Internet DRAFT - draft-fujikawa-iphone-url
draft-fujikawa-iphone-url
INTERNET DRAFT FUJIKAWA Kenji
draft-fujikawa-iphone-url-01.txt Kyoto University
OHTA Masataka
Tokyo Institute of Technology
12 October 2001
IPhone URL
Status of this Memo
This document is an Internet-Draft and is subject to all provisions
of Section 10 of RFC2026.
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Abstract
This memo describes IPhone URL, which is employed for Internet
telephone using NOTASIP protocol.
1. Introduction
In NOTASIP protocol [NOTASIP], end hosts does not negotiate each
other for information on CODEC, UDP port number of a callee host,
etc. Such information is written in Internet Phone (IPhone) URL in
advance. IPhone URL provides NOTASIP with sufficient information for
calling.
IPhone URL is defined with referring to Session Description Protocol
(SDP) [RFC2327] and simplifying SDP.
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2. Syntax
iphoneurl = "iphone:" hostport [ "/" [ formats | media *[ "," media ] ]
formats = format | formats "," format
format = digits | encodingname [ ":" clockrate
[ ":" encodingparameter ] ]
media = medium *[ "&" attribute ] *[ "&" medium *[ "&" attribute ] ]
medium = rtpmedium
rtpmedium = "m=rtp:" port ":" payloadtype
payloadtype = format | dynamicpayloadtype ":" format
dynamicpayloadtype = digits
encodingname = 1*unreserved
clockrate = digits
encodingparameter = digits
attribute = dtmfattr
dtmfattr = "a=dtmf:" dtmfdigits
dtmfdigits = 1*[ digit | "*" | "#" | "u" | "p" ]
Refer to [RFC1738] for undefined symbols.
3. Semantics
"hostport" indicates an IP address or DNS name of a callee host, and
can also indicate a port number. A port number specified by
"hostport" is used as long as "medium" indicates no port number. If
a port number is not specified in "hostport" or "medium", XXXX (to be
defined by IANA) is used instead.
There are two types of indications. One uses just "formats" and the
other uses "media".
If both of "formats" and "media" that follow "/" are omitted, formats
0(PCMU=G.711mulaw, 64Kbps) and 5(DVI4=DVI ADPCM Wave Type, 32Kbps)
are regarded to be available.
3.1 Simple Indication Just by "formats"
"formats" indicates one or more formats (payload types, encoding
methods) determined by a callee. A caller specifies one of them when
calling.
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"format" is one of the formats defined in RTP/AVP [RFC1890], and it
is specified by digit", or by "encodingname", "clockrate" and
"encodingparameter"s. When digits are used, the value must be from 0
to 127. (Note that there is the name "1016" as a encoding name, this
is distinguished from the range of the value.) "clockrate" is a
clock rate, and the meanings of "encodingparameter"s are depend on
"encodingname." However, for audio streams, the first
"encodingparameter" is the number of channels by default, according
to RFC2327. If "encodingname" cannot uniquely identify a encoding
method (e.g. DVI4), "clockrate" and/or "encodingparameter" must be
also specified.
When "format" is used as an encoding method, the payload type is set
to the value of the encoding method indicated by "format", which is
defined in RFC2327.
3.2 Advanced Indication by "Media"
"Media" consists of "medium" and 0 or more "attribute"s. When
multiple "media" are specified with divided by ",", the caller
selects one of "media" and makes a call. The URL must be written so
that the callee can judge which "media" is specified by the port
number and/or the payload type that the caller specified.
"Medium" makes a port number to correspond to an encoding method.
"rtpmedium" that employs RTP is currently defined.
"Rtpmedium" means that the payload type is set to the value indicated
by "payloadtype" and send at the port number indicated by "port".
"Paylaodtype" consists of just "format" or a pair of
"dynamicpayloadtype" and "format". The latter is the way to assign a
payload type dynamically.
If just "format" is specified, then the encoding method is what the
format indicates, and the payload type in RTP packets is the value of
the format.
