The Sync button in this section of the GUI will attempt automatic adjustment between channels, which works on the basis of the previously assessed tempo of each track. This beat detection feature works pretty well for four-to-the-floor dance music like techno or house, but less well for the complex rhythms found in drum 'n' bass.
If beat detection fails and is displayed as 0.0, you have the option to enter the tempo of a track manually. To do this, rightclick on a file in the Library window, and select Properties to open the Track Editor dialog box. With the track in question playing, click the 'Push To Tap Tempo' button in time with the song, which in dance music usually means in time with the kick drum. The better you are at console games like Guitar Hero, the closer the result will be to the actual tempo of the song.
Sometimes beat detection doesn't work because the tempo is outside the range that Mixxx expects (by default, 70 to 140 beats per minute). To correct this for a fast song, use the Track Editor dialog to up the maximum end of the BPM range, perhaps to 150, then click on the Go button to begin detection. If the song has a slow intro that unbalances the result, check the 'Analyze Entire Song' box and try again.
Beat matching
Of course, there's more to mixing than just having two songs playing at the same speed. To enable smooth crossfades, beats and bars have to be lined up in a musical way. While that's largely a matter of the DJ's skill and judgement, Mixxx does allow you full control over the position in the track of the two waveforms.
Click anywhere in the waveform display and drag the mouse – the farther you pull the mouse to the right, the faster Mixxx will scrub through the file. Move the mouse to the left and the track will slow to a stop, then play backwards at progressively greater speed.
Mixxx draws lines on the waveforms to indicate the positions of the beats, but unless you're mixing very similar tracks, these beat lines can be misleading. There's really no substitute for using your ears, and that's where the real fun begins.
You can also play with the built-in equaliser (the knobs labelled High, Mid and Low on each channel) and the flanger effect to make your mixes more creative. When you've practised a bit and you're happy with the results, use Options > Record Mix so you can prove your abilities to the non-believers. And of course, if you create something that you think other people might like, let us hear it!
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First published in Linux Format, Issue 114
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