.go

package main

import (
	"math"
	"time"

	"github.com/faiface/pixel/audio"
	"github.com/faiface/pixel/audio/speaker"
)

func sin(freq, volume float64) audio.Streamer {
	t := 0.0
	dt := 1.0 / audio.SampleRate
	return audio.StreamerFunc(func(samples [][2]float64) (n int, ok bool) {
		for i := range samples {
			val := math.Sin(math.Pi*freq*t) * volume
			samples[i][0] = val
			samples[i][1] = val
			t += dt
		}
		return len(samples), true
	})
}

func main() {
	speaker.Init(time.Second / 15)

	speaker.Play(audio.Mix(
		audio.Seq(
			audio.Take(time.Second*3, sin(440, 0.3)),
			audio.Take(time.Second*3, sin(550, 0.3)),
			audio.Take(time.Second*3, sin(880, 0.3)),
		),
		audio.Seq(
			audio.Take(time.Second, sin(440, 0.1)),
			audio.Take(time.Second, sin(550, 0.1)),
			audio.Take(time.Second, sin(880, 0.1)),
			audio.Take(time.Second, sin(440, 0.1)),
			audio.Take(time.Second, sin(550, 0.1)),
			audio.Take(time.Second, sin(880, 0.1)),
			audio.Take(time.Second, sin(440, 0.1)),
			audio.Take(time.Second, sin(550, 0.1)),
			audio.Take(time.Second, sin(880, 0.1)),
		),
	))

	time.Sleep(time.Second * 10)
}