Block diagram
The Real-time Transport Protocol (RTP) is a widely used network protocol for transmitting audio or video. It usually works with the RTP Control Protocol (RTCP). The transmission can be based on Transmission Control Protocol (TCP) or User Datagram Protocol (UDP).
This page hosts a formal specification of RTP (Real-time Transport Protocol) using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
meta:
id: rtp_packet
title: RTP (Real-time Transport Protocol)
xref:
justsolve: RTP
rfc:
- 3550
- 3551
wikidata: Q321213
license: Unlicense
endian: be
doc: |
The Real-time Transport Protocol (RTP) is a widely used network
protocol for transmitting audio or video. It usually works with the
RTP Control Protocol (RTCP). The transmission can be based on
Transmission Control Protocol (TCP) or User Datagram Protocol (UDP).
seq:
- id: version
type: b2
- id: has_padding
type: b1
- id: has_extension
type: b1
- id: csrc_count
type: b4
- id: marker
type: b1
- id: payload_type
type: b7
enum: payload_type_enum
- id: sequence_number
type: u2
- id: timestamp
type: u4
- id: ssrc
type: u4
- id: header_extension
type: header_extention
if: has_extension
- id: data
size: _io.size - _io.pos - len_padding
doc: Payload without padding.
- id: padding
size: len_padding
instances:
len_padding_if_exists:
pos: _io.size - 1
type: u1
if: has_padding
doc: |
If padding bit is enabled, last byte of data contains number of
bytes appended to the payload as padding.
len_padding:
value: 'has_padding ? len_padding_if_exists : 0'
doc: Always returns number of padding bytes to in the payload.
types:
header_extention:
seq:
- id: id
type: u2
- id: length
type: u2
enums:
# https://datatracker.ietf.org/doc/html/rfc3551#section-6
payload_type_enum:
0: pcmu
1: reserved1
2: reserved2
3: gsm
4: g723
5: dvi4_1
6: dvi4_2
7: lpc
8: pcma
9: g722
10: l16_1
11: l16_2
12: qcelp
13: cn
14: mpa
15: g728
16: dvi4_3
17: dvi4_4
18: g729
19: reserved19
20: unassigned20
21: unassigned21
22: unassigned22
23: unassigned23
24: unassigned24
25: celb
26: jpeg
27: unassigned27
28: nv
29: unassigned29
30: unassigned30
31: h261
32: mpv
33: mp2t
34: h263
96: mpeg_ps