main.go

// +build windows
package main

import (
	"bytes"
	"context"
	"encoding/binary"
	"flag"
	"fmt"
	"io/ioutil"
	"log"
	"math"
	"os"
	"os/signal"
	"strings"
	"sync"
	"time"
	"unsafe"

	"github.com/go-ole/go-ole"
	"github.com/moutend/go-wav"
	"github.com/moutend/go-wca"
)

var version = "latest"
var revision = "latest"
var wg sync.WaitGroup
var inputChan chan float64
var latency uint32 = 200 // millisecond

type FilenameFlag struct {
	Value string
}

func (f *FilenameFlag) Set(value string) (err error) {
	if !strings.HasSuffix(value, ".wav") {
		err = fmt.Errorf("specify WAVE audio file (*.wav)")
		return
	}
	f.Value = value
	return
}

func (f *FilenameFlag) String() string {
	return f.Value
}

func main() {
	var err error
	if err = run(os.Args); err != nil {
		log.Fatal(err)
	}
	fmt.Println("Successfully done")
}

func run(args []string) (err error) {
	var filenameFlag FilenameFlag
	var versionFlag bool
	var audio = &wav.File{}
	var file []byte

	f := flag.NewFlagSet(args[0], flag.ExitOnError)
	f.Var(&filenameFlag, "input", "Specify WAVE format audio (e.g. music.wav)")
	f.Var(&filenameFlag, "i", "Alias of --input")
	f.BoolVar(&versionFlag, "version", false, "Show version")
	f.Parse(args[1:])

	if versionFlag {
		fmt.Printf("%s-%s\n", version, revision)
		return
	}
	if filenameFlag.Value == "" {
		return
	}
	if file, err = ioutil.ReadFile(filenameFlag.Value); err != nil {
		return
	}
	if err = wav.Unmarshal(file, audio); err != nil {
		return
	}

	errChan := make(chan error, 1)
	signalChan := make(chan os.Signal, 1)
	signal.Notify(signalChan, os.Interrupt)
	ctx, cancel := context.WithCancel(context.Background())

	fs := audio.Float64s()
	fmt.Println("fs:", len(fs))
	inputChan = make(chan float64, len(fs))
	for _, v := range fs {
		inputChan <- v
	}
	close(inputChan)

	wg.Add(1)
	go func() {
		if err = renderSharedTimerDriven(ctx, audio); err != nil {
			errChan <- err
		}
		wg.Done()
	}()
	go func() {
		select {
		case err = <-errChan:
		case <-signalChan:
			fmt.Println("Interrupted by SIGINT")
			cancel()
		}
	}()
	wg.Wait()
	return
}

func renderSharedTimerDriven(ctx context.Context, audio *wav.File) (err error) {
	if err = ole.CoInitializeEx(0, ole.COINIT_APARTMENTTHREADED); err != nil {
		return
	}
	defer ole.CoUninitialize()

	var de *wca.IMMDeviceEnumerator
	if err = wca.CoCreateInstance(wca.CLSID_MMDeviceEnumerator, 0, wca.CLSCTX_ALL, wca.IID_IMMDeviceEnumerator, &de); err != nil {
		return
	}
	defer de.Release()

	var mmd *wca.IMMDevice
	if err = de.GetDefaultAudioEndpoint(wca.ERender, wca.EConsole, &mmd); err != nil {
		return
	}
	defer mmd.Release()

	var ps *wca.IPropertyStore
	if err = mmd.OpenPropertyStore(wca.STGM_READ, &ps); err != nil {
		return
	}
	defer ps.Release()

	var pv wca.PROPVARIANT
	if err = ps.GetValue(&wca.PKEY_Device_FriendlyName, &pv); err != nil {
		return
	}
	fmt.Printf("Rendering audio to: %s\n", pv.String())

	var ac *wca.IAudioClient
	if err = mmd.Activate(wca.IID_IAudioClient, wca.CLSCTX_ALL, nil, &ac); err != nil {
		return
	}
	defer ac.Release()

