<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML xmlns="http://www.w3.org/TR/REC-html40" xmlns:v =
"urn:schemas-microsoft-com:vml" xmlns:o =
"urn:schemas-microsoft-com:office:office" xmlns:w =
"urn:schemas-microsoft-com:office:word"><HEAD><TITLE>Asterisk Codecs Extension</TITLE>
<META http-equiv=Content-Type content="text/html; charset=iso-8859-1">
<META content="MSHTML 6.00.2800.1106" name=GENERATOR><!--[if !mso]>
<STYLE>v\:* {
BEHAVIOR: url(#default#VML)
}
o\:* {
BEHAVIOR: url(#default#VML)
}
w\:* {
BEHAVIOR: url(#default#VML)
}
.shape {
BEHAVIOR: url(#default#VML)
}
</STYLE>
<![endif]-->
<STYLE>
<!--
/* Font Definitions */
@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:0cm;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman";}
a:link, span.MsoHyperlink
{color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{color:blue;
text-decoration:underline;}
p
{mso-margin-top-alt:auto;
margin-right:0cm;
mso-margin-bottom-alt:auto;
margin-left:0cm;
font-size:12.0pt;
font-family:"Times New Roman";}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:Arial;
color:navy;}
@page Section1
{size:612.0pt 792.0pt;
margin:72.0pt 90.0pt 72.0pt 90.0pt;}
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 vLink=blue link=blue bgColor=white>
<DIV><FONT face=Arial size=2>Pedro,</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I am not entirely sure as far as the video codecs
go, but asterisk can certainly pass-thru any codec that it recognizes. You will
probably need to add an asterisk constant (#define) for this codec and create
mappings to it in RTP/SDP and maybe some other stacks. The constant is only
for asterisk to uniquely identify the codec internally. If this is a codec that
is not well-defined by RTP/SDP standard, the codec will have to be passed by
name in SDP and mapped to a dynamic RTP packet type. So asterisk has to
recognize it (through mappings) to be able to pass it.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Cheers!</FONT></DIV>
<DIV><FONT face=Arial size=2>Alex.</FONT></DIV>
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=est-p-bgoncalves@ptinovacao.pt
href="mailto:est-p-bgoncalves@ptinovacao.pt">Pedro Bessa Goncalves</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=asterisk-dev@lists.digium.com
href="mailto:asterisk-dev@lists.digium.com">asterisk-dev@lists.digium.com</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Wednesday, April 14, 2004 5:57
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> RE: [Asterisk-Dev] Asterisk
Codecs Extension</DIV>
<DIV><BR></DIV>
<DIV class=Section1>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Hi Alex, what if the
codec I want to add is for video? I noticed H263 is only available in
asterisk/formats/. Does that mean H263 is only being coded in client side and
being passed-through by *?<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">In that case, if I
wanted to support the pass-through of a video stream the only thing I would
have to do would be changing the SIP header to indicate the new codec
name?<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Thank
you,<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial">Pedro<o:p></o:p></SPAN></FONT></P>
<P class=MsoNormal><FONT face=Arial color=navy size=2><SPAN
style="FONT-SIZE: 10pt; COLOR: navy; FONT-FAMILY: Arial"><o:p> </o:p></SPAN></FONT></P>
<DIV>
<DIV class=MsoNormal style="TEXT-ALIGN: center" align=center><FONT
face="Times New Roman" size=3><SPAN style="FONT-SIZE: 12pt">
<HR tabIndex=-1 align=center width="100%" SIZE=2>
</SPAN></FONT></DIV>
<P class=MsoNormal><B><FONT face=Tahoma size=2><SPAN
style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: Tahoma">From:</SPAN></FONT></B><FONT
face=Tahoma size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Tahoma"> Alex
Volkov [mailto:avolkov@bpvn.com] <BR><B><SPAN
style="FONT-WEIGHT: bold">Sent:</SPAN></B> quarta-feira, 14 de Abril de 2004
