main.go

package main

import (
	"fmt"
	"math"

	"github.com/jfreymuth/pulse"
)

func main() {
	c, err := pulse.NewClient()
	if err != nil {
		fmt.Println(err)
		return
	}
	defer c.Close()

	stream, err := c.NewPlayback(pulse.Float32Reader(synth), pulse.PlaybackLatency(.1))
	if err != nil {
		fmt.Println(err)
		return
	}

	stream.Start()
	stream.Drain()
	fmt.Println("Underflow:", stream.Underflow())
	if stream.Error() != nil {
		fmt.Println("Error:", stream.Error())
	}
	stream.Close()
}

var t, phase float32

func synth(out []float32) (int, error) {
	for i := range out {
		if t > 4 {
			return i, pulse.EndOfData
		}
		x := float32(math.Sin(2 * math.Pi * float64(phase)))
		out[i] = x * 0.1
		f := [...]float32{440, 550, 660, 880}[int(2*t)&3]
		phase += f / 44100
		if phase >= 1 {
			phase--
		}
		t += 1. / 44100
	}
	return len(out), nil
}