[asterisk-bugs] [JIRA] (ASTERISK-26498) codec formats: attributes not negotiated properly on 200 OK

[Kevin Harwell (JIRA)]

Kevin Harwell created ASTERISK-26498:
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             Summary: codec formats: attributes not negotiated properly on 200 OK
                 Key: ASTERISK-26498
                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-26498
             Project: Asterisk
          Issue Type: Bug
      Security Level: None
          Components: Resources/res_format_attr_opus
    Affects Versions: 14.0.2, 13.11.2
            Reporter: Kevin Harwell


The format attributes received in a 200 OK are not negotiated across to the other side of the call leg. For instance using an opus call as an example the following is seen:

Endpoint 'A'->Asterisk:
{noformat}
a=rtpmap:111 opus/48000/2
a=fmtp:111 minptime=10;useinbandfec=1
{noformat}

In codecs.conf an opus format (that is specified on the above endpoint) was set to have a bitrate=12000, so then the following joint attributes between endpoint 'A' and asterisk get built and sent to endpoint 'B':

Asterisk->Endpoint 'B'
{noformat}
a=rtpmap:107 opus/48000/2
a=fmtp:107 maxaveragebitrate=12000
{noformat}

200 OK from endpoint 'B'->Asterisk:
{noformat}
a=rtpmap:107 opus/48000/2
a=fmtp:107 maxptime=20;maxplaybackrate=8000;maxaveragebitrate=12000;sprop-maxcapturerate=8000;usedtx=0
{noformat}

Finally, after the 200 OK is received from 'B' one is sent to 'A' with the following:
{noformat}
a=rtpmap:111 opus/48000/2
a=fmtp:111 maxaveragebitrate=12000
{noformat}
Because both sides are setup for 'opus', and the proper negotiated attributes were not sent back to 'A' then audio can be dropped when doing pass through due to mismatched bitrates (or some other attribute).




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