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About Mumble

What is Mumble?

Mumble is a voice chat application for groups. While it can be used for any kind of activity, it is primarily intended for gaming. It can be compared to programs like Ventrilo or TeamSpeak. People tend to simplify things, so when they talk about Mumble they either talk about "Mumble" the client application or about "Mumble & Murmur" the whole voice chat application suite.

What is Murmur?

"Murmur" is the name of the server application. In any case, if anyone talks about Murmur it is for sure the server part.

What platforms does it run on?

The client, Mumble, runs on Windows, Mac OS X and Linux.

The server component, Murmur, should run on anything you can compile Qt 4 on.

What are the system requirements?

The client runs on any Windows, Linux or Mac OS X machine. You also need a microphone. The server is mostly bandwidth bound, so as long as your network hardware is sufficient it should run on pretty much anything.

Please note that the Windows binaries distributed from SourceForge are compiled for SSE (Pentium 3 or Athlon-XP). Mumble is a VOIP solution for gaming, and as most modern games require at least that good a CPU it makes little sense for us not to optimize for it.

Installing Mumble


Compiling Mumble



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.

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 noticeable 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 asymmetric lines and hence it is only upload that is a bottleneck.

What tools did you use to make this?

See Development Tools.

How can I help or contact you?

A good start would be just using Mumble. If you like it, tell all your friends. If you do not like it, tell us what is wrong so we can fix it. You can do so via the forums or meet us on IRC at irc://irc.freenode.org/mumble If you have a bug or error that you need help with it also helps to read over Debugging to learn how to give the developers the information needed to help fix the bug.

Audio Features

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. You can find a list of supported games in the Games article.

Why does Mumble sound so much better than other voice products?

One word: Denoising. This is a standard part of Speex 1.1 and above, and any voice product already implementing speex should be able to trivially include the same filtering. Removing the noise from the input means that the audio will be clearer and that the needed bitrate will decrease. It takes fewer bits to model clear voice than it does to accurately represent the noise, so in any noisy transmission a large share of the bits will be noise modelling.

The text-to-speech quality is horrible!

We use the standard MS Speech API, and the included voices are not all that good. If you have installed either MS Office or the Speech SDK, you will get more voices which can be configured from the Speech control panel. You can also buy a commercial Text-To-Speech engine; as long as it's SAPI5 compatible it can be used by Mumble. The main developers are currently using NeoSpeech Kate (buyable standalone from NextUp).

Why do some voices sound metallic?

Mumble uses Speex noise filtering, and if the environment of the sender is especially noisy, some parts of the voice will be filtered as well. The alternative would be noisy sound, meaning precious bandwidth would be used to encode noise and the clarity of the voice would also decrease.

Why doesn't the voice activity detect my voice any more?

If you change your audio environment suddenly and drastically, by for example disconnecting and reconnecting your microphone or dragging a piece of paper directly over the microphone, you will throw the voice preprocessor off balance. It will recover, but it will take time.

To reset the preprocessor, choose 'Reset' from the 'Audio' menu.

What is this weird echo I hear of myself from other users?

Unfortunately, a lot of popular headsets produce tiny traces of echo. In other VOIP products, you will not notice it because the echo is lower than the noise level, but as Mumble dutifully removes all noise, the echo suddenly becomes clear. There is little the person hearing the echo can do, but there are a few things the person producing the echo can do. On Vista, we support echo cancellation for any sound card. On Linux, we support echo cancellation when using PulseAudio, and on Windows XP we support echo cancellation using ASIO (which unfortunately requires a very high quality soundcard with ASIO drivers).

The more troublesome solution is to modify the headset. If it is possible to pry the arm with the microphone from the headphones, do so and reattach it with a thick piece of rubber tape; this should insulate it from vibrations. If your headset is open (no large earmuffs), there exists an echo path through air from the headphones to the microphone. You can fix this by attaching anything foam-like to the front of the headphones to muffle the sound heard outside them, but this will most likely ruin the ergonomics of the headset as well as look somewhat odd.

We might put up a page of "tested headsets" if anyone wants it.


What sort of bandwidth will I need for the server?

Worst case scenario: Number of users × Number of talking users × 60 kbit/s. With less aggressive quality settings, it's ~20 kbit/s, and the bare minimum is 12kbit/s. Note that Mumble is geared towards social gaming; its quality enables people to talk naturally to each other instead of just barking short commands, so the amount of "users talking at the same time" can be somewhat higher than expected.

This means that a server with 20 players and 2 players talking at once requires 0.8-2.4 Mbit/s, depending on quality settings. In the server's .ini file, you can specify the maximum allowed bitrate for users as well as the maximum number of clients to allow.

Where do I configure the welcome message, listen port and so on?

murmur.ini, it is self-documenting.

murmur.ini is located in your Mumble Program Files folder on Windows, and in /etc/mumble-server.ini on Ubuntu.

