it asks about notifications.
More about this screen

Notifications have to be allowed. In step 5 you type the six-digit pairing code into this app's notification. Refuse notifications and that box never appears, so setup cannot be finished. If you have already refused, allow it again under Settings → Apps → LunaMixer → Notifications.

6

Setup is six steps

Each step runs "what it is for → the button → what to do".
1

Reveal the developer menu

Settings → About phone → Build number
Tap "Build number" seven times in a row, which makes the developer menu available.
What to do on this screen
  1. Open About phone.
  2. Tap Build number seven times.
  3. Enter your PIN or pattern if you are asked for it.
  4. "You are now a developer!" means it worked — go back and continue.
Button inside the app
Open About phone

Already turned on before? Move straight on.

2

Turn on developer options

Settings → System → Developer options
Turn on "Use developer options" at the top of the screen.
What to do on this screen
  1. Open Developer options.
  2. Turn on the switch at the top.
  3. Come back to the app and continue.
Button inside the app
Open Developer options
3

Connect to Wi-Fi

Settings → Network & internet → Wi-Fi
Wireless debugging only works while you are on Wi-Fi. That Wi-Fi does not have to reach the internet.
What to do on this screen
  1. Pick the Wi-Fi network to use.
  2. Wait until it says connected.
  3. Come back to this app.
Button inside the app
Open Wi-Fi settings

Mobile data on its own will not get you past this. It is the one step that will not let you continue until it is done.

4

Turn on wireless debugging

Developer options → Wireless debugging
Turn on the switch beside Wireless debugging in the list → if "Allow wireless debugging?" appears, tap Allow.
What to do on this screen
  1. Open Developer options.
  2. Find Wireless debugging under the Debugging heading.
  3. Turn on the switch beside it (you do not have to open the screen).
Button inside the app
Open Developer options
If you cannot find it
Searching Settings for "wireless" is the surest way. It sits under the Debugging heading, near USB debugging, though the order differs from phone to phone.
5

Enter the six-digit pairing code in the notification

Wireless debugging → Pair device with pairing code
The code goes into the notification, without leaving Settings
123 456
✓ Leave the Settings screen✓ Pull down the shade ✓ Type it in the notification× Do not go home × Do not write it down× Do not open another app
ImportantThe six-digit code stops working the moment you leave that screen. Pulling down the notification shade is not leaving the screen — it sits on top of Settings, and the code stays as it is.
What to do on this screen
  1. Open Developer options.
  2. Wireless debugging → "Pair device with pairing code".
  3. When the six-digit code appears, pull down the notification shade without leaving the screen.
  4. On the "Type the six-digit pairing code here" notification, tap Enter, type the code and send.
Button inside the app
Open Developer options
✓
The notification turns into "Connected"

After you send it the notification reads "Checking the six-digit code", then "Connected / Pairing is done". Come back to the app once it is done.

6

Allow the bubble to show

Settings → Display over other apps → LunaMixer
The sliders do not live in the app itself — they open from a bubble that floats on screen. Without this permission the bubble cannot appear.
What to do on this screen
  1. If a list of apps appears, choose LunaMixer.
  2. Turn the switch on.
  3. Come back to LunaMixer.
Button inside the app
Allow drawing over apps
✓
That is setup finished

Back in the app, Show bubble can now be tapped.

From here on, it all happens in the bubble.

The sliders open from the bubble floating over your screen, not from the app itself. Next time, all you do is tap Show bubble.

Using it

  1. Open the app and tap Show bubble.
  2. Drag the round bubble wherever you want it.
  3. Tap the bubble to open the list of apps that are playing.
  4. Move a slider and that app's volume changes as you go.
↘
Finer control at low volumes

Most adjustments land between 0 and 30%, so the bottom 60% or so of the slider is given to that range.

To put everything back: tap Stop volume control in the panel, or close both the app and the bubble. Volumes return to normal a few seconds later.

↔

Settings the connection needs

Four combinations, that is all.
✓
Leaving USB debugging on is the easy option

With USB debugging on, the connection survives even after wireless debugging is turned off.

