Sound Overview - ClanLib SDK

Sound Overview

THIS PAGE REQUIRES UPDATING FOR CLANLIB 3.0

ClanSound provides you with easy-to-use and powerful sound functionality.

## Sound overview

To play sound in ClanLib, you have to initialize clan::SetupSound and also create a clan::SoundOutput. clan::SoundOutput is the interface to a sound output device, which is used to control the main mixer volume and other global settings. It is used as a singleton.

#include <ClanLib/sound.h>
clan::SetupSound setup_sound;
clan::SoundOutput output(44100);
clan::SoundOutput
SoundOutput interface in ClanLib.
Definition soundoutput.h:48

## Playing wav samples

A clan::SoundBuffer contains a sample or music stream. To load and play a WAV file, you do the following:

// Load a sample from a wave file:
clan::SoundBuffer sample("beep.wav");
// Play sample
sample.play();
clan::SoundBuffer
Sample interface in ClanLib.
Definition soundbuffer.h:56

You can set the volume and panning of soundbuffers. This will change the default attributes of the soundbuffer, and will be effective on all subsequent calls to play().

// Turn down volume on this soundbuffer.
sample.set_volume(0.1f);
// Play only in left speaker.
sample.set_pan(-1.0f);

Note that setting these attributes don't affect already playing soundbuffers, only when you call play() again afterwards. To have individual control over each playing sound, you need to use a sound session - read about that further down.

## Playing music streams

There isn't much difference between playing wav samples and music stream. ClanSound itself doesn't provide more than wav samples playback, so you'll need one or more additional music modules. ClanLib currently has two, MikMod and Vorbis. They are initialized using clan::SetupMikMod and clan::SetupVorbis.

#include <ClanLib/sound.h>
#include <ClanLib/vorbis.h>
#include <ClanLib/mikmod.h>
clan::SetupSound setup_sound;
clan::SetupMikMod setup_mikmod;
clan::SetupVorbis setup_vorbis;
clan::SoundOutput output(44100);

Then to play music, you use the same approach as with wav samples:

// Load ogg file into a soundbuffer
clan::SoundBuffer vorbis("cheer1.ogg");
// Play vorbis stream
vorbis.play();
...
// Load an XM mod into a soundbuffer
clan::SoundBuffer mod("clanbeat.xm");
// Play mod
mod.play();

## Sessions

If you want to control the playback of sound, or want to know if the sound is still playing, you use clan::SoundBuffer_Session. This can be created in two ways, either by calling clan::SoundBuffer::play() or clan::SoundBuffer::prepare(). The difference between prepare() and play() is that prepare will just load the sound, but not play it. You can then call play() from your resulting clan::SoundBuffer_Session.

// Load ogg file into a soundbuffer
clan::SoundBuffer vorbis("cheer1.ogg");
// Create a session from soundbuffer.
clan::SoundBuffer_Session playback = vorbis.play();
..
// Load ogg file into a soundbuffer
clan::SoundBuffer vorbis("cheer1.ogg");
// Create a session from soundbuffer.
clan::SoundBuffer_Session playback = vorbis.prepare();
playback.play();
clan::SoundBuffer_Session
SoundBuffer_Session provides control over a playing soundeffect.
Definition soundbuffer_session.h:51
clan::SoundBuffer_Session::play
void play()
Starts playback of the session.

When you have a session object, you can modify the attributes of the playing sound in many ways. These take effect immidiately, you can change it while it is playing. You can set the volume, panning, position, and frequency (speed). You can make it loop, and adding filters. You can query if it is still playing, and you can ofcourse start and stop it as you want.

// Load ogg file into a soundbuffer
clan::SoundBuffer vorbis("cheer1.ogg");
// Create a session from soundbuffer.
clan::SoundBuffer_Session playback = vorbis.prepare();
playback.set_volume(0.5f);
playback.set_looping(true);
playback.play();
clan::SoundBuffer_Session::set_looping
void set_looping(bool loop)
Determines whether this session should loop.
clan::SoundBuffer_Session::set_volume
void set_volume(float new_volume)
Sets the volume of the session in a relative measure (0->1)

## Filters

If you want to modify sounds in special, dynamic ways, you can apply a clan::SoundFilter to it. There are three builtin filters: clan::EchoFilter, clan::FadeFilter and clan::InverseEchoFilter.

Example of the fade filter:

// Load ogg file into a soundbuffer
clan::SoundBuffer vorbis("cheer1.ogg");
// Create a session from soundbuffer.
clan::SoundBuffer_Session playback = vorbis.prepare();
clan::FadeFilter fade(0.0f);
playback.add_filter(&fade);
playback.play();
fade.fade_to_volume(1.0f, 10*1000); // fade in, duration 10 seconds.
clan::FadeFilter
Fade Filter Class.
Definition fadefilter.h:43
clan::SoundBuffer_Session::add_filter
void add_filter(SoundFilter &filter)
Adds the sound filter to the session. See SoundFilter for details.

Example of the echo filter:

// Load ogg file into a soundbuffer
clan::SoundBuffer vorbis("cheer1.ogg");
// Create a session from soundbuffer.
clan::SoundBuffer_Session playback = vorbis.prepare();
playback.add_filter(new clan::EchoFilter(8*1024), true);
playback.play();
clan::EchoFilter
Echo Filter Class.
Definition echofilter.h:43

You can also code your own filters. Check the SoundFilters example how do to that.

It is also possible to add filters on mixer level too. I.e. fade all sound out alltogether. Use clan::SoundOutput::add_filter() just like with clan::SoundBuffer_Session.

## Sound providers

It is also possible to create sound on-the-fly, or adding extra sound providers. See the StreamSoundProvider example for code how to do this.