Re: [iaxmodem-users] [hylafax-users] Modems Wedging

[Lee H. <fa...@ho...>]

James Lamanna wrote:
> On Thu, Aug 27, 2009 at 9:21 PM, Lee Howard<fa...@ho...> wrote:
>   
>> James Lamanna wrote:
>>     
>>>> Here's the last few lines from the iaxmodem output:
>>>>
>>>> [2009-08-27 09:15:07] Registration completed successfully.
>>>> [2009-08-27 09:16:02] Registration completed successfully.
>>>> [2009-08-27 09:16:57] Registration completed successfully.
>>>> [2009-08-27 09:17:52] Registration completed successfully.
>>>> [2009-0[2009-08-27 09:32:53] IAX2 jitter - last_ts: 50000, ts: -15516
>>>>
>>>>
>>>> Maybe the jitter line being the last line explains the Freeze?
>>>>
>>>>         
>>> I thought the negative value for ts was a bit suspicious, so I decided to
>>> dig
>>> around in the source a bit, and also disabled the jitterbuffer.
>>>
>>> Disabling the jitterbuffer seems to have prevented the wedge/hang problem
>>> of the modem, but I don't see in the code why it would hang on that
>>> condition,
>>> since the while loop is (last_ts + 20 < iaxevent->ts)
>>>       
>> Okay, that's some good information.  I'll have to look into it more deeply
>> when I have some time (hopefully this weekend?).
>>
>> But truth told the iaxmodem jitterbuffer was probably a bad idea.  I'm not
>> sure that I've ever seen it do any real good.
>>     
>
> Ahh, now I understand what is going on here and why I was confused.
> iaxevent->ts and last_ts are both _unsigned_, but the printf is printing them
> as signed integers. -15516 is a pretty large number when it is unsigned :)
> So that while loop was only going to execute (4294951780 - 50020) / 20 =
> 214,745,088 times! ouch.

To be honest I don't know why the IAX2 timestamp would suddenly have 
high bits set and then go back to not having them set.  They must be 
indications of something I missed while reading the IAX2 spec... or a 
bug of some sort.

However, in the next release any jump in the timestamp that seems 
obviously too long to be jitter will simply be ignored.  So the 
wedge/hang shouldn't happen in the next release.

Thanks,

Lee.