Volume, pitch, and looping

Volume, pitch, and looping#

Goal: control a sound’s volume and playback speed at runtime.

Building on Play a sound, this tutorial walks through Demo01_SoundProperties: load a sound, then change its level and pitch on the fly.

Source: Demo01_SoundProperties.cpp.

Volume#

volume() is overloaded — call it with no arguments to read, with a value to set.

void DemoSoundProperties::IncVolume()
{
	sound.volume(sound.volume() + 0.1f);
}

void DemoSoundProperties::DecVolume()
{
	sound.volume(sound.volume() - 0.1f);
}

The value is a linear gain in [0.0, 1.0]. volume(value, time) also exists and fades over time milliseconds — much friendlier than the default instant change for runtime gain riding.

Playback speed#

speed() controls both pitch and playback rate together — there is no independent pitch-shift in libYSE. Doppler effect from listener / source velocity layers on top of this unless doppler(false) is set.

void DemoSoundProperties::IncSpeed()
{
	sound.speed(sound.speed() + 0.1f);
}

void DemoSoundProperties::DecSpeed()
{
	sound.speed(sound.speed() - 0.1f);
}

  • 1.0 is the natural speed (and pitch).

  • 2.0 is one octave up, 0.5 is one octave down.

  • Negative values play backwards (not supported for streaming sounds).

Looping#

The third argument to sound::create is the loop flag. The demo passes true because the test asset is short:

	// load a sound in memory
	sound.create(YSE_TEST_RESOURCES_DIR "/contact.ogg", nullptr, true);

Toggle it at runtime with sound::looping(bool).

What you learned#

  • volume(value) sets, volume() reads. Use volume(value, time) to fade.

  • speed(value) changes pitch and playback rate together.

  • The create loop flag enables looping at load time; looping(bool) toggles it later.

Next#