Engine::Core::SteamAudioBackend Class Reference

Binaural HRTF spatialization backend built on Steam Audio. More...

#include <SteamAudioBackend.h>

Collaboration diagram for Engine::Core::SteamAudioBackend:

Public Types
using	SourceId = std::uint32_t
using	ReadFramesCallback = std::function<std::uint64_t(float* pFramesOut, std::uint64_t frameCount)>
	Reads interleaved PCM frames in the source's native channel layout.
using	DestroyCallback = std::function<void()>
	Frees the source PCM backend (e.g. a miniaudio buffer). Invoked on the audio thread when the source is finally released.

Public Member Functions
	SteamAudioBackend ()
	~SteamAudioBackend ()
	SteamAudioBackend (const SteamAudioBackend &)=delete
SteamAudioBackend &	operator= (const SteamAudioBackend &)=delete
bool	init (std::uint32_t sampleRate, std::uint32_t frameSize)
	Initialize Steam Audio with the built-in HRTF.
bool	init (std::uint32_t sampleRate, std::uint32_t frameSize, const char *sofaFilePath)
	Initialize Steam Audio with an individualized HRTF from a SOFA file.
void	shutdown ()
	Shut down Steam Audio and release all sources and effects. Must not run concurrently with render() (call after the device stopped).
bool	isInitialized () const
	Returns whether init() succeeded and shutdown() has not been called.
void	setListener (const glm::vec3 &position, const glm::quat &orientation)
	Set the listener pose (headset position and world orientation).
SourceId	addSource (ReadFramesCallback readFrames, DestroyCallback onDestroy, std::uint32_t channels, const glm::vec3 &position, float volume, bool loop)
	Register a spatialized source.
void	updateSourcePosition (SourceId source, const glm::vec3 &position)
	Move an existing source to a new world position.
void	updateSourceVolume (SourceId source, float volume)
	Change the base gain of an existing source.
bool	isSourceFinished (SourceId source) const
	Check whether a source reached the end of its audio.
void	removeSource (SourceId source)
	Release a source. The read backend is destroyed asynchronously on the audio thread; the source stops contributing immediately.
void	render (float *pFramesOutInterleavedStereo, std::uint32_t frameCount)
	Accumulate the spatialized mix into an interleaved stereo buffer.

Static Public Attributes
static constexpr SourceId	INVALID_SOURCE = 0

Private Attributes
std::unique_ptr< Impl >	impl_
bool	initialized_ = false

Detailed Description

Binaural HRTF spatialization backend built on Steam Audio.

Owns a Steam Audio context, an HRTF (built-in or loaded from a SOFA file), and one binaural effect per active source. Gameplay updates the listener pose and the per-source world positions on the game thread; render() is invoked from the audio thread (miniaudio engine onProcess hook) and accumulates the spatialized output into the final mix.

All sources are mixed down to mono and rendered with the binaural effect. Distance attenuation is applied with a gentle curve that keeps a floor so localized cues stay audible regardless of distance.

Definition at line 23 of file SteamAudioBackend.h.

Member Typedef Documentation

DestroyCallback

using Engine::Core::SteamAudioBackend::DestroyCallback = std::function<void()>

Frees the source PCM backend (e.g. a miniaudio buffer). Invoked on the audio thread when the source is finally released.

Definition at line 38 of file SteamAudioBackend.h.

ReadFramesCallback

using Engine::Core::SteamAudioBackend::ReadFramesCallback = std::function<std::uint64_t(float* pFramesOut, std::uint64_t frameCount)>

Reads interleaved PCM frames in the source's native channel layout.

Returns

Number of frames actually read; 0 signals the end of the source.

Definition at line 32 of file SteamAudioBackend.h.

SourceId

using Engine::Core::SteamAudioBackend::SourceId = std::uint32_t

Definition at line 25 of file SteamAudioBackend.h.

Constructor & Destructor Documentation

SteamAudioBackend() [1/2]

Engine::Core::SteamAudioBackend::SteamAudioBackend

(

)

Referenced by operator=(), and SteamAudioBackend().

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~SteamAudioBackend()

Engine::Core::SteamAudioBackend::~SteamAudioBackend

(

)

SteamAudioBackend() [2/2]

Engine::Core::SteamAudioBackend::SteamAudioBackend ( const SteamAudioBackend & )

delete

References SteamAudioBackend().

