# Music Streaming

file-backed loops that crossfade and duck under dialogue.

```{raw} html
<span class="example-docs-badge">📄 Docs only</span>


```

**Tags:** `audio` `music` `streaming` `crossfade` `fades`

## What it demonstrates
- Two short music loops synthesised at startup and written as WAV files into a
  temp directory with the stdlib `wave` module. Only file-backed clips can
  stream (synthetic `AudioClip.tone`/`from_pcm` cannot), so this is the recipe
  for streaming music without shipping an asset.
- `AudioPlayer(stream_mode="streaming", loop=True)`: the file is decoded in
  chunks each frame instead of being loaded whole, which is the mode for music.
- `a.crossfade(b, 2.0)`: one call hands playback over on an equal-power curve,
  so the pair holds a steady loudness through the middle of the fade.
- Ducking under a fake dialogue line with `fade_to(0.25, 0.3)`, then restoring
  with `fade_to(1.0, 0.5)` once the line ends.
- Fades and the streaming feed both tick in `on_update`, so the players must be
  in the tree; a detached player's fade never advances.

## Controls
- `SPACE`: crossfade to the other track (2 s, equal power).
- `D`: play a dialogue line: duck the music to a quarter amplitude, restore after.
- `ESC`: quit.

Run: uv run python examples/features/audio/music.py
Headless self-check: uv run python examples/features/audio/music.py --test

## Source

```{literalinclude} ../../examples/features/audio/music.py
:language: python
:linenos:
```