Archive for the 'Embedded' Category

PJNATH ICE Heap Memory Usage Analyzed and Optimized

A new article was posted in PJSIP wiki: PJNATH ICE Heap Usage Analysis and Optimization, that shows how to optimize ICE heap memory usage, from around 76 KB of peak heap usage per call (or 25 KB after the call settles down), down to just 21 KB of peak heap usage per call (or 15 KB after the call settles down). And this was with STUN, ICE, and TURN enabled.

Evaluating PJMEDIA Performance

Performance is one of the most common questions that developers asked. We’ve been asked questions like, can I run X on platform Y, or how much MIPS required to run component X, and so far our answer would be I don’t know, or at best, why don’t you try it yourself and see what happens.

So we decided to do a bit of benchmarking for pjmedia for several platforms that we have, and you can see the result here:

The test covers various platforms, and sometimes the same H/W platform but different OS’es (Linux/gcc vs Windows/Visual Studio) to see how they fare, and of course various PJMEDIA components.

As the article says, there are some drawbacks about the test method used, but nevertheless I think it could be useful to see the rough CPU requirements of various PJMEDIA components. Certainly it has been useful to us, and in fact there have been some surprises with the results. For example, we expected that WSOLA (Waveform Similarity Overlap and Add, the algorithm that we use to conceal packet lost and to handle clock drifts) to take large chunks of CPU usage, but turns out it is quite fast. Also resampling with small filter looks to be quite affordable too.

We’ll look forward to measure the performance on more platforms (notably, Symbian), and we’ll keep track of the performance for future releases. In the meantime, enjoy the article.

Live from FOSDEM 2008: Day Two

This is the day for pjsip presentation, available as a Google Docs presentation.

The busyness of the FOSDEM is still here, probably a slower start due to Sunday morning (arrived at 09.00 for the Mozilla DevRoom Extensions Workshop, with only a few people but started filling up quickly).

I’m currently listening to Toshiharu Harada, a very nice chap from Japan discussing a secure Linux distribution.

Live from FOSDEM 2008: Day One

I arrived a bit late in the day, around 15.00. This is my first time going to FOSDEM, so I was not sure what to expect.

What I got was a lively bunch of free software and open source ‘enthusiasts’ (ok, hackers and geeks really), going in these lecture rooms. Tables on the corridors are populated by most well-known software projects, such various Linux distros, Mozilla, PostgreSQL, and others. The university settings of ULB gave it that extra touch of casual but studious atmosphere. I would guesstimate the attendace to be in the lower thousands.

As I am not due to present until tomorrow, I roam around a bit, and currently listening to the embedded power management session. As the whole place where FOSDEM is wired with wifi (meaning to provide wifi they run wires everywhere!), everyone is whipping out their laptops, smartphone, Nokia N810, Asus Eee and other devices, and probably doing three things at once.

All in all, if you are interested in free and open source software programming, this is the right place to be.

Open source SIP stack, media, STUN, and ICE for Symbian OS

Just yesterday I finished back porting the Symbian branch to the trunk, and I think it’s good to go.

It’s been a roller-coaster way, supporting Symbian. It’s not the most developer friendly OS to port your programs to (see Readers Write about Symbian, OS X, and the iPhone), but we knew that, and I felt that this should make a good challenge for PJLIB, to see if it lives to its extreme portability claim. So we first started the port on May 2006, created a Symbian branch based on, and estimated that the work will need couple of months work. It wasn’t long before we realized we needed more time, and we revised the target to September 2006. But we still missed the target anyway.

Only about two months later, on Nov 2006, where we really had all of the libraries ported (only sound device is missing). But by this time, this branch was lagging waay behind the trunk, so it will take significant efforts (and commitments) to bring the port into the trunk.

But finally we had gathered enough “motivations” to do this, few days back, and it’s here.

Symbian target is officially supported in the trunk. All libraries have been ported. All seems to be running fine. No more panics. No memory leaks. All is good to go. Sound device is still missing, unfortunately.

So what do we have for the Symbian port again? For those new to PJSIP projects, here’s all of them:

  • pjlib, our platform abstraction hero.
  • pjlib-util, an auxiliary library containing parts needed by upper layer libraries (things like text scanning, XML, DNS SRV resolution, and various encryption algorithm),
  • pjnath, a NAT helper library containing the latest STUN, TURN, and ICE,
  • pjmedia, the media stack,
  • pjsip, pjsip-ua, pjsip-simple, libraries containing the bunch of SIP features,
  • pjsua-lib, a library combining SIP, media, and DNS SRV/STUN/ICE into high level API, and
  • symbian_ua, a simple console based SIP user agent for Symbian, based on pjsua-lib.

Some screenshot? Sure:

SIP User Agent on Symbian Emulator

Screenshot of symbian_ua on S60 Emulator

It’s been fun programming on Symbian. Learning curve has been steep. The tools are not perfect. But now I think I’m relatively more comfortable with it, and it becomes just another target for coding.

For more information about using the Symbian port, please see Porting PJ to Symbian OS. The porting effort itself is tracked on this Symbian-Porting Trac page.

Have fun yourself!

pjsip for Windows Mobile and Windows Embedded CE – what’s the difference?

You can see for yourself the difference between Windows Mobile and Windows Embedded CE. As for pjsip, it should run fine on both of them, according to the documentation page Building for Windows Mobile Targets (WinCE/ PDA/ SmartPhone).

Let me know if you have problems or found significant differences when building pjsip for Windows Mobile versus Windows Embedded CE!

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