Soundify

Bring your stems. Mix them anywhere. Or remove the music from a video or audio file.

Soundify is a free, offline Android app with three modes:

• Stem Mixer — play 2–8 stems you already have, with gain, pan, mute, solo, offset, looping and WAV export.
• Clean Media (beta) — pick an audio or video file, remove its music on-device, keep voice and sound effects, then export cleaned audio (MP3 or M4A) or, when the source has a video track, a cleaned video with the original video stream copied.
• Audio editor — import one audio file, trim it on a waveform, split it, fade it, set clip volume, reorder clips and export a new file without ever modifying the original.

Clean Media uses a bundled on-device model. The app does not request the INTERNET permission, and no audio or video leaves the phone.

Download

Get the latest APK from the Releases page. The release APK includes the separation model.

Release APKs are signed with a dedicated release key. Builds from before 0.6.0 used the debug key, so upgrading from one of those requires a one-time uninstall (app data is removed).

Update with Obtainium

1. Install Obtainium.
2. Add the repository URL: https://github.com/m0-3az/Soundify.
3. Enable update notifications for the app.

Obtainium checks GitHub Releases; Soundify itself stays offline and has no network permission. Updates still require the Android install confirmation.

Screenshots

Library	Mixer

Status

• Stem Mixer: MVP complete and verified on a physical phone.
• Clean Media: beta. End-to-end on-device tests pass for 12 s and 60 s clips. A 20-minute video is processed in roughly 29 minutes on a Samsung SM-A576B; the pipeline streams chunks and writes stems to disk, so memory stays bounded.
• Audio editor: 0.6.0. Import, trim, split, fade, volume, clip reorder, preview and WAV/FLAC/MP3/M4A export are implemented and covered by 187 JVM and 49 device tests.
• Open issues: separation quality varies by mix, and Clean Media currently exports a cleaned mix rather than an interactive three-stem mixer.

Features

Stem Mixer

• Import 2–8 audio files through the system file picker
• WAV, FLAC, MP3, M4A/AAC at 44.1 kHz or 48 kHz
• Automatic channel-role detection from filenames
• Sample-aligned playback with one transport clock
• Per-stem gain, pan, mute and solo
• Per-stem offset nudge for compressed stems with decoder delay
• Loop region for practice
• Background playback with a media notification
• Local project library with saved mix state
• WAV export (16-bit PCM)

Clean Media

• Import any audio or video file through the system file picker
• Extract audio at its original level to 44.1 kHz stereo float
• Separate music / voice / sound effects with the bundled MRX model
• Match the cleaned mix to -16 LUFS / -1.5 dBTP after separation; near-silent mixes keep their existing level instead of being boosted into noise
• Stream 6-second chunks to disk so 20-minute videos do not exhaust RAM
• Four outputs: voice, sound effects, music and clean mix, each with playback and a level control
• Foreground service with a progress notification, chunk count, ETA and Cancel
• Cancelling or failing removes the partial stem files automatically
• Delete stems removes the four outputs from the app without touching files you saved
• Save one track as WAV, FLAC, MP3 or M4A through the system document picker
• Put a track back into the video, copying the original video stream; video saves are hidden for audio-only sources, including audio with cover art
• MP4 is offered only for H.264/HEVC/AV1/MPEG-4 video; MKV is the fallback for other codecs (VP8/VP9, MPEG-2, Theora, unknown) and WebM only for VP8/VP9/AV1
• Clear errors for files without an audio track and for FFmpeg failures

Audio editor

• Import one audio file through the system picker; the app keeps its own copy and never modifies the picked original
• Waveform view with draggable trim handles and exact millisecond fields
• Split at the playhead, fade in/out, and per-clip volume from −24 to +24 dB
• Clip list: add, reorder, select and delete clips; undo/redo (50 steps)
• Preview playback with trim-end stop, seek and a project timeline
• Export WAV, FLAC, MP3 or M4A at 44.1 kHz stereo through the system document picker, with progress and Cancel
• Fades, crossfade and effects are applied on export; preview is approximate
• Future-schema projects open read-only so a newer version's data is not rewritten

Why

• Free: no ads, subscriptions, accounts or in-app purchases.
• Offline: no INTERNET permission; the model and FFmpeg are bundled.
• Private: your media never leaves the device.
• Local AI: one small on-device model, no cloud processing, no tracking.

