Mumble uses Qt, the Cross-Platform Rich Client Development Framework. Qt is used for cross-platform GUI, network and database functions. Its superior audio quality comes in large parts from Speex, a high quality voice codec and DSP library for echo cancellation and denoising.
It has been analyzed with Klocwork source code analysis, the most accurate and comprehensive tool for finding critical programming errors and security vulnerabilities
Mumble was made to improve voice communication in games. This program features shorter delay and better implementation of Speex than most other free clients. Plug-in support for postional audio in games has been implemented, and it comes with a plug-in for Battlefield 2. Installer includes the client Mumble and the server Murmur.
The current overlay texture system is designed for high speed texture transfers in a format that happens to be 60 pixels high. This is no coincidence.
Using H.264 encoding, 80x60 pixels is small enough that we can encode a 15fps video stream with minimal CPU impact. The bitrate will also be low (lower than existing audio streams), and with a bit of filtering the quality is near perfect. I really mean this; what filtering did for the audio quality in Mumble it also does for video quality.
I'd like to see this happen; I miss seeing my friends when we're gaming. It's one thing to hear enthusiasm, it's quite another to see it.
There are two major challenges. The first is a technical one. 80x60 pixels is not much. It is enough to see a face clearly, if the face is the only thing in the picture. However, most people have their cameras placed so that 70% of the picture area is the room they are sitting in. That will not give a good enouh picture. So, we'll need a method to extract what we need from the image.
The second is bandwidth. Yes, the video stream will use less bandwidth that an audio stream, but it will be going the whole time. This means that while audio bandwidth scales linearly with the number of users, video bandwidth scales exponentially. For example, if we assume that each user has 30 kbit/s of audio and 20 kbit/s of video. When one user talks, the others shut up. With 10 users, that's 9*30=270 kbit/s out from the server. Video, which is going the entire time, is 9*20=180kbit/s for each user, giving us a total of 1.8Mbit/s.
The license of this software is Freeware, you can free download and free use this audio utility software.