VoIP Spear has always included the ability to calculate MOS using the big three codecs of VoIP: G.711, G.723, and G.729. We’ve recently added support for GSM, G.722, Speex, and iLBC.
VoIP Spear uses the E-Model of computation for estimating MOS from network statistics like packet loss, latency, and jitter. In order to complete the E-model calculations, we need to know some characteristics about each codec. For example, how much does the codec itself degrade voice quality. Another characteristic would be: how does the codec perform under packet loss conditions.
For G.711, G.723, and G.729, it’s very easy to find this information because these codecs have been studied a great deal. This isn’t the case for Speex and iLBC. It’s hard to find information because they are newer codecs and weren’t developed by the ITU. As a result, there haven’t been many studies that look at these codecs in the context of the E-Model. Nevertheless, we managed to track down a few papers here and there. We’re confident our MOS calculations for Speex and iLBC are accurate.
Calculating MOS from G.722 is a different situation altogether. G.722 is a family of codecs (G.722.1, G.722.2) that is available at several different bit rates. In fact, quality is greatly affected by the bit rate that is used. We didn’t want to include all of these bit rates because we want VoIP Spear to be easy to use. Also, some of the other codecs (G.723, iLBC) also provide different options for bit rates so we wanted to be consistent.
In the end, the compromise we arrived at was to assume that G.722 is used at 64kbps. Without any impairments caused by the network, this will provide quality better than even G.711.
We hope you enjoy the new codec choices. If you have any other to suggest, let us know.
It’s not news that VoIP is becoming more and more mainstream all the time, but it sometimes amazes me how far it’s come. I first started up a VoIP company about 9 years ago and VoIP was so far out on the fringes that we would never use that term when speaking to customers.
Today, I came across a blog posting about potential uses for VoIP in a physician’s medical practice. Seven Great Applications for IP-PBXs in the Medical Practice is a quick read and worth a few minutes of your time. For me, the most interesting takeaway from the article is that it confirms how far into the mainstream VoIP is when there’s articles discussing its uses for such a narrow vertical.
And as VoIP use increases and becomes more commonplace, there will be an increased need for our VoIP Spear monitoring service.
A while back, I noticed a nice little feature about VoIP Spear at VoIP Resources. It’s flattering to see a positive review like this.
We’re especially pleased that the author of the article really seems to get VoIP Spear. She starts off by describing VoIP QoS problems at a high level. When VoIP Spear is introduced as a tool, the article mentions that one advantage is that it is “no-client side”. This is a subtle point that is easy to overlook — there’s no software to install. You can just enter your IP address into the VoIP Spear web site and it will start its monitoring.
The article also mentions that you can view your VoIP QoS results in a chart or table format, and that there are several options with regards to our account packages. About the only the article gets wrong is when it mentions that VoIP Spear servers run tests to the endpoints every 5 minutes. In fact, our servers monitor the endpoints every 1 minute.
In any case, thanks for the great article, Lauren.
My family and I are on holiday in Croatia right now. We’re staying in a bungalow on the Adriatic Sea in a little town called Brodarica and it’s been very hot (35°C or 95°F). As I type this, I’m looking onto a peaceful morning on the Mediterranean. There’s boats sailing by, children playing in the sea, and I can hear all sorts of sounds from birds and insects in the trees.
This morning, I logged into my VoIP Spear account to check how things have been going. There was a bunch of new signups, and a couple of new paid subscriptions since yesterday. I’m happy. In fact, I’m more than happy. I’m ecstatic. I’m able to keep tabs on my world (email, VoIP Spear) from the comfort of this other world.
Life is good.
Just a quick posting to tell you that we’ve replaced our “North America: North” server. It’s been giving us problems of late so we decided the best solution was to retire it. The new server is on the East Coast and we’re pretty happy about that — we now have servers on the West Coast, East Coast, and in the middle of North America.
It was a performance issue that finally caused us to make this decision. It had degrading to the point where the results from our VoIP testing was compromised. We found ourselves spending time diagnosing the issues and making little changes here and there to work around the problems. In the end, we’re happy to rid ourselves of that headache.
We have automatically updated all VoIP tests to use the East server if they were using the North server previously.
May 17, 2010
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