[asterisk-bugs] [Asterisk 0010500]: [patch] teach chan_iax2 to offer the calling channel's codec first, like chan_sip does it

[noreply at bugs.digium.com]

A NOTE has been added to this issue. 
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http://bugs.digium.com/view.php?id=10500 
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Reported By:                stevedavies
Assigned To:                russell
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Project:                    Asterisk
Issue ID:                   10500
Category:                   Channels/chan_iax2
Reproducibility:            N/A
Severity:                   minor
Priority:                   normal
Status:                     assigned
Asterisk Version:            SVN 
SVN Branch (only for SVN checkouts, not tarball releases):  trunk 
SVN Revision (number only!): 80048 
Disclaimer on File?:        N/A 
Request Review:              
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Date Submitted:             08-20-2007 11:24 CDT
Last Modified:              09-10-2007 06:40 CDT
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Summary:                    [patch] teach chan_iax2 to offer the calling
channel's codec first, like chan_sip does it
Description: 
We discussed this issue on asterisk-dev under the title "IAX codec
selection".

Currently, outgoing IAX NEW packets contain two codec-related IEs. 
"FORMAT" will contain the format bits for the calling channel.  CODEC_PREFS
is a list of codecs allowed, taken as-is from the allow= of the peer.

Now it is preferable not to transcode - so it makes sense that the calling
channel's codec should be moved first in the CODEC_PREFS list (provided
that it is one of the allowed codecs).  

This is what chan_sip does.

So this patch brings that behaviour to IAX.

As a demonstration of the issue, here's a peer:

[xxxx]
type=friend
host=xxx.co.za
username=us
secret=ourpass
trunk=no
notransfer=yes
transfer=no
context=from-peer-xxxx
disallow=all
allow=alaw
allow=ulaw
allow=g729
allow=ilbc
allow=gsm
allow=speex
qualify=500
qualifysmoothing=yes

Now we send a call to this peer from a phone using iLBC.  chan_iax2 as was
sends this NEW:

Tx-Frame Retry[000] -- OSeqno: 000 ISeqno: 000 Type: IAX     Subclass:
NEW
Timestamp: 00017ms  SCall: 00001  DCall: 00000 [A.B.C.D:4569]
VERSION         : 2
CALLED NUMBER   : 082XXXXXXX
CODEC_PREFS     : (alaw|ulaw|g729|ilbc|gsm|speex)
CALLING NUMBER  : 021XXXXXXX
CALLING PRESNTN : 35
CALLING TYPEOFN : 0
CALLING TRANSIT : 0
CALLING NAME    : Steve Davies
LANGUAGE        : en
USERNAME        : us
FORMAT          : 1024
CAPABILITY      : 59150
ADSICPE         : 2
DATE TIME       : 2007-08-15  10:18:02

So even though ILBC is the current codec, the CODEC_PREFS has ALAW first.

After my patch, the NEW is:

Tx-Frame Retry[000] -- OSeqno: 000 ISeqno: 000 Type: IAX     Subclass: NEW
   
Timestamp: 00016ms  SCall: 00012  DCall: 00000 [A.B.C.D:4569]
VERSION         : 2
CALLED NUMBER   : 082XXXXXXX
CODEC_PREFS     : (ilbc|alaw|ulaw|g729|gsm|speex)
CALLING NUMBER  : 021XXXXXXX
CALLING PRESNTN : 35
CALLING TYPEOFN : 0
CALLING TRANSIT : 0
CALLING NAME    : Steve Davies
LANGUAGE        : en
USERNAME        : us
FORMAT          : 1024
CAPABILITY      : 59150
ADSICPE         : 2
DATE TIME       : 2007-08-20  18:37:16


====================================================================== 

---------------------------------------------------------------------- 
 pj - 09-10-07 06:40  
---------------------------------------------------------------------- 
I tried both, codecpriority= (ie. caller or without specified, default -
host), same result, 
iax debug from asterisk A (192.168.36.134), 
client idefisk (192.168.164.154), has only gsm permited in idefisk config

 iax2 show peer 777 (idefisk)
  Codec Order  : (gsm|ilbc|alaw)
 iax2 show peer bill-gw (asteriskA)
  Codec Order  : (alaw|gsm|g729)



[Sep 10 13:43:09]     -- Accepting AUTHENTICATED call from
192.168.164.154:
       > requested format = ilbc,
       > requested prefs = (),
       > actual format = gsm,
       > host prefs = (gsm|ilbc|alaw),
       > priority = mine


[Sep 10 13:43:09]     -- Executing [968 at xxxx:2] Dial("IAX2/777-7",
"IAX2/bill-gw/968,,tT") in new stack


[Sep 10 13:43:09]    VERSION         : 2
[Sep 10 13:43:09]    CALLED NUMBER   : 968
[Sep 10 13:43:09]    CODEC_PREFS     : (gsm|alaw|g729)
[Sep 10 13:43:09]    CALLING NUMBER  : 324
[Sep 10 13:43:09]    CALLING PRESNTN : 1
[Sep 10 13:43:09]    CALLING TYPEOFN : 0
[Sep 10 13:43:09]    CALLING TRANSIT : 0
[Sep 10 13:43:09]    CALLING NAME    : Pavel Jezek
[Sep 10 13:43:09]    LANGUAGE        : en
[Sep 10 13:43:09]    USERNAME        : ipbx
[Sep 10 13:43:09]    FORMAT          : 2
[Sep 10 13:43:09]    CAPABILITY      : 57610
[Sep 10 13:43:09]    ADSICPE         : 2
[Sep 10 13:43:09]    DATE TIME       : 2007-09-10  13:43:08


[Sep 10 13:43:09]     -- Call accepted by 192.168.36.134 (format alaw)
[Sep 10 13:43:09]     -- Format for call is alaw 

Issue History 
Date Modified   Username       Field                    Change               
====================================================================== 
09-10-07 06:40  pj             Note Added: 0070248                          
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