BlitzMax/Modules/Audio/Audio playback

The BlitzMax audio module contains commands to load and play sounds.

A sound file can be played in BlitzMax with a combination of LoadSound that loads a sound file and PlaySound which plays the sound through the systems audio system if available.

BlitzMax contains native support for sound files in both .wav (uncompressed) and .ogg (compressed) file formats.

Playback of sounds can be controlled with various audio channel operators including SetChannelVolume, SetChannelPan, SetChannelDepth and SetChannelRate.

A channel handle is obtained from either the return value of PlaySound and CueSound or from reserving a channel with AllocChannel.

=Types=

TSound
Audio sound type


 * Play
 * Cue


 * Load

TSound: Methods
Method Play:TChannel( alloced_channel:TChannel=Null )

Description: Play the sound

Returns: An audio channel object

Information: Starts a sound playing through an audio channel. If no channel is specified, Play automatically allocates a channel for you.

Method Cue:TChannel( alloced_channel:TChannel=Null )

Description: Cue the sound for playback

Returns: An audio channel object

Information: Prepares an audio channel for playback of a sound. To actually start the sound, you must use the channel's SetPaused method. If no channel is specified, Cue automatically allocates a channel for you.

Cue allows you to setup various audio channel states such as volume, pan, depth and rate before a sound actually starts playing.

TSound: Functions
Function Load:TSound( url:Object,loop_flag )

Description: Load sound

Returns: A sound object

Information: url can be either a string, a stream or an audio sample object. The returned sound object can be played using Play or Cue.

TChannel
Audio channel Type


 * Stop
 * SetPaused
 * SetVolume
 * SetPan
 * SetDepth
 * SetRate
 * Playing

TChannel: Methods
Method Stop

Description: Stop audio channel playback

Information: Shuts down the audio channel. Further commands on this audio channel will have no effect.

Method SetPaused( paused )

Description: Pause or unpause audio channel playback

Information: If paused is True, the audio channel is paused. Otherwise, the audio channel is unpaused.

Method SetVolume( volume# )

Description: Set audio channel volume

Information: volume should be in the range 0 (silence) to 1 (full volume).

Method SetPan( pan# )

Description: Set audio channel stereo pan

Information: pan should be in the range -1 (full left) to 1 (full right).

Method SetDepth( depth# )

Description: Set audio channel depth

Information: depth should be in the range -1 (back) to 1 (front).

Method SetRate( rate# )

Description: Set audio channel playback rate

Information: rate is a multiplier used to modify the audio channel's frequency. For example, a rate of .5 will cause the audio channel to play at half speed (i.e.: an octave down) while a rate of 2 will cause the audio channel to play at double speed (i.e.: an octave up).

Method Playing

Description: Determine whether audio channel is playing

Returns: True if channel is currently playing

Information: Playing will return False if the audio channel is either paused, or has been stopped using Stop.

=Functions=

LoadSound
Function LoadSound:TSound( url:Object,flags=0 )

Description: Load a sound

Returns: A sound object

Information: url can be either a string, a stream or a TAudioSample object. The returned sound can be played using PlaySound or CueSound.

The flags parameter can be any combination of:

To combine flags, use the binary 'or' operator: '|'.

Example: Rem Load and Play a small example wav file. End Rem

sound=LoadSound("shoot.wav") PlaySound sound

Input "Press any key to continue"

PlaySound
Function PlaySound:TChannel( sound:TSound,channel:TChannel=Null )

Description: Play a sound

Returns: An audio channel object

Information: PlaySound starts a sound playing through an audio channel. If no channel is specified, PlaySound automatically allocates a channel for you.

Example: Rem Load and Play a small example wav file with looping. End Rem

sound=LoadSound("shoot.wav",true) PlaySound sound

Input "Press any key to continue"

CueSound
Function CueSound:TChannel( sound:TSound,channel:TChannel=Null )

Description: Cue a sound

Returns: An audio channel object

Information: Prepares a sound for playback through an audio channel. To actually start the sound, you must use ResumeChannel. If no channel is specified, CueSound automatically allocates a channel for you.

CueSound allows you to setup various audio channel states such as volume, pan, depth and rate before a sound actually starts playing.

Example: Rem CueSound example End Rem

sound=LoadSound("shoot.wav") channel=CueSound(sound)

Input "Press return key to play cued sound"

ResumeChannel channel

Input "Press return key to quit"

AllocChannel
Function AllocChannel:TChannel

Description: Allocate audio channel

Returns: An audio channel object

Information: Allocates an audio channel for use with PlaySound and CueSound. Once you are finished with an audio channel, you should use StopChannel.

