SFML - Simple and Fast Multimedia Library

SFML

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sf
SoundStream

Abstract base class for streamed audio sources. More...

#include <SoundStream.hpp>

Inheritance diagram for sf::SoundStream:

Classes
struct	Chunk
	Structure defining a chunk of audio data to stream. More...

Public Types
enum	Status { Stopped, Paused, Playing }
	Enumeration of the sound source states. More...

Public Member Functions
virtual	~SoundStream ()
	Destructor. More...

void	play ()
	Start or resume playing the audio stream. More...

void	pause ()
	Pause the audio stream. More...

void	stop ()
	Stop playing the audio stream. More...

unsigned int	getChannelCount () const
	Return the number of channels of the stream. More...

unsigned int	getSampleRate () const
	Get the stream sample rate of the stream. More...

Status	getStatus () const
	Get the current status of the stream (stopped, paused, playing) More...

void	setPlayingOffset (Time timeOffset)
	Change the current playing position of the stream. More...

Time	getPlayingOffset () const
	Get the current playing position of the stream. More...

void	setLoop (bool loop)
	Set whether or not the stream should loop after reaching the end. More...

bool	getLoop () const
	Tell whether or not the stream is in loop mode. More...

void	setPitch (float pitch)
	Set the pitch of the sound. More...

void	setVolume (float volume)
	Set the volume of the sound. More...

void	setPosition (float x, float y, float z)
	Set the 3D position of the sound in the audio scene. More...

void	setPosition (const Vector3f &position)
	Set the 3D position of the sound in the audio scene. More...

void	setRelativeToListener (bool relative)
	Make the sound's position relative to the listener or absolute. More...

void	setMinDistance (float distance)
	Set the minimum distance of the sound. More...

void	setAttenuation (float attenuation)
	Set the attenuation factor of the sound. More...

float	getPitch () const
	Get the pitch of the sound. More...

float	getVolume () const
	Get the volume of the sound. More...

Vector3f	getPosition () const
	Get the 3D position of the sound in the audio scene. More...

bool	isRelativeToListener () const
	Tell whether the sound's position is relative to the listener or is absolute. More...

float	getMinDistance () const
	Get the minimum distance of the sound. More...

float	getAttenuation () const
	Get the attenuation factor of the sound. More...

Protected Member Functions
	SoundStream ()
	Default constructor. More...

void	initialize (unsigned int channelCount, unsigned int sampleRate)
	Define the audio stream parameters. More...

virtual bool	onGetData (Chunk &data)=0
	Request a new chunk of audio samples from the stream source. More...

virtual void	onSeek (Time timeOffset)=0
	Change the current playing position in the stream source. More...

Protected Attributes
unsigned int	m_source
	OpenAL source identifier. More...

Detailed Description

Abstract base class for streamed audio sources.

Unlike audio buffers (see sf::SoundBuffer), audio streams are never completely loaded in memory.

Instead, the audio data is acquired continuously while the stream is playing. This behavior allows to play a sound with no loading delay, and keeps the memory consumption very low.

Sound sources that need to be streamed are usually big files (compressed audio musics that would eat hundreds of MB in memory) or files that would take a lot of time to be received (sounds played over the network).

sf::SoundStream is a base class that doesn't care about the stream source, which is left to the derived class. SFML provides a built-in specialization for big files (see sf::Music). No network stream source is provided, but you can write your own by combining this class with the network module.

A derived class has to override two virtual functions:

onGetData fills a new chunk of audio data to be played
onSeek changes the current playing position in the source

It is important to note that each SoundStream is played in its own separate thread, so that the streaming loop doesn't block the rest of the program. In particular, the OnGetData and OnSeek virtual functions may sometimes be called from this separate thread. It is important to keep this in mind, because you may have to take care of synchronization issues if you share data between threads.

Usage example:

class CustomStream : public sf::SoundStream
{
public:
 bool open(const std::string& location)
    {
 // Open the source and get audio settings
        ...
 unsigned int channelCount = ...;
 unsigned int sampleRate = ...;
 // Initialize the stream -- important!
 initialize(channelCount, sampleRate);
    }
private:
 virtual bool onGetData(Chunk& data)
    {
 // Fill the chunk with audio data from the stream source
 // (note: must not be empty if you want to continue playing)
        data.samples = ...;
        data.sampleCount = ...;
 // Return true to continue playing
 return true;
    }
 virtual void onSeek(Uint32 timeOffset)
    {
 // Change the current position in the stream source
        ...
    }
}
// Usage
CustomStream stream;
stream.open("path/to/stream");
stream.play();

See also: sf::Music

Definition at line 45 of file SoundStream.hpp.

