Before you actually get the warping process going, its a good idea to get Live’s master tempo set close to the tempo of the song you’re warping. Why? A couple of reasons. First off, when using Auto-Warp (which you may do later on) Live can use the current tempo as a hint. Second, when you turn on the Warp switch, Live will immediately begin trying to match the song to the master tempo. If this is far off from the song’s actual tempo, you’re going to hear a sudden jump in tempo that’s not going be helpful at all.
If you’re not sure of the song’s tempo, use the Tap button to tap along. You won’t get the tempo exactly right, but you’ll get close and that’s all that is necessary.
Remember, for this to work properly, the Warp switch must be turned off. The point here is to listen to the song at its original tempo and tap along to detect it.
With certain genres of electronic music, certain BPMs are so prevalent that I’ll skip tapping. For example, if its a techno track, I’ll just type in 127. Or if it’s Dubstep, I’ll type in 140 (or 70).