sf::SoundStream Class Reference

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 Member Functions
	~SoundStream () override
	Destructor.
	SoundStream (SoundStream &&) noexcept
	Move constructor.
SoundStream &	operator= (SoundStream &&) noexcept
	Move assignment.
void	play () override
	Start or resume playing the audio stream.
void	pause () override
	Pause the audio stream.
void	stop () override
	Stop playing the audio stream.
unsigned int	getChannelCount () const
	Return the number of channels of the stream.
unsigned int	getSampleRate () const
	Get the stream sample rate of the stream.
std::vector< SoundChannel >	getChannelMap () const
	Get the map of position in sample frame to sound channel.
Status	getStatus () const override
	Get the current status of the stream (stopped, paused, playing).
void	setPlayingOffset (Time timeOffset)
	Change the current playing position of the stream.
Time	getPlayingOffset () const
	Get the current playing position of the stream.
void	setLooping (bool loop)
	Set whether or not the stream should loop after reaching the end.
bool	isLooping () const
	Tell whether or not the stream is in loop mode.
void	setEffectProcessor (EffectProcessor effectProcessor) override
	Set the effect processor to be applied to the sound.
Public Member Functions inherited from sf::SoundSource
	SoundSource (const SoundSource &)=default
	Copy constructor.
	SoundSource (SoundSource &&) noexcept=default
	Move constructor.
SoundSource &	operator= (SoundSource &&) noexcept=default
	Move assignment.
virtual	~SoundSource ()=default
	Destructor.
void	setPitch (float pitch)
	Set the pitch of the sound.
void	setPan (float pan)
	Set the pan of the sound.
void	setVolume (float volume)
	Set the volume of the sound.
void	setSpatializationEnabled (bool enabled)
	Set whether spatialization of the sound is enabled.
void	setPosition (const Vector3f &position)
	Set the 3D position of the sound in the audio scene.
void	setDirection (const Vector3f &direction)
	Set the 3D direction of the sound in the audio scene.
void	setCone (const Cone &cone)
	Set the cone properties of the sound in the audio scene.
void	setVelocity (const Vector3f &velocity)
	Set the 3D velocity of the sound in the audio scene.
void	setDopplerFactor (float factor)
	Set the doppler factor of the sound.
void	setDirectionalAttenuationFactor (float factor)
	Set the directional attenuation factor of the sound.
void	setRelativeToListener (bool relative)
	Make the sound's position relative to the listener or absolute.
void	setMinDistance (float distance)
	Set the minimum distance of the sound.
void	setMaxDistance (float distance)
	Set the maximum distance of the sound.
void	setMinGain (float gain)
	Set the minimum gain of the sound.
void	setMaxGain (float gain)
	Set the maximum gain of the sound.
void	setAttenuation (float attenuation)
	Set the attenuation factor of the sound.
float	getPitch () const
	Get the pitch of the sound.
float	getPan () const
	Get the pan of the sound.
float	getVolume () const
	Get the volume of the sound.
bool	isSpatializationEnabled () const
	Tell whether spatialization of the sound is enabled.
Vector3f	getPosition () const
	Get the 3D position of the sound in the audio scene.
Vector3f	getDirection () const
	Get the 3D direction of the sound in the audio scene.
Cone	getCone () const
	Get the cone properties of the sound in the audio scene.
Vector3f	getVelocity () const
	Get the 3D velocity of the sound in the audio scene.
float	getDopplerFactor () const
	Get the doppler factor of the sound.
float	getDirectionalAttenuationFactor () const
	Get the directional attenuation factor of the sound.
bool	isRelativeToListener () const
	Tell whether the sound's position is relative to the listener or is absolute.
float	getMinDistance () const
	Get the minimum distance of the sound.
float	getMaxDistance () const
	Get the maximum distance of the sound.
float	getMinGain () const
	Get the minimum gain of the sound.
float	getMaxGain () const
	Get the maximum gain of the sound.
float	getAttenuation () const
	Get the attenuation factor of the sound.
SoundSource &	operator= (const SoundSource &right)
	Overload of assignment operator.

