Here are a couple of threads that deal with various aspects of the subject (quite a bit to plough through, unfortunately )…
But the basic principle is…
- Put all tracks (MIDI, and audio if present) into Linear Timebase, as opposed to Musical Timebase (toggle the “quarter-note” icon of each track into a “clock” icon). Also, if present, make sure that all audio clips (in the Pool) do not have Musical Mode activated.
- Make sure that Tempo is set to “Track” rather than “Fixed” (in the Transport Bar). Open the Tempo Track Editor, and set a basic tempo in Cubase that is reasonably close to the starting tempo of your music.(don’t worry, because you have set to Linear Timebase, this will not affect the actual tempo of the music )
- Drag the events on all tracks, so as to make the first downbeat of the music correspond with a barline in the Cubase grid. (allow yourself a bar or two at the beginning… you might eventually have need for a count-in, for example )
- Create a MIDI track (Linear Timebase, this one also ), with its output set to some metronome-type sound, and record, “tapping along” with the recorded music (probably quarter-notes is best).
Because this is just a regular MIDI track, you can edit this tapped performance until you are satisfied with it (the better, and more “musical”, this click track sounds against the music, the better the eventual Tempo Map will be )
- Select the MIDI Part containing the tapping, then go to the MIDI menu>Functions>“Merge Tempo from Tapping”… set the parameters as desired… if you had tapped as quarter-notes, then set “Tapping” to 1/4, and “Begin at Bar Start” (unless the music starts with an up-beat, of course ). Hit “O.K.”
Normally, that should be it!
Now (and only now, not before), if there are any time signature changes to be made, do so. (Cubase always makes its calculations in “beats” rather than “bars”).