The opaque handle that represents an audio stream. More...

Inheritance diagram for SDL::AudioStreamBase:

[legend]

Public Member Functions
	AudioStreamBase (OptionalRef< const AudioSpec > src_spec, OptionalRef< const AudioSpec > dst_spec)
	Create a new audio stream.

	AudioStreamBase (const AudioDeviceBase &devid, OptionalRef< const AudioSpec > spec=std::nullopt, AudioStreamCallback callback=nullptr, void *userdata=nullptr)
	Convenience function for straightforward audio init for the common case.

	AudioStreamBase (const AudioDeviceBase &devid, OptionalRef< const AudioSpec > spec, AudioStreamCB callback)
	Convenience function for straightforward audio init for the common case.

PropertiesRef	GetProperties () const
	Get the properties associated with an audio stream.

AudioSpec	GetInputFormat () const
	Query the current input format of an audio stream.

AudioSpec	GetOutputFormat () const
	Query the current output format of an audio stream.

void	GetFormat (AudioSpec src_spec, AudioSpec dst_spec) const
	Query the current format of an audio stream.

void	SetInputFormat (const AudioSpec &spec)
	Change the input format of an audio stream.

void	SetOutputFormat (const AudioSpec &spec)
	Change the output format of an audio stream.

void	SetFormat (OptionalRef< const AudioSpec > src_spec, OptionalRef< const AudioSpec > dst_spec)
	Change the input and output formats of an audio stream.

float	GetFrequencyRatio () const
	Get the frequency ratio of an audio stream.

void	SetFrequencyRatio (float ratio)
	Change the frequency ratio of an audio stream.

float	GetGain () const
	Get the gain of an audio stream.

void	SetGain (float gain)
	Change the gain of an audio stream.

OwnArray< int >	GetInputChannelMap () const
	Get the current input channel map of an audio stream.

OwnArray< int >	GetOutputChannelMap () const
	Get the current output channel map of an audio stream.

void	SetInputChannelMap (std::span< int > chmap)
	Set the current input channel map of an audio stream.

void	SetOutputChannelMap (std::span< int > chmap)
	Set the current output channel map of an audio stream.

void	PutData (SourceBytes buf)
	Add data to the stream.

int	GetData (TargetBytes buf)
	Get converted/resampled data from the stream.

int	GetAvailable () const
	Get the number of converted/resampled bytes available.

int	GetQueued () const
	Get the number of bytes currently queued.

void	Flush ()
	Tell the stream that you're done sending data, and anything being buffered should be converted/resampled and made available immediately.

void	Clear ()
	Clear any pending data in the stream.

void	PauseDevice ()
	Use this function to pause audio playback on the audio device associated with an audio stream.

void	ResumeDevice ()
	Use this function to unpause audio playback on the audio device associated with an audio stream.

bool	DevicePaused () const
	Use this function to query if an audio device associated with a stream is paused.

AudioStreamLock	Lock ()
	Lock an audio stream for serialized access.

void	SetGetCallback (AudioStreamCB callback)
	Set a callback that runs when data is requested from an audio stream.

void	SetGetCallback (AudioStreamCallback callback, void *userdata)
	Set a callback that runs when data is requested from an audio stream.

void	SetPutCallback (AudioStreamCB callback)
	Set a callback that runs when data is added to an audio stream.

void	SetPutCallback (AudioStreamCallback callback, void *userdata)
	Set a callback that runs when data is added to an audio stream.

void	Bind (AudioDeviceBase &devid)
	Bind a single audio stream to an audio device.

void	Unbind ()
	Unbind a single audio stream from its audio device.

AudioDeviceRef	GetDevice () const
	Query an audio stream for its currently-bound device.

constexpr	Resource (T resource={})
	Constructs the underlying resource.

constexpr	Resource (std::nullptr_t)
	Equivalent to default ctor.

constexpr	Resource (std::nullopt_t)
	Equivalent to default ctor.

	Resource (const Resource &other)=delete

	Resource (Resource &&other)=delete

Public Member Functions inherited from SDL::Resource< SDL_AudioStream * >
constexpr	Resource (SDL_AudioStream * resource={})
	Constructs the underlying resource.

constexpr	Resource (std::nullptr_t)
	Equivalent to default ctor.

constexpr	Resource (std::nullopt_t)
	Equivalent to default ctor.

