Harmonisk

An Android application for pitch detection and musical practice.

License

Harmonisk is licensed under the GNU Affero General Public License v3.0.

Attributions

This app ships and uses the following third-party works:

• GeneralUser GS SoundFont by S. Christian Collins, used for melody playback and note previews. Licensed under the GeneralUser GS License v2.0 (see https://schristiancollins.com/generaluser.php).
• TinySoundFont by Bernhard Schelling (based on SFZero by Steve Folta), which synthesises the soundfont. Licensed under the MIT License.
• CREPE by Jong Wook Kim et al. (2018), the pitch detection model. Licensed under the MIT License (see https://github.com/marl/crepe).
• alphaTab by Daniel Kuschny and contributors, used to render sheet music. Licensed under the Mozilla Public License 2.0; the bundled Bravura font is licensed under the SIL Open Font License 1.1, and the bundled Sonic Network samples under the Apache License 2.0.

The complete list of dependencies and bundled assets, with licenses, is in THIRD_PARTY_LICENSES.md.

Building

./gradlew assembleDebug

Install the app to a connected device

android-sdk/platform-tools/adb install app/build/outputs/apk/debug/app-debug.apk

Start the app on the device

android-sdk/platform-tools/adb shell am start -n net.exent.harmonisk/.MainActivity

Run unit tests

./gradlew :app:test

Test audio fixtures live in app/src/test/resources/audio.

Release

Versioning is derived from the build time (UTC). versionName is yyyy.MM.dd and versionCode is yyMMdd followed by a three-digit slot that splits the day into 1000 segments:

versionCode = yyMMdd * 1000 + (secondsSinceMidnight * 1000 / 86400)

For 2026-10-11 19:22 UTC that is 261011806: 261011 is the date and 806 is the time slot. Slots are about 86 seconds long, so the number always grows with the clock, needs no counter, and nothing resets daily. The only collision case is two builds inside the same ~86-second slot, so leave a couple of minutes between releases. The largest possible value this century is 991231999, well under Google Play's 2,100,000,000 limit.

Release signing reads keystore.properties in the project root (gitignored):

storeFile=harmonisk-upload.jks
storePassword=...
keyAlias=harmonisk
keyPassword=...

Build the signed App Bundle for Google Play:

./gradlew :app:bundleRelease

The bundle is written to app/build/outputs/bundle/release/app-release.aab. The upload keystore and keystore.properties are not tracked by git, so back them up somewhere safe; losing them means you can no longer update the app under this key.

Release builds run R8 (shrinking, obfuscation and optimization) with resource shrinking enabled; debug builds stay unminified. Release stack traces are therefore obfuscated: the build writes app/build/outputs/mapping/release/mapping.txt, Play deobfuscates crashes automatically from the copy embedded in the bundle, and Android Studio or retrace can use the local file.