[Freeswitch-users] Choppy sound with PCMU

Michael Jerris mike at jerris.com
Wed Dec 2 20:00:00 PST 2009

In short.  No, you can not for many reasons. The milisecond tic is  
used throughout the code even when there is not any calls up.  You can  
grep for switch_cond_next if you would like to see where but it is  
required to keep our global timestamp and for pacing the scheduler  
among other services that run all the time.


On Dec 2, 2009, at 7:31 PM, eaf <erandr-junk at usa.net> wrote:

> Can I reduce resolution of that timer thread 10 times? I mean, I  
> glanced
> through the code, and see that among others (are there others?) RTP  
> and IVR
> set up their timers that are subsequently managed by this thread.  
> RTP timers
> should be eliminated by that setting you've suggested. IVR timers  
> are set at
> 20ms... So, if the thread is set to wake up every 10ms instead of  
> 1ms it
> should be able to wake up those IVR timers just fine. Right?
> That's a cool design to have one dedicated thread that maintains  
> accurate
> timing and then broadcasts via condition variables to hundreds of  
> other
> threads events that they can register for. I'm sure it's one of the  
> reasons
> why FS scales so much better than Asterisk. But for poor low-end  
> setups that
> sit in the closet, eat only 6W of power and hardly ever run more  
> than two
> calls at the same time, can I hack it somehow to be more UNIX- 
> friendly? I.e.
> make it stuck in select() or recv() when there is nothing to do, call
> clock_gettime() right from the thread that wants and when it wants  
> to know
> current time?
> Say, what if that thread is made to suspend on a condition variable  
> in case
> if there are no timers registered in TIMER_MATRIX? Then, if some other
> thread comes up and adds its timer into the matrix, it could wake up  
> the
> timer thread and enjoy accurate timing as needed, on demand? And in- 
> between
> the calls, when there is no RTP or IVR, it will all go silent? I mean,
> sitting on a wait queue in the kernel is way better than go back and  
> forth
> incrementing counters that nobody even needs at the moment?
> Anthony Minessale-2 wrote:
>> idle is a 4 letter word to a realtime application.
>> The core keeps a single high-priority thread to keep 1ms timing and
>> expands
>> that broadcasting
>> to hundreds or thousand of threads who need accurate timing.
>> Your choppy audio is caused by linksys lying about the packet len  
>> that
>> it's
>> using and we set our timer
>> to the wrong speed.
> -- 
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