SoVRMLAudioClip -

#include <Inventor/VRMLnodes/SoVRMLAudioClip.h>

Inherits SoNode.

The SoVRMLAudioClip class is used to load and store audio data.

Audio data is loaded using the simage library, so make sure you have built the simage library with support for the audio file formats you intend to use (libogg, libvorbis and libvorbisfile for OggVorbis, libsndfile for WAV and several other formats).

The detailed class documentation is taken verbatim from the VRML97 standard (ISO/IEC 14772-1:1997). It is copyright The Web3D Consortium, and is used by permission of the Consortium:

  AudioClip {
    exposedField   SFString description      ""
    exposedField   SFBool   loop             FALSE
    exposedField   SFFloat  pitch            1.0        # (0, inf)
    exposedField   SFTime   startTime        0          # (-inf, inf)
    exposedField   SFTime   stopTime         0          # (-inf, inf)
    exposedField   MFString url              []
    eventOut       SFTime   duration_changed
    eventOut       SFBool   isActive
  }
  .fi


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 http://www.web3d.org/x3d/specifications/vrml/ISO-IEC-14772-IS-VRML97WithAmendment1/part1/bibliography.html#[WAV]). It is recommended that browsers also support the MIDI file type 1 sound format (see http://www.web3d.org/x3d/specifications/vrml/ISO-IEC-14772-IS-VRML97WithAmendment1/part1/references.html#[MIDI]); MIDI files are presumed to use the General MIDI patch set. Subclause 4.5, VRML and the World Wide Web (<http://www.web3d.org/x3d/specifications/vrml/ISO-IEC-14772-IS-VRML97WithAmendment1/part1/concepts.html#4.5>), 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 (<http://www.web3d.org/x3d/specifications/vrml/ISO-IEC-14772-IS-VRML97WithAmendment1/part1/concepts.html#4.6.9>). 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)
  


 

Public Types

Public Member Functions

Static Public Member Functions

Public Attributes

Protected Member Functions

Static Protected Member Functions

Protected Attributes

Friends

SoVRMLAudioClip::SoVRMLAudioClip (void)

SoVRMLAudioClip::~SoVRMLAudioClip () [protected, virtual]

SoType SoVRMLAudioClip::getClassTypeId (void) [static]

SoType SoVRMLAudioClip::getTypeId (void) const [virtual]

  void foo(SoNode * node)
  {
    if (node->getTypeId() == SoFile::getClassTypeId()) {
      SoFile * filenode = (SoFile *)node;  // safe downward cast, knows the type
    }
    else if (node->getTypeId().isOfType(SoGroup::getClassTypeId())) {
      SoGroup * group = (SoGroup *)node;  // safe downward cast, knows the type
    }
  }

const SoFieldData ** SoVRMLAudioClip::getFieldDataPtr (void) [static, protected]

const SoFieldData * SoVRMLAudioClip::getFieldData (void) const [protected, virtual]

void SoVRMLAudioClip::initClass (void) [static]

void * SoVRMLAudioClip::open (const SbStringList & urlref)

size_t SoVRMLAudioClip::read (void * datasource, void * buffer, int numframes, int & channels)

int SoVRMLAudioClip::seek (void * datasource, long offset, int whence)

long SoVRMLAudioClip::tell (void * datasource)

int SoVRMLAudioClip::close (void * datasource)

void SoVRMLAudioClip::setCallbacks (open_func * opencb, read_func * readcb, seek_func * seekcb, tell_func * tellcb, close_func * closecb, void * userdataptr)

SoSFString SoVRMLAudioClip::description

SoSFBool SoVRMLAudioClip::loop

SoSFFloat SoVRMLAudioClip::pitch

SoSFTime SoVRMLAudioClip::startTime

SoSFTime SoVRMLAudioClip::stopTime

SoMFString SoVRMLAudioClip::url

SoVRMLAudioClip::duration_changed [protected]

SoVRMLAudioClip::isActive [protected]

Generated automatically by Doxygen for Coin from the source code.