USB debugging ONWireless debugging ON
Stays on○
Restart○
USB debugging ONWireless debugging OFF
Stays on○
Restart×
USB debugging OFFWireless debugging ON
Stays on○
Restart○
USB debugging OFFWireless debugging OFF
Stays on×
Restart×

Stays on: a connection that has been made is not dropped. Close the app and it is ready the moment you open it again.

Restart: a dropped connection can be made again with "Turn volume control back on". You need this after both switches have been off.

?

If something goes wrong

Wireless debugging will not turn on
Connect to Wi-Fi first. A Wi-Fi network with no internet access is fine.
The notification for the code never appears
Notifications are probably not allowed. Check Settings → Apps → LunaMixer → Notifications. The notification appears the moment you tap [Open Developer options] inside the app.
The code was sent but nothing connects
The code has probably changed. Going home or opening another app changes the digits (pulling down the notification shade does not). Opening the app tells you the current reason; start the pairing again from the beginning.
It was working, now it says "Not connected"
Both USB debugging and wireless debugging probably ended up off. Get on Wi-Fi, turn wireless debugging back on, and tap "Turn volume control back on".
The volumes went back to normal on their own
Closing both the app and the bubble returns everything to normal after a few seconds. Leave the bubble showing to keep your settings in effect.
One app ignores the slider
A few apps produce sound in an unusual way — some games in particular — and cannot be controlled this way.
!

If you leave USB debugging on

1
Always read the prompt when a new computer connects
You will be asked "Allow USB debugging?". If you were not expecting it, refuse.
2
"Always allow" only for computers you trust
Once allowed, that computer may connect again without asking.
3
Avoid unknown USB devices, chargers and cables
If a public charging point brings up a connection prompt you did not expect, always refuse.

If it bothers you, turn USB debugging back off when you are not using it. Next time, get on Wi-Fi, turn wireless debugging on, and tap Turn volume control back on.

§

Licences

Third-party code and attribution.

This app contains code written by other people. Where it came from, the licence chosen, and the changes made are set out below.

  • Apache License 2.0 / full text at the bottom of this page
    libadb-android (Muntashir Al-Islam and others) — used to pair with wireless debugging and connect to it from inside the device. Apache chosen, where GPL-3.0 was the alternative. Modified: package names changed; the SPAKE2 implementation replaced with our own, in place of LGPL-3.0 spake2-java.
    Conscrypt (The Android Open Source Project) — used for TLS during pairing. Unmodified.
    AndroidX / Jetpack Compose (Google) — used to draw the screens and for the app's basic machinery. Unmodified.
    kotlinx.coroutines (JetBrains) — used to get slow work done without stopping the screen. Unmodified.
    com.google.android.datatransport (3) / com.google.firebase:firebase-encoders (3) / com.google.guava:listenablefuture / javax.inject / org.jspecify / org.jetbrains:annotations — used internally by the in-app purchase library. Unmodified.
  • Android Software Development Kit License / text not bundled
    com.android.billingclient:billing / billing-ktx — used for the in-app purchase. Unmodified.
    com.google.android.gms:play-services-base / basement / location / places-placereport / tasks — used internally by the libraries above; not asked for directly. Unmodified.
    Terms at developer.android.com/studio/terms.html
  • Play Core Software Development Kit Terms of Service / text not bundled
    com.google.android.play:review / review-ktx — used to ask for a review from inside the app. Unmodified.
    com.google.android.play:core-common — used internally by the libraries above; not asked for directly. Unmodified.
    Terms at developer.android.com/guide/playcore/license
  • Bouncy Castle Licence (MIT-style)
    org.bouncycastle:bcprov-jdk15to18 / bcpkix-jdk15to18 / bcutil-jdk15to18 — used for key derivation (HKDF), encryption (AES-GCM), and building the certificate used to connect. Unmodified.
    Terms at bouncycastle.org/licence.html
  • Permissive, ISC-style licence
    SPAKE2 / edwards25519 (BoringSSL, Google Inc.) — used for the key exchange during pairing. Modified: ported to Kotlin from the BoringSSL C implementation.
  • SIL Open Font License 1.1 / full text ships inside the app (assets/fonts/)
    Zen Kaku Gothic New / Manrope — bundled as the app's typefaces. Unmodified.

