Communicator and Mac Messenger Video Protocol support – H.263

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The question that was asked: How come Communicator works with the Polycom HDX solution but not Mac Messenger?

Office Communicator supports both RTVideo and H.263 and it is the later codec that the Polycom HDX solution works with today. The codec is the result of a library being supplied by Intel of which there is no equivalent for the Mac.

<March 23 edit - You never want to omit folks that help you with a discussion and alas I did omit Steve Lessard unintentionally. Thanks Steve >

<March 22 edit - including the additional details below>

Mike Stacy with Polycom followed up with me on this and noted that the client is showing the protocol in the SDP, turns out this is a bug with the shipping 7.x client. The bug being that Mac Messenger advertises the protocol while it does not support it. Here is the log output he shared with me -

User-Agent: UCCP/2.0.6362.0 MM/7.0.4663.2 (Mac Messenger 7.0.2)

  ...

 a=rtpmap:121 x-rtvc1/90000

 a=rtpmap:34 H263/90000

 Calling from Mac Messenger to an HDX, the Mac just sends a BYE message with no error code anywhere in the SIP trace.

 Calling from the HDX to Mac Messenger you see the same codec in the invite:

 a=rtpmap:34 H263/90000 

But Mac Messenger rejects it with a 488…

Start-Line: SIP/2.0 488 Not Acceptable Here

  ...

User-Agent: UCCP/2.0.6362.0 MM/7.0.4663.2 (Mac Messenger 7.0.2)

  

Thanks Mike for the follow up.

November 4, 2010 Update - At this time there is no plan to include support for H.253 with the Mac client.

TomL LCSKid