dndmusicbot/ffmpeg/pcm.go

package ffmpeg

import (
	"fmt"
	"io"
	"log"
	"math"
	"time"

	"github.com/faiface/beep"
)

type PCM struct {
	f      beep.Format
	pos    int
	sr     int
	c      int
	Player *FFmpeg
	Uri    string
	Base   float64
	Volume float64
}

func NewPCM(uri string, sampleRate int, channels int) (*PCM, error) {
	out := new(PCM)

	ff, err := NewFFmpeg(uri, sampleRate, channels)
	if err != nil {
		return nil, err
	}

	out.Player = ff
	format := beep.Format{
		SampleRate:  beep.SampleRate(sampleRate),
		NumChannels: channels,
		Precision:   2,
	}

	return &PCM{
		format,
		0,
		sampleRate,
		channels,
		ff,
		uri,
		2,
		-2,
	}, nil
}

func (d *PCM) Stream(samples [][2]float64) (n int, ok bool) {
	tmp := make([]byte, d.c+2)

	for i := range samples {
		dn, err := d.Player.Out.Read(tmp)
		if dn == len(tmp) {
			samples[i], _ = d.f.DecodeSigned(tmp)
			d.pos += dn
			ok = true
		}
		if err == io.EOF {
			ok = false
			break
		}
		if err != nil {
			log.Println(err)
			ok = false
			break
		}
		gain := math.Pow(d.Base, d.Volume)
		samples[i][0] *= gain
		samples[i][1] *= gain
	}

	return len(samples), ok
}

func (d PCM) Err() error {
	return nil
}

func (d PCM) Position() int {
	t, _ := time.ParseDuration(fmt.Sprintf("%ds", ((d.pos / d.sr) / 4)))
	return int(t.Milliseconds())
}

func (d PCM) Close() error {
	d.Player.Close()
	return nil
}

func (d PCM) Len() int {
	return int(d.Player.Len.Milliseconds())
}

func (d PCM) Seek(p int) error {
	return nil
}