Add Channels and Info methods on decoder

stream.go

@@ -115,6 +115,59 @@ func (s *Stream) Init(read io.Reader) error {
 	return nil
 }
 
+const ChannelCountMax = int(C.OPUS_CHANNEL_COUNT_MAX)
+
+// Information a mapped OpusHead struct, see https://opus-codec.org/docs/opusfile_api-0.5/structOpusHead.html
+type Information struct {
+	Version         int
+	ChannelCount    int
+	PreSkip         uint
+	InputSampleRate uint
+	OutputGain      int
+	MappingFamily   int
+	StreamCount     int
+	CoupledCount    int
+	Mapping         [ChannelCountMax]uint8
+}
+
+//Info Returns the information of the current link
+func (s *Stream) Info() *Information {
+	if s.oggfile == nil {
+		return nil
+	}
+
+	head := C.op_head(s.oggfile, C.int(-1))
+
+	if head == nil {
+		return nil
+	}
+
+	info := &Information{
+		Version:         int(head.version),
+		ChannelCount:    int(head.channel_count),
+		PreSkip:         uint(head.pre_skip),
+		InputSampleRate: uint(head.input_sample_rate),
+		OutputGain:      int(head.output_gain),
+		MappingFamily:   int(head.mapping_family),
+		StreamCount:     int(head.stream_count),
+		CoupledCount:    int(head.coupled_count),
+	}
+
+	copy(info.Mapping[:], unsafe.Slice((*uint8)(&head.mapping[0]), ChannelCountMax))
+
+	return info
+
+}
+
+//Channels Returns the channel count of the current link
+func (s *Stream) Channels() int {
+	if s.oggfile == nil {
+		return 0
+	}
+
+	return int(C.op_channel_count(s.oggfile, C.int(-1)))
+}
+
 // Read a chunk of raw opus data from the stream and decode it. Returns the
 // number of decoded samples per channel. This means that a dual channel
 // (stereo) feed will have twice as many samples as the value returned.