8:20<BR><B><SPAN style="FONT-WEIGHT: bold">To:</SPAN></B>
asterisk-dev@lists.digium.com<BR><B><SPAN
style="FONT-WEIGHT: bold">Subject:</SPAN></B> Re: [Asterisk-Dev] Asterisk
Codecs Extension</SPAN></FONT><o:p></o:p></P></DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P>
<DIV>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Pedro,</SPAN></FONT><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"> <o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Simply look at any codec code in
asterisk/codecs/. I suggest codec_ulaw.c or codec_alaw.c. The bulk of both of
these is the necessary interfacing code to make whatever-generic-codec work
with asterisk, and the actual conversions from xlaw to PCM and back are simple
2-liner loops. Once you understand the basic structure of an * codec, look at
codec_g723_1.c for an example on how to handle a whatever-generic-codec that
is an opaque library.</SPAN></FONT><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Model your new * codec on
those, as I think those provide the best examples of an adaptation/abstraction
layer.</SPAN></FONT><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"> <o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Cheers!</SPAN></FONT><o:p></o:p></P></DIV>
<DIV>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">Alex.</SPAN></FONT><o:p></o:p></P></DIV>
<BLOCKQUOTE
style="BORDER-RIGHT: medium none; PADDING-RIGHT: 0cm; BORDER-TOP: medium none; PADDING-LEFT: 4pt; PADDING-BOTTOM: 0cm; MARGIN: 5pt 0cm 5pt 3.75pt; BORDER-LEFT: black 1.5pt solid; PADDING-TOP: 0cm; BORDER-BOTTOM: medium none">
<DIV>
<P class=MsoNormal><FONT face=Arial size=2><SPAN
style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">----- Original Message -----
<o:p></o:p></SPAN></FONT></P></DIV>
<DIV style="font-color: black">
<P class=MsoNormal style="BACKGROUND: #e4e4e4"><B><FONT face=Arial
size=2><SPAN
style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: Arial">From:</SPAN></FONT></B><FONT
face=Arial size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <A
title=est-p-bgoncalves@ptinovacao.pt
href="mailto:est-p-bgoncalves@ptinovacao.pt">Pedro Bessa Goncalves</A>
<o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><B><FONT face=Arial size=2><SPAN
style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: Arial">To:</SPAN></FONT></B><FONT
face=Arial size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial"> <A
title=asterisk-dev@lists.digium.com
href="mailto:Asterisk-Dev@Lists.%20Digium.%20Com%20(asterisk-dev@lists.digium.com)">Asterisk-Dev@Lists.
Digium. Com (asterisk-dev@lists.digium.com)</A>
<o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><B><FONT face=Arial size=2><SPAN
style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: Arial">Sent:</SPAN></FONT></B><FONT
face=Arial size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
Tuesday, April 13, 2004 7:35 AM<o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><B><FONT face=Arial size=2><SPAN
style="FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: Arial">Subject:</SPAN></FONT></B><FONT
face=Arial size=2><SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: Arial">
[Asterisk-Dev] Asterisk Codecs Extension<o:p></o:p></SPAN></FONT></P></DIV>
<DIV>
<P class=MsoNormal><FONT face="Times New Roman" size=3><SPAN
style="FONT-SIZE: 12pt"><o:p> </o:p></SPAN></FONT></P></DIV>
<P><FONT face="Times New Roman" size=2><SPAN style="FONT-SIZE: 10pt">Hi,
does anyone know the required function headers for extending Asterisk
codecs?</SPAN></FONT> <BR><FONT size=2><SPAN style="FONT-SIZE: 10pt">Is
there another way to import 3rd party codecs?</SPAN></FONT> <o:p></o:p></P>
<P><FONT face="Times New Roman" size=2><SPAN style="FONT-SIZE: 10pt">Thank
you,</SPAN></FONT> <BR><FONT size=2><SPAN style="FONT-SIZE: 10pt">Pedro
Goncalves</SPAN></FONT>
<o:p></o:p></P></BLOCKQUOTE></DIV></BLOCKQUOTE></BODY></HTML>