Example: 'AllocChannel.bmx

timer=CreateTimer(20)

sound=LoadSound ("shoot.wav") channel=AllocChannel

For i=1 To 20 WaitTimer timer PlaySound sound,channel Next

StopChannel
Function StopChannel( channel:TChannel )

Description: Stop an audio channel

Information: Shuts down an audio channel. Further commands using this channel will have no effect.

Example: Rem StopChannel example End Rem

sound=LoadSound("shoot.wav",true) channel=PlaySound(sound)

print "channel="+channel

Input "Press return key to stop sound"

StopChannel channel

Input "Press return key to quit"

ChannelPlaying
Function ChannelPlaying( channel:TChannel )

Description: Determine whether an audio channel is playing

Returns: True if channel is currently playing

Information: ChannelPlaying will return False if either the channel has been paused using PauseChannel, or stopped using StopChannel.

Example: ' channelplaying.bmx

sound = LoadSound ("shoot.wav")

Input "Hit return to begin channelplaying test, use ctrl-C to exit"

channel=PlaySound (sound) While True Print "ChannelPlaying(channel)="+ChannelPlaying(channel) Wend

SetChannelVolume
Function SetChannelVolume( channel:TChannel,volume# )

Description: Set playback volume of an audio channel

Information: volume should be in the range 0 (silent) to 1 (full volume)

Example: ' setchannelvolume.bmx

timer=CreateTimer(20)

sound = LoadSound ("shoot.wav")

For volume#=.1 To 2 Step .05 WaitTimer timer channel=CueSound(sound) SetChannelVolume channel,volume ResumeChannel channel Next

SetChannelPan
Function SetChannelPan( channel:TChannel,pan# )

Description: Set stereo balance of an audio channel

Information: pan should be in the range -1 (left) to 1 (right)

Example: ' setchannelpan.bmx

Graphics 640, 480

channel = AllocChannel sound = LoadSound ("shoot.wav") ' Use a short sample...

Repeat If MouseHit(1) PlaySound sound,channel pan# = MouseX / (GraphicsWidth  / 2.0) - 1 vol# = 1 - MouseY / 480.0 SetChannelPan channel, pan SetChannelVolume channel, vol*2

Cls DrawText "Click to play...", 240, 200 DrawText "Pan  : " + pan, 240, 220 DrawText "Volume: " + vol, 240, 240

Flip Until KeyHit (KEY_ESCAPE)

End

SetChannelDepth
Function SetChannelDepth( channel:TChannel,depth# )

Description: Set surround sound depth of an audio channel

Information: depth should be in the range -1 (back) to 1 (front)

Example: ' setchanneldepth.bmx

Graphics 640, 480

channel = AllocChannel sound = LoadSound ("shoot.wav") ' Use a short sample...

Repeat If MouseHit(1) PlaySound sound,channel pan# = MouseX / (640 / 2.0) - 1 depth# = MouseY / (480 /2.0) -1 SetChannelPan channel,pan SetChannelDepth channel,depth

Cls DrawText "Click to play...", 240, 200 DrawText "Pan  : " + pan, 240, 220 DrawText "Depth : " + depth, 240, 240

Flip Until KeyHit (KEY_ESCAPE)

End

SetChannelRate
Function SetChannelRate( channel:TChannel,rate# )

Description: Set playback rate of an audio channel

Information: rate is a multiplier used to modify the audio channel's frequency. For example, a rate of .5 will cause the audio channel to play at half speed (i.e.: an octave down) while a rate of 2 will cause the audio channel to play at double speed (i.e.: an octave up).

Example: ' setchannelrate.bmx

timer=CreateTimer(20)

sound = LoadSound ("shoot.wav",True) channel=CueSound(sound) ResumeChannel channel

For rate#=1.0 To 4 Step 0.01 WaitTimer timer SetChannelRate channel,rate Next

PauseChannel
Function PauseChannel( channel:TChannel )

Description: Pause audio channel playback

Information: Pauses audio channel playback.

ResumeChannel
Function ResumeChannel( channel:TChannel )

Description: Resume audio channel playback

Information: Resumes audio channel playback after it has been paused by CueSound or PauseChannel.

AudioDrivers
Function AudioDrivers$[]

Description: Get audio drivers

Information: Returns an array of strings, where each string describes an audio driver.

AudioDriverExists
Function AudioDriverExists( name$ )

Description: Determine if an audio driver exists

Information: Returns True if the audio driver specified by driver exists.

SetAudioDriver
Function SetAudioDriver( name$ )

Description: Set current audio driver

Information: Returns true if the audio driver was successfully set.