diff --git a/codec.go b/codec.go
new file mode 100644
index 0000000..d4eb2db
--- /dev/null
+++ b/codec.go
@@ -0,0 +1,46 @@
+package codec
+
+import (
+	"github.com/nareix/av"
+)
+
+type AudioCodecData struct {
+	CodecType int
+	CodecSampleRate int
+	CodecChannelLayout av.ChannelLayout
+	CodecSampleFormat av.SampleFormat
+}
+
+func (self AudioCodecData) Type() int {
+	return self.CodecType
+}
+
+func (self AudioCodecData) IsAudio() bool {
+	return true
+}
+
+func (self AudioCodecData) IsVideo() bool {
+	return false
+}
+
+func (self AudioCodecData) SampleRate() int {
+	return self.CodecSampleRate
+}
+
+func (self AudioCodecData) ChannelLayout() av.ChannelLayout {
+	return self.CodecChannelLayout
+}
+
+func (self AudioCodecData) SampleFormat() av.SampleFormat {
+	return self.CodecSampleFormat
+}
+
+func NewPCMMulawCodecData() av.AudioCodecData {
+	return AudioCodecData{
+		CodecType: av.PCM_MULAW,
+		CodecSampleFormat: av.S16,
+		CodecChannelLayout: av.CH_MONO,
+		CodecSampleRate: 8000,
+	}
+}
+