Not required by any licence, recorded anyway: Shizuku (RikkaApps). Starting a separate process with shell privileges and taking a Binder from it is a technique Shizuku established. This app uses none of its source and was written independently from published descriptions, so no attribution is required. Putting it in the list above would make that list — the terms this app is under — inaccurate, so it sits here instead.

Show the full text of the Apache License 2.0
Apache License
                           Version 2.0, January 2004
                        http://www.apache.org/licenses/

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
      the copyright owner that is granting the License.

      "Legal Entity" shall mean the union of the acting entity and all
      other entities that control, are controlled by, or are under common
      control with that entity. For the purposes of this definition,
      "control" means (i) the power, direct or indirect, to cause the
      direction or management of such entity, whether by contract or
      otherwise, or (ii) ownership of fifty percent (50%) or more of the
      outstanding shares, or (iii) beneficial ownership of such entity.

      "You" (or "Your") shall mean an individual or Legal Entity
      exercising permissions granted by this License.

      "Source" form shall mean the preferred form for making modifications,
      including but not limited to software source code, documentation
      source, and configuration files.

      "Object" form shall mean any form resulting from mechanical
      transformation or translation of a Source form, including but
      not limited to compiled object code, generated documentation,
      and conversions to other media types.

      "Work" shall mean the work of authorship, whether in Source or
      Object form, made available under the License, as indicated by a
      copyright notice that is included in or attached to the work
      (an example is provided in the Appendix below).

      "Derivative Works" shall mean any work, whether in Source or Object
      form, that is based on (or derived from) the Work and for which the
      editorial revisions, annotations, elaborations, or other modifications
      represent, as a whole, an original work of authorship. For the purposes
      of this License, Derivative Works shall not include works that remain
      separable from, or merely link (or bind by name) to the interfaces of,
      the Work and Derivative Works thereof.

      "Contribution" shall mean any work of authorship, including
      the original version of the Work and any modifications or additions
      to that Work or Derivative Works thereof, that is intentionally
      submitted to Licensor for inclusion in the Work by the copyright owner
      or by an individual or Legal Entity authorized to submit on behalf of
      the copyright owner. For the purposes of this definition, "submitted"
      means any form of electronic, verbal, or written communication sent
      to the Licensor or its representatives, including but not limited to
      communication on electronic mailing lists, source code control systems,
      and issue tracking systems that are managed by, or on behalf of, the
      Licensor for the purpose of discussing and improving the Work, but
      excluding communication that is conspicuously marked or otherwise
      designated in writing by the copyright owner as "Not a Contribution."

      "Contributor" shall mean Licensor and any individual or Legal Entity
      on behalf of whom a Contribution has been received by Licensor and
      subsequently incorporated within the Work.

   2. Grant of Copyright License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      copyright license to reproduce, prepare Derivative Works of,
      publicly display, publicly perform, sublicense, and distribute the
      Work and such Derivative Works in Source or Object form.

   3. Grant of Patent License. Subject to the terms and conditions of
      this License, each Contributor hereby grants to You a perpetual,
      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
      (except as stated in this section) patent license to make, have made,
      use, offer to sell, sell, import, and otherwise transfer the Work,
      where such license applies only to those patent claims licensable
      by such Contributor that are necessarily infringed by their
      Contribution(s) alone or by combination of their Contribution(s)
      with the Work to which such Contribution(s) was submitted. If You
      institute patent litigation against any entity (including a
      cross-claim or counterclaim in a lawsuit) alleging that the Work
      or a Contribution incorporated within the Work constitutes direct
      or contributory patent infringement, then any patent licenses
      granted to You under this License for that Work shall terminate
      as of the date such litigation is filed.

