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glupa4e 05-18-2013 08:17 AM

Interruptions during Skype to Skype audio calls
 
Hello,
i am using the latest stable version of Skype for Linux - 4.1.0.20. I have Slackware64 14 with kernel 3.2.29. My internet connection is quite stable and fast enough for Skype. When I have audio calls with other Skype users, they report that in some time there are interruptions during the call and they cannot even understand a word I am saying. I can hear them well. It seems like in the beginning of the call, the quality is OK but in some time - a couple of minutes it starts to disrupt.
Any idea how to diagnose where the problem is?

chemfire 05-19-2013 07:26 AM

Well the first thing I would say is you need to narrow down the problem. Is it network or is it something to do with the application or audio subsystem. My guess is your Internet connection is asymmetric. So it may be that you are constrained going up but not going down. Usually VOIP ( I am not 100% about skype don't use it ) set up two separate network sockets, rather than write back on the same; especially if TCP is used. That way a lost or delayed packet on one stream does not impact the other. You can get a perfectly clear call in one direction and jitter in the other for network reasons alone.

Its crude but you could start with something like:
ping -s 1 -D $DFGW > $SOMEFILE

Where $DFGW is your default gateway and a $SOMEFILE is a file to write the output to. Do this during a call. If you see the intervals between pings changing much it could indicate congestion. You could then make another test call while your ping your partners public ip address. This might help identify congestion on your ISPs network.

glupa4e 05-22-2013 01:00 PM

Thanks for the answer, but let me go into details. What do you mean by default gateway actually? I have a router at home (IP 192.168.0.1) . My computer is connected via cable to that router. Then this router is in my ISP's network.
I have a real IP address which can be obtained using www.whatismyip.com. Do you want me to ping my real IP address and store the output to a file?
If a do
Code:

traceroute google.com
i get a list of IPs but as my surprise i could not see my real IP in that list of IPs.
Please let me know if i understand correctly your post.

mrclisdue 05-22-2013 01:25 PM

He wants you to ping your gateway (192.168.0.1) and direct the output to a file so you can review the output once your call has ended....

ping -s 1 -D $DFGW > $SOMEFILE

ping -s 1 -D 192.168.0.1 > skype_log

edit: oh yeah, I had a query: Have you opened ports for skype, or dmz?

cheers,

glupa4e 05-22-2013 01:34 PM

Quote:

Originally Posted by mrclisdue (Post 4956657)
He wants you to ping your gateway (192.168.0.1) and direct the output to a file so you can review the output once your call has ended....

ping -s 1 -D $DFGW > $SOMEFILE

ping -s 1 -D 192.168.0.1 > skype_log

edit: oh yeah, I had a query: Have you opened ports for skype, or dmz?

cheers,

OK, i will do that, i will ping my router' IP.
The other stuff i could not understand ;-(. I have never configured DMZ or opened any ports. I am with the default settings of a Slackware64 14 full install.

mrclisdue 05-22-2013 02:27 PM

Quote:

Originally Posted by glupa4e (Post 4956669)
...I have never configured DMZ or opened any ports. I am with the default settings of a Slackware64 14 full install.

Fair enough. Well, a down-and-dirty way to test whether it's a port issue would be to put your machine in a dmz. Be *warned* that this effectively removes your box from your router's default firewall. Just follow your router's documentation in order to do this; it should be a fairly trivial process.

My google-foo indicates that skype generally uses ports 80 and 443, but since it's proprietary and relies on proprietary mim servers, it's a toss up. According to this:

http://forums.whirlpool.net.au/archive/1980603 ,

it appears that your call quality may improve if you dedicate at least one port (other than the default) to listening, and open that port on your router's firewall if your machine isn't dmz'ed.

I don't have the greatest internet bandwidth speed, and the few times I've used skype it's done its job, so I can't serve as a decent example, but I would expect that unless your speed is horrible, you should be getting decent results by default.

Hope I haven't muddied the waters.

cheers,

glupa4e 05-22-2013 03:46 PM

Skype logs
 
3 Attachment(s)
Hello
here are the 3 logs that I made during the Skype calls. I can see that they look identical.
This time there was no interruption during those 3 calls.
Before, when i had noticed the problems, i was using the default sound device in Skype. Then i installed jack and pusle and some devices were removed. Then i chose another device which luckily still was working. Then i made those 3 calls. I am not sure if that could be the problem.
I will take some time for router settings next time.


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