move subfolders in pkg/

pkg/base/interleavedframe.go

@@ -0,0 +1,137 @@
+package base
+
+import (
+	"bufio"
+	"encoding/binary"
+	"fmt"
+	"io"
+)
+
+const (
+	interleavedFrameMagicByte = 0x24
+)
+
+// ReadInterleavedFrameOrRequest reads an InterleavedFrame or a Response.
+func ReadInterleavedFrameOrRequest(frame *InterleavedFrame, req *Request, br *bufio.Reader) (interface{}, error) {
+	b, err := br.ReadByte()
+	if err != nil {
+		return nil, err
+	}
+	br.UnreadByte()
+
+	if b == interleavedFrameMagicByte {
+		err := frame.Read(br)
+		if err != nil {
+			return nil, err
+		}
+		return frame, err
+	}
+
+	err = req.Read(br)
+	if err != nil {
+		return nil, err
+	}
+	return req, nil
+}
+
+// ReadInterleavedFrameOrResponse reads an InterleavedFrame or a Response.
+func ReadInterleavedFrameOrResponse(frame *InterleavedFrame, res *Response, br *bufio.Reader) (interface{}, error) {
+	b, err := br.ReadByte()
+	if err != nil {
+		return nil, err
+	}
+	br.UnreadByte()
+
+	if b == interleavedFrameMagicByte {
+		err := frame.Read(br)
+		if err != nil {
+			return nil, err
+		}
+		return frame, err
+	}
+
+	err = res.Read(br)
+	if err != nil {
+		return nil, err
+	}
+	return res, nil
+}
+
+// InterleavedFrame is an interleaved frame, and allows to transfer binary data
+// within RTSP/TCP connections. It is used to send and receive RTP and RTCP packets with TCP.
+type InterleavedFrame struct {
+	// track id
+	TrackId int
+
+	// stream type
+	StreamType StreamType
+
+	// frame content
+	Content []byte
+}
+
+// Read reads an interleaved frame.
+func (f *InterleavedFrame) Read(br *bufio.Reader) error {
+	var header [4]byte
+	_, err := io.ReadFull(br, header[:])
+	if err != nil {
+		return err
+	}
+
+	if header[0] != interleavedFrameMagicByte {
+		return fmt.Errorf("wrong magic byte (0x%.2x)", header[0])
+	}
+
+	framelen := int(binary.BigEndian.Uint16(header[2:]))
+	if framelen > len(f.Content) {
+		return fmt.Errorf("frame length greater than maximum allowed (%d vs %d)",
+			framelen, len(f.Content))
+	}
+
+	// convert channel into TrackId and StreamType
+	channel := header[1]
+	f.TrackId, f.StreamType = func() (int, StreamType) {
+		if (channel % 2) == 0 {
+			return int(channel / 2), StreamTypeRtp
+		}
+		return int((channel - 1) / 2), StreamTypeRtcp
+	}()
+
+	f.Content = f.Content[:framelen]
+
+	_, err = io.ReadFull(br, f.Content)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+// Write writes an InterleavedFrame into a buffered writer.
+func (f InterleavedFrame) Write(bw *bufio.Writer) error {
+	// convert TrackId and StreamType into channel
+	channel := func() uint8 {
+		if f.StreamType == StreamTypeRtp {
+			return uint8(f.TrackId * 2)
+		}
+		return uint8((f.TrackId * 2) + 1)
+	}()
+
+	_, err := bw.Write([]byte{0x24, channel})
+	if err != nil {
+		return err
+	}
+
+	buf := make([]byte, 2)
+	binary.BigEndian.PutUint16(buf, uint16(len(f.Content)))
+	_, err = bw.Write(buf)
+	if err != nil {
+		return err
+	}
+
+	_, err = bw.Write(f.Content)
+	if err != nil {
+		return err
+	}
+
+	return bw.Flush()
+}