Real-time audio and video conferencing and communication applications that use the Real-time Transport Protocol (RTP) employ a standardized description format (Session Description Protocol, SDP) to describe the media streams carried in a multi-media session. This description format specifies the technical parameters of the media streams. Such a set of RTP parameters of the media stream and its compression or encoding methods is known as a media profile, or RTP audio video profile (RTP/AVP). Each profile is identified by a standardized payload type identifier (RFC 3551 and others).[1]
Contents |
RTP/AVP audio and video payload types
| Payload type | Name | Type | No. of channels | Clock rate (Hz) | Description | References |
|---|---|---|---|---|---|---|
| 0 | PCMU | audio | 1 | 8000 | ITU G.711 PCM µ-Law Audio 64 kbit/s | RFC 3551 |
| 1 | reserved (previously 1016) | audio | 1 | 8000 | reserved, previously CELP Audio 4.8 kbit/s | RFC 3551, previously RFC 1890 |
| 2 | reserved (previously G721) | audio | 1 | 8000 | reserved, previously ITU G.721 ADPCM Audio 32 kbit/s | RFC 3551, previously RFC 1890 |
| 3 | GSM | audio | 1 | 8000 | European GSM Full Rate Audio 13 kbit/s (GSM 06.10) | RFC 3551 |
| 4 | G723 | audio | 1 | 8000 | ITU G.723.1 | RFC 3551 |
| 5 | DVI4 | audio | 1 | 8000 | IMA ADPCM Audio 32 kbit/s | RFC 3551 |
| 6 | DVI4 | audio | 1 | 16000 | IMA ADPCM 64 kbit/s | RFC 3551 |
| 7 | LPC | audio | 1 | 8000 | Experimental Linear Predictive Coding Audio | RFC 3551 |
| 8 | PCMA | audio | 1 | 8000 | ITU G.711 PCM A-Law Audio 64 kbit/s | RFC 3551 |
| 9 | G722 | audio | 1 | 8000 | ITU G.722 Audio | RFC 3551 - Page 14 |
| 10 | L16 | audio | 2 | 44100 | uncompressed Linear PCM 16-bit Stereo Audio 1411.2 kbit/s | RFC 3551, Page 27 |
| 11 | L16 | audio | 1 | 44100 | uncompressed Linear PCM 16-bit Audio 705.6 kbit/s | RFC 3551, Page 27 |
| 12 | QCELP | audio | 1 | 8000 | Qualcomm Code Excited Linear Prediction | RFC 2658, RFC 3551 |
| 13 | CN | audio | 1 | 8000 | Comfort noise | RFC 3389 |
| 14 | MPA | audio | 1 | 90000 | MPEG-1 or MPEG-2 Audio Only | RFC 3551, RFC 2250 |
| 15 | G728 | audio | 1 | 8000 | ITU G.728 Audio 16 kbit/s | RFC 3551 |
| 16 | DVI4 | audio | 1 | 11025 | IMA ADPCM | RFC 3551 |
| 17 | DVI4 | audio | 1 | 22050 | IMA ADPCM | RFC 3551 |
| 18 | G729 | audio | 1 | 8000 | ITU G.729 and G.729a | RFC 3551, Page 20 |
| 25 | CELB | video | 1 | 90000 | Sun's CellB Video Encoding[2] | RFC 2029 |
| 26 | JPEG | video | 1 | 90000 | JPEG Video | RFC 2435 |
| 28 | NV | video | 1 | 90000 | Xerox PARC's Network Video (nv)[3] | RFC 3551, Page 32 |
| 31 | H261 | video | 1 | 90000 | ITU H.261 Video | RFC 4587 |
| 32 | MPV | video | 1 | 90000 | MPEG-1 and MPEG-2 Video | RFC 2250 |
| 33 | MP2T | audio/video | 1 | 90000 | MPEG-2 transport stream Video | RFC 2250 |
| 34 | H263 | video | 90000 | H.263 video, first version (1996) | RFC 3551, RFC 2190 | |
| dynamic | H263-1998 | video | 90000 | H.263 video, second version (1998) | RFC 3551, RFC 4629, RFC 2190 | |
| dynamic | H263-2000 | video | 90000 | H.263 video, third version (2000) | RFC 4629 | |
