[asterisk-bugs] [Asterisk 0018397]: IAX2 CODEC_PRES wrong (offset error?)

[Asterisk Bug Tracker]

A NOTE has been added to this issue. 
====================================================================== 
https://issues.asterisk.org/view.php?id=18397 
====================================================================== 
Reported By:                birgita
Assigned To:                
====================================================================== 
Project:                    Asterisk
Issue ID:                   18397
Category:                   Channels/chan_iax2
Reproducibility:            always
Severity:                   minor
Priority:                   normal
Status:                     feedback
Asterisk Version:           SVN 
JIRA:                        
Regression:                 No 
Reviewboard Link:            
SVN Branch (only for SVN checkouts, not tarball releases): N/A 
SVN Revision (number only!): 296230 
Request Review:              
====================================================================== 
Date Submitted:             2010-11-29 08:41 CST
Last Modified:              2010-11-30 16:17 CST
====================================================================== 
Summary:                    IAX2 CODEC_PRES wrong (offset error?)
Description: 
On an incoming IAX2 call, the console reports (correctly):

Tx-Frame Retry[000] -- OSeqno: 000 ISeqno: 000 Type: IAX     Subclass: NEW
   
   Timestamp: 00005ms  SCall: 09646  DCall: 00000 [94.12.29.127:2705]
   VERSION         : 2
   CODEC_PREFS     : (gsm|ulaw)
   FORMAT          : 2
   FORMAT2         : gsm
   CAPABILITY      : 6
   CAPABILITY2     : unknown
   ADSICPE         : 2

However, Asterisk sends over the wire as value for CODEC_PREFS: "CD"
This is incorrect. It should be "BC":

A = "AUDIO_G723",
B = "AUDIO_GSM",
C = "AUDIO_ULAW",
D = "AUDIO_ALAW",

In this case codec negotiation does not fail because of FORMAT(2).
====================================================================== 

---------------------------------------------------------------------- 
 (0129222) tilghman (administrator) - 2010-11-30 16:17
 https://issues.asterisk.org/view.php?id=18397#c129222 
---------------------------------------------------------------------- 
More to the point, that IAX2's codec preferences start at 'B' is a legacy
behavior that would break every version to date, if this were to change. 
There is no specific information on how the encoding should occur in RFC
5456, so interoperation with existing implementations, namely Asterisk and
iaxclient, becomes the primary source. 

Issue History 
Date Modified    Username       Field                    Change               
====================================================================== 
2010-11-30 16:17 tilghman       Note Added: 0129222                          
======================================================================