The Real-time Transport Protocol (RTP) specifies a general-purpose data format and network protocol for transmitting digital media streams on Internet Protocol (IP) networks. The details of media encoding, such as signal sampling rate, frame size and timing, are specified in an RTP payload format. The format parameters of the RTP payload are typically communicated between transmission endpoints with the Session Description Protocol (SDP), but other protocols, such as the Extensible Messaging and Presence Protocol (XMPP) may be used.

Payload types and formats

The technical parameters of payload formats for audio and video streams are standardised. The standard also describes the process of registering new payload types with IANA.

  • RFC – "RTP: A Transport Protocol for Real-Time Applications," Internet Standard 64.
  • RFC – "RTP Profile for Audio and Video Conferences with Minimal Control," Internet Standard 65.
  • RFC – "RTP Control Protocol Extended Reports (RTCP XR)," Proposed Standard.
  • RFC – "Media Type Registration of Payload Formats in the RTP Profile for Audio and Video Conferences," Proposed Standard.

Text messaging payload types

Payload formats and types for text messaging are defined in the following specifications:

  • RFC – "RTP Payload for Text Conversation," Proposed Standard. Obsoletes RFC . Updated by RFC .
  • RFC – "RTP-Mixer Formatting of Multiparty Real-Time Text," Proposed Standard.

MIDI payload types

Payload formats and types for MIDI are defined in the following specifications:

Audio and video payload types

Payload formats and types for audio and video are defined in the following specifications:

  • RFC – "RTP Payload Format of Sun's CellB Video Encoding," Proposed Standard.
  • RFC – "RTP Payload Format for H.263 Video Streams," Historic.
  • RFC – "RTP Payload for Redundant Audio Data," Proposed Standard.
  • RFC – "RTP Payload Format for MPEG1/MPEG2 Video," Proposed Standard.
  • RFC – "RTP Payload Format for Bundled MPEG," Experimental.
  • RFC – "RTP Payload Format for JPEG-compressed Video," Proposed Standard.
  • RFC – "The Audio/L16 MIME content type," Informational.
  • RFC – "RTP Payload Format for PureVoice(tm) Audio," Proposed Standard.
  • RFC – "RTP Payload Format for 12-bit DAT Audio and 20- and 24-bit Linear Sampled Audio," Proposed Standard.
  • RFC – "Real-time Transport Protocol (RTP) Payload for Comfort Noise (CN)," Proposed Standard.
  • RFC – "RTP Payload Format for Society of Motion Picture and Television Engineers (SMPTE) 292M Video," Informational.
  • RFC – "RTP Payload Format for Transport of MPEG-4 Elementary Streams," Proposed Standard.
  • RFC – "Real-time Transport Protocol (RTP) Payload Format for internet Low Bit Rate Codec (iLBC) Speech," Experimental.
  • RFC – "RTP Payload Format for Uncompressed Video," Proposed Standard.
  • RFC – "RTP Payload Format for AC-3 Audio," Proposed Standard.
  • RFC – "RTP Payload Format for the Extended Adaptive Multi-Rate Wideband (AMR-WB+) Audio Codec," Proposed Standard.
  • RFC – "RTP Payload Format for H.261 Video Streams," Proposed Standard.
  • RFC – "Real-time Transport Protocol (RTP) Payload Format for Enhanced AC-3 (E-AC-3) Audio," Proposed Standard.
  • RFC – "RTP Payload Format for ITU-T Rec. H.263 Video," Proposed Standard.
  • RFC – "RTP Payload for DTMF Digits, Telephony Tones, and Telephony Signals," Proposed Standard.
  • RFC – "RTP Payload Format for the G.729.1 Audio Codec," Proposed Standard.
  • RFC – "Enhancements to RTP Payload Formats for EVRC Family Codecs," Proposed Standard.
  • RFC – "RTP Payload Format and File Storage Format for the Adaptive Multi-Rate (AMR) and Adaptive Multi-Rate Wideband (AMR-WB) Audio Codecs," Proposed Standard.
  • RFC – "RTP Payload Format for the Enhanced Variable Rate Wideband Codec (EVRC-WB) and the Media Subtype Updates for EVRC-B Codec," Proposed Standard.
  • RFC – "RTP Payload Format for Vorbis Encoded Audio," Proposed Standard.
  • RFC – "RTP Payload Format for JPEG 2000 Video Streams," Proposed Standard.
  • RFC – "RTP Payload Format for ITU-T Recommendation G.711.1," Proposed Standard.
  • RFC – "RTP Payload Format for G.719," Proposed Standard.
  • RFC – "RTP Payload Format for the Speex Codec," Proposed Standard.
  • RFC – "RTP Payload Format for ITU-T Recommendation G.722.1," Proposed Standard.
  • RFC – "RTP Payload Format for the Adaptive TRansform Acoustic Coding (ATRAC) Family," Proposed Standard.
  • RFC – "RTP Payload Format for mU-law EMbedded Codec for Low-delay IP Communication (UEMCLIP) Speech Codec," Proposed Standard.
  • RFC – "RTP Payload Format for Global System for Mobile Communications Half Rate (GSM-HR)," Proposed Standard.
  • RFC – "RTP Payload Format for H.264 Video," Proposed Standard.
  • RFC – "RTP Payload Format for Scalable Video Coding," Proposed Standard.
  • RFC – "RTP Payload Format for MPEG-4 Audio/Visual Streams," Proposed Standard.
  • RFC – "RTP Payload Format for DV (IEC 61834) Video," Proposed Standard.
  • RFC – "RTP Payload Format for Standard apt-X and Enhanced apt-X Codecs," Proposed Standard.
  • RFC – "RTP Payload Format for the Opus Speech and Audio Codec," Proposed Standard.
  • RFC – "RTP Payload Format for VP8 Video," Proposed Standard.
  • RFC – "RTP Payload Format for High Efficiency Video Coding (HEVC)," Proposed Standard.
  • RFC – "RTP Payload Format for ISO/IEC 21122 (JPEG XS)," Proposed Standard.
  • RFC – "RTP Payload Format for the Secure Communication Interoperability Protocol (SCIP) Codec," Proposed Standard.
  • RFC – "RTP Payload Format for VP9 Video," Proposed Standard.

