av/stream/flc: using my own writeSeeker implementation - working

stream/flac/decode.go

@@ -4,16 +4,55 @@ import (
 	"bytes"
 	"errors"
 	"io"
-	"io/ioutil"
 
 	"github.com/go-audio/audio"
 	"github.com/go-audio/wav"
 	"github.com/mewkiz/flac"
-	"github.com/orcaman/writerseeker"
 )
 
 const wavAudioFormat = 1
 
+type WriterSeeker struct {
+	buf []byte
+	pos int
+}
+
+func (ws *WriterSeeker) Bytes() []byte {
+	return ws.buf
+}
+
+func (m *WriterSeeker) Write(p []byte) (n int, err error) {
+	minCap := m.pos + len(p)
+	if minCap > cap(m.buf) { // Make sure buf has enough capacity:
+		buf2 := make([]byte, len(m.buf), minCap+len(p)) // add some extra
+		copy(buf2, m.buf)
+		m.buf = buf2
+	}
+	if minCap > len(m.buf) {
+		m.buf = m.buf[:minCap]
+	}
+	copy(m.buf[m.pos:], p)
+	m.pos += len(p)
+	return len(p), nil
+}
+
+func (m *WriterSeeker) Seek(offset int64, whence int) (int64, error) {
+	newPos, offs := 0, int(offset)
+	switch whence {
+	case io.SeekStart:
+		newPos = offs
+	case io.SeekCurrent:
+		newPos = m.pos + offs
+	case io.SeekEnd:
+		newPos = len(m.buf) + offs
+	}
+	if newPos < 0 {
+		return 0, errors.New("negative result pos")
+	}
+	m.pos = newPos
+	return int64(newPos), nil
+}
+
 // Decode takes a slice of flac and decodes to wav
 func Decode(buf []byte) ([]byte, error) {
 	r := bytes.NewReader(buf)
@@ -21,7 +60,7 @@ func Decode(buf []byte) ([]byte, error) {
 	if err != nil {
 		return nil, errors.New("Could not parse FLAC")
 	}
-	ws := &writerseeker.WriterSeeker{}
+	ws := &WriterSeeker{}
 	enc := wav.NewEncoder(ws, int(stream.Info.SampleRate), int(stream.Info.BitsPerSample), int(stream.Info.NChannels), wavAudioFormat)
 	defer enc.Close()
 	var data []int
@@ -54,9 +93,6 @@ func Decode(buf []byte) ([]byte, error) {
 			return nil, err
 		}
 	}
-	d, err := ioutil.ReadAll(ws.Reader())
-	if err != nil {
-		return nil, err
-	}
-	return d, nil
+
+	return ws.Bytes(), nil
 }