A simple audio engine for Go with an SDL2 back-end and others to come eventually.
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package sdl
import (
"github.com/veandco/go-sdl2/mix"
"github.com/veandco/go-sdl2/sdl"
)
// Track is a music or sound effect file.
type Track struct {
isMusic bool // false = is sound effect
// If isMusic
mus *mix.Music
// Sound effect
wav *mix.Chunk
channel int
}
// LoadMusic loads a music file from disk.
func (e *Engine) LoadMusic(filename string) (Track, error) {
mus, err := mix.LoadMUS(filename)
return Track{
isMusic: true,
mus: mus,
}, err
}
// LoadMusicBin loads a music file from bytes data.
func (e *Engine) LoadMusicBin(data []byte) (Track, error) {
// Create an SDL RWOps from the binary.
rw, err := sdl.RWFromMem(data)
if err != nil {
return Track{}, err
}
mus, err := mix.LoadMUSRW(rw, 0)
return Track{
isMusic: true,
mus: mus,
}, err
}
// LoadSound loads a wave file from disk.
func (e *Engine) LoadSound(filename string) (Track, error) {
wav, err := mix.LoadWAV(filename)
return Track{
isMusic: false,
wav: wav,
channel: -1,
}, err
}
// LoadSoundBin loads a wave file from bytes data.
func (e *Engine) LoadSoundBin(data []byte) (Track, error) {
// Create an SDL RWOps from the binary.
rw, err := sdl.RWFromMem(data)
if err != nil {
return Track{}, err
}
wav, err := mix.LoadWAVRW(rw, false)
return Track{
isMusic: false,
wav: wav,
channel: -1,
}, err
}
// Play the track.
func (t *Track) Play(loops int) error {
if t.isMusic {
return t.mus.Play(loops)
}
// Normalize the `loops` value for sound effects to work around
// a quirk in the SDL mixer between Music and Sound behaviors:
//
// For music:
// loops=0 plays it one time
// loops=1 plays it one time
// loops=2 plays it twice
// For sounds:
// loops=0 plays it one time
// loops=1 plays it twice!
// loops=2 plays it three times!
//
// For both, a loops of -1 plays it on an infinite loop. So to make
// the API consistent on our end, subtract 1 from a Sound loop only
// when the given value is >= 1 itself.
if loops > 0 {
loops--
}
channel, err := t.wav.Play(-1, loops)
t.channel = channel
return err
}
// Pause the track.
func (t Track) Pause() error {
if t.isMusic {
mix.PauseMusic()
return nil
}
mix.Pause(t.channel)
return nil
}
// Stop the track.
func (t Track) Stop() error {
if t.isMusic {
mix.HaltMusic()
return nil
}
mix.HaltChannel(t.channel)
return nil
}
// Destroy the track.
func (t Track) Destroy() error {
if t.isMusic {
t.mus.Free()
return nil
}
t.wav.Free()
return nil
}