Getting Started

What is HYDRA?

HYDRA (HYbrid Dynamically Responsive Audio) is OCEAN's adaptive audio system. It wraps Unity's AudioSource and AudioMixer APIs into a higher-level layer built around three ideas:

• Stems — a single music track is many synchronized layers, each faded independently.
• Transitions — crossfades happen at musically correct moments (beat, bar, or immediate).
• Reactivity — the mix responds to gameplay events, spatial position, and emotional state.

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Scene setup

1 — AudioManager

HYDRA requires one AudioManager in your scene. It acts as the central registry for all playing tracks and handles group-level volume, ducking, and snapshots.

Add the AudioManager component to a persistent GameObject (e.g. tagged DontDestroyOnLoad).

In the Inspector, configure:

Field	What it is
Audio Groups	List of AudioGroup assets — one per mixer group (SFX, Music, Dialogue, Ambience)
Audio Parent	Transform under which dynamically created track GameObjects are parented
Generic Audio Prefab	A barebones AudioSource prefab used for raw-clip transitions

Dependency injection

AudioManager implements IAudioManager and binds itself via Stream.DI. Other systems can receive IAudioManager through constructor or field injection instead of using AudioManager.Instance directly.

2 — AudioGroups

Create an AudioGroup asset for each mixer group you want HYDRA to manage:

Assets → Create → OCEAN → HYDRA → AudioGroup

Field	What it is
Type	SFX, Dialogue, Music, or Ambience
Mixer	The AudioMixerGroup this asset represents
Volume Group	Toggle on and set the exposed parameter name (e.g. MusicVolume) to allow fading
Ducking	List of other groups this group ducks when it plays (see Auto-Ducking)

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Your first AudioTrack

An AudioTrack is a ScriptableObject that describes a single piece of music (or ambience) as a set of stems.

Assets → Create → OCEAN → HYDRA → Audio Track

Configure it:

1. Set Group to your Music AudioGroup.
2. Set Loop to true for looping music.
3. Set BPM to the track's tempo (used for beat-synced transitions).
4. Under Stems, add one entry per layer — give each a unique ID (e.g. drums, bass, melody) and assign its AudioClip.
5. Mark isActive on the stems that should start audible.

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Playing a track

Option A — AudioInitializer (no code)

Add the AudioInitializer component to any scene GameObject, assign your AudioTrack assets to its list, and they start playing when the scene loads.

Option B — AudioTracksManager (transitions)

Add AudioTracksManager to a GameObject when you need the track to transition to other tracks based on game state. See Transitions for full details.

Option C — code

// Play a track through the manager (fade in over 1 second)
await AudioManager.Instance.PlayAudioTrack(myTrack, fadeDuration: 1f);

// Or via the extension method on AudioTrack
await myTrack.Play();

// Stop it
AudioManager.Instance.StopAudioTrack(myTrack, fadeDuration: 1f);

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Next steps

• Audio Tracks — stems, parameters, and clip variation
• Transitions — beat-synced crossfades and the Transition asset
• Sequences — ordered track playlists
• Vertical Mixing — fading stems and emotional state
• Spatial Audio — blend zones, acoustic zones, and occlusion
• Variation — scatterers, impulses, and stochastic clips