Mumble v1.1.1
Platform: Windows

What is Mumble?

Mumble is a voice chat application for groups and gaming. While it can be used for any kind of activity,
it is primarily intended for gaming.

The client, Mumble, runs on Windows (XP/2003)
and Linux.

What are the system requirements?
The client runs on any Linux or Windows machine,
and you also need a microphone to voice chat.

What makes Mumble better?

Mumble has very low latency combined with good sound quality; it uses Speex extensively, not just the voice compression technology, but also the voice preprocessing to remove noise and improve clarity. Mumble also has positional audio for supported games, meaning the other players' voice will come from the direction their character is in game.
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What are the bandwidth requirements?

From 0.9.1, this is highly variable, and mostly up to the user. With top quality, minimum latency and positional information sent, it is 64.6 kbit/s including the IP and UDP overhead. With 80 ms transmission delay, the lowest quality speech and no positional information, it is 11.0 kbit/s (again with IP and UDP overhead). The default uses 45.4 kbit/s; we did not hear any noticable improvement in quality from the last 20 kbit/s. When comparing with other products, remember to compare the total bandwidth use and not just the bitrate of the audio encoding.

There are two parts to tuning the bandwidth; the audio bitrate per audio frame (20ms) and the amount of frames to put in each packet. Each transmitted packet has a overhead of 28 bytes from IP and UDP alone, so at the highest transmission rate (50 packets per second), that is 1400 bytes of data for raw network overhead alone. You should try to find a balance that works well for you, but we generally recommend sacrificing high audio bitrate for lower latency; Mumble sounds quite good even on the lowest quality setting.

There is no way to adjust the amount of incoming bandwidth; you will have to have enough to sustain the total amount of speaking players. This should be a minor issue; most players these days are on asymetric lines and hence it is only upload that is a bottleneck.

How does the positional sound work?

Your position ingame is transmitted along with every audio packet, and Mumble uses standard DirectSound 3D to position the audio on the receiver side. Only games for which a plug-in has been written get positional audio. All other games will work as well, you just will not get 3D sound.