   4. Redistribution. You may reproduce and distribute copies of the
      Work or Derivative Works thereof in any medium, with or without
      modifications, and in Source or Object form, provided that You
      meet the following conditions:

      (a) You must give any other recipients of the Work or
          Derivative Works a copy of this License; and

      (b) You must cause any modified files to carry prominent notices
          stating that You changed the files; and

      (c) You must retain, in the Source form of any Derivative Works
          that You distribute, all copyright, patent, trademark, and
          attribution notices from the Source form of the Work,
          excluding those notices that do not pertain to any part of
          the Derivative Works; and

      (d) If the Work includes a "NOTICE" text file as part of its
          distribution, then any Derivative Works that You distribute must
          include a readable copy of the attribution notices contained
          within such NOTICE file, excluding those notices that do not
          pertain to any part of the Derivative Works, in at least one
          of the following places: within a NOTICE text file distributed
          as part of the Derivative Works; within the Source form or
          documentation, if provided along with the Derivative Works; or,
          within a display generated by the Derivative Works, if and
          wherever such third-party notices normally appear. The contents
          of the NOTICE file are for informational purposes only and
          do not modify the License. You may add Your own attribution
          notices within Derivative Works that You distribute, alongside
          or as an addendum to the NOTICE text from the Work, provided
          that such additional attribution notices cannot be construed
          as modifying the License.

      You may add Your own copyright statement to Your modifications and
      may provide additional or different license terms and conditions
      for use, reproduction, or distribution of Your modifications, or
      for any such Derivative Works as a whole, provided Your use,
      reproduction, and distribution of the Work otherwise complies with
      the conditions stated in this License.

   5. Submission of Contributions. Unless You explicitly state otherwise,
      any Contribution intentionally submitted for inclusion in the Work
      by You to the Licensor shall be under the terms and conditions of
      this License, without any additional terms or conditions.
      Notwithstanding the above, nothing herein shall supersede or modify
      the terms of any separate license agreement you may have executed
      with Licensor regarding such Contributions.

   6. Trademarks. This License does not grant permission to use the trade
      names, trademarks, service marks, or product names of the Licensor,
      except as required for reasonable and customary use in describing the
      origin of the Work and reproducing the content of the NOTICE file.

   7. Disclaimer of Warranty. Unless required by applicable law or
      agreed to in writing, Licensor provides the Work (and each
      Contributor provides its Contributions) on an "AS IS" BASIS,
      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
      implied, including, without limitation, any warranties or conditions
      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
      PARTICULAR PURPOSE. You are solely responsible for determining the
      appropriateness of using or redistributing the Work and assume any
      risks associated with Your exercise of permissions under this License.

   8. Limitation of Liability. In no event and under no legal theory,
      whether in tort (including negligence), contract, or otherwise,
      unless required by applicable law (such as deliberate and grossly
      negligent acts) or agreed to in writing, shall any Contributor be
      liable to You for damages, including any direct, indirect, special,
      incidental, or consequential damages of any character arising as a
      result of this License or out of the use or inability to use the
      Work (including but not limited to damages for loss of goodwill,
      work stoppage, computer failure or malfunction, or any and all
      other commercial damages or losses), even if such Contributor
      has been advised of the possibility of such damages.

   9. Accepting Warranty or Additional Liability. While redistributing
      the Work or Derivative Works thereof, You may choose to offer,
      and charge a fee for, acceptance of support, warranty, indemnity,
      or other liability obligations and/or rights consistent with this
      License. However, in accepting such obligations, You may act only
      on Your own behalf and on Your sole responsibility, not on behalf
      of any other Contributor, and only if You agree to indemnify,
      defend, and hold each Contributor harmless for any liability
      incurred by, or claims asserted against, such Contributor by reason
      of your accepting any such warranty or additional liability.

   END OF TERMS AND CONDITIONS

   APPENDIX: How to apply the Apache License to your work.

      To apply the Apache License to your work, attach the following
      boilerplate notice, with the fields enclosed by brackets "[]"
      replaced with your own identifying information. (Don't include
      the brackets!)  The text should be enclosed in the appropriate
      comment syntax for the file format. We also recommend that a
      file or class name and description of purpose be included on the
      same "printed page" as the copyright notice for easier
      identification within third-party archives.

   Copyright [yyyy] [name of copyright owner]

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.