	Resource (const Resource &other)=delete

	Resource (Resource &&other)=delete

Resource &	operator= (const Resource &other)=delete

Resource &	operator= (Resource &&other)=delete

constexpr	operator bool () const
	True if contains a valid resource.

constexpr bool	operator== (const Resource &other) const=default
	Comparison.

constexpr bool	operator== (std::nullopt_t) const
	Comparison.

constexpr bool	operator== (std::nullptr_t) const
	Comparison.

constexpr SDL_AudioStream *	get () const
	Return contained resource;.

constexpr SDL_AudioStream *	release (SDL_AudioStream * newResource={})
	Return contained resource and empties or replace value.

constexpr const SDL_AudioStream *	operator-> () const
	Access to fields.

constexpr SDL_AudioStream *	operator-> ()
	Access to fields.

Detailed Description

AudioStreamBase is an audio conversion interface.

It can handle resampling data in chunks without generating artifacts, when it doesn't have the complete buffer available.
It can handle incoming data in any variable size.
It can handle input/output format changes on the fly.
It can remap audio channels between inputs and outputs.
You push data as you have it, and pull it when you need it
It can also function as a basic audio data queue even if you just have sound that needs to pass from one place to another.
You can hook callbacks up to them when more data is added or requested, to manage data on-the-fly.

Audio streams are the core of the SDL3 audio interface. You create one or more of them, bind them to an opened audio device, and feed data to them (or for recording, consume data from them).

Since: This struct is available since SDL 3.2.0.

See also: AudioStreamBase.AudioStreamBase

Category:: Resource

See also: AudioStream; AudioStreamRef

Constructor & Destructor Documentation

◆ AudioStreamBase() [1/3]

SDL::AudioStreamBase::AudioStreamBase	(	OptionalRef< const AudioSpec >	src_spec,
		OptionalRef< const AudioSpec >	dst_spec
	)

inline

Parameters

src_spec	the format details of the input audio.
dst_spec	the format details of the output audio.

Postcondition: a new audio stream on success.

Exceptions

Error on failure.

Thread safety:: It is safe to call this function from any thread.

Since: This function is available since SDL 3.2.0.

See also: AudioStreamBase.PutData; AudioStreamBase.GetData; AudioStreamBase.GetAvailable; AudioStreamBase.Flush; AudioStreamBase.Clear; AudioStreamBase.SetFormat

◆ AudioStreamBase() [2/3]

SDL::AudioStreamBase::AudioStreamBase	(	const AudioDeviceBase &	devid,
		OptionalRef< const AudioSpec >	spec = `std::nullopt`,
		AudioStreamCallback	callback = `nullptr`,
		void *	userdata = `nullptr`
	)

inline

If all your app intends to do is provide a single source of PCM audio, this function allows you to do all your audio setup in a single call.

This is also intended to be a clean means to migrate apps from SDL2.

This function will open an audio device, create a stream and bind it. Unlike other methods of setup, the audio device will be closed when this stream is destroyed, so the app can treat the returned AudioStreamBase as the only object needed to manage audio playback.

Also unlike other functions, the audio device begins paused. This is to map more closely to SDL2-style behavior, since there is no extra step here to bind a stream to begin audio flowing. The audio device should be resumed with AudioStreamBase.ResumeDevice(stream);

This function works with both playback and recording devices.

The spec parameter represents the app's side of the audio stream. That is, for recording audio, this will be the output format, and for playing audio, this will be the input format. If spec is nullptr, the system will choose the format, and the app can use AudioStreamBase.GetFormat() to obtain this information later.

If you don't care about opening a specific audio device, you can (and probably should), use AUDIO_DEVICE_DEFAULT_PLAYBACK for playback and AUDIO_DEVICE_DEFAULT_RECORDING for recording.

One can optionally provide a callback function; if nullptr, the app is expected to queue audio data for playback (or unqueue audio data if capturing). Otherwise, the callback will begin to fire once the device is unpaused.

Destroying the returned stream with AudioStreamRef.reset will also close the audio device associated with this stream.

Parameters

devid	an audio device to open, or AUDIO_DEVICE_DEFAULT_PLAYBACK or AUDIO_DEVICE_DEFAULT_RECORDING.
spec	the audio stream's data format. Can be std::nullopt.
callback	a callback where the app will provide new data for playback, or receive new data for recording. Can be nullptr, in which case the app will need to call AudioStreamBase.PutData or AudioStreamBase.GetData as necessary.
userdata	app-controlled pointer passed to callback. Can be nullptr. Ignored if callback is nullptr.

Postcondition: an audio stream on success.

Exceptions

Error on failure.

Thread safety:: It is safe to call this function from any thread.

Since: This function is available since SDL 3.2.0.

See also: AudioStreamBase.GetDevice; AudioStreamBase.ResumeDevice

◆ AudioStreamBase() [3/3]

SDL::AudioStreamBase::AudioStreamBase	(	const AudioDeviceBase &	devid,
		OptionalRef< const AudioSpec >	spec,
		AudioStreamCB	callback
	)