Overview

The Audio Ribbon Editor differs from standard audio placement tools by allowing sound sources to be dynamic rather than static. instead of placing hundreds of individual point emitters along a river or road, you can place a single “Ribbon” that manages the audio for the entire length.

Audio Ribbon Example

How It Works

An Audio Ribbon is a spline path defined by nodes. The system continuously monitors the position of the Audio Listener (usually the camera or the player’s vehicle).

1. Real-time Tracking: On every frame, the tool updates the closest point on the ribbon to the listener.
2. Dynamic Positioning: The actual audio emitter is moved to this closest point.
3. Seamless Experience: As the player moves along the river or road, the sound source “follows” them along the path, ensuring the sound always comes from the correct direction and distance without needing manual placement of many emitters.

Emitter Types

The tool supports two primary modes of operation:

1. Single Emitter (Ambient)

Best for general environmental sounds that don’t need complex directionality, such as general wind or background city noise.

• Uses a single FMOD event.
• Simple setup, lower performance cost.
• The sound source is simply placed at the closest point on the spline.

2. Quad Emitter (4-Channel)

Best for complex, volumetric sounds like rushing rivers or heavy traffic where directionality matters.

• Uses four separate FMOD events: Front, Rear, Left, and Right.
• Listener-Relative Positioning: Unlike standard emitters, these four sources are positioned relative to the Listener’s orientation, not the spline’s.
  • The tool calculates a “radius” based on distance.
  • It places virtual emitters in front, behind, and to the sides of the listener, projected from the closest point on the spline.
• Effect: This creates a convincing “surround” effect. For a river, you can hear the water rushing towards you (Front channel) differently than it flowing away (Rear channel), or hear the width of the river (Left/Right channels).

Surface & Volume

Ribbons can be configured to treat their area as either a 2D Surface or a 3D Volume.

• 2D Surface: Useful for things that lie flat on the ground, like rivers.
  • Top/Bottom: You can choose to emit from the Top (e.g., water surface) or Bottom (e.g., underwater) face.
  • Width Interpolation: The sound volume is weighted by the interpolated width of the ribbon at the closest point.
• 3D Volume: Useful for areas the player might move through, like a fog bank or a tunnel.
  • Depth Attenuation: Volume attenuates based on the Depth setting and how far the listener is from the center of the ribbon volume.

Audio Parameters

The tool maps physical properties of the ribbon to FMOD parameters, allowing the sound engine to react to the geometry:

• Pitch (Speed): The Speed slider directly controls the pitch of the audio event. This allows a single water loop to sound “faster” (higher pitch) or “slower” (lower pitch) depending on the ribbon settings.
• Volume: The final output volume is a product of three factors: Speed × Width × Depth.
  • Speed: Faster flows generate louder sound.
  • Width: Wider sections of the river (interpolated between nodes) produce more sound than narrow bottlenecks.
  • Depth: Deeper ribbons produce more sound.
• Color & Texture: The tool also passes Width to the Color parameter and Distance Attenuation to the Texture parameter, allowing for advanced FMOD parameter automation (e.g., changing EQ based on river width).

Conformity

The tool includes logic to automatically snap ribbon nodes to:

• Terrain: The ground height map.
• Rivers: Existing river objects in the scene (checks for intersection with river surface triangles).
• Water Planes: Global water levels.

This ensures your audio path perfectly matches the visual geometry without manual height adjustments.