Limitations

• Clean Media quality depends on the mix. Music with vocals, heavy compression, or loud sound effects can bleed between stems.
• Near-silent clean mixes are kept at their existing level instead of being amplified into separation noise; the result screen explains why.
• A 20-minute video takes roughly 29 minutes on the tested phone. Processing continues in the background with a notification.
• The Audio editor is single-track and clip-based, not a multi-track timeline. Recording, merge, batch convert and real-time effects are later releases.
• Stem Mixer requires all stems in a project to share the same sample rate.
• MP3/AAC stems may need a manual offset because of encoder delay.

Build

Requirements:

• JDK 17
• Android SDK 35
• Gradle 8.9 (the wrapper is included)
• The separation model, which is not stored in git because it is 117 MB

Download mrx_mask.onnx from the latest release assets and place it here:

app/src/main/assets/mrx_mask.onnx

Then:

./gradlew assembleDebug

The APK is written to:

app/build/outputs/apk/debug/app-debug.apk

For a release build, provide the signing material through environment variables (never commit it):

export SOUNDIFY_KEYSTORE=/path/to/soundify-release.jks
export SOUNDIFY_KEYSTORE_PASSWORD_FILE=/path/to/storepass.txt
export SOUNDIFY_KEY_PASSWORD_FILE=/path/to/storepass.txt
export SOUNDIFY_KEY_ALIAS=soundify
./gradlew assembleRelease

The signed APK is written to:

app/build/outputs/apk/release/app-release.apk

Without those variables the release build is unsigned, so a debug key can never silently ship. See docs/releases/README.md for the full release checklist.

Test

./gradlew testDebugUnitTest
./gradlew connectedDebugAndroidTest   # requires a device or emulator

The instrumentation tests include synthetic short and 60-second videos, so the separation pipeline is exercised without copyrighted sample media.

Install

adb install -r app/build/outputs/apk/release/app-release.apk

Or copy the APK to a device and open it. A build signed with the release key cannot update a debug-signed build; uninstall the old app once. After that, every release keeps the same key and updates in place.

Usage

Stem Mixer

1. Tap New project.
2. Choose 2–8 stem files.
3. Confirm the project name and import.
4. Play the project and adjust gain, pan, mute and solo.
5. Toggle Loop to repeat a section.
6. Tap Export WAV to render the current mix.

Clean Media

1. On the library screen, tap Clean Media.
2. Choose an audio or video file. Files without an audio track are rejected with a clear message.
3. Tap Clean and keep the app open.
4. Play the cleaned result, then save the MP3, M4A or, for a video source, the cleaned video.
5. Tap Delete stems to remove the four outputs from the app. Files you saved to another folder are kept. Cancelling a run also removes its partial stems.

The result screen shows the levels you will get when saving: voice, sound effects and music are restored by +6 dB on export, while the clean mix is already normalized.

Audio editor

1. On the library screen, tap Audio editor.
2. Tap New edit and choose one audio file. The app copies it; the original is never modified.
3. Drag the waveform handles or type exact start/end milliseconds.
4. Use Split at the playhead, Fade and Volume on the selected clip.
5. Add more clips, reorder them, and select a clip from the list to edit it.
6. Tap Save audio, choose a format and name, then pick a destination.
7. Tap Export; progress and Cancel stay visible while it runs.

Exports are always 44.1 kHz stereo. Fades, crossfade and effects are applied on export; preview is approximate. Deleting an edit removes only the app's copy.

Project structure

app/src/main/java/com/soundify/app/
  data/         Project and stem models, local store, role mapping
  audio/        MediaCodec decoders, ring buffer, mixer, WAV writer
  cleanvideo/   STFT/iSTFT, ONNX mask model, streaming cleaner, FFmpeg
  editor/       Editor model/store/importer, waveform, player, exporter
  ui/           Compose screens and theme

Privacy

Soundify does not collect, transmit or sell data. It has no network permission. Imported media and exports live in app-private storage and are removed when you delete a project or uninstall the app.

License

MIT. See LICENSE.

Third-party components and model notices are listed in THIRD_PARTY_LICENSES.md.

Contributing

Issues and pull requests are welcome. Please keep the app free, offline and private by default.