support voice message (#31)

pkg/util/silk/silk.go

@@ -0,0 +1,36 @@
+package silk
+
+import (
+	"fmt"
+
+	"github.com/sjzar/go-lame"
+	"github.com/sjzar/go-silk"
+)
+
+func Silk2MP3(data []byte) ([]byte, error) {
+
+	sd := silk.SilkInit()
+	defer sd.Close()
+
+	pcmdata := sd.Decode(data)
+	if len(pcmdata) == 0 {
+		return nil, fmt.Errorf("silk decode failed")
+	}
+
+	le := lame.Init()
+	defer le.Close()
+
+	le.SetInSamplerate(24000)
+	le.SetOutSamplerate(24000)
+	le.SetNumChannels(1)
+	le.SetBitrate(16)
+	// IMPORTANT!
+	le.InitParams()
+
+	mp3data := le.Encode(pcmdata)
+	if len(mp3data) == 0 {
+		return nil, fmt.Errorf("mp3 encode failed")
+	}
+
+	return mp3data, nil
+}