Having found and programed the drum score for Stairway to Heaven into Superior Drummer it became necessary to setup the time matrix inside the DAW (Reaper). In most songs you set the time signature and BPM, and start recording your tracks. Stairway is a bit more complicated than that as it has several tempo changes in the song and a gradual tempo crescendo through different sections. (there’s even a tempo crescendo during a decaying note rest/transition that confounds even the best time keepers). This makes setting up your DAW very challenging and there’s no way to do it beyond trial and error.
Options that were available to me were to drag the actual Zeppelin recording into Reaper and start beat mapping the 1 for each measure based on visual transients in the wave file or through old fashioned knee slapping (possibly using the knee slapping to trigger a midi tempo marker). Instead I opted for a more analytical approach. I’d follow song using sheet music as a reference and a timer. After a finite number of measures I would count the beats (based on the 4/4 time signature) and divide them by the time on the clock, working out the tempos in various blocks of the song. This allowed me to determine the starting tempo and to detect when the song tempo started to accelerate. I checked every major section and transition and got starting tempos for each and when I detected an acceleration I tried to find out exactly where it started was able to program that acceleration in Reaper (see below).
Once I had determined the tempos and tempos accelerations and sketched out the song’s structure in the DAW using markers and notation, it was just a matter of dragging the drum mid into Reaper and positioning it correctly in the matrix to be ready to record. The whole process from drum auditing to programing to temp mapping etc took me about two months. At this point I was ready to start recording.