RTP Profile for Audio and Video Conferences with Minimal Control

Publisher

IETF / RFC Editor

URL

https://www.rfc-editor.org/rfc/rfc3551.html

Published

2003-07-01

Updated

unknown

Accessed

2026-09-24

HTTP status

200

License

IETF Trust Legal Provisions; no-redistribution; short excerpts and locators only

Source notes citing this source

• Comfort noise (CN) has static RTP payload type 13 with an 8000 Hz clock rate in the RTP/AVP profile. in context
• RFC 3551 says the default audio packetization interval SHOULD be 20 ms or one frame, whichever is longer. in context
• The RTP/AVP profile describes PCMU and PCMA as carrying eight bits per sample after logarithmic scaling. in context
• In the RTP/AVP profile, G.711 mu-law (PCMU) has static payload type 0 and G.711 A-law (PCMA) has static payload type 8, both with an 8000 Hz clock rate and one channel. in context
• G.722 has static RTP payload type 9 in the RTP/AVP profile. in context
• G.722 audio is sampled at 16,000 Hz, but its RTP clock rate is 8,000 Hz. RFC 1890 assigned that value in error, and it is kept for backward compatibility. in context
• A G.729 RTP packet may carry zero or more G.729 frames followed by zero or one G.729 Annex B (silence compression) frame. in context
• G.729 has static RTP payload type 18. It runs at 8 kbit/s, and each 10 ms frame is 10 octets. in context
• Under RFC 3551 the default audio packetization interval SHOULD be 20 ms or one frame, whichever is longer, unless otherwise noted. in context
• PCMU (static payload type 0) and PCMA (static payload type 8) use an RTP clock rate of 8000 Hz. in context
• G.722 (static payload type 9) samples at 16000 Hz but its RTP clock rate is 8000 Hz for backward compatibility with an erroneous RFC 1890 assignment. in context
• G.729 uses static payload type 18 with an RTP timestamp clock rate of 8000 Hz for all data rates. in context
• RTP payload types 96 to 127 are the dynamic range, used for codecs such as telephone-event, Opus or SILK whose mapping is set in SDP. in context
• The RTP clock rate for G722 is 8000 Hz even though G.722 samples at 16000 Hz, kept for backward compatibility with an error in RFC 1890. in context
• RFC 3551 assigns static RTP payload types 0 to PCMU, 8 to PCMA, 9 to G722 and 18 to G729. in context

Cite this source record

APA

WarmTransfer. (2003, July 1). RTP Profile for Audio and Video Conferences with Minimal Control. WarmTransfer. https://warmtransfer.net/knowledge/sources/rfc-3551-rtp-av-profile

BibTeX

@misc{warmtransfer-rfc-3551-rtp-av-profile,
  title  = {RTP Profile for Audio and Video Conferences with Minimal Control},
  author = {{WarmTransfer}},
  year   = {2003},
  url    = {https://warmtransfer.net/knowledge/sources/rfc-3551-rtp-av-profile},
  note   = {IETF / RFC Editor, accessed 2026-09-24}
}