Creating and playing sounds

This lesson covers the basics of playing sounds with DirectX Tool Kit for Audio.

Setup

First create a new project using the instructions from these four lessons to enable the audio engine for DirectX Tool Kit for Audio: The basic game loop, Adding the DirectX Tool Kit, Adding the DirectX Tool Kit for Audio, and Adding audio to your project. We'll be using the result of that process for this lesson.

Sounds

Save the following files to your new project's folder: Explo1.wav, Explo2.wav, Explo3.wav, Explo4.wav, NightAmbienceSimple_02.wav. Use the top menu and select Project / Add Existing Item.... Select each .wav file in turn and hit "OK".

These .wav files are from the XNA Game Studio SoundLab which provides a small collection of sounds under the MS-PL license.

In the Game.h file, add the following variables to the bottom of the Game class's private declarations:

std::unique_ptr<DirectX::SoundEffect> m_explode;
std::unique_ptr<DirectX::SoundEffect> m_ambient;

In Game.cpp, add to the end of Initialize:

m_explode = std::make_unique<SoundEffect>( m_audEngine.get(), L"explo1.wav" );
m_ambient = std::make_unique<SoundEffect>( m_audEngine.get(),
    L"NightAmbienceSimple_02.wav" );

Build and run. No sounds will be heard, but the audio files are loaded.

Troubleshooting: If you get a runtime exception, then you may have the .wav files in the wrong folder, have modified the "Working Directory" in the "Debugging" configuration settings, or otherwise changed the expected paths at runtime of the application. You should set a break-point on std::make_unique<SoundEffect and step into the code to find the exact problem.

Playing a sound

In the pch.h file, add after the other includes:

#include <random>

In the Game.h file, add the following variables to the bottom of the Game class's private declarations:

std::unique_ptr<std::mt19937> m_random;
float explodeDelay;

In Game.cpp, add to the end of Initialize:

std::random_device rd;
m_random = std::make_unique<std::mt19937>(rd());

explodeDelay = 2.f;

In Game.cpp, add to the TODO of Update:

explodeDelay -= elapsedTime;
if (explodeDelay < 0.f)
{
    m_explode->Play();

    std::uniform_real_distribution<float> dist(1.f, 10.f);
    explodeDelay = dist(*m_random);
}

In Game.cpp, add to the TODO of OnResuming:

explodeDelay = 2.f;

Build and run. You will hear an explosion sound effect every 1 to 10 seconds. This is a 'one-shot' sound that you trigger and the audio engine will handle all the voice management automatically. You can trigger the same sound many times at once and each one-shot will play on it's own 'voice'.

The SoundEffect itself must remain in memory as all playback uses the audio data directly from that object. XAudio does not copy the source audio data into it's own buffers, but fetches from the application's memory periodically from a worker thread.

Looping a sound

In the Game.h file, add the following variables to the bottom of the Game class's private declarations:

std::unique_ptr<DirectX::SoundEffectInstance> m_nightLoop;

In Game.cpp, add to the end of Initialize:

m_nightLoop = m_ambient->CreateInstance();
m_nightLoop->Play(true);

In Game.cpp, modify the handling of m_retryAudio in Update as follows:

...
if (m_retryAudio)
{
    m_retryAudio = false;

    if (m_audEngine->Reset())
    {
        // TODO: restart any looped sounds here
        if ( m_nightLoop )
            m_nightLoop->Play(true);
    }
}
...

In Game.cpp, modify the destructor:

Game::~Game()
{
    if (m_audEngine)
    {
        m_audEngine->Suspend();
    }

    m_nightLoop.reset();
}

Build and run to hear an ambient night sound looping in the background. In this case, the SoundEffectInstance has a single assigned voice, so stopping and starting it affects the one playing sound.

Again, the SoundEffect must remain in memory as the audio data is used directly from that object.

Technical notes

We need to ensure that the looping SoundEffectInstance is destroyed before the object it was created from is released. We therefore added an explicit reset to the Game's destructor to avoid being dependent on the order of destruction in the Game class. We also do this after the audio engine has been explicitly suspended since XAudio2 is multi-threaded and references data directly from the application's objects.

Adjusting pitch, volume, and panning

When you use Play on a one-shot sound, you can specify pitch, volume, and panning settings to use for the playback. If you have a SoundEffectInstance you can modify the sound pitch, volume, and panning settings while it is playing.

In the Game.h file, add the following variables to the bottom of the Game class's private declarations:

float nightVolume;
float nightSlide;

In Game.cpp, add to the end of Initialize:

nightVolume = 1.f;
nightSlide = -0.1f;

In Game.cpp, add to the TODO of Update:

nightVolume += elapsedTime * nightSlide;
if (nightVolume < 0.f)
{
    nightVolume = 0.f;
    nightSlide = -nightSlide;
}
else if (nightVolume > 1.f)
{
    nightVolume = 1.f;
    nightSlide = -nightSlide;
}
m_nightLoop->SetVolume( nightVolume );

Build and run. The looping night ambient sound will slowly decrease and increase volume over time.

Next lesson: Making use of wave banks

Further reading

DirectX Tool Kit docs SoundEffect, SoundEffectInstance

XAudio2BasicSound, SimplePlaySoundUWP samples