# Interstellar — sound theme for KDE Plasma

<img src="preview/avatar.png" alt="Interstellar" width="120" align="right">

*A long look out of the window*

A complete, [freedesktop Sound Theme
specification](https://specifications.freedesktop.org/sound-theme-spec/latest/)
compliant sound theme for **KDE Plasma 6** (and any other desktop that honours
the spec). 61 cues, all of them synthesised from scratch — no sample
library, no third-party audio, no attribution burden. The whole theme is
reproducible from the script in `tools/`.

```
kde-sound-theme-interstellar/
├── Interstellar/
│   ├── index.theme          # [Sound Theme] + [stereo] OutputProfile
│   └── stereo/              # 61 × Ogg Vorbis 48 kHz stereo
├── tools/
│   ├── gen_sounds.py        # the synthesis engine (reproducible)
│   ├── verify_theme.py      # spec + audio + KDE coverage checks
│   ├── make_preview.py      # rebuilds preview/index.html
│   └── preview_template.html
├── preview/
│   ├── index.html           # player nel browser per ogni cue
│   └── avatar.png           # icona del tema (512×512)
├── LICENSES/
├── Makefile
└── install.sh
```

## Character

Interstellar is the view, not the console. Harmonic two-operator FM (ratio 2.0) folded into wide detuned additive pads on D3, lydian shimmer an octave and two above, and a 4.2 s hall that lets a login bloom. It is the warmest of the three and the one that benefits most from the differentiated reverb bus: chat and volume cues stay close, session and outcome cues open up.

| Motif | Used for |
|---|---|
| Wide detuned pad swell | login, session, vast space |
| Lydian shimmer cluster | wonder, arrival, highlight |
| Perfect fifth arpeggio | affirmation, information |
| Bell glissando | entering and leaving |
| Plucked-string arpeggio | organic, gentle completion |

## Requirements

* KDE Plasma 6, or any desktop implementing the freedesktop sound theme spec
* nothing at runtime — the cues are plain Ogg Vorbis files
* `ffmpeg` (libvorbis), `python3`, `numpy`, `scipy` **only** if you want to
  regenerate the audio

## Install

User-local (recommended, no root needed):

```sh
git clone https://git.enne2.net/enne2/kde-sound-theme-interstellar.git
cd kde-sound-theme-interstellar
./install.sh              # copies Interstellar/ into ~/.local/share/sounds/
```

System-wide:

```sh
sudo make install-system  # copies Interstellar/ into /usr/share/sounds/
```

## Select the theme

**System Settings → Colors & Themes → System Sounds → Interstellar**

Or from the command line:

```sh
kwriteconfig6 --file kdeglobals --group Sounds --key Theme Interstellar
```

To go back to the Plasma default:

```sh
kwriteconfig6 --file kdeglobals --group Sounds --key Theme ocean
```

The theme declares `Inherits=freedesktop`, so any event it does not provide
(e.g. multi-channel test signals) falls back to the stock desktop theme instead
of going silent.

## What is inside

`Interstellar/index.theme` declares the theme, `Directories=stereo`,
`OutputProfile=stereo` and `Example=theme-demo`. The `Example` key is what the
Plasma *System Sounds* KCM uses for its preview button, so `theme-demo.oga` is a
montage of the theme's signatures rather than an arbitrary cue.

`Name[it]` and `Comment[it]` are also provided, so Plasma in an Italian locale
lists the theme as **Interstellare**. That is a display name only: the theme id — the
folder name in `~/.local/share/sounds/` and the value written to
`kdeglobals` — is always `Interstellar`, exactly like KDE's own Ocean theme shows up
as *Oceano* in Italian.

