portaudio-go-mp3.go

package main

import (
        "bytes"
        "encoding/binary"
        "io"
        "os"
        "os/signal"

        "github.com/gordonklaus/portaudio"
        "github.com/hajimehoshi/go-mp3"
)

func main() {
        sig := make(chan os.Signal, 1)
        signal.Notify(sig, os.Interrupt, os.Kill)

        fileName := "sample.mp3"
        f, err := os.Open(fileName)
	chk(err)
        defer f.Close()

        decoder, err := mp3.NewDecoder(f)
        chk(err)

        // get audio format information
        rate := decoder.SampleRate()
        channels := 2

        portaudio.Initialize()
        defer portaudio.Terminate()
	
	bufsize := 8192
        out := make([]int16, bufsize)
	stream, err := portaudio.OpenDefaultStream(0, channels, float64(rate), len(out), &out)
        chk(err)
        defer stream.Close()

        chk(stream.Start())
        defer stream.Stop()

        audio := make([]byte, 2*len(out))
        for {
                _, err = decoder.Read(audio)
                if err == io.EOF {
                        break
                }
                chk(err)
                chk(binary.Read(bytes.NewReader(audio), binary.LittleEndian, out))
                chk(stream.Write())
                select {
                case <-sig:
                        return
                default:
                }
        }
}

func chk(err error) {
        if err != nil {
                panic(err)
        }
}