XdkWrl: AudioClip Class Reference

6.4 AudioClip

An AudioClip node specifies audio data that can be referenced by Sound nodes.

The description field specifies 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 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.[WAV]). 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. Subclause 4.5, VRML and the World Wide Web, contains details on the url field. The results are undefined when no URLs refer to supported data types

The loop, startTime, and stopTime exposedFields and the isActive eventOut, and their effects on the AudioClip node, are discussed in detail in 4.6.9, Time-dependent nodes. 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. Values for the pitch field shall be greater than zero. 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 shall 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 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. A duration_changed event shall be generated if the AudioClip node is loaded when the VRML file is read or the AudioClip node is added to the scene graph.

The isActive eventOut may be used by other nodes to determine if the clip is currently active. If an AudioClip is active, it shall 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)

Constructor & Destructor Documentation

AudioClip ( const char * name = "" )

Construct a node with all its fields set to default value, which is equivalent to the code below:

  description = string("");
  loop = false;
  pitch = 1;
  startTime.setNbSeconds(0);
  stopTime.setNbSeconds(0);

Member Function Documentation

wrl::Node * duplicate ( std::map< const Node *, Node * > & ) const [virtual]

Implements Node.

wrl::Node * duplicate ( ) const [virtual]

Returns a deep copy of this node, that is a fully independant node with all children (if any) also copied. This is mainly useful for instanciating protos.

Implements Node.

wrl::Node::EventInHandle eventIn ( const unsigned int n ) [virtual]

Return a handle on the i th event in of the node or a "unknown" typed handle if there is no such node. emarks This class has no eventIn. This function is useful, with nbEventsIn() if you want to traverse all events in of a Node.

Implements Node.

wrl::Node::EventInHandle eventIn ( const std::string & n ) [virtual]

Return a handle on the event in named n of the node or a "unknown" typed handle if there is no such event. Valid names are:

set_description
set_loop
set_pitch
set_startTime
set_stopTime
set_url

Implements Node.

wrl::Node::EventOutHandle eventOut ( const unsigned int n ) [virtual]

Return a handle on the i th event out of the node or a "unknown" typed handle if there is no such node. Here is how i is related to fields:

0 : duration_changed
1 : isActive
2 : description_changed
3 : loop_changed
4 : pitch_changed
5 : startTime_changed
6 : stopTime_changed
7 : url_changed This function is useful, with nbEventsOut() if you want to traverse all events in of a Node.

Implements Node.

wrl::Node::EventOutHandle eventOut ( const std::string & n ) [virtual]

Return a handle on the event out named n of the node or a "unknown" typed handle if there is no such event. Valid names are:

duration_changed
isActive
description_changed
loop_changed
pitch_changed
startTime_changed
stopTime_changed
url_changed

Implements Node.

wrl::Node::FieldHandle field ( const unsigned int n ) [virtual]

Return a handle on the i th field of the node or a "unknown" typed handle if there is no such node. Here is how i is related to fields:

0 : description
1 : loop
2 : pitch
3 : startTime
4 : stopTime
5 : url This function is useful, with nbFields() if you want to traverse all fields of a Node.

Implements Node.

wrl::Node::FieldHandle field ( const std::string & n ) [virtual]

Return a handle on the field named n of the node or a "unknown" typed handle if there is no such field. Valid names are:

description
loop
pitch
startTime
stopTime
url

Implements Node.

bool isSetToDefaultValue ( const unsigned int i ) const [virtual]

Implements Node.

unsigned int nbEventsIn ( ) const [inline, virtual]

Returns the number of events in for this node type.

Implements Node.

unsigned int nbEventsOut ( ) const [inline, virtual]

Returns the number of events out for this node type.

Implements Node.

unsigned int nbFields ( ) const [inline, virtual]

Returns the number of fields (exposed or not) for this node type.

Implements Node.

const char * typeName ( ) const [inline, virtual]

Returns "AudioClip". Useful for printing.

Implements Node.


Public Member Functions
	AudioClip (const char *name="")
virtual	~AudioClip ()
virtual unsigned int	nbFields () const
virtual FieldHandle	field (const std::string &n)
virtual FieldHandle	field (const unsigned int i)
virtual bool	isSetToDefaultValue (const unsigned int i) const
virtual unsigned int	nbEventsIn () const
virtual EventInHandle	eventIn (const std::string &n)
virtual EventInHandle	eventIn (const unsigned int i)
virtual unsigned int	nbEventsOut () const
virtual EventOutHandle	eventOut (const std::string &n)
virtual EventOutHandle	eventOut (const unsigned int i)
const char *	typeName () const
virtual Node *	duplicate () const
virtual Node *	duplicate (std::map< const Node , Node > &) const
Public Attributes
Exposed Fields
A field that is capable of receiving events via an eventIn to change its value(s), and generating events via an eventOut when its value(s) change.
SFString	description
SFBool	loop
SFFloat	pitch
SFTime	startTime
SFTime	stopTime
MFString	url
Events In
EventIn< SFString >	set_description
EventIn< SFBool >	set_loop
EventIn< SFFloat >	set_pitch
EventIn< SFTime >	set_startTime
EventIn< SFTime >	set_stopTime
EventIn< MFString >	set_url
Events Out
EventOut< SFTime >	duration_changed
EventOut< SFBool >	isActive
EventOut< SFString >	description_changed
EventOut< SFBool >	loop_changed
EventOut< SFFloat >	pitch_changed
EventOut< SFTime >	startTime_changed
EventOut< SFTime >	stopTime_changed
EventOut< MFString >	url_changed

AudioClip Class Reference
[Standard Node Types]

Public Member Functions

Public Attributes

Detailed Description

6.4 AudioClip

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation

AudioClip Class Reference [Standard Node Types]

Public Member Functions

Public Attributes

Detailed Description

6.4 AudioClip

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation

AudioClip Class Reference
[Standard Node Types]