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<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">Hello!<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">I have
following problem: <o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">My current
session is connected to a third-party Application by using an
own Freeswitch application
"DoingReadAndWriteFrames". The communication between Freeswitch
Session and third-party application is done by reading and
writing frames in a
while loop.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">At start of
Freeswitch session the codec is PCMA, which I need for voice
recognition.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">Customer reports,
that the codec of the Freeswitch session changes from PCMA to
PCMU.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">If an
external call comes in, I’m playing an audio ringing tone into
the Freeswitch
session.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">I have realize,
that the codec is changed back from u-law to a-law.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">I have
recorded the voice stream and I have heard the codec change. <o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">I have
never reproduced the codec change of an active Freeswitch
session on my test
system.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">Some
customer reports, that the system is running fine (no codec
change) for half a
year.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">My own bug fix
is to manually translate PCMU data to PCMA, if session codec is
switched to
PCMU.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">But I
cannot test my bug fix, because I can't force the changing of
codec within a
running session.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">Maybe the
"codec change" was a bug from Freeswitch version at October
2010.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">Maybe the
hardware SPA3102 sends a sip re-invite message on special cases.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">I have no
idea.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">I have some
questions about codec negotiation and sip re-invite:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">A) On what
reasons can a re-invite message triggered and why is the session
codec changed?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">B) What
must be happen, that a codec is changing, after a codec
negotiation was done,
on a running Freeswitch session?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">C) Why is
there a codec change back to a-law, when I’m playing an own
ringing tone?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">D) Is there
a solution for forcing Freeswitch always use PCMA?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">My
configuration of Freeswitch in “vars.xml” to force codec PCMA:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB"><X-PRE-PROCESS
cmd="set" data="global_codec_prefs=PCMA"/><o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB"><X-PRE-PROCESS
cmd="set" data="outbound_codec_prefs=PCMA"/><o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-ansi-language:EN-GB"
lang="EN-GB">Greetings</span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Achim Stamm</p>
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