What is the default server port for Murmur?

The default server port for Murmur is UDP and TCP 64738.

Can I run multiple servers on one host?

Yes, Murmur supports virtual servers. See Running_Murmur

How do the ACLs work?

See ACL and Groups

Where is the administrator account?

The topmost user in the Mumble hierarchy is the useraccount "SuperUser", which bypasses all permission checks and is always allowed to do anything. SuperUser can't be used as a normal user account (it can't talk) and should only be used for initial configuration or to recover from misconfiguration.

To set the superuser password, start murmur with

murmur.exe -supw supersecretpw


murmurd -supw supersecretpw

How can I reset the database?

Delete the murmur.sqlite file.
Rerun the command:

murmur -supw <password>

How can I add an user?

See Running_Murmur

How can I change a user's password?

See Running_Murmur

How do I backup the database?

Shut down the server (kill the process), and make a copy of murmur.sqlite. That file is the database.

How do I run Murmur as a Linux/Unix Sys V service?

There's an example in scripts/murmur.init

Common Problems and Resolutions

Can't hear other users/users can't hear me

First check that you can hear yourself in the Audio Wizard. If you can't, then there's something wrong with your local audio configuration.

Next, turn on the Expert Config options, and turn the Loopback Mode to "Server" under "Audio Output". If you can hear yourself talk while connected to the server, your network settings are fine; the problem is other users.

If you can hear yourself in the audio wizard, but not when using server loopback mode, something between you and the server is blocking UDP packets. Try turning on "Use TCP Mode" and reconnect to the server.

My server has multiple IP addresses. How can I make Murmur listen on a specific address?

The host= option in murmur.ini lets you do this. If the option is blank (the default), it will listen on all addresses.

Server connection rejected: Invalid Password.

This simply means the server password was incorrect, next time make sure you type in the password in the password box on the connect window.

Server connection failed: Host not found.

This means that there is no computer at that ip address, double check this is the right IP

Server connection failed: Connection refused.

This means there is a computer there but that is the incorrect port, double check the IP to make sure that this is the right computer, if it is then check what port you are supposed to connect on and put that in the port box on the connect screen.

I get disconnected from the server as soon as I connect.

This can be due to a version mismatch between the server and the client. Ask the server owner about the version that its being used, and get that version.

I've Tried the above but it will not connect

Are you on a Network make sure the port is open and the same if the host is on a network.

I tried but the port is open and it still will not connect

Then you should enable port forwarding on your router to your computer for the port. To get your LAN IP address:

  • Windows: press run then type "cmd" (no quotes) and type in "ipconfig" and it will display your IP address next to IP Address.
  • Linux and other unixes: On a console, type ifconfig. Your IP is next to inet addr:

Mumble gives me a BSOD when I try to start it.

Mumble has no kernel components, and as such cannot cause a BSOD. A BSOD is an indication of faulty drivers or faulty hardware. Run several stress tests such as Prime95 to ensure that your system is stable, and also check all other components of your system. A few runs with Memtest86+ are also recommended. Besides this, install the latest drivers, firmware, and BIOS's for your computer.

For some reason my game will crash when I'm running Mumble

The Mumble Overlay is a nice feature that many people use, but because of the rendering methods it uses to display the overlay while you're in a game, it can sometimes make the game crash or not work properly. You can find a list of games that are known to have issues with the overlay and how to solve problems experienced in these games in the Games article. You can also find an application incompatibility list on this page as well.

I'm running many virtual servers or have many users connected, and the server becomes unstable

A phenomenon experienced mostly by commercial hosters who have a lot of virtual servers running. To fix the issues, you need to make sure you use a Qt with glib support.

Second, you need to make sure your per-process file limit is high enough. For most distros, this is done by editing /etc/security/limits.conf. Add the following:

*       hard    nofile  8192
*       soft    nofile  8192

Restart your sshd, log back in and recheck the limit is now 8192 by checking 'ulimit -n'. If you run murmurd as

murmurd -descriptors

It will perform a file descriptor test

Compilation / installation problems

mumble.pri:8: Unknown test function: CONFIG

Mumble requires Qt version 4.3 or better; you are running qmake from Qt 3

Error message in murmur.cgi line 118

You need an MTA on localhost unless you have defined a different SMTP server.

Language Translation

If you want to get more information about Mumble Translations or want to help out translating Mumble, take a look at the Language Translation Page.


Many people use Mumble for podcasting/radio because of it's high quality and low latency, and we realize that some people want to record their conversation on Mumble for these types of purposes.

On Windows this is fairly simple, there are many different programs that can capture audio. Audacity is a good program for doing this. Many people just use a spare computer they have and login to the Murmur server and set Audacity to record "What U Hear".

If you using PulseAudio, read this this guide on how to record Mumble conversations. The guide is written for Gentoo Linux, but users of other systems should be able to adapt this guide to their system.