Payload identifiers 96–127 are used for payloads defined dynamically during a session. It is recommended to dynamically assign port numbers, although port numbers 5004 and 5005 have been registered for use of the profile when a dynamically assigned port is not required.

Applications should always support PCMU (payload type 0). Previously, DVI4 (payload type 5) was also recommended, but this was removed in 2013.

Payload type (PT)NameTypeNo. of channelsClock rate (Hz)Frame size (byte)Default packet interval (ms)DescriptionReferences
0PCMUaudio18000any20ITU-T G.711 PCM μ-Law audio 64 kbit/sRFC
1reserved (previously FS-1016 CELP)audio18000reserved, previously FS-1016 CELP audio 4.8 kbit/sRFC
2reserved (previously G721 or G726-32)audio18000reserved, previously ITU-T G.721 ADPCM audio 32 kbit/s or ITU-T G.726 audio 32 kbit/sRFC
3GSMaudio180002020European GSM Full Rate audio 13 kbit/s (GSM 06.10)RFC
4G723audio180003030ITU-T G.723.1 audioRFC
5DVI4audio18000any20IMA ADPCM audio 32 kbit/sRFC
6DVI4audio116000any20IMA ADPCM audio 64 kbit/sRFC
7LPCaudio18000any20Experimental Linear Predictive Coding audio 5.6 kbit/sRFC
8PCMAaudio18000any20ITU-T G.711 PCM A-Law audio 64 kbit/sRFC
9G722audio18000any20ITU-T G.722 audio 64 kbit/sRFC
10L16audio244100any20Linear PCM 16-bit Stereo audio 1411.2 kbit/s, uncompressedRFC
11L16audio144100any20Linear PCM 16-bit audio 705.6 kbit/s, uncompressedRFC
12QCELPaudio180002020Qualcomm Code Excited Linear PredictionRFC , RFC
13CNaudio18000Comfort noise. Payload type used with audio codecs that do not support comfort noise as part of the codec itself such as G.711, G.722.1, G.722, G.726, G.727, G.728, GSM 06.10, Siren, and RTAudio.RFC
14MPAaudio1, 2900008–72MPEG-1 or MPEG-2 audio onlyRFC , RFC
15G728audio180002.520ITU-T G.728 audio 16 kbit/sRFC
16DVI4audio111025any20IMA ADPCM audio 44.1 kbit/sRFC
17DVI4audio122050any20IMA ADPCM audio 88.2 kbit/sRFC
18G729audio180001020ITU-T G.729 and G.729a audio 8 kbit/s; Annex B is implied unless the annexb=no parameter is usedRFC , RFC
19reserved (previously CN)audioreserved, previously comfort noiseRFC
25CELLBvideo90000Sun CellB videoRFC
26JPEGvideo90000JPEG videoRFC
28nvvideo90000Xerox PARC's Network Video (nv)RFC
31H261video90000ITU-T H.261 videoRFC
32MPVvideo90000MPEG-1 and MPEG-2 videoRFC
33MP2Taudio/video90000MPEG-2 transport streamRFC
34H263video90000H.263 video, first version (1996)RFC , RFC
72–76reservedreserved because RTCP packet types 200–204 would otherwise be indistinguishable from RTP payload types 72–76 with the marker bit setRFC , RFC
77–95unassignednote that RTCP packet type 207 (XR, Extended Reports) would be indistinguishable from RTP payload types 79 with the marker bit setRFC , RFC
dynamicH263-1998video90000H.263 video, second version (1998)RFC , RFC , RFC
dynamicH263-2000video90000H.263 video, third version (2000)RFC
dynamic (or profile)H264 AVCvideo90000H.264 video (MPEG-4 Part 10)RFC
dynamic (or profile)H264 SVCvideo90000H.264 videoRFC
dynamic (or profile)H265video90000H.265 video (HEVC)RFC
dynamic (or profile)theoravideo90000Theora video
dynamiciLBCaudio1800020, 3020, 30Internet low Bitrate Codec 13.33 or 15.2 kbit/sRFC
dynamicPCMA-WBaudio1160005ITU-T G.711.1 A-lawRFC