	var wfx *wca.WAVEFORMATEX
	if err = ac.GetMixFormat(&wfx); err != nil {
		return
	}
	defer ole.CoTaskMemFree(uintptr(unsafe.Pointer(wfx)))

	if wfx.WFormatTag != wca.WAVE_FORMAT_PCM {
		wfx.WFormatTag = 1
		wfx.NSamplesPerSec = uint32(audio.SamplesPerSec())
		wfx.WBitsPerSample = uint16(audio.BitsPerSample())
		wfx.NChannels = uint16(audio.Channels())
		wfx.NBlockAlign = uint16(audio.BlockAlign())
		wfx.NAvgBytesPerSec = uint32(audio.AvgBytesPerSec())
		wfx.CbSize = 0
	}

	fmt.Println("--------")
	fmt.Printf("Format: PCM %d bit signed integer\n", wfx.WBitsPerSample)
	fmt.Printf("Rate: %d Hz\n", wfx.NSamplesPerSec)
	fmt.Printf("Channels: %d\n", wfx.NChannels)
	fmt.Println("--------")

	var defaultPeriod int64
	var minimumPeriod int64
	var renderingPeriod time.Duration
	if err = ac.GetDevicePeriod(&defaultPeriod, &minimumPeriod); err != nil {
		return
	}
	renderingPeriod = time.Duration(int(defaultPeriod) * 100)
	fmt.Printf("Default rendering period: %d ms\n", renderingPeriod/time.Millisecond)

	if err = ac.Initialize(wca.AUDCLNT_SHAREMODE_SHARED, 0, latency*10000, 0, wfx, nil); err != nil {
		return
	}

	var bufferFrameSize uint32
	if err = ac.GetBufferSize(&bufferFrameSize); err != nil {
		return
	}
	fmt.Printf("Allocated buffer size: %d\n", bufferFrameSize)

	var arc *wca.IAudioRenderClient
	if err = ac.GetService(wca.IID_IAudioRenderClient, &arc); err != nil {
		return
	}
	defer arc.Release()

	if err = ac.Start(); err != nil {
		return
	}
	fmt.Println("Start rendering audio with shared-timer-driven mode")
	fmt.Println("Press Ctrl-C to stop rendering")

	time.Sleep(renderingPeriod)

	var data *byte
	var padding uint32
	var availableFrameSize uint32
	var b *byte
	var isPlaying bool = true

	scale := math.Pow(2.0, float64(wfx.WBitsPerSample)-1.0)
	fmt.Println("scale", scale)
	for {
		if !isPlaying {
			break
		}
		select {
		case <-ctx.Done():
			isPlaying = false
			break
		default:
			if err = ac.GetCurrentPadding(&padding); err != nil {
				return
			}
			availableFrameSize = bufferFrameSize - padding
			if availableFrameSize == 0 {
				continue
			}
			if err = arc.GetBuffer(availableFrameSize, &data); err != nil {
				return
			}

			start := unsafe.Pointer(data)
			lim := int(availableFrameSize) * int(wfx.NBlockAlign)
			samples := int(availableFrameSize) * int(wfx.NChannels)
			ds := make([]byte, lim)
			var f float64

			for i := 0; i < samples; i++ {
				f, isPlaying = <-inputChan
				v := int16(scale * f)
				buf := new(bytes.Buffer)
				binary.Write(buf, binary.LittleEndian, v)
				bs := buf.Bytes()
				ds[i*2] = bs[0]
				ds[i*2+1] = bs[1]
			}
			for n := 0; n < lim; n++ {
				b = (*byte)(unsafe.Pointer(uintptr(start) + uintptr(n)))
				*b = ds[n]
			}
			if err = arc.ReleaseBuffer(availableFrameSize, 0); err != nil {
				return
			}
			time.Sleep(renderingPeriod)
		}
	}

	time.Sleep(time.Duration(latency) * time.Millisecond)
	if err = ac.Stop(); err != nil {
		return
	}
	fmt.Println("Stop rendering loopback audio")
	return
}