ArSoundPlayer Class Reference

This class provides a cross-platform interface for playing short sound samples. More...

#include <ArSoundPlayer.h>

Static Public Member Functions
static ArRetFunctor2< bool, const char *, const char * > *	getPlayWavFileCallback ()
	Return the static functor for playWavFile.
static ArFunctor *	getStopPlayingCallback ()
	Return the static functor for stopPlaying(). More...
static bool	playNativeFile (const char *filename, const char *params)
	Play a file in some native file format for the compilation platform. More...
static bool	playSoundPCM16 (char *data, int numSamples)
	Play raw uncompressed PCM16 sound data. More...
static bool	playWavFile (const char *filename, const char *params)
	Play a WAV (Windows RIFF) file. More...
static bool	playWavFile (const char *filename)
static void	setVolume (double v)
	Set a volume adjustment applied to all sounds right before playing. More...
static void	setVolumePercent (double pct)
	Set volume as a "percent" of normal, where 100% is normal or natural volume, 50% is increased by 50%, -50% is decreased by 50%, etc. More...
static void	stopPlaying ()
	Cancel (interrupt) any current sound or file playback. More...

Static Protected Attributes
static int	ourPlayChildPID = -1
	Only used on Linux.
static ArGlobalRetFunctor2< bool, const char *, const char * >	ourPlayWavFileCB
static ArGlobalFunctor	ourStopPlayingCB
static double	ourVolume = 1.0

Detailed Description

This class provides a cross-platform interface for playing short sound samples.

(Currently implemented for Windows and Linux).

See also

For I/O and network transfer of encoded audio, see the ArNetAudio library.

ArSoundsQueue

Note

Uses an external program to play WAV files on Linux. If an environment variable named PLAY_WAV is set, that program is used, otherwise, 'play' from the 'sox' toolset is used. PLAY_WAV must contain one word (the command; no arguments) A call to playWavFile() will return immediately after 'play' has finished, even though Linux may still be playing back the sound data. In general, this kind of thing is a problem, especially with speech recognition immediately after playing a sound. Ideally, we should be able to truly block until the sound has finished playback. Alas, it is not an ideal world. Another potential pitfall due to the use of an external program invocation: the program you call must not attempt to issue any output. 'play' from the 'sox' toolset automatically supresses normal output if it isn't called from an interactive terminal, but it may still issue some error messages, which will cause it to hang indefinately.

The volume (level) of audio output from a robot is determined by two things: the computer sound device mixer, and also the amplifier which drives the speakers. The computer's mixer can be adjusted through the operating system: on Linux, you can use the 'aumix' program to adjust the Master and PCM levels. On Windows, use the Windows mixer program. If on Linux, ArSoundPlayer also prodives the setVolume() method, which adjusts the volume of the sound before it is played.

Member Function Documentation

getStopPlayingCallback()

ArFunctor * ArSoundPlayer::getStopPlayingCallback ( )

static

Return the static functor for stopPlaying().

Examples:

soundsQueueExample.cpp.

playNativeFile()

bool ArSoundPlayer::playNativeFile ( const char *  filename, const char *  params  )

static

Play a file in some native file format for the compilation platform.

playSoundPCM16()

bool ArSoundPlayer::playSoundPCM16 ( char *  data, int  numSamples  )

static

Play raw uncompressed PCM16 sound data.

The format of this data is numSamples samples of two bytes each. Each byte pair is a signed little endian integer. The sound will be played back at 16kHz, monaurally.

Returns

false on error, true on success.

playWavFile()

bool ArSoundPlayer::playWavFile ( const char *  filename, const char *  params  )

static

Play a WAV (Windows RIFF) file.

Note

Uses an external program to play WAV files on Linux. If an environment variable named PLAY_WAV is set, that program is used, otherwise, 'play' from the 'sox' toolset is used. See detailed note in the overview for this cass.

Parameters

filename	Name of the file to play
params	ignored

setVolume()

void ArSoundPlayer::setVolume ( double  v )

static

Set a volume adjustment applied to all sounds right before playing.

(So this adjusts the volume in addition to, not instead of, the computer audio mixer). Any value less than or equal to 0 is no volume i.e. muted or no output.

Note

Available on Linux only

setVolumePercent()

void ArSoundPlayer::setVolumePercent ( double  pct )

static

Set volume as a "percent" of normal, where 100% is normal or natural volume, 50% is increased by 50%, -50% is decreased by 50%, etc.

(-100.0% is no volume, or mute.)

Note

Available on Linux only

Examples:

soundsQueueExample.cpp.

stopPlaying()

void ArSoundPlayer::stopPlaying ( )

static

Cancel (interrupt) any current sound or file playback.

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The documentation for this class was generated from the following files:

• ArSoundPlayer.h
• ArSoundPlayer.cpp