dynamicPCMU-WBaudio1160005ITU-T G.711.1 μ-lawRFC
dynamicG718audio32000 (placeholder)20ITU-T G.718
dynamicG719audio(various)4800020ITU-T G.719RFC
dynamicG7221audio16000, 3200020ITU-T G.722.1 and G.722.1 Annex CRFC
dynamicG726-16audio18000any20ITU-T G.726 audio 16 kbit/sRFC
dynamicG726-24audio18000any20ITU-T G.726 audio 24 kbit/sRFC
dynamicG726-32audio18000any20ITU-T G.726 audio 32 kbit/sRFC
dynamicG726-40audio18000any20ITU-T G.726 audio 40 kbit/sRFC
dynamicG729Daudio180001020ITU-T G.729 Annex DRFC
dynamicG729Eaudio180001020ITU-T G.729 Annex ERFC
dynamicG7291audio1600020ITU-T G.729.1RFC
dynamicGSM-EFRaudio180002020ITU-T GSM-EFR (GSM 06.60)RFC
dynamicGSM-HR-08audio1800020ITU-T GSM-HR (GSM 06.20)RFC
dynamic (or profile)AMRaudio(various)800020Adaptive Multi-Rate audioRFC
dynamic (or profile)AMR-WBaudio(various)1600020Adaptive Multi-Rate Wideband audio (ITU-T G.722.2)RFC
dynamic (or profile)AMR-WB+audio1, 2 or omit7200013.3–40Extended Adaptive Multi Rate – WideBand audioRFC
dynamic (or profile)vorbisaudio(various)(various)Vorbis audioRFC
dynamic (or profile)opusaudio1, 2480002.5–6020Opus audioRFC
dynamic (or profile)speexaudio18000, 16000, 3200020Speex audioRFC
dynamicmpa-robustaudio1, 29000024–72Loss-Tolerant MP3 audioRFC
dynamic (or profile)MP4A-LATMaudio90000 or othersMPEG-4 Audio (includes AAC)RFC
dynamic (or profile)MP4V-ESvideo90000 or othersMPEG-4 VisualRFC
dynamic (or profile)mpeg4-genericaudio/video90000 or otherMPEG-4 Elementary StreamsRFC
dynamicVP8video90000VP8 videoRFC
dynamicVP9video90000VP9 videoRFC
dynamicAV1video90000AV1 video
dynamicL8audio(various)(various)any20Linear PCM 8-bit audio with 128 offsetRFC
dynamicDAT12audio(various)(various)any20 (by analogy with L16)IEC 61119 12-bit nonlinear audioRFC
dynamicL16audio(various)(various)any20Linear PCM 16-bit audioRFC , RFC
dynamicL20audio(various)(various)any20 (by analogy with L16)Linear PCM 20-bit audioRFC
dynamicL24audio(various)(various)any20 (by analogy with L16)Linear PCM 24-bit audioRFC
dynamicrawvideo90000Uncompressed VideoRFC
dynamicac3audio(various)32000, 44100, 48000Dolby AC-3 audioRFC
dynamiceac3audio(various)32000, 44100, 48000Enhanced AC-3 audioRFC
dynamict140text1000Text over IPRFC
dynamicEVRC EVRC0 EVRC1audio8000EVRC audioRFC
dynamicEVRCB EVRCB0 EVRCB1audio8000EVRC-B audioRFC
dynamicEVRCWB EVRCWB0 EVRCWB1audio16000EVRC-WB audioRFC
dynamicjpeg2000video90000JPEG 2000 videoRFC
dynamicUEMCLIPaudio8000, 16000UEMCLIP audioRFC
dynamicATRAC3audio44100ATRAC3 audioRFC
dynamicATRAC-Xaudio44100, 48000ATRAC3+ audioRFC
dynamicATRAC-ADVANCED-LOSSLESSaudio(various)ATRAC Advanced Lossless audioRFC
dynamicDVvideo90000DV videoRFC
dynamicBT656videoITU-R BT.656 videoRFC
dynamicBMPEGvideoBundled MPEG-2 videoRFC
dynamicSMPTE292MvideoSMPTE 292M videoRFC
dynamicREDaudioRedundant Audio DataRFC
dynamicVDVIaudioVariable-rate DVI4 audioRFC
dynamicMP1SvideoMPEG-1 Systems Streams videoRFC
dynamicMP2PvideoMPEG-2 Program Streams videoRFC
dynamictoneaudio8000 (default)toneRFC
dynamictelephone-eventaudio8000 (default)DTMF toneRFC
dynamicaptxaudio2 – 6(equal to sampling rate)4000 ÷ sample rate4aptX audioRFC
dynamicjxsvvideo90000JPEG XS videoRFC
dynamicscipaudio/video8000 or 90000SCIPRFC

See also

External links