sf::SoundStream Class Reference

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

#include <SoundStream.hpp>

Inheritance diagram for sf::SoundStream:

Collaboration diagram for sf::SoundStream:

Classes
struct	Chunk
	Structure defining a chunk of audio data to stream. 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...
Public Member Functions inherited from sf::SoundSource
	SoundSource (const SoundSource &copy)
	Copy constructor. More...
virtual	~SoundSource ()
	Destructor. 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...
SoundSource &	operator= (const SoundSource &right)
	Overload of assignment operator. More...
virtual void	play ()=0
	Start or resume playing the sound source. More...
virtual void	pause ()=0
	Pause the sound source. More...
virtual void	stop ()=0
	Stop playing the sound source. More...
virtual Status	getStatus () const
	Get the current status of the sound (stopped, paused, playing) More...

Protected Types
enum	{ NoLoop = -1 }

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...
virtual Int64	onLoop ()
	Change the current playing position in the stream source to the beginning of the loop. More...
Protected Member Functions inherited from sf::SoundSource
	SoundSource ()
	Default constructor. More...

Additional Inherited Members
Public Types inherited from sf::SoundSource
enum	Status { Stopped , Paused , Playing }
	Enumeration of the sound source states. More...
Protected Attributes inherited from sf::SoundSource
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

anonymous enum

anonymous enum

protected

Enumerator
NoLoop	"Invalid" endSeeks value, telling us to continue uninterrupted

Definition at line 183 of file SoundStream.hpp.

Constructor & Destructor Documentation

~SoundStream()

virtual sf::SoundStream::~SoundStream ( )

virtual

Destructor.

SoundStream()

sf::SoundStream::SoundStream ( )

protected

Default constructor.

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

Member Function Documentation

getChannelCount()

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

getLoop()

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

getPlayingOffset()

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

getSampleRate()

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

getStatus()

Status sf::SoundStream::getStatus ( ) const

virtual

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

Returns

Current status

Reimplemented from sf::SoundSource.

initialize()

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

onGetData()

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.

onLoop()

virtual Int64 sf::SoundStream::onLoop ( )

protectedvirtual

Change the current playing position in the stream source to the beginning of the loop.

This function can be overridden by derived classes to allow implementation of custom loop points. Otherwise, it just calls onSeek(Time::Zero) and returns 0.

Returns

The seek position after looping (or -1 if there's no loop)

Reimplemented in sf::Music.

onSeek()

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.

pause()

void sf::SoundStream::pause ( )

virtual

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

Implements sf::SoundSource.

play()

void sf::SoundStream::play ( )

virtual

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

Implements sf::SoundSource.

setLoop()

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

setPlayingOffset()

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

stop()

void sf::SoundStream::stop ( )

virtual

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

Implements sf::SoundSource.

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

• SoundStream.hpp