Changes between Initial Version and Version 1 of Ticket #2088


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Timestamp:
Nov 8, 2019 10:11:37 AM (3 years ago)
Author:
nanang
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  • Ticket #2088

    • Property Type changed from defect to enhancement
    • Property Summary changed from Match telephone-event's clock rate in generating SDP answer to Generate and negotiate telephone-event with multiple clock-rates in SDP offer/answer
  • Ticket #2088 – Description

    initial v1  
    1 There seem to be an 'issue' in RFC4733 regarding telephone-event and multiple clock rates (see also [https://www.ietf.org/mail-archive/web/mmusic/current/msg12930.html here]), so some implementations put multiple telephone-events in its SDP when it offers codecs with various clock rates. 
     1Currently PJMEDIA will only generate and answer SDP with one telephone-event format, i.e: {{{telephone-event/8000}}}. But in the stream session, it will send DTMF using timestamp correctly according to the audio codec clock rate. 
    22 
    3 Unfortunately, for telephone-event format, currently PJMEDIA will only match the name, i.e: "telephone-event" and ignore the clock rate, so when answering SDP offer with multiple telephone-events, it will simply pick the first. 
     3This ticket will update the PJMEDIA behavior in SDP offer/answer: 
     4 - in generatig SDP offer, it will generate one or more telephone-event formats, one for each clock rate, in accordance with the clock rates of the offered audio codecs. 
     5 - in generating SDP answer, it will select telephone-event clock rate based on the clock rate of the selected audio codec.