Files
gortsplib/interleaved-frame.go
2020-07-12 22:45:28 +02:00

96 lines
2.0 KiB
Go

package gortsplib
import (
"bufio"
"encoding/binary"
"fmt"
"io"
)
const (
_INTERLEAVED_FRAME_MAGIC = 0x24
)
// StreamType is the type of a stream.
type StreamType int
const (
// StreamTypeRtp is a stream that contains RTP packets
StreamTypeRtp StreamType = iota
// StreamTypeRtcp is a stream that contains RTCP packets
StreamTypeRtcp
)
// ConvChannelToTrackIdAndStreamType converts a channel into a track id and a streamType.
func ConvChannelToTrackIdAndStreamType(channel uint8) (int, StreamType) {
if (channel % 2) == 0 {
return int(channel / 2), StreamTypeRtp
}
return int((channel - 1) / 2), StreamTypeRtcp
}
// ConvTrackIdAndStreamTypeToChannel converts a track id and a streamType into a channel.
func ConvTrackIdAndStreamTypeToChannel(trackId int, StreamType StreamType) uint8 {
if StreamType == StreamTypeRtp {
return uint8(trackId * 2)
}
return uint8((trackId * 2) + 1)
}
// InterleavedFrame is a structure that allows to send and receive binary data
// within RTSP connections. It is usually deployed to send RTP and RTCP packets via TCP.
type InterleavedFrame struct {
Channel uint8
Content []byte
}
func (f *InterleavedFrame) read(r io.Reader) error {
var header [4]byte
_, err := io.ReadFull(r, header[:])
if err != nil {
return err
}
if header[0] != _INTERLEAVED_FRAME_MAGIC {
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))
}
f.Channel = header[1]
f.Content = f.Content[:framelen]
_, err = io.ReadFull(r, f.Content)
if err != nil {
return err
}
return nil
}
func (f *InterleavedFrame) write(bw *bufio.Writer) error {
_, err := bw.Write([]byte{0x24, f.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()
}