<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii">
<meta name=Generator content="Microsoft Word 12 (filtered medium)">
<style>
<!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
em
{mso-style-priority:20;
font-weight:bold;
font-style:normal;}
p.MsoListParagraph, li.MsoListParagraph, div.MsoListParagraph
{mso-style-priority:34;
margin-top:0in;
margin-right:0in;
margin-bottom:0in;
margin-left:.5in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri","sans-serif";}
span.EmailStyle19
{mso-style-type:personal;
font-family:"Calibri","sans-serif";
color:windowtext;}
span.EmailStyle20
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-size:10.0pt;}
@page Section1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.Section1
{page:Section1;}
-->
</style>
<!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]-->
</head>
<body lang=EN-US link=blue vlink=purple>
<div class=Section1>
<p class=MsoNormal><span style='color:#1F497D'>Forgot to mention : Running
trunk – build 17104<o:p></o:p></span></p>
<p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p>
<div>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Chris Fowler <br>
<b>Sent:</b> Thursday, March 25, 2010 12:48 PM<br>
<b>To:</b> 'freeswitch-users@lists.freeswitch.org'<br>
<b>Subject:</b> Guidance on debugging audio glitches<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Hi,<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Here’s the problem I’m “hearing”:<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Test Case #1<o:p></o:p></p>
<p class=MsoNormal>x1001 calls x1002<o:p></o:p></p>
<p class=MsoNormal>- Audio is rock solid<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Test Case #2<o:p></o:p></p>
<p class=MsoNormal>x1001 calls x3001 (Conference Bridge)<o:p></o:p></p>
<p class=MsoNormal>x1002 calls x3001 (Conference Bridge)<o:p></o:p></p>
<p class=MsoNormal>- Audio is mostly perfect. However, occasional
“glitches” in the audio can be heard<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Notes:<o:p></o:p></p>
<p class=MsoNormal>- Bypass media is switched off. FreeSWITCH routes
audio for both the bridged, and the conferenced call<o:p></o:p></p>
<p class=MsoNormal>- rtp<span style='font-family:"Arial","sans-serif";
color:black'>-</span>autoflush<span style='font-family:"Arial","sans-serif";
color:black'>-during-bridge is “true” on Sofia profile internal.xml<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:black'>-
I enabled the debug trace for auto-flush in switch_rtp.c (line 1895) and see
occasional auto flush of rtp packets for *<b>both</b>* test cases. The
glitches don’t coincide with the flushing. In fact with flushing you
can’t hear when data gets flushed (2x20ms packets).<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-family:"Arial","sans-serif";color:black'><o:p> </o:p></span></p>
<p class=MsoNormal>Environment<o:p></o:p></p>
<p class=MsoNormal>- CentOS 5.4<o:p></o:p></p>
<p class=MsoNormal>- Tested on AWS EC2 Small, Medium, Large instances. On
Medium and Large CPU affinity for FreeSWITCH set to the 2<sup>nd</sup> core.<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Questions:<o:p></o:p></p>
<p class=MsoNormal>- What’s different between bridging a call and a conference
call run through mod_conference in terms of audio processing? <o:p></o:p></p>
<p class=MsoNormal>- Thoughts on how to debug this?<o:p></o:p></p>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Thanks, Chris.<o:p></o:p></p>
</div>
</body>
</html>