Protected Member Functions
	SoundStream ()
	Default constructor.
void	initialize (unsigned int channelCount, unsigned int sampleRate, const std::vector< SoundChannel > &channelMap)
	Define the audio stream parameters.
virtual bool	onGetData (Chunk &data)=0
	Request a new chunk of audio samples from the stream source.
virtual void	onSeek (Time timeOffset)=0
	Change the current playing position in the stream source.
virtual std::optional< std::uint64_t >	onLoop ()
	Change the current playing position in the stream source to the beginning of the loop.
Protected Member Functions inherited from sf::SoundSource
	SoundSource ()=default
	Default constructor.
Protected Member Functions inherited from sf::AudioResource
	AudioResource ()
	Default constructor.
	AudioResource (const AudioResource &)=default
	Copy constructor.
AudioResource &	operator= (const AudioResource &)=default
	Copy assignment.
	AudioResource (AudioResource &&) noexcept=default
	Move constructor.
AudioResource &	operator= (AudioResource &&) noexcept=default
	Move assignment.

Additional Inherited Members
Public Types inherited from sf::SoundSource
enum class	Status { Stopped , Paused , Playing }
	Enumeration of the sound source states. More...
using	EffectProcessor
	Callable that is provided with sound data for processing.

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:
 
    [[nodiscard]] 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);
        return true;
    }
 
private:
 
    bool onGetData(Chunk& data) override
    {
        // Fill the chunk with audio data from the stream source
        // (note: must not be empty if you want to continue playing)
        data.samples = ...;
 
        // Return true to continue playing
        data.sampleCount = ...;
        return true;
    }
 
    void onSeek(sf::Time timeOffset) override
    {
        // Change the current position in the stream source
        ...
    }
};
 
// Usage
CustomStream stream;
stream.open("path/to/stream");
stream.play();

See also

sf::Music

Constructor & Destructor Documentation

~SoundStream()

sf::SoundStream::~SoundStream ( )

override

Destructor.

SoundStream() [1/2]

sf::SoundStream::SoundStream ( SoundStream && )

noexcept

Move constructor.

SoundStream() [2/2]

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

nodiscard

Return the number of channels of the stream.

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

Returns

Number of channels

getChannelMap()

std::vector< SoundChannel > sf::SoundStream::getChannelMap ( ) const

nodiscard

Get the map of position in sample frame to sound channel.

This is used to map a sample in the sample stream to a position during spatialisation.

Returns

Map of position in sample frame to sound channel

getPlayingOffset()

Time sf::SoundStream::getPlayingOffset ( ) const

nodiscard

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

nodiscard

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

nodiscardoverridevirtual

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

Returns

Current status

Implements sf::SoundSource.

initialize()

void sf::SoundStream::initialize ( unsigned int channelCount, unsigned int sampleRate, const std::vector< SoundChannel > & channelMap )

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
channelMap	Map of position in sample frame to sound channel

isLooping()

bool sf::SoundStream::isLooping ( ) const

nodiscard

Tell whether or not the stream is in loop mode.

Returns

True if the stream is looping, false otherwise

See also

setLooping

onGetData()

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

nodiscardprotectedpure 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 std::optional< std::uint64_t > 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 std::nullopt 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.

operator=()

SoundStream & sf::SoundStream::operator= ( SoundStream && )

noexcept

Move assignment.

pause()

void sf::SoundStream::pause ( )

overridevirtual

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 ( )

overridevirtual

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.

setEffectProcessor()

void sf::SoundStream::setEffectProcessor ( EffectProcessor effectProcessor )

overridevirtual

Set the effect processor to be applied to the sound.

The effect processor is a callable that will be called with sound data to be processed.

Parameters

effectProcessor

The effect processor to attach to this sound, attach an empty processor to disable processing

Reimplemented from sf::SoundSource.

setLooping()

void sf::SoundStream::setLooping

(

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 setLooping(false) is called. The default looping state for streams is false.

Parameters

loop	True to play in loop, false to play once

See also

isLooping

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 ( )

overridevirtual

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:

• SFML/Audio/SoundStream.hpp