protocol/rtsp/rtcp: start writing rtcp structs

Wrote structure for Header, ReceiverReport, ReportBlocks, Chunks and Source Description. Wrote Bytes function for ReceiverReport.

protocol/rtsp/rtcp/rtcp.go

@@ -1,10 +1,98 @@
 package rtcp
 
 import (
+	"encoding/binary"
 	"io"
 	"io/ioutil"
 )
 
+const (
+	reportBlockSize = 6
+)
+
+type Header struct {
+	Version     uint8  // RTCP version.
+	Padding     bool   // Padding indicator.
+	ReportCount uint8  // Number of reports contained.
+	Type        uint8  // Type of RTCP packet.
+	SSRC        uint32 // Source identifier.
+}
+
+type ReportBlock struct {
+	SSRC            uint32 // Source identifier.
+	FractionLost    uint8  // Fraction of packets lost.
+	PacketsLost     uint32 // Cumulative number of packets lost.
+	HighestSequence uint32 // Extended highest sequence number received.
+	Jitter          uint32 // Interarrival jitter.
+	LSR             uint32 // Last sender report timestamp.
+	DLSR            uint32 // Delay since last sender report.
+}
+
+type ReceiverReport struct {
+	Header
+
+	Blocks     []ReportBlock
+	Extensions [][4]byte
+}
+
+func (r *ReceiverReport) Bytes() []byte {
+	l := 8 + 4*reportBlockSize*len(r.Blocks) + 4*len(r.Extensions)
+	buf := make([]byte, l)
+
+	buf[0] = r.Version<<6 | asByte(r.Padding)<<5 | 0x1f&r.ReportCount
+	buf[1] = r.Type
+
+	l = 1 + reportBlockSize*len(r.Blocks) + len(r.Extensions)
+	binary.BigEndian.PutUint16(buf[2:], uint16(l))
+
+	buf[4] = byte(r.SSRC)
+
+	idx := 8
+	for _, b := range r.Blocks {
+		binary.BigEndian.PutUint32(buf[idx:], b.SSRC)
+		idx += 4
+		binary.BigEndian.PutUint32(buf[idx:], b.PacketsLost)
+		buf[idx] = b.FractionLost
+		idx += 4
+		binary.BigEndian.PutUint32(buf[idx:], b.HighestSequence)
+		idx += 4
+		binary.BigEndian.PutUint32(buf[idx:], b.Jitter)
+		idx += 4
+		binary.BigEndian.PutUint32(buf[idx:], b.LSR)
+		idx += 4
+		binary.BigEndian.PutUint32(buf[idx:], b.DLSR)
+		idx += 4
+	}
+
+	for _, e := range r.Extensions {
+		binary.BigEndian.PutUint32(buf[idx:], binary.BigEndian.Uint32(e[:]))
+		idx += 4
+	}
+
+	return buf
+}
+
+type Chunk struct {
+	Type uint8
+	Test []byte
+}
+
+type SourceDescription struct {
+	Header
+
+	Chunks []Chunk
+}
+
+func (d *SourceDescription) Bytes() []byte {
+
+}
+
+func asByte(b bool) byte {
+	if b {
+		return 0x01
+	}
+	return 0x00
+}
 func Handle(r io.Reader) error {
 	io.Copy(ioutil.Discard, r)
 	return nil