If "dynamicpayloadtype" and "format" are specified, the encoding
method is what "format" indicates, and the payload type in RTP
packets is "dynamicpayloadtype".
"attribute" is an attribute of "media", and "dtmfattr" are currently
defined.
If "dtmfattr" exists, after a stream of a "media" that precedes the
"dtmfattr" is established, "dtmfdigits" are sent by DTMF tone using
one of "format"s in the "media". There are special tones represented
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by "u" and "p". "u" means a user number, and "p" means a PIN,
respectively. If these numbers are registered in a caller host, and
the caller host finds "u" and/or "p" in a URL, then it sends these
numbers by DTMF tone.
4. Examples
1. iphone://130.54.0.1:10000
2. iphone://130.54.0.1:10000/0,5
3. iphone://phone.ooi.co.jp/m=rtp:10000:0,m=rtp:10000:5
4. iphone://phone.ooi.co.jp/m=rtp:10000:0&a=dtmf:1234
5. iphone://130.54.0.1/m=rtp:9001:26
6. iphone://130.54.0.1/m=rtp:9001:JPEG
7. iphone://130.54.0.1/m=rtp:9001:100:JPEG:30
8. iphone://130.54.0.1/m=rtp:9000:5,
m=rtp:9000:99:DVI4:8000&m=rtp:9001:100:JPEG:8000
Both of #1 and #2 examples mean that an IP address is 192.168.0.250,
a port number is 10000, and encoding methods are PCMU (0) and DVI4
(5).
#3 is the same as the 1st and the 2nd, except that a DNS name is
applied instead of an IP address, and different notation is used.
#4 specifies to send 1234 by DTMF tone after stream establishment.
#5 an #6 is the same. They send JPEG stream. Here, payload type 26
means JPEG. The default clockrate is 90kHz according to RFC2035.
Note that the frame rate can be determined by means of checking the
received RTP packets.
#7 sends JPEG stream with setting the payload type number to 100 and
the clock rate to 30.
#8 enables to select an audio stream only or both of audio and video
streams. In the case of an audio stream only, the stream is sent to
the port number of 9000 with the payload type of 5. In the case of
both audio and video streams, the audio stream is sent with the port
number of 9000, the payload type of 99 and the format of DVI4 8kHz,
and the video stream is sent with the port number of 9001, the
payload type of 100 and the format of JPEG. (Here, for
synchronization, the clock rate of JPEG stream is adjusted to 8kHz.
For instance, a JPEG stream becomes 29.96 fps by means of adding 267
to the time stamp for each frame.)
9. References
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[NOTASIP] Ohta, M., and Fujikawa, K., "Nothing Other Than A Simple
Internet Phone (NOTASIP)", Internet Draft draft-ohta-
notasip-03.txt (work in progress), October 2001.
[RFC2327] Handley, M. and Jacobson, V., ``SDP: Session Description Pro-
tocol,'' RFC 2327, November 1997.
[RFC1738] Berners-Lee, T., Masinter, L., McCahill, M., "Uniform Resource
Locators (URL)", RFC 1738, December 1994.
[RFC1890] Schulzrinne. H., "RTP Profile for Audio and Video Conferences
with Minimal Control", RFC 1890, January 1996.
Security Considerations
No security issues are addressed in this document.
Authors' Addresses
FUJIKAWA Kenji
Graduate School of Informatics
Kyoto University
Yoshidahonmachi, Sakyo-Ku, Kyoto City, 606-8501, JAPAN
Phone: +81-75-753-5387
Fax: +81-75-751-0482
EMail: fujikawa@kuis.kyoto-u.ac.jp
OHTA Masataka
Computer Center
Tokyo Institute of Technology
2-12-1, O-okayama, Meguro-ku, Tokyo 152-8550, JAPAN
Phone: +81-3-5734-3299
Fax: +81-3-5734-3415
EMail: mohta@necom830.hpcl.titech.ac.jp
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