[SIPForum-discussion] Help plesae..very urgent...

Mon Jun 11 20:33:02 UTC 2007

Please check http://www.openh323.org 
It is a bit dated, but should help you with the source code portion of
your request.

Peter

________________________________

From: discussion-bounces at sipforum.org
[mailto:discussion-bounces at sipforum.org] On Behalf Of poan selvi
Sent: Wednesday, June 06, 2007 8:02 PM
To: discussion at sipforum.org; sip-implementors at cs.columbia.edu;
balasubramanian_neelakantan at quintum.com
Subject: [SIPForum-discussion] Help plesae..very urgent...

Hi all,

             I am doin my project in SIP ..I implemented audio,video
chat ..and instant messaging....But in my college they asked me to
compare this with H.323...

So i am in need of free H.323 source code....Is it availbale..If it
so,based on what factors i can show SIP is best....I have 2 days time to
show this..Please help me folks....

kaushik at ncoretech.com wrote:

	I guess it is "answerer's" prerogative to select the preferred
codec.

	But I agree that there should be a way for offerer also to
	indicate preferences. Not sure how this can be done.

	Also, it is not clear what should happen if answerer responds
with
	both these codecs.

	Regards,
	Kaushik

	Quoting Manpreet Singh :

	> I was reading some threads on this last year and there is says
this way
	> there is no way to find out the priority of the codecs to be
used. So if one
	> does implement this how would the priority be decided? So in
the example
	> below, which has higher preference, payload 18 or 4?
	>
	> Is this defined somewhere formally?
	>
	> thanks
	>
	> _____
	>
	> From: Bala Neelakantan [mailto:neel at quintum.com]
	> Sent: Wednesday, May 16, 2007 10:34 PM
	> To: 'Manpreet Singh'; sip-implementors at cs.columbia.edu
	> Subject: RE: [Sip-implementors] ptime/Maxptime support in SDP
	>
	>
	>
	> For that, you have to have multiple m lines, with each having
just one
	> codec, and the ptime can be specified for that.
	>
	>
	>
	> In your example, you can try separate m= line for each codec
in the Offer.
	>
	>
	>
	> m=audio 22836 RTP/AVP 4
	> c=IN IP4 216.168.161.230
	> a=rtpmap:18 G729/8000
	> a=fmtp:18 annexb=yes;
	>
	> a=ptime:20
	> a=maxptime:40
	>
	> m=audio 22838 RTP/AVP 18
	>
	> a=rtpmap:4 G723/8000
	> a=fmtp:4 bitrate=6.3;annexa=yes;
	>
	> a=ptime:30
	> a=maxpime:60
	>
	>
	>
	>
	> Thanks,
	>
	> Neel
	>
	>
	>
	> -----Original Message-----
	> From: Manpreet Singh [mailto:msingh at ibasis.net]
	> Sent: Wednesday, May 16, 2007 3:28 PM
	> To: balasubramanian_neelakantan at quintum.com;
	> sip-implementors at cs.columbia.edu
	> Subject: RE: [Sip-implementors] ptime/Maxptime support in SDP
	>
	>
	>
	> Well each codec is defined as the media attribute so for each
media
	> attribute, one can define packetization to be used. Different
codec support
	> different packetizations so they have to be defined explicitly
and we cant
	> use a session level ptime for all media attribiutes.
	>
	> So how does one specify packetization in the SDP for each
codec used is
	> really my question. Lets assume a UA wants to use G723 with 30
ms
	> packetization and G729 with 40 ms packetization.
	>
	> -----Original Message-----
	> From: Bala Neelakantan [mailto:neel at quintum.com ]
	> Sent: Wednesday, May 16, 2007 4:15 PM
	> To: 'Manpreet Singh'; sip-implementors at cs.columbia.edu
	> Subject: RE: [Sip-implementors] ptime/Maxptime support in SDP
	>
	> Ptime is media attribute. It can't be specified per codec.
	>
	> >From 2327.
	>
	> a=ptime:
	> This gives the length of time in milliseconds represented by
the
	> media in a packet. This is probably only meaningful for audio
	> data. It should not be necessary to know ptime to decode RTP
or
	> vat audio, and it is intended as a recommendation for the
	> encoding/packetisation of audio. It is a media attribute, and
is
	> not dependent on charset.
	>
	>
	>
	> You can see some notes on usage of ptime in rfc3264.
	>
	> >From RFC 4040.
	>
	> Optional parameters: ptime, maxptime
	>
	> "ptime" gives the length of time in milliseconds
	> represented by the media in a packet, as described in RFC
	> 2327 [6].
	>
	> "maxptime" represents the maximum amount of media, which
	> can be encapsulated in each packet, expressed as time in
	> milliseconds, as described in RFC 3267 [9].
	>
	>
	>
	> Thanks,
	> Neel
	>
	>
	>
	> > -----Original Message-----
	> > From: sip-implementors-bounces at cs.columbia.edu
	> > [mailto:sip-implementors- 
	> bounces at cs.columbia.edu] On Behalf Of
	> > Manpreet Singh
	> > Sent: Wednesday, May 16, 2007 2:22 PM
	> > To: sip-implementors at cs.columbia.edu
	> > Subject: [Sip-implementors] ptime/Maxptime support in SDP
	> >
	> > Whats the right implementation for ptime/maxptime in the
SDP. I read
	> > few recommendations but what is the correct way of doing it?
	> >
	> > m=audio 22836 RTP/AVP 4 18
	> > c=IN IP4 216.168.161.230
	> > a=rtpmap:18 G729/8000
	> > a=fmtp:18 annexb=yes;ptime=20
	> > a=maxptime:40
	> > a=rtpmap:4 G723/8000
	> > a=fmtp:4 bitrate=6.3;annexa=yes;ptime=30 a=maxpime:60
	> >
	> > OR
	> >
	> > m=audio 22836 RTP/AVP 4 18
	> > c=IN IP4 216.168.161.230
	> > a=rtpmap:18 G729/8000
	> > a=fmtp:18 annexb=yes;
	> > a=ptime:20
	> > a=maxptime:40
	> > a=rtpmap:4 G723/8000
	> > a=fmtp:4 bitrate=6.3;annexa=yes
	> > a=ptime:30
	> > a=maxpime:60
	> >
	> > is this how we can define ptime and maxptime per media
attribute? Any
	> > place this has been defined?
	> >
	> > Thanks
	> > _______________________________________________
	> > Sip-implementors mailing list
	> > Sip-implementors at cs.columbia.edu
	> >
https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
	> 
	>
	>

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k.poanselvi 

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