If you've got a question that's not answered here, please post in the forums! Also see the Troubleshooting page.

This requires either a sound card with 4 (mono) output channels or multiple sound cards. Nearly all sound cards built into computers have only one output pair, so you will need to add a second sound card with one or more additional output pairs. See the DJ Hardware Guide for more information.

To make the track playing in your headphones not play on the main output, turn the volume down on the deck you do not want your audience to hear yet (or push the crossfader all the way to the opposite side) then press the headphone ('PFL') button for that deck. This will not turn down the volume in your headphones; it will only turn down the volume on the main output.

Click “Options” and select “Record Mix”. When you're done recording, go back to “Options “and toggle “Record Mix” again, or just exit Mixxx. To choose the recording format, click “Options”, then “Preferences”, then “Recording” and set the options as you like.

Yes. There are two ways to do it depending on what you want to achieve:

• Direct deck outputs: Direct deck outputs is a feature of Mixxx 1.9.0 onwards. Set the outputs in Options→Preferences→Sound Hardware and you're done. If you are on 1.8.x or below, the trick is to force Mixxx's master output to play back the left/top track, and the headphone output to playback the right/bottom track. (Each track will come out a separate output, suitable for plugging right into an external DJ mixer.) The way one does this is by sliding Mixxx's crossfader all the way to the left, and turning on the headphone cue for the right channel. This forces the first track to play out the master out, and the second track to play out the headphone out. (Since both outputs are now going straight into an external mixer, you'd use the headphone cue on the mixer as well as it's crossfader.) Using an external mixer is also described briefly in the Threadbox tutorial.
• Software mixing as an additional sound source: If you want to mix on-screen but need to integrate with an external mixer (such as when playing CDs and/or records as well, or in a radio studio) you can plug the headphone output into one channel of the mixer, and the main output into another. Then bring the channel fader of the headphone one all the way down on the mixer and set it to play in your headphones all the time (thereby adding Mixxx's headphone bus to the mixer's.) Then use the other fader (with Mixxx's main output) when you want to bring Mixxx's output into/out of the main mix.

See the manual chapter.

No, Mixxx does not write to or move any files in your library. It's safe to use Mixxx with your iTunes library - Mixxx will not change anything in your library.

There is an option to write metadata changes back to the file tags (e.g. ID3, Xiph/Ogg, APE) but this is disabled by default. You can enable it from the Mixxx Library Preferences.

Yes. Yes it does.

• Windows XP and newer. Windows 10 Beta support is spotty.
• GNU/Linux, with official binary packages for Ubuntu 10.04 (Lucid) and newer
• Mac OS X 10.4+

Many GNU/Linux distributions (e.g. Debian) bundle their own copy of Mixxx rather than relying on our official releases, check with your distribution for more details.

Of course as an open source project, source is always available to build for whatever platform you work on, either a Linux distribution which doesn't provide Mixxx packages or something more exotic. Historically Mixxx has been known to compile on FreeBSD.

We are always happy to hear from people building Mixxx on other platforms, whether you are doing a one-time build for yourself or maintaining a Mixxx package for a distribution please get in touch.

• MP3
• OGG
• FLAC
• WAV, AIFF
• AAC/M4A/MP4 (with plugin)
• WavPack (WV) (with plugin)

If your music isn't currently in one of these formats (or you don't have a suitable plugin installed) it won't show up in the Mixxx library. You'll need to use a program like Sox or Audacity to convert it.

Mixxx performs sample rate conversion on the fly.

Note that the quality of the re-sampling depends on the setting of the pitch behaviour. Having key lock disabled (“vinyl emulation” in 1.8.x and below) will use linear interpolation, which doesn't sound very good (you will notice graininess and increased noise, especially obvious on high, long notes). When you enable key lock (“pitch-independent time-stretch” in 1.8.x and below) Mixxx will use a vocoder-based algorithm from the SoundTouch library, which sounds a lot better (but is not recommended when scratching).

Unfortunately, this does not yet work automagically but needs some manual fiddling with the music configuration files. Here is one way of doing it:

1. Backup your mixxx configuration files (under Linux, this is .mixxx/ in the home folder)
2. Move your music folder to the new folder or new hard drive
3. Install SQLite Manager, which is a Firefox extension that lets you manipulate the mixxx database: https://addons.mozilla.org/de/firefox/addon/sqlite-manager/
4. Open the SQLite Manager from within firefox. Within SQLite Manager open the file mixxxdb.sqlite that can be found in your mixxx configuration folder
5. Go on Execute SQL and enter:

   update track_locations set directory = replace (directory, '/old/path/DJ/Music/', '/new/path/DJ/Music/'); 
   update track_locations set location = replace (location, '/old/path/DJ/Music/', '/new/path/DJ/Music/');

   where the old and new paths point to your corresponding music folders.

6. Then hit Run SQL. The above statements will replace all instances of /old/path/DJ/Music/ to /new/path/DJ/Music/ in the field of location and directory of track_locations table.
7. Start mixxx and under settings change your music folder to the new one. If you want you can do a rescan to check that the music files do not turn up twice suddenly (if you are on linux, do especially check music files which where in symbolically linked directory). Check if bpm and other meta infomation like cue points are still stored with the files.

Make sure Mixxx is closed, then look for “mixxxdb.sqlite” (or “mixxxtrack.xml” if using Mixxx 1.8.x or below) in:

• Windows: %USERPROFILE%\Local Settings\Application Data\Mixxx
• Linux/BSD/Unix: ~/.mixxx
• Mac OS X: ~/Library/Application Support/Mixxx/
  • If using Mixxx 1.8.x or below it is just like on Linux in ~/.mixxx

If you can't find it, search your computer for “mixxxdb.sqlite” (or “mixxxtrack.xml” if using Mixxx 1.8.x or below)

• If on Windows, Click Start→Run, type %USERPROFILE%\Local Settings\Application Data\Mixxx and click OK.
  • If you want to use “Find files/folders”, make sure to open “Advanced Options” and mark “Search Hidden Files/Folders”.
• If on Mac OSX, press Shift-Command-G or “Go to folder…” command in the Finder's Go menu. Then enter ~/Library/Application Support/Mixxx/.