Hi all,
I think Link.xie is right that till the attribute is
registered 'X-mptime' should be the attribute name used.
Though, we should move towards standardizing this
attribute in a draft.... because chances are other
implementations will not understand this unregistered
attribute and may lead to inter-op issues later.
PacketCable seems to have taken a step forward already
in this regard.
PS: Some more digging into the archive shows that we did
agree to bring out a draft on the 'mptime' attrib
for exactly the same reason.... Perhaps Kevin and
Colin could tell if one is already on its way :)
Else we can prepare one now ?
(ref:
http://www1.ietf.org/mail-archive/working-groups/mmusic/current/msg01030.ht
ml)
Cheers,
Siddharth.
--------------------------------------------------------
Siddharth Toshniwal
Hughes Software Systems
Prestige Opal http://www.hssworld.com
146, Infantry Road Ph (O): +91-80-2286390 (7094)
Bangalore-560001, India Mobile: +91-9845154068
--------------------------------------------------------
"link.xie" <[EMAIL PROTECTED]> on 03/12/2003 04:49:12 PM
To: "Attila Sipos" <[EMAIL PROTECTED]>, "'Christian Stredicke'"
<[EMAIL PROTECTED]>
cc: [EMAIL PROTECTED] (bcc: Siddharth J Toshniwal/HSSBLR)
Subject: Re: [Sip-implementors] SDP packet times for muliple codecs
I think X-mptime is better. Cause in rfc2327,
"Unregistered attributes should begin with "X-" to prevent inadvertent
collision with registered attributes"
----- Original Message -----
From: "Attila Sipos" <[EMAIL PROTECTED]>
To: "'Christian Stredicke'" <[EMAIL PROTECTED]>; "'link.xie'"
<[EMAIL PROTECTED]>; "Attila Sipos" <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>
Sent: Wednesday, March 12, 2003 4:44 PM
Subject: RE: [Sip-implementors] SDP packet times for muliple codecs
>
> Hello all,
>
> Link Xie, thanks for your response:
> > > m=audio 10000 RTP/AVP 0 8
> > > a=X-ptime: 20 30
>
> Following Siddharth's link
>
http://lists.cs.columbia.edu/pipermail/sip-implementors/2003-February/00455
6
> .html
>
> It seems that from this link the answer is to use "mptime":
>
> >So instead of redefining ptime, create a new "mptime" parm that has a
> >construct similar to the m line:
> >
> >m=audio 49170 RTP/AVP 0 4 18
> >A=mptime:10 30 30
> >
>
> The packetcable spec (from http://www.packetcable.com/specifications/ )
> http://www.packetcable.com/downloads/specs/PKT-SP-EC-MGCP-I06-021127.pdf
> also seem to use mptime:
>
> (taken from PacketCable(tm) Network-Based Call Signaling Protocol
> Specification)
>
> m=audio 3456 RTP/AVP 96 97 0
> a=rtpmap:96 G726-32/8000
> a=rtpmap:97 telephone-event/8000
> a=mptime: 10 - 10
>
> Here, rfc2833 doesn't have a packet time so it's shown with a '-'
> (rfc2833 is supposed to have the same packet time as the selected
> audio codec).
>
>
> Which is correct mptime or X-ptime?
>
>
> Regards,
>
> Attila
>
>
> > -----Original Message-----
> > From: Christian Stredicke [mailto:[EMAIL PROTECTED]
> > Sent: 12 March 2003 08:31
> > To: 'link.xie'; 'Attila Sipos'
> > Cc: [EMAIL PROTECTED]
> > Subject: AW: [Sip-implementors] SDP packet times for muliple codecs
> >
> >
> > The "X-" is a bad idea. We were using this in another
> > scenario and many
> > SDP parsers complained about "x-" headers. Better use
> > something without
> > "x-" (e.g. "xptime").
> >
> > Christian
> >
> > > -----Urspr
�ngliche Nachricht-----
> > > Von: [EMAIL PROTECTED]
> > [mailto:sip-implementors-
> > > [EMAIL PROTECTED] Im Auftrag von link.xie
> > > Gesendet: Mittwoch, 12. M�rz 2003 03:46
> > > An: Attila Sipos; [EMAIL PROTECTED]
> > > Betreff: Re: [Sip-implementors] SDP packet times for muliple codecs
> > >
> > > Hi,Attila
> > > I think your suggestion is wrong. We also use this solution
> > before.
> > > But we find that the meaning of 2 "m=" line repesent 2 media stream.
> > So
> > > it's not suitalbe for this case.
> > > Our solution is introducing a new attribut "X-mptime"
> > which means
> > > multiple ptime
> > > and the SDP would like:
> > >
> > > m=audio 10000 RTP/AVP 0 8 ----- 0 means g711u-law
> > and 8 means
> > > g711a-law
> > > a=X-ptime: 20 30 -----20 for
> > g711u 30 for
> > > g711a
> > >
> > > I think this can solve your problem
> > >
> > > Best Regard
> > > Link.Xie
> > > ----- Original Message -----
> > > From: "Attila Sipos" <[EMAIL PROTECTED]>
> > > To: <[EMAIL PROTECTED]>
> > > Sent: Tuesday, March 11, 2003 7:33 PM
> > > Subject: [Sip-implementors] SDP packet times for muliple codecs
> > >
> > >
> > > >
> > > > Hello everyone,
> > > >
> > > > For multiple codecs we can have an SDP like this:
> > > > m=audio 10000 RTP/AVP 0 8 ----- 0 means g711u-law and 8 means
> > > g711a-law
> > > > a=ptime:20
> > > > But this is only correct if the packet times match for
> > > > u-law and a-law.
> > > >
> > > >
> > > > What if you have a system where, for some reason, the
> > > > codecs have different packet times?
> > > >
> > > > Can you do this?
> > > > m=audio 10000 RTP/AVP 0 - ---- g711-ulaw
> > > > a=ptime:20
> > > > m=audio 10000 RTP/AVP 8 ---- g711 a-law
> > > > a=ptime:30
> > > >
> > > > Regards,
> > > >
> > > > Attila
> > > >
> > > > <http://www.vegastream.com>
> > > > VegaStream : A World of difference for your Integrated
> > Communications
