[Asterisk-bugs] [Asterisk 0009631]: improve jitterbuffer (jbtargetextra/minjitterbuffer)

[noreply at bugs.digium.com]

A NOTE has been added to this issue. 
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http://bugs.digium.com/view.php?id=9631 
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Reported By:                pj
Assigned To:                
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Project:                    Asterisk
Issue ID:                   9631
Category:                   Channels/chan_iax2
Reproducibility:            always
Severity:                   tweak
Priority:                   normal
Status:                     feedback
Asterisk Version:            SVN 
SVN Branch (only for SVN checkouts, not tarball releases):  trunk 
SVN Revision (number only!): 61800 
Disclaimer on File?:        No 
Request Review:              
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Date Submitted:             04-29-2007 06:32 CDT
Last Modified:              07-19-2007 12:19 CDT
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Summary:                    improve jitterbuffer (jbtargetextra/minjitterbuffer)
Description: 
I discovered, that jittertargetextra option works maybe not good as it
can,
eg. if I have jitter spike (rtt 5ms to 100ms) and jittertargetextra set to
150ms, so that total jb size (155ms) can compensate this (95ms) jitter
change,
but nagative aspect of how jittertargetextra is now implemented is, that
it _immediatelly_ extend jitterbuffer from 155ms to 250ms!
so it have all negative consequenses to voice quality as "primary" jitter
spike.
this can be improved by growing jitterbuffer size _gently_ and not make jb
size jumps.
I think also, that it will be really usefull to add similar concept like
maxjitterbuffer, to be able to specify also _minimum_ jb size, that jb size
shouldn't never drop below lower limit, regardless of actual measured
jitter.
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---------------------------------------------------------------------- 
 pj - 07-19-07 12:19  
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I agree, that consequence of jitter spike is legitimate audio dropout, but
my suggestion is to eliminate fast jitterbuffer groving (not to eliminate
dropouts at any time), that you alone said, is negative. Imagine current
situation with jbtargetextra, if it doesn't have some sliding mechanizm,
jitterbuffer is groving immediatelly and that spike is propagated to end
device, that react also with groving own's internal jitterbuffer, so we
even evoke two groving jitterbuffers in sequence - in asterisk and in end
device.
I also think, that _configurable_ minimum jitterbuffer threshhold should
help in some situations to eliminate negative consequences of frequent
jitterbuffer changes, that happened in some situations. 

Issue History 
Date Modified   Username       Field                    Change               
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07-19-07 12:19  pj             Note Added: 0067600                          
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