1.What is the relationship between H.323 and RTP?
(From Sun's JMF developer discussion group)
RTP is an IETF standard for payload delivery. It defines a packet
format and protocol (i.e. behavior convention) for sending audio,
video and other real-time data over a network. It includes support for
multicast and unreliable networks. RTCP is a related protocol for
managing control of RTP streams.
H.323 is an ITU-T (formerly CCITT) standard which defines an entire
video-conferencing system including call set-up, transport, control,
tear-down. H.323 uses RTP/RTCP for audio and video transport.
The H.323 standard is complex. It builds upon a large number of other
standards such as H.225 and H.245. H.245 in turn references standards
X.680, X.690 and X.691, relating to Abstract Syntax Notation (ASN.1)
encoding.
The IETF MMUSIC group has defined a suite of protocols
to provide complete audio/video conferencing analogous
to H.323. This suite includes SIP, SAP, and SDP.
Implementors found the H.323 standard to be quite difficult to implement,
and ambiguously defined in some areas. The standard documents
themselves must be purchased from the ITU. The MMUSIC standards
by contrast are freely available, are relatively simple to implement,
and do not require the use of royalty-encumbered codecs for
standards compliance.
References:
ITU-T:
http://www.itu.int/ITU-T/
IETF:
http://www.ietf.org/
MMUSIC:
http://www.ietf.org/html.charters/mmusic-charter.html
RTP/RTCP:
http://www.ietf.org/rfc/rfc2326.txt
SIP:
http://www.ietf.org/rfc/rfc3261.txt