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SFML 2.5.1

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sf::SoundStream Class Referenceabstract
Audio module

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 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 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();
sf::SoundStream
Abstract base class for streamed audio sources.
Definition: SoundStream.hpp:46

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.

## ◆ Status

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

## ◆ ~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

## ◆ getAttenuation()

float sf::SoundSource::getAttenuation | ( |  | ) | const
| inherited

Get the attenuation factor of the sound.

Returns
  Attenuation factor of the sound

See also
  setAttenuation, getMinDistance

## ◆ 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

## ◆ getMinDistance()

float sf::SoundSource::getMinDistance | ( |  | ) | const
| inherited

Get the minimum distance of the sound.

Returns
  Minimum distance of the sound

See also
  setMinDistance, getAttenuation

## ◆ getPitch()

float sf::SoundSource::getPitch | ( |  | ) | const
| inherited

Get the pitch of the sound.

Returns
  Pitch of the sound

See also
  setPitch

## ◆ 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

## ◆ getPosition()

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

## ◆ 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.

## ◆ getVolume()

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

## ◆ 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

## ◆ isRelativeToListener()

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

## ◆ 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.

## ◆ setAttenuation()

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

## ◆ 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

## ◆ setMinDistance()

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

## ◆ setPitch()

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

## ◆ 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

## ◆ setPosition() [1/2]

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

## ◆ setPosition() [2/2]

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

## ◆ setRelativeToListener()

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

## ◆ setVolume()

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

## ◆ 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.

## Member Data Documentation

## ◆ m_source

unsigned int sf::SoundSource::m_source
| protectedinherited

OpenAL source identifier.

Definition at line 309 of file SoundSource.hpp.

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

- SoundStream.hpp