Dynamic Driving

Music that follows the road. Dynamic Driving plays layered songs whose stems fade in and out with how fast you are actually moving: standing still the mix is quiet and muffled, and as you speed up the layers arrive.

It runs on the phone, in Android Auto, and on Android Automotive OS, and ships with a Windows editor for authoring the songs.

Phone / Android Auto	mobile — Material 3 Compose app, media notification, Android Auto templated media
Android Automotive OS	automotive — the same app built against the vehicle's own speed sensor
Windows editor	desktop_editor — .NET 10 WPF song editor, published as a portable ZIP
Bundled demo	Open Road, an original CC0 song, so there is something to play immediately

Everything stays on the device: no accounts, no analytics, no network calls. Neither APK declares the INTERNET permission, so the app cannot make one. See docs/PRIVACY.md.

How adaptive playback works

A song is a folder holding a song.json manifest and one 16-bit PCM WAV per stem.

• Base stems are speed bands. A stem with minMph: 30 is silent in town and arrives on the motorway. Bands have hysteresis, so a speed hovering on a threshold does not chatter the layer.
• Overlay stems are timed one-shots grouped by groupId. One overlay per group plays at a time, for a set duration, then waits out a randomised cooldown.
• Events apply gain and reverb changes while a speed condition holds.
• Song muffle rolls a low-pass filter across everything while you are barely moving, and releases as you pick up speed.
• The loop region is what repeats. Audio after it is the tail, played once on the way out to the next song.

The format is documented in SONG_JSON.md and specified by contracts/song.schema.json.

The app

Four destinations:

• Now Playing — artwork, title, artist, album, previous/play/next, the active playlist, the playback mode, and the current speed with the source it came from.
• Library — the selected folder, change and refresh, scan progress, readable diagnostics, and a card per song.
• Playlists — create, rename, delete, drag-reorder playlists and their songs, add and remove.
• Settings — speed source, manual speed, playback mode, loops before advancing, permissions, and an About section.

Speed sources

Selection	Behaviour
Automatic (default)	AAOS prefers native vehicle speed; Android Auto prefers projected car speed and falls back to phone GPS; an unconnected phone uses GPS
Car	Only the vehicle's speed. Never falls back
Phone GPS	Only this phone's GPS. Never falls back
Manual	A speed you set with a slider

An explicit selection is strict on purpose: if the source it names cannot produce a reading, the app shows 0 mph with an explanation and a one-tap route back to Automatic, rather than quietly substituting a different source.

Playback modes

Repeat song (default), Play in order, and Shuffle, with a 1–8 setting for how many loops elapse before moving on. Next and previous always step within the active collection and wrap.

Building

Requirements: JDK 21, the Android SDK with platform 36, and the .NET 10 SDK for the editor.

./gradlew test lintRelease :mobile:assembleRelease :automotive:assembleRelease

dotnet test desktop_editor/DynamicDriving.slnx -c Release

Full instructions, including how to produce the portable editor ZIP, are in CONTRIBUTING.md.

Releases

Each tagged release publishes four files:

Artifact	What it is
DynamicDriving-mobile-v1.0.0.apk	Phone and Android Auto build, signed
DynamicDriving-automotive-v1.0.0.apk	Android Automotive OS build, signed
DynamicDriving-Editor-v1.0.0-win-x64.zip	Portable Windows editor, self-contained
SHA256SUMS.txt	Checksums for the three files above

Verifying what you downloaded

Check the hashes:

sha256sum --check --ignore-missing SHA256SUMS.txt

On Windows PowerShell:

Get-FileHash .\DynamicDriving-mobile-v1.0.0.apk -Algorithm SHA256

Check that an APK really is signed, and see the signing certificate:

apksigner verify --print-certs --verbose DynamicDriving-mobile-v1.0.0.apk

The editor ZIP is unsigned for v1.0.0, so Windows SmartScreen will warn the first time you run it. Verify the checksum before trusting it. Authenticode signing is future scope. Because the editor is a self-contained, unsigned .NET application, some antivirus products flag it heuristically; the build is reproducible from source with the command in CONTRIBUTING.md if you would rather build it yourself.

Running the editor

The editor ZIP contains one file: DynamicDriving.Editor.exe. Unzip it anywhere and run it. Nothing to install: no Python, loose dependency folders, or separate .NET runtime.

Three panes: the song and its stems on the left, the waveform with loop handles and the transport in the middle, and a typed inspector on the right. Drag the speed slider to hear the stem rules take effect, and watch the live level beside each stem.

The editor can check itself against a song folder, which is what CI runs against the published ZIP:

DynamicDriving.Editor.exe --self-check path\to\song\folder

Repository layout

mobile/          Phone + Android Auto application
automotive/      Android Automotive OS application
shared/          Domain, playback engine, media session, and the Compose UI both apps use
projected/       Android Auto templated-media entry point
contracts/       song.json schema and the fixtures both parsers are tested against
desktop_editor/  .NET 10 WPF editor (Core, Editor, Tests)
docs/            Privacy and screenshots

Licence

MIT. The bundled demo song is CC0 — see its notice.