Adding Sound

Motivation

• Sounds can be triggered by viewer actions
  • Clicks, horn honks, door latch noises
• Sounds can be continuous in the background
  • Wind, crowd noises, elevator music
• Sounds emit from a location, in a direction, within an area

Creating sounds

Sounds have two components:

• A sound source providing a sound signal
  • Like a stereo component
• A sound emitter converts a signal to virtual sound
  • Like a stereo speaker

Syntax: AudioClip

An AudioClip node creates a digital sound source:

• url - a sound file URL
• pitch - playback speed
• playback controls, like a TimeSensor node

XML Encoding

<Sound>
  <AudioClip
      url='"myfile.mp3"'
      pitch='1.0'
      startTime='0.0'
      stopTime='0.0'
      loop='false'/>
</Sound>

Classic VRML Encoding

Sound {
  source AudioClip {
    url "myfile.mp3"
    pitch 1.0
    startTime 0.0
    stopTime  0.0
    loop FALSE
  }
}

Syntax: MovieTexture

A MovieTexture node creates a movie sound source:

• url - a texture movie file URL
• speed - playback speed
• playback controls, like a TimeSensor node

XML Encoding

<Sound>
  <MovieTexture containerField='source'
      url='"movie.mp4"'
      speed='1.0'
      startTime='0.0'
      stopTime='0.0'
      loop='false'/>
</Sound>

Classic VRML Encoding

Sound {
  source MovieTexture {
    url "movie.mp4"
    speed 1.0
    startTime 0.0
    stopTime  0.0
    loop FALSE
  }
}

Selecting sound source types

Supported by the AudioClip node:

• MP3 or WAV - digital sound files Good for sound effects

Supported by the MovieTexture node:

• MP4 - movie file with sound Good for virtual TVs

Syntax: Sound

A Sound node describes a sound emitter:

• source - AudioClip or MovieTexture node
• location and direction - emitter placement

XML Encoding

<Sound
    location='0.0 0.0 0.0'
    direction='0.0 0.0 1.0'>
  <AudioClip ... />
</Sound>

Classic VRML Encoding

Sound {
  source AudioClip { ... }
  location  0.0 0.0 0.0
  direction 0.0 0.0 1.0
}

A Sound node describes a sound emitter:

• intensity - volume
• spatialize - use spatialize processing
• priority - prioritize the sound

XML Encoding

<Sound
    ...
    intensity='1.0'
    spatialize='true'
    priority='0.0'>
</Sound>

Classic VRML Encoding

Sound {
  ...
  intensity 1.0
  spatialize TRUE
  priority 0.0
}

A Sound node describes a sound emitter:

• minFront, minBack - inner ellipsoid
• maxFront, maxBack - outer ellipsoid

Setting the sound range

• The sound range fields specify two ellipsoids
  • minFront and minBack control an inner ellipsoid
  • maxFront and maxBack control an outer ellipsoid
• Sound has a constant volume inside the inner ellipsoid
• Sound drops to zero volume from the inner to the outer ellipsoid

Creating triggered sounds

AudioClip node:

• loop FALSE
• Set startTime from a sensor node

Sound node:

• spatialize TRUE
• minFront etc. with small values
• priority 1.0

A sample using triggered sound

XML Encoding

<Group>
  <Shape>
    <Appearance>
      <Material
          diffuseColor='1 1 1'/>
    </Appearance>
    <Box
        size='0.23 0.1 1.5'/>
  </Shape>
  <TouchSensor DEF='C4'/>
  <Sound
      maxBack='100'
      maxFront='100'>
    <AudioClip DEF='PitchC4'
        url='"tone1.mp3"'/>
  </Sound>
</Group>
<ROUTE fromNode='C4' fromField='touchTime' toNode='PitchC4' toField='set_startTime'/>

Classic VRML Encoding

Group {
  children [
    Shape {
      appearance Appearance {
        material Material {
          diffuseColor 1.0 1.0 1.0
        }
      }
      geometry Box {
        size 0.23 0.1 1.5
      }
    }
    DEF C4 TouchSensor { }
    Sound {
      maxFront 100.0
      maxBack 100.0
      source DEF PitchC4 AudioClip {
        url "tone1.mp3"
        pitch 1.0
      }
    }
  ]
}
ROUTE C4.touchTime TO PitchC4.set_startTime

Example

• Download ZIP Archive
• View Source in Playground

Creating continuous localized sounds

AudioClip node:

• loop TRUE
• startTime 0.0 (default)
• stopTime 0.0 (default)

Sound node:

• spatialize TRUE (default)
• minFront etc. with medium values
• priority 0.0 (default)

A sample using continuous localized sound

XML Encoding

<Sound
    minBack='5'
    minFront='5'>
  <AudioClip
      url='"willow1.mp3"'
      loop='true'
      startTime='1'/>
</Sound>
<Transform
    translation='0 -1.65 0'>
  <Inline
      url='"sndmark.wrl"'/>
</Transform>

Classic VRML Encoding

Sound {
  minFront 5.0
  minBack  5.0
  maxFront 10.0
  maxBack  10.0
  source AudioClip {
    url "willow1.mp3"
    loop TRUE
    startTime 1.0
    stopTime 0.0
  }
}
Transform {
  translation 0.0 -1.65 0.0
  children [
    Inline {
      url "sndmark.wrl"
    }
  ]
}

Creating continuous background sounds

AudioClip node:

• loop TRUE
• startTime 0.0 (default)
• stopTime 0.0 (default)

Sound node:

• spatialize FALSE (default)
• minFront etc. with large values
• priority 0.0 (default)

Summary

An AudioClip node or a MovieTexture node describe a sound source:

• A URL gives the sound file
• Looping, start time, and stop time control playback

A Sound node describes a sound emitter:

• A source node provides the sound
• Range fields describe the sound volume