Hey there, I just tried to make couple of skype calls with my girlfriend and despite the fact that everything ran smoothly and there were no issues with the call itself whatsoever, I noticed a huge cpu load during the call. Something that does not happen when making a regular (non-skype) call. I took some screenshots of Conky, so you guys can see what I am talking about.





For some reason pulseaudio and telepathy-strea use too much CPU... Is there a way to fix this, cuz my battery drain while I'm on a skype call is really sky high... Any help will be appreciated

Normal phone calls use the phone's dedicated GSM hardware. Skype calls use the processor. The CPU load is as expected.

I see...didnt know that. Checked my mom's iPhone CPU load during a skype call and its the same thing...I guess I will have to carry a spare battery with me if I want to talk for more than 2 hours - 2hours and a half

Then, does having a higher cpu provide a definitive solution for this overload or having a dedicated hardware to handle voip communications?

A very good question indeed. Looking forward to an answer

Having a beefier CPU may not be enough. Think about it this way: some years ago, would you be able to run Skype on your 486 / early Pentium machine without feeling the strain on anything else running on it simultaneously?
What suddenly changed the desktop experience was hyperthreading and multiple cores. Then frequency stopped being so relevant.

I'm sure eventually multi-core ARM processors will be the norm for smartphones and as we move towards that, the strain of Skype and voip on the phone's processor will keep dropping.

Dedicated voip hardware would be awesome, but that may mean much higher prices. Also the more hardware you put into a machine, the more power it draws. There is always a compromise between capabilities and battery life.

I would possibly trade that GSM processor with a VOIP processor since I still continue my N900 communication based on WiFi only

What about the DSP, can't it be used for that?

I don't have any idea if the existing peripheral hardware (DSP and GSM modules) could be software modified to handle voip communications. Really, is this a software or hardware specific issue?

I just did a little armchair research on (read: "Googled for") "using DSP for VOIP". It seems that it should be possible for codec implementors to use the DSP in the cortex A8 in the n900.
I don't know if this is already being done. It may be possible to look up the source for the Nokia Sofia SIP stack - but I'm not sure if the voice codec is as open source as the SIP stack is.
Skype on the other hand is entirely closed source and the only way to find out is to ask the people at Skype. I've asked them questions before, but I've never gotten a straight answer for anything. The community forum around Skype is well meaning and as helpful as they can be, but they still don't know enough to answer implementation issues.