Re: [MMUSIC] What is an m-line?

Kevin Dempsey <kevindempsey70@gmail.com> Wed, 15 May 2013 13:36 UTC

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Date: Wed, 15 May 2013 14:36:13 +0100
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From: Kevin Dempsey <kevindempsey70@gmail.com>
To: jonathan@vidyo.com, mmusic@ietf.org
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Subject: Re: [MMUSIC] What is an m-line?
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I hadn't seen the MMT idea before, but I like it. It does seem a bit
awkward to use though.

Perhaps with a few adjustments an offer could be:

v=0
o=alice 2890844526 2890844526 IN IP4 host.atlanta.com
s=
c=IN IP4 host.atlanta.com
t=0 0
m=anymedia 30000 UDP 1
a=rtcp-mux
a=candidate:1 1 UDP 1694498815 host.atlanta.com 30000 typ host
a=candidate:1 2 UDP 1694498815 host.atlanta.com 30000 typ host
a=media:audio 1 RTP/AVP 0 8 97
b=AS:200
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:97 iLBC/8000
a=media:video 2 RTP/AVP 31 32
b=AS:1000
a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000
m=audio 10000 RTP/AVP 0 8 97
a=anymedia-equivalent:1 1
a=rtcp-mux
b=AS:200
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:97 iLBC/8000
a=candidate:1 1 UDP 1694498815 host.atlanta.com 10000 typ host
a=candidate:1 2 UDP 1694498815 host.atlanta.com 10000 typ host
m=video 20000 RTP/AVP 31 32
a=anymedia-equivalent:1 2
a=rtcp-mux
b=AS:1000
a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000
a=candidate:1 1 UDP 1694498815 host.atlanta.com 20000 typ host
a=candidate:1 2 UDP 1694498815 host.atlanta.com 20000 typ host

where the 'PT' on the m=anymedia line and the 'port' on the a=media: lines
are  identifiers for the a=anymedia-equivalent attributes. The a=media:
line identifiers would need to be non-zero in the offer, but could be zero
in the answer to reject that component.

In this case the answer with anymedia support the reply would be something
like:

v=0
o=bob 2890844526 2890844526 IN IP4 host.atlanta.com
s=
c=IN IP4 host.atlanta.com
t=0 0
m=anymedia 60000 UDP 1
a=rtcp-mux
a=media:audio 1 RTP/AVP 0 8 97
b=AS:200
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:97 iLBC/8000
a=media:video 2 RTP/AVP 31 32
b=AS:1000
a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000
a=candidate:1 1 UDP 1694498815 host.atlanta.com 60000 typ host
a=candidate:1 2 UDP 1694498815 host.atlanta.com 60000 typ host
m=audio 0 RTP/AVP 0 8 97
m=video 0 RTP/AVP 31 32


and without anymedia support the reply would be something like:

v=0
o=bob 2890844526 2890844526 IN IP4 host.atlanta.com
s=
c=IN IP4 host.atlanta.com
t=0 0
m=anymedia 0 UDP 1
m=audio 40000 RTP/AVP 0 8 97
a=rtcp-mux
b=AS:200
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:97 iLBC/8000
a=candidate:1 1 UDP 1694498815 host.atlanta.com 40000 typ host
a=candidate:1 2 UDP 1694498815 host.atlanta.com 40000 typ host
m=video 50000 RTP/AVP 31 32
a=rtcp-mux
b=AS:1000
a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000
a=candidate:1 1 UDP 1694498815 host.atlanta.com 50000 typ host
a=candidate:1 2 UDP 1694498815 host.atlanta.com 50000 typ host