AudioClip { exposedField SFString description "" exposedField SFBool loop FALSE exposedField SFFloat pitch 1.0 exposedField SFTime startTime 0 exposedField SFTime stopTime 0 exposedField MFString url [] eventOut SFTime duration_changed eventOut SFBool isActive }Explanation :
An AudioClip node specifies audio data that can be referenced by other nodes that require an audio source.
The description field is a textual description of the audio source. A browser is not required to display the description field but may choose to do so in addition to, or in place of, playing the sound.
The url field specifies the URL from which the sound is loaded. Browsers shall support at least the wavefile format in uncompressed PCM format (see E.[WAVE]), It is recommended that browsers also support the MIDI file type 1 sound format (see 2.[MIDI]), MIDI files are presumed to use the General MIDI patch set. Results are not defined when the URL references unsupported data types.
The loop, startTime, and stopTime exposedFields and the isActive eventOut, and their effects on the AudioClip node. The "cycle" of an AudioClip is the length of time in seconds for one playing of the audio at the specified pitch.
The pitch field specifies a multiplier for the rate at which sampled sound is played. Only positive values shall be valid for pitch. A value of zero or less will produce undefined results. Changing the pitch field affects both the pitch and playback speed of a sound. A set_pitch event to an active AudioClip is ignored and no pitch_changed eventOut is generated. If pitch is set to 2.0, the sound should be played one octave higher than normal and played twice as fast. For a sampled sound, the pitch field alters the sampling rate at which the sound is played. The proper implementation of the pitch control for MIDI (or other note sequence sound clips) is to multiply the tempo of the playback by the pitch value and adjust the MIDI Coarse Tune and Fine Tune controls to achieve the proper pitch change.A duration_changed event is sent whenever there is a new value for the "normal" duration of the clip. Typically, this will only occur when the current url in use changes and the sound data has been loaded, indicating that the clip is playing a different sound source. The duration is the length of time in seconds for one cycle of the audio for a pitch set to 1.0. Changing the pitch field will not trigger a duration_changed event. A duration value of "-1" implies that the sound data has not yet loaded or the value is unavailable for some reason.
The isActive eventOut can be used by other nodes to determine if the clip is currently active. If an AudioClip is active, then it should be playing the sound corresponding to the sound time (i. e., in the sound's local time system with sample 0 at time 0):
t = (now - startTime) modulo (duration / pitch)