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Re: [Linphone-users] typical delay (latency) time ?


From: Simon Morlat
Subject: Re: [Linphone-users] typical delay (latency) time ?
Date: 25 Aug 2002 13:26:15 +0200

Hi,

You don't have to choose the alsa mode in linphone. Alsa drivers are
fully compatible with oss ones. The alsa mode of linphone makes linphone
using the alsa drivers through their native user level library
(alsa-lib). However it is deprecated since it only works with
alsa-lib-0.5.x.
Try linphone-0.9.0pre4, the sound selection combo box has desapeared (no
more confusion possible), and some work has been done to improve
latency.
Don't forget that you can reduce latency by reducing the jitter
compensation parameter in the rtp section of the property box.

Simon

Le lun 12/08/2002 à 18:24, Marc-Olivier Bernard a écrit :
> 
> Thanks for your helpfull comments.
> 
> We change the drivers to alsa, and the size of the exchanged blocks was 
> shorted from 2048 to 512, and the delay is quite acceptable now.
> 
> But i still got some errors message, when launching linphone :
> 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> address@hidden mob]$ linphone &     
> [1] 2241
> address@hidden mob]$ L3 -1029168427- <osipua.c: 59> info: Starting osip stack 
> and osipua layer.
> L4 -1029168427- <udp.c: 75> info: Entering osipua thread.
> You cannot use alsa drivers: recompile linphone with installed alsa 
> drivers and library for that, or use oss.Found 3 interfaces.
> Found ppp0 interface with ip address 212.11.36.114
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> and when selecting alsa driver in connection > parameter > sound 
> I can read  the following  message on the terminal :
> 
> 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ERROR: Linphone was not compiled with alsa support. Recompile it or use 
> OSS.
> Sound source selection changed to m.
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ps : I'm using linphone-0.8.0-1
> 
> Marc-Olivier BERNARD
> 
> On 4 Aug 2002, Simon Morlat wrote:
> 
> > Hi,
> > 
> > Usually most part of the delay comes from the sound driver/card. Good
> > drivers/cards have low latency, this means that blocks of data exchanged
> > with the application can be short (256 or 512 bytes). Bad drivers/card
> > can only exchange data with a size of 8192 bytes (0.5 sec) or sometimes
> > 16384 bytes (1 sec) for some old isa cards.
> > Alsa drivers usually have a better latency, that 's why I recommend
> > them.
> > Here is a formula that should give the delay for one direction:
> > delay=MAX(local_driver_latency,codec_latency)+jitt_comp+
> >     (ping_delay/2)+MAX(remote_driver_latency,codec_latency)
> > You can see the driver latency on the terminal when linphone is running:
> > you should see a message "blocksize=8192" or something like this. The
> > value is given in number of byte, just divide by 16000 to get it in
> > seconds.
> > 
> > So there two things to try for you to improve this delay:
> > -alsa drivers (but don't change anything in linphone's configuration,
> > and don't recompile it)
> > -set jitter compensation to the minimum on both (perhaps you are
> > already)
> > 
> > With two PC's connected by ethernet cards (ping=1ms), and alsa drivers
> > (ens1374, cs41xx), jitt_comp=60ms I have a one way delay of approx 1/4
> > seconds. This is very acceptable. With adsl connections, the ping time
> > is about 80ms, however this is still very acceptable (not very different
> > of a cellular phone call).
> > 
> > Salutations,
> > Simon
> > 
> > Le dim 04/08/2002 à 19:02, Marc-Olivier BERNARD a écrit :
> > > Hi there,    
> > >     
> > > I encounter important delay by using VoIP/liphone, about 1s and don't  
> > > understand why.  
> > >   
> > > I'm using linphone between 2 computer (see below for system infos) both  
> > > connected to internet with (A)DSL, with   
> > >   
> > > * ping average time is 120 ms.  
> > > * sound traitement at both ends are quite quick (I did not try with an 
> > > ALSA  
> > > driver)  
> > > * both machines are directly connected to internet  
> > > * no delay due to firewall (i tried without firewall)  
> > > * codecs G711  
> > > * jitter compensation of 60 ms  
> > > * no proxy  
> > >   
> > > and the delay is around 1s. I don't understand the origin of such a delay 
> > > ? 
> > >  
> > > What kind of delay do you have ? and do you have any idea how to get it 
> > > better 
> > > (install ALSA driver for ex.) ? 
> > >   
> > > system infos :  
> > > ~~~~~~~~~~~~~~  
> > > linphone-0.8.0-1  
> > > redhat 7.3  
> > > OSS driver  
> > > SoundBlaster 5.1 live (full duplex)  
> > >     
> > > --     
> > > Marc-Olivier BERNARD    
> > > 
> > > _______________________________________________
> > > Linphone-users mailing list
> > > address@hidden
> > > http://mail.freesoftware.fsf.org/mailman/listinfo/linphone-users
> > > 
> > 
> > 
> > 
> > 
> 
> -- 
> Marc-Olivier BERNARD
> address@hidden
> 
> 
> 
> 
> 
> 
> 






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