Member Enumeration Documentation

enum sf::SoundSource::Status

inherited

Enumeration of the sound source states.

Enumerator
Stopped	Sound is not playing.
Paused	Sound is paused.
Playing	Sound is playing.

Definition at line 50 of file SoundSource.hpp.

Constructor & Destructor Documentation

virtual sf::SoundStream::~SoundStream ( )

virtual

Destructor.

sf::SoundStream::SoundStream ( )

protected

Default constructor.

This constructor is only meant to be called by derived classes.

Member Function Documentation

float sf::SoundSource::getAttenuation ( ) const

inherited

Get the attenuation factor of the sound.

Returns: Attenuation factor of the sound

See also: setAttenuation, getMinDistance

unsigned int sf::SoundStream::getChannelCount ( ) const

Return the number of channels of the stream.

1 channel means a mono sound, 2 means stereo, etc.

Returns: Number of channels

bool sf::SoundStream::getLoop ( ) const

Tell whether or not the stream is in loop mode.

Returns: True if the stream is looping, false otherwise

See also: setLoop

float sf::SoundSource::getMinDistance ( ) const

inherited

Get the minimum distance of the sound.

Returns: Minimum distance of the sound

See also: setMinDistance, getAttenuation

float sf::SoundSource::getPitch ( ) const

inherited

Get the pitch of the sound.

Returns: Pitch of the sound

See also: setPitch

Time sf::SoundStream::getPlayingOffset ( ) const

Get the current playing position of the stream.

Returns: Current playing position, from the beginning of the stream

See also: setPlayingOffset

Vector3f sf::SoundSource::getPosition ( ) const

inherited

Get the 3D position of the sound in the audio scene.

Returns: Position of the sound

See also: setPosition

unsigned int sf::SoundStream::getSampleRate ( ) const

Get the stream sample rate of the stream.

The sample rate is the number of audio samples played per second. The higher, the better the quality.

Returns: Sample rate, in number of samples per second

Status sf::SoundStream::getStatus ( ) const

Get the current status of the stream (stopped, paused, playing)

Returns: Current status

float sf::SoundSource::getVolume ( ) const

inherited

Get the volume of the sound.

Returns: Volume of the sound, in the range [0, 100]

See also: setVolume

void sf::SoundStream::initialize	(	unsigned int	channelCount,
		unsigned int	sampleRate
	)

protected

Define the audio stream parameters.

This function must be called by derived classes as soon as they know the audio settings of the stream to play. Any attempt to manipulate the stream (play(), ...) before calling this function will fail. It can be called multiple times if the settings of the audio stream change, but only when the stream is stopped.

Parameters

channelCount	Number of channels of the stream
sampleRate	Sample rate, in samples per second

bool sf::SoundSource::isRelativeToListener ( ) const

inherited

Tell whether the sound's position is relative to the listener or is absolute.

Returns: True if the position is relative, false if it's absolute

See also: setRelativeToListener

virtual bool sf::SoundStream::onGetData ( Chunk & data )

protectedpure virtual

Request a new chunk of audio samples from the stream source.

This function must be overridden by derived classes to provide the audio samples to play. It is called continuously by the streaming loop, in a separate thread. The source can choose to stop the streaming loop at any time, by returning false to the caller. If you return true (i.e. continue streaming) it is important that the returned array of samples is not empty; this would stop the stream due to an internal limitation.

Parameters

data	Chunk of data to fill

Returns: True to continue playback, false to stop

Implemented in sf::Music.

virtual void sf::SoundStream::onSeek ( Time timeOffset )

protectedpure virtual

Change the current playing position in the stream source.

This function must be overridden by derived classes to allow random seeking into the stream source.

Parameters

timeOffset New playing position, relative to the beginning of the stream

Implemented in sf::Music.

void sf::SoundStream::pause ( )

Pause the audio stream.

This function pauses the stream if it was playing, otherwise (stream already paused or stopped) it has no effect.

