/
audio.go
245 lines (204 loc) · 4.51 KB
/
audio.go
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package main
import (
"fmt"
"github.com/gordonklaus/portaudio"
"gopkg.in/hraban/opus.v2"
)
const (
sampleRate = 16000
readBufferSize = 1600
writeBufferSize = 1600
audioChannels = 1
opusFrameMs = 20
opusFrameSamples = sampleRate / 1000 * opusFrameMs
opusFrameBufferSize = 160
)
func packFrames(frames [][]byte) []byte {
size := 2 * len(frames)
for _, frame := range frames {
size += len(frame)
}
data := make([]byte, size)
offset := 0
for _, frame := range frames {
size := len(frame)
data[offset] = byte(size >> 8)
data[offset+1] = byte(size)
copy(data[offset+2:], frame)
offset += size + 2
}
return data
}
func unpackFrames(data []byte) ([][]byte, error) {
offset := 0
frames := [][]byte{}
for offset < len(data) {
size := (int(data[offset]) << 8) + int(data[offset+1])
if size > len(data)-offset-2 {
return nil, fmt.Errorf("Unpack error")
}
frames = append(frames, data[offset+2:offset+2+size])
offset += size + 2
}
return frames, nil
}
func opusCompress(samples []int16) ([]byte, error) {
enc, err := opus.NewEncoder(sampleRate, audioChannels, opus.AppVoIP)
if err != nil {
return nil, err
}
nFrames := len(samples) / opusFrameSamples
frames := make([][]byte, nFrames)
for i := range frames {
offset := i * opusFrameSamples
pcm := samples[offset : offset+opusFrameSamples]
frames[i] = make([]byte, opusFrameBufferSize)
n, err := enc.Encode(pcm, frames[i])
if err != nil {
return nil, err
}
frames[i] = frames[i][:n]
}
return packFrames(frames), nil
}
func opusDecompress(data []byte) ([]int16, error) {
frames, err := unpackFrames(data)
if err != nil {
return nil, err
}
dec, err := opus.NewDecoder(sampleRate, audioChannels)
if err != nil {
return nil, err
}
nFrames := len(frames)
samples := make([]int16, nFrames*opusFrameSamples)
for i := range frames {
offset := i * opusFrameSamples
pcm := samples[offset : offset+opusFrameSamples]
n, err := dec.Decode(frames[i], pcm)
if err != nil {
return nil, err
}
if n != opusFrameSamples {
return nil, fmt.Errorf("Wrong number of samples: %d != %d", n, opusFrameSamples)
}
}
return samples, nil
}
type Microphone struct {
stream *portaudio.Stream
errChan chan error
stopChan chan bool
doneChan chan bool
contentChan chan []byte
readBuffer []int16
read []int16
}
func NewMicrophone() (*Microphone, error) {
m := &Microphone{
errChan: make(chan error, 1),
stopChan: make(chan bool, 1),
doneChan: make(chan bool, 1),
readBuffer: make([]int16, readBufferSize),
read: []int16{},
}
var err error
m.stream, err = portaudio.OpenDefaultStream(1, 0, sampleRate, readBufferSize, m.readBuffer)
if err != nil {
return nil, err
}
return m, nil
}
func (m *Microphone) setContentChan(content chan []byte) {
m.contentChan = content
}
func (m *Microphone) readStream() {
defer func() {
m.doneChan <- true
}()
for {
select {
case <-m.stopChan:
m.stream.Stop()
return
default:
err := m.stream.Read()
if err != nil {
m.errChan <- err
return
}
opus, err := opusCompress(m.readBuffer)
if err != nil {
m.errChan <- err
return
}
m.contentChan <- opus
//m.read = append(m.read, m.readBuffer...)
}
}
}
func (m *Microphone) Start() error {
err := m.stream.Start()
if err != nil {
return err
}
go m.readStream()
return nil
}
func (m *Microphone) Stop() ([]byte, error) {
select {
case err := <-m.errChan:
return nil, err
default:
}
m.stopChan <- true
<-m.doneChan
/*opus, err := opusCompress(m.read)
if err != nil {
return nil, err
}*/
m.read = m.read[:0]
return nil, nil
}
func (m *Microphone) Close() error {
return m.stream.Close()
}
type Speaker struct {
writeBuffer []int16
stream *portaudio.Stream
}
func NewSpeaker() (*Speaker, error) {
s := &Speaker{
writeBuffer: make([]int16, writeBufferSize),
}
var err error
s.stream, err = portaudio.OpenDefaultStream(0, 1, sampleRate, writeBufferSize, s.writeBuffer)
if err != nil {
return nil, err
}
err = s.stream.Start()
if err != nil {
return nil, err
}
return s, nil
}
func (s *Speaker) Play(opus []byte) error {
clip, err := opusDecompress(opus)
if err != nil {
return err
}
buffer := make([]int16, len(clip))
copy(buffer, clip)
for len(buffer) > 0 {
if len(s.writeBuffer) > len(buffer) {
s.writeBuffer = s.writeBuffer[:len(buffer)]
}
copy(s.writeBuffer, buffer)
buffer = buffer[len(s.writeBuffer):]
err := s.stream.Write()
if err != nil {
return err
}
}
return nil
}