Understanding RTP Header Compression
The general functions of RTP can be described as follows:
Provides end-to-end network transport functions for audio and video
over multicast or unicast services
Supports real-time conferencing of groups
Supports source identification of gateways and multicast-to-unicast
translators
Provides feedback from receivers on QoS
Synchronizes video and audio streams with time stamping
There has been a growing interest in RTP in AVVID environments because
of its interoperability among different implementations of network audio and
video applications. However, RTP has a header field of 12 bytes.This, combined
with the encapsulated UDP and IP, increases the total overhead to 40 bytes.
Because of the large amount of header information for the relatively small size of
multimedia data payloads, extending RTP to slow links (dial-up modems,
ISDN/BRI, subrate T1s) has been difficult. RTP Header Compression (CRTP)
was created to offset the large header size associated with Real-Time Transport
Protocol (RTP).