[asterisk-bugs] [Asterisk 0016999]: Bug in Calculating T.38 far max IFP?

[Asterisk Bug Tracker]

The following issue has been UPDATED. 
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https://issues.asterisk.org/view.php?id=16999 
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Reported By:                jasmin-annika
Assigned To:                
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Project:                    Asterisk
Issue ID:                   16999
Category:                   Channels/chan_sip/T.38
Reproducibility:            always
Severity:                   minor
Priority:                   normal
Status:                     acknowledged
Asterisk Version:           1.6.2.5 
JIRA:                        
Regression:                 No 
Reviewboard Link:            
SVN Branch (only for SVN checkouts, not tarball releases): N/A 
SVN Revision (number only!):  
Request Review:              
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Date Submitted:             2010-03-09 14:21 CST
Last Modified:              2010-03-10 10:13 CST
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Summary:                    Bug in Calculating T.38 far max IFP?
Description: 
Hi,

after having some problems with far_max_ifp, I noticed, that in the case
of a supplied value of max_datagram (from the far end) of "200" the
far_max_ifp is only 60.

When I unterstand the comment of the calculate_far_max_ifp function in
udptl.c correctly, it should try to produce a value greater than 80
(through decreasing the EC entries), but keep one EC entry in any way.

So in our example of 200 (far_max_datagram) the correct result should be
an IFP of 96 I think. (the main data (96B), One EC entry (96B), 8 Bytes
other Info).
But the function produces a value of 64 (the 5% extra space added later is
not considered), but this value is smaller than 80 and we have more than
one EC entry (exactly space for 2 of them, but the variable value is "1"
(which is also incorrect)). Pls see additional information for code example
and fix proposal.

I hope the calculations are correct and I am not telling nonsense ;-)

Thanks
Jasmin
 
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Issue History 
Date Modified    Username       Field                    Change               
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2010-03-10 10:13 lmadsen        Description Updated                          
2010-03-10 10:13 lmadsen        Additional Information Updated                  
 
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