SoundStreamInstance

SoundStreamInstance is an instance for playing waves from a streaming WaveBank making use of non-buffered asynchronous I/O. It can be played with 3D positional audio effects, volume and panning control, looping, and pause/resume control.

Note that the SoundStreamInstance refers to data 'owned' by the WaveBank. Therefore, the parent object must be kept "live" until all sounds playing from it are finished.

Header

#include <Audio.h>

Initialization

The stream instance is created for an entry in a streaming WaveBank (which is returned as a std::unique_ptr<SoundStreamInstance>):

auto stream = wb->CreateStreamInstance( 2 );
if ( !stream )
    // Index not found in wave bank

It can optionally support 3D positional audio:

auto stream = wb->CreateStreamInstance( 2, SoundEffectInstance_Use3D );
if ( !stream )
    // Index not found in wave bank

Or use 3D positional audio with reverb effects (if AudioEngine was created using AudioEngine_EnvironmentalReverb | AudioEngine_ReverbUseFilters):

auto stream = wb->CreateStreamInstance( 2,
    SoundEffectInstance_Use3D | SoundEffectInstance_ReverbUseFilters);
if ( !stream )
    // Index not found in wave bank

Instance flags

This is a combination of sound effect instance flags. It defaults to SoundEffectInstance_Default.

See Instance flags

Playback control

Play ( bool loop = false ): Starts the playback of the sound. If loops is set to true, it loops continuously. If paused, it resumes playback.

Note if a source voice limit is in effect (see AudioEngine), then a C++ exception can be generated from this method if there are too many source voices already allocated.

Stop ( bool immediate = true ): Stops the playback of the voice. If immediate is true, the sound is immediately halted. Otherwise the current loop is exited (if looping) and any 'tails' are played. The sound still not completely stop playing until a future point so the state will remain PLAYING for a while.
Resume: Resumes playback if the sound is paused.
Pause: Pauses the sound playback. Note that for a 'game' pause, you should use AudioEngine::Suspend / Resume instead of 'pausing' the sounds individually.

Volume and panning

SetVolume ( float volume ): Sets playback volume. Playback defaults to 1
SetPitch ( float pitch ): Sets a pitch-shift factor. Ranges from -1 to +1, playback defaults to 0 (which is no pitch-shifting). This will trigger a C++ exception if the object was created with SoundEffectInstance_NoSetPitch.
SetPan ( float pan ): Sets a pan settings: -1 is fully left, +1 is fully right, and 0 is balanced.

Panning is only supported for mono and stereo sources, and will overwrite any Apply3D settings.

Positional 3D audio

See Positional 3D audio.

Voice management

A SoundStreamInstance will allocate a XAudio2 source voice when played, and will keep that source voice for the life of the object. You can force all SoundStreamInstance that currently have source voices but are not currently playing to release them by calling AudioEngine::TrimVoicePool.

By default the number of XAudio2 source voices that can be allocated is 'unlimited'. You can set a specific limit using AudioEngine::SetMaxVoicePool which will be enforced by generating a C++ exception if there are too many allocated source voices when Play is called.

See AudioEngine for more details.