| sound name | duration | size |
|---|---:|---:|
| `alarm-clock-elapsed` | 2.66 s | 35.7 KiB |
| `audio-test-signal` | 1.10 s | 20.2 KiB |
| `audio-volume-change` | 0.13 s | 6.9 KiB |
| `battery-caution` | 1.18 s | 19.5 KiB |
| `battery-full` | 1.05 s | 17.5 KiB |
| `battery-low` | 1.18 s | 17.8 KiB |
| `bell-terminal` | 0.15 s | 7.2 KiB |
| `bell-window-system-attention` | 0.94 s | 15.2 KiB |
| `bell-window-system` | 0.88 s | 14.6 KiB |
| `bell` | 1.26 s | 19.5 KiB |
| `button-pressed-modifier` | 0.12 s | 7.0 KiB |
| `button-pressed` | 0.11 s | 6.9 KiB |
| `camera-shutter` | 0.26 s | 9.6 KiB |
| `complete-media-burn` | 2.26 s | 35.9 KiB |
| `complete-media-error` | 1.72 s | 36.9 KiB |
| `complete` | 0.83 s | 14.3 KiB |
| `completion-fail` | 1.38 s | 19.3 KiB |
| `completion-partial` | 1.12 s | 17.2 KiB |
| `completion-rotation` | 1.68 s | 23.0 KiB |
| `completion-success` | 2.14 s | 35.6 KiB |
| `desktop-login` | 2.90 s | 38.6 KiB |
| `desktop-logout` | 2.20 s | 28.8 KiB |
| `device-added` | 0.64 s | 15.2 KiB |
| `device-removed` | 0.64 s | 15.2 KiB |
| `dialog-error-critical` | 2.32 s | 47.8 KiB |
| `dialog-error-serious` | 1.80 s | 38.3 KiB |
| `dialog-error-veryserious` | 2.70 s | 34.4 KiB |
| `dialog-error` | 1.48 s | 32.8 KiB |
| `dialog-information` | 1.13 s | 17.5 KiB |
| `dialog-question` | 1.14 s | 18.5 KiB |
| `dialog-special` | 1.86 s | 34.6 KiB |
| `dialog-warning-auth` | 1.00 s | 18.8 KiB |
| `dialog-warning` | 1.27 s | 18.3 KiB |
| `game-over-loser` | 2.60 s | 52.5 KiB |
| `game-over-winner` | 3.02 s | 51.1 KiB |
| `media-insert-request` | 0.87 s | 17.1 KiB |
| `message-attention` | 1.16 s | 24.6 KiB |
| `message-contact-in` | 1.05 s | 17.3 KiB |
| `message-contact-out` | 1.05 s | 17.2 KiB |
| `message-highlight` | 0.86 s | 16.1 KiB |
| `message-new-email` | 1.48 s | 23.7 KiB |
| `message-new-instant` | 0.92 s | 14.7 KiB |
| `message-sent-instant` | 0.45 s | 10.5 KiB |
| `message` | 0.80 s | 14.0 KiB |
| `network-connectivity-established` | 1.66 s | 27.4 KiB |
| `network-connectivity-lost` | 1.26 s | 18.8 KiB |
| `outcome-failure` | 1.32 s | 29.7 KiB |
| `outcome-success` | 1.62 s | 27.5 KiB |
| `phone-incoming-call` | 2.44 s | 37.5 KiB |
| `phone-outgoing-busy` | 1.30 s | 23.5 KiB |
| `phone-outgoing-calling` | 1.16 s | 24.6 KiB |
| `power-plug` | 0.78 s | 15.2 KiB |
| `power-unplug` | 0.88 s | 19.6 KiB |
| `screen-capture` | 0.30 s | 10.6 KiB |
| `service-login` | 1.34 s | 19.8 KiB |
| `service-logout` | 1.24 s | 18.6 KiB |
| `suspend-error` | 1.92 s | 40.4 KiB |
| `theme-demo` | 11.39 s | 177.0 KiB |
| `trash-empty` | 0.95 s | 20.5 KiB |
| `window-attention` | 1.43 s | 20.8 KiB |
| `window-question` | 1.04 s | 17.2 KiB |

## Rebuilding from source

The audio is generated, not sampled, so it is fully reproducible:

```sh
make generate     # rewrites Interstellar/stereo/*.oga from tools/gen_sounds.py
make verify       # spec + audio + KDE coverage checks
make preview      # rebuild preview/index.html
make dist         # build dist/kde-sound-theme-interstellar-1.0.0.tar.gz
```

`make verify` fails loudly on a clipped sample, a DC offset, a click at a file
edge, a wrong sample rate or channel count, a missing `stereo` directory in
`Directories=`, a broken `Example`/`Inherits` reference, and it reports how many
of the sound names actually requested by the installed KDE `*.notifyrc` files
the theme resolves.

## Design notes

### One instrument set, not sixty unrelated beeps

Every cue is assembled from the same small library of motifs — FM bells, sub
impacts, band-limited noise sweeps, additive pads, plucked strings, telemetry
blips — so the theme reads as a single instrument rather than a folder of
noises. The palette below is what turns that library into *this* theme:

| Parameter | Interstellar |
|---|---|
| Root | D3 — 146.83 Hz |
| Scale | lydian (0 2 4 6 7 9 11) |
| FM voice | ratio 2.0, index 1.15, index decay 450 ms |
| Detune | ±14 cents |
| Space | 4.2 s synthetic hall, 40–53 % wet on the vast cues |

### A differentiated reverb bus

A single reverb setting is wrong for a desktop theme: frequent cues (chat,
volume, button clicks) would smear into each other during a burst, while rare
dramatic cues would sound dry and small. Cues here are assigned one of five
reverb classes — from near-dry clicks through a small room up to a vast hall
with an extra half-second of tail — by motif, with per-sound overrides. The
result is that a chat notification stays crisp and a login blooms.

### Loudness-aware normalisation

Peak-normalising every file is not enough: a sparse bell and a dense error
cluster end up at wildly different perceived levels. After peak normalisation
each cue gets a bounded gain (±6 dB) that pulls the RMS of its *active* portion
towards −16 dBFS, with the peak ceiling always winning. That keeps the theme
consistent without introducing clipping.

### No clicks

Every cue is high-passed (30–130 Hz depending on the class), given a 1.5 ms
raised-cosine fade in and a 35 ms fade out before the reverb is applied, so the
convolution never sees a discontinuity. `make verify` enforces this: it rejects
any file whose first samples are not at zero.

## Licence

* **Audio** (`Interstellar/stereo/*.oga`, `Interstellar/index.theme`) —
  [CC BY-SA 4.0](LICENSES/CC-BY-SA-4.0.txt), the same licence the KDE sound
  themes use.
* **Code and documentation** (`tools/`, `Makefile`, `install.sh`, `preview/`,
  `README.md`) — [BSD-2-Clause](LICENSES/BSD-2-Clause.txt).

The sounds are original synthesis; nothing is derived from the KDE Ocean sound
theme or any other recording. You may therefore use this theme commercially and
adapt it freely, subject to CC BY-SA 4.0's attribution and share-alike terms.

## Credits

Created by **enne2** (2026). Designed for Plasma 6.3 on Debian 13.

The avatar illustration in `preview/avatar.png` is an AI-generated image (Google
Gemini via Antigravity). It is included only to identify the theme, and is **not**
covered by either grant below: neither the CC BY-SA 4.0 that applies to the audio
nor the BSD-2-Clause that applies to the code.