Re: [MMUSIC] AD Evaluation of draft-ietf-mmusic-rfc4566bis-32: Media Description

Hi Paul,
I am not sure why we need to  change the definition.

A media description describes the media and it start with a m= line  ... (and so on)

If want to expand maybe say that it must start with an m= line and will include the sdp types as listed in section 5

Media description, if present
         m=  (media name and transport address)
         i=* (media title)
         c=* (connection information -- optional if included at
              session level)
         b=* (zero or more bandwidth information lines)
         k=* (encryption key)
         a=* (zero or more media attribute lines)

Media description is not about RTP since the proto attribute in the m-line can define others see https://www.iana.org/assignments/sdp-parameters/sdp-parameters.xhtml#sdp-parameters-2  

for example in draft data-channel-sdpneg we have:  m=application 10001 UDP/DTLS/SCTP webrtc-datachannel which is not RTP.

Roni Even

-----Original Message-----
From: mmusic [mailto:mmusic-bounces@ietf.org] On Behalf Of Paul Kyzivat
Sent: Monday, February 18, 2019 10:24 PM
To: Ben Campbell; draft-ietf-mmusic-rfc4566bis.all@ietf.org
Cc: Magnus Westerlund; mmusic WG; 'Colin Perkins'
Subject: Re: [MMUSIC] AD Evaluation of draft-ietf-mmusic-rfc4566bis-32: Media Description

> On 2/11/19 10:45 PM, Ben Campbell wrote:

>> §2, “Media Description”: While true, the text here is not a 
>> definition of anything but syntax. Please add a sentence or two to 
>> say what the media description semantically represents.
I'm having trouble finding a suitable semantic definition of Media Description.

My first thought is that it provides the information necessary to establish a media session. But while *Multimedia Session* is described, media Session isn't defined in the document.

I looked at RFC7656 (Taxonomy) for a definition, but it doesn't have one either. It defines RTP Session, and Multimedia Session as one or more RTP Sessions. That is close, but in SDP media sessions need not be RTP.

Is there any suitable existing definition???

If not, then how about:

"A Media Description contains the information needed for one party to establish an application layer network protocol connection to another party." ???

OR

"A Media Description contains the information needed for one party to establish a Media Session with another party."

"A Media Session is an application layer network protocol connection between two parties."

It seems important to get this right! It is essentially a broadening of
RFC7656 beyond RTP.

	Thanks,
	Paul

_______________________________________________
mmusic mailing list
mmusic@ietf.org
https://www.ietf.org/mailman/listinfo/mmusic