| dynamic (or profile) | H264 | video | 90000 | H.264 video | RFC 3984 | |
| dynamic (or profile) | theora | video | 90000 | Theora video | draft-ietf-avt-rtp-theora-00, draft-barbato-avt-rtp-theora-01 | |
| dynamic | iLBC | audio | 1 | — | Internet low Bitrate Codec 13.33 or 15.2 kbit/s | RFC 3951 |
| dynamic | PCMA-WB | audio | 16000 | ITU-T G.711.1, A-law | RFC 5391 | |
| dynamic | PCMU-WB | audio | 16000 | ITU-T G.711.1, µ-law | RFC 5391 | |
| dynamic | G718 | audio | 32000 | ITU-T G.718 | draft-ietf-avt-rtp-g718-01 | |
| dynamic | G719 | audio | (various) | 48000 | ITU-T G.719 | RFC 5404 |
| dynamic | G7221 | audio | 16 or 32kHz | ITU-T G.722.1 | RFC 5577 | |
| dynamic | G726-16 | audio | 1 | 8000 | ITU-T G.726 audio with 16 kbit/s | RFC 3551 |
| dynamic | G726-24 | audio | 1 | 8000 | ITU-T G.726 audio with 24 kbit/s | RFC 3551 |
| dynamic | G726-32 | audio | 1 | 8000 | ITU-T G.726 audio with 32 kbit/s | RFC 3551 |
| dynamic | G726-40 | audio | 1 | 8000 | ITU-T G.726 audio with 40 kbit/s | RFC 3551 |
| dynamic | G729D | audio | 1 | 8000 | ITU-T G.729 Annex D | RFC 3551 |
| dynamic | G729E | audio | 1 | 8000 | ITU-T G.729 Annex E | RFC 3551 |
| dynamic | G7291 | audio | (various) | ITU-T G.729.1 | RFC 4749 | |
| dynamic | GSM-EFR | audio | 1 | 8000 | ITU-T GSM-EFR (GSM 06.60) | RFC 3551 |
| dynamic | GSM-HR-08 | audio | 1 | 8000 | ITU-T GSM-HR (GSM 06.20) | draft-ietf-avt-rtp-gsm-hr-00 |
| dynamic (or profile) | AMR | audio | (various) | 8000 | Adaptive Multi-Rate audio | RFC 4867 |
| dynamic (or profile) | AMR-WB | audio | (various) | 16000 | Adaptive Multi-Rate Wideband audio | RFC 4867 |
| dynamic (or profile) | AMR-WB+ | audio | 1, 2 or omit | 72000 | Extended Adaptive Multi Rate – WideBand audio (G.722.2) | RFC 4352 |
| dynamic (or profile) | vorbis | audio | (various) | from 8kHz to 192kHz | RTP Payload Format for Vorbis Encoded Audio | RFC 5215 |
| dynamic (or profile) | speex | audio | 1 | 8000, 16000 or 32000 | RTP Payload Format for the Speex Codec | RFC 5574 |
| dynamic (96-127) | mpa-robust | audio | 90000 | A More Loss-Tolerant RTP Payload Format for MP3 Audio | RFC 5219 |
RFC 3551 lists details of the codec, or a reference for the details is provided. Payload identifiers 96–127 are reserved for payloads defined dynamically during a session. The minimum payload support is defined as 0 (PCMU) and 5 (DVI4). The document recommends dynamically assigned port numbers, although 5004 and 5005 have been registered for use of the profile and can be used instead. The standard also describes the process of registering new payload types with IANA.
See also
References
- ^ RFC 3551, RTP Profile for Audio and Video Conferences with Minimal Control, H. Schulzrinne, S. Casner, The Internet Society (July 2003)
- ^ SUN CellB Codec, Retrieved on 2009-07-09
- ^ nv - network video on Henning Schulzrinne's website, Network Video on The University of Toronto's website, Retrieved on 2009-07-09
External links
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