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SDP O ffer/Answer mechanism to negotiate the usage of bundled media

SDP O ffer/Answer mechanism to negotiate the usage of bundled media. IETF#85, Atlanta, U.S.A Christer.Holmberg@ericsson.com Harald.Alvestrand@google.com. GOAL. SELECT A MECHANISM TO MOVE FORWARD WITH IMPLEMENTATIONS EXPECTED TO SHIP SOON. ALTERNATIVES. BUNDLE

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SDP O ffer/Answer mechanism to negotiate the usage of bundled media

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  1. SDP Offer/Answer mechanism to negotiate the usage of bundled media IETF#85, Atlanta, U.S.A Christer.Holmberg@ericsson.com Harald.Alvestrand@google.com

  2. GOAL • SELECT A MECHANISM TO MOVE FORWARD WITH • IMPLEMENTATIONS EXPECTED TO SHIP SOON

  3. ALTERNATIVES • BUNDLE • draft-ietf-mmusic-sdp-bundle-negotiation • New SDP grouping framework extension, “BUNDLE” • Each m- line associated with a group shares the same port number • Multiplexed media described in each associated m- line. • Cullen BUNDLE (TOGETHER) • draft-nandakumar-rtcweb-sdp , draft-alvestrand-one-rtp • Similar to BUNDLE • Difference: Each m- line associated with a group uses different port number • If multiplexing is used, the port of the top-most m- line is used • MMT • draft-holmberg-mmusic-sdp-mmt-negotiation • New SDP grouping framework extension, “MMT” • New SDP media type, “anymedia”, used to describe the multiplexed media session • New SDP attribute, “mmtype”, used to map PT values to specific media types

  4. EXAMPLE: BUNDLE v=0 o=alice 2890844526 2890844526 IN IP4 host.atlanta.com s= c=IN IP4 host.atlanta.com t=0 0 a=group:BUNDLE foo bar m=audio10000 RTP/AVP 0 8 97 a=mid:foo b=AS:200 a=rtpmap:0 PCMU/8000 a=rtpmap:8 PCMA/8000 a=rtpmap:97 iLBC/8000 m=video10000 RTP/AVP 31 32 a=mid:bar b=AS:1000 a=rtpmap:31 H261/90000 a=rtpmap:32 MPV/90000

  5. EXAMPLE: Cullen BUNDLE v=0 o=alice 2890844526 2890844526 IN IP4 host.atlanta.com s= c=IN IP4 host.atlanta.com t=0 0 a=group:BUNDLE foo bar m=audio10000 RTP/AVP 0 8 97 a=mid:foo b=AS:200 a=rtpmap:0 PCMU/8000 a=rtpmap:8 PCMA/8000 a=rtpmap:97 iLBC/8000 m=video20000 RTP/AVP 31 32 a=mid:bar b=AS:1000 a=rtpmap:31 H261/90000 a=rtpmap:32 MPV/90000

  6. EXAMPLE: MMT v=0 o=alice 2890844526 2890844526 IN IP4 host.atlanta.com s= c=IN IP4 host.atlanta.com t=0 0 a=group:MMT foo bar zoe m=audio 10000 RTP/AVP 0 8 97 a=mid:foo b=AS:200 a=rtpmap:0 PCMU/8000 a=rtpmap:8 PCMA/8000 a=rtpmap:97 iLBC/8000 m=video 20000 RTP/AVP 31 32 a=mid:bar b=AS:1000 a=rtpmap:31 H261/90000 a=rtpmap:32 MPV/90000 m=anymedia 30000 RTP/AVP 0 8 97 31 32 a=mid:zoe a=rtpmap:0 PCMU/8000 a=rtpmap:8 PCMA/8000 a=rtpmap:97 iLBC/8000 a=rtpmap:31 H261/90000 a=rtpmap:32 MPV/90000 a=mmtype: 0 audio a=mmtype: 8 audio a=mmtype: 97 audio a=mmtype: 31 video a=mmtype: 32 video

  7. ISSUES: BUNDLE • Usage of same port number • Offer might be rejected • Need to describe how existing, and new, SDP parameters in each m- line affects the multiplexed media • E.g. bandwidth calculation based on the bandwidth given for each m- line

  8. ISSUES: Cullen BUNDLE • Non-supporting intermediaires • Will send media, and expect media to be received, on the different ports indicated in SDP • No knowledge that the port of the top-most m- line is to be used • Non-supporting endpoint copies grouping attribute into SDP answer • Offerer will think that Cullen BUNDLE is used • Not possible to set top-most m- line to zero? • ICE candidates for multiple ports • Need to describe how existing, and new, SDP parameters in each m- line affects the multiplexed media • E.g. bandwidth calculation based on the bandwidth given for each m- line

  9. ISSUES: MMT • Rejection of unknown media type • Large SDP • Only if both individual media and anymedia are offered • Only initial offer • ICE candidates for multiple ports • Only if both individual media and anymedia are offered • RTP only? • Currently RTP/AVP is used as protocol

  10. NEXT STEP • WHICH APPROACH DO WE MOVE FORWARD WITH?

  11. THANK YOU FOR LISTENING! http://tools.ietf.org/html/draft-ietf-mmusic-sdp-bundle-negotiation-00

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