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Member Function Documentation

addSource()

SourceId Engine::Core::SteamAudioBackend::addSource	(	ReadFramesCallback	readFrames,
		DestroyCallback	onDestroy,
		std::uint32_t	channels,
		const glm::vec3 &	position,
		float	volume,
		bool	loop )

Register a spatialized source.

Parameters

readFrames	Callback that fills interleaved PCM frames in the source's channel layout.
onDestroy	Callback invoked on the audio thread when the source is released.
channels	Number of interleaved channels produced by readFrames.
position	Initial world position.
volume	Base gain (0.0 - 1.0) before distance attenuation.
loop	Whether readFrames loops automatically.

Returns

Stable source id, or INVALID_SOURCE on failure.

init() [1/2]

bool Engine::Core::SteamAudioBackend::init	(	std::uint32_t	sampleRate,
		std::uint32_t	frameSize )

Initialize Steam Audio with the built-in HRTF.

Parameters

sampleRate	Shared engine sample rate (see Audio::SAMPLE_RATE).
frameSize	Fixed processing frame size (see Audio::FRAME_SIZE).

Returns

true when the context and HRTF initialized successfully.

init() [2/2]

bool Engine::Core::SteamAudioBackend::init	(	std::uint32_t	sampleRate,
		std::uint32_t	frameSize,
		const char *	sofaFilePath )

Initialize Steam Audio with an individualized HRTF from a SOFA file.

Parameters

sofaFilePath

Path to a SOFA HRTF dataset, or nullptr for the built-in HRTF.

isInitialized()

bool Engine::Core::SteamAudioBackend::isInitialized ( ) const

inlinenodiscard

Returns whether init() succeeded and shutdown() has not been called.

Definition at line 67 of file SteamAudioBackend.h.

References initialized_.

isSourceFinished()

bool Engine::Core::SteamAudioBackend::isSourceFinished ( SourceId source ) const

nodiscard

Check whether a source reached the end of its audio.

Returns

true when the source is finished or no longer registered.

operator=()

SteamAudioBackend & Engine::Core::SteamAudioBackend::operator= ( const SteamAudioBackend & )

delete

References SteamAudioBackend().

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removeSource()

void Engine::Core::SteamAudioBackend::removeSource

(

SourceId

source

)

Release a source. The read backend is destroyed asynchronously on the audio thread; the source stops contributing immediately.

render()

void Engine::Core::SteamAudioBackend::render	(	float *	pFramesOutInterleavedStereo,
		std::uint32_t	frameCount )

Accumulate the spatialized mix into an interleaved stereo buffer.

Parameters

pFramesOut	Interleaved stereo buffer (2 channels) to add into.
frameCount	Number of stereo frames.

setListener()

void Engine::Core::SteamAudioBackend::setListener	(	const glm::vec3 &	position,
		const glm::quat &	orientation )

Set the listener pose (headset position and world orientation).

Parameters

position	World position of the headset.
orientation	World orientation of the headset.

shutdown()

void Engine::Core::SteamAudioBackend::shutdown

(

)

Shut down Steam Audio and release all sources and effects. Must not run concurrently with render() (call after the device stopped).

updateSourcePosition()

void Engine::Core::SteamAudioBackend::updateSourcePosition	(	SourceId	source,
		const glm::vec3 &	position )

Move an existing source to a new world position.

updateSourceVolume()

void Engine::Core::SteamAudioBackend::updateSourceVolume	(	SourceId	source,
		float	volume )

Change the base gain of an existing source.

Member Data Documentation

impl_

std::unique_ptr<Impl> Engine::Core::SteamAudioBackend::impl_

private

Definition at line 116 of file SteamAudioBackend.h.

initialized_

bool Engine::Core::SteamAudioBackend::initialized_ = false

private

Definition at line 117 of file SteamAudioBackend.h.

Referenced by isInitialized().

INVALID_SOURCE

SourceId Engine::Core::SteamAudioBackend::INVALID_SOURCE = 0

staticconstexpr

Definition at line 26 of file SteamAudioBackend.h.

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

• /workspace/magerbeton/gl3-vulkan/code/Engine/include/Engine/Audio/SteamAudioBackend.h