See also: play, stop

void sf::SoundStream::play ( )

Start or resume playing the audio stream.

This function starts the stream if it was stopped, resumes it if it was paused, and restarts it from the beginning if it was already playing. This function uses its own thread so that it doesn't block the rest of the program while the stream is played.

See also: pause, stop

void sf::SoundSource::setAttenuation ( float attenuation )

inherited

Set the attenuation factor of the sound.

The attenuation is a multiplicative factor which makes the sound more or less loud according to its distance from the listener. An attenuation of 0 will produce a non-attenuated sound, i.e. its volume will always be the same whether it is heard from near or from far. On the other hand, an attenuation value such as 100 will make the sound fade out very quickly as it gets further from the listener. The default value of the attenuation is 1.

Parameters

attenuation New attenuation factor of the sound

See also: getAttenuation, setMinDistance

void sf::SoundStream::setLoop ( bool loop )

Set whether or not the stream should loop after reaching the end.

If set, the stream will restart from beginning after reaching the end and so on, until it is stopped or setLoop(false) is called. The default looping state for streams is false.

Parameters

loop	True to play in loop, false to play once

See also: getLoop

void sf::SoundSource::setMinDistance ( float distance )

inherited

Set the minimum distance of the sound.

The "minimum distance" of a sound is the maximum distance at which it is heard at its maximum volume. Further than the minimum distance, it will start to fade out according to its attenuation factor. A value of 0 ("inside the head of the listener") is an invalid value and is forbidden. The default value of the minimum distance is 1.

Parameters

distance New minimum distance of the sound

See also: getMinDistance, setAttenuation

void sf::SoundSource::setPitch ( float pitch )

inherited

Set the pitch of the sound.

The pitch represents the perceived fundamental frequency of a sound; thus you can make a sound more acute or grave by changing its pitch. A side effect of changing the pitch is to modify the playing speed of the sound as well. The default value for the pitch is 1.

Parameters

pitch New pitch to apply to the sound

See also: getPitch

void sf::SoundStream::setPlayingOffset ( Time timeOffset )

Change the current playing position of the stream.

The playing position can be changed when the stream is either paused or playing. Changing the playing position when the stream is stopped has no effect, since playing the stream would reset its position.

Parameters

timeOffset New playing position, from the beginning of the stream

See also: getPlayingOffset

void sf::SoundSource::setPosition	(	float	x,
		float	y,
		float	z
	)

inherited

Set the 3D position of the sound in the audio scene.

Only sounds with one channel (mono sounds) can be spatialized. The default position of a sound is (0, 0, 0).

Parameters

x	X coordinate of the position of the sound in the scene
y	Y coordinate of the position of the sound in the scene
z	Z coordinate of the position of the sound in the scene

See also: getPosition

void sf::SoundSource::setPosition ( const Vector3f & position )

inherited

Set the 3D position of the sound in the audio scene.

Only sounds with one channel (mono sounds) can be spatialized. The default position of a sound is (0, 0, 0).

Parameters

position Position of the sound in the scene

See also: getPosition

void sf::SoundSource::setRelativeToListener ( bool relative )

inherited

Make the sound's position relative to the listener or absolute.

Making a sound relative to the listener will ensure that it will always be played the same way regardless of the position of the listener. This can be useful for non-spatialized sounds, sounds that are produced by the listener, or sounds attached to it. The default value is false (position is absolute).

Parameters

relative True to set the position relative, false to set it absolute

See also: isRelativeToListener

void sf::SoundSource::setVolume ( float volume )

inherited

Set the volume of the sound.

The volume is a value between 0 (mute) and 100 (full volume). The default value for the volume is 100.

Parameters

volume Volume of the sound

See also: getVolume

void sf::SoundStream::stop ( )

Stop playing the audio stream.

This function stops the stream if it was playing or paused, and does nothing if it was already stopped. It also resets the playing position (unlike pause()).

See also: play, pause

Member Data Documentation

unsigned int sf::SoundSource::m_source

protectedinherited

OpenAL source identifier.

Definition at line 274 of file SoundSource.hpp.

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

SoundStream.hpp

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SFML - Simple and Fast Multimedia Library

SFML

Classes

Public Types

Public Member Functions

Protected Member Functions

Protected Attributes

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation