Additionally, you can create a tempo change at the cursor position by clicking the small note icon next to the name of the tempo ruler, and Pro Tools will automatically shift the time scale accordingly. Alternatively, you can drag out a selection in the Edit Window, and tell Identify Beat which bars lie at the start and end of this selection. This lets you specify the bar number at the current cursor position. A simple way of creating anchor points (and the only way in non-TDM systems) is to use the Edit Menu's Identify Beat command. Pro Tools' tempo map consists of anchor points marked out along the tempo and meter rulers in Edit Window signifying changes in these parameters. Beat Detective can also achieve this latter result by storing tempo-map snapshots as Groove Templates for later use, leaving the song's grid alone. More subtly, you might wish to take the 'feel' of a good performance, and imprint the timing variations into the tempo map so that other tracks can be quantised with a similar groove. Constructing a Bars/Beats grid around the audio will make it possible to add extra MIDI tracks, and speed up editing and arranging.
For a start, you might have a multitrack song that's been recorded as audio without any absolute timing reference (maybe from tape), and you want to bring it into Pro Tools. There are a number of reasons why you might want to do this. However, Beat Detective can also be used the other way around: for taking existing audio and conforming a song's tempo map to the recorded performance.
When quantising MIDI, the notes are moved closer to the Bars/Beats grid, and last month we saw how the TDM/HD-only Beat Detective tool is used to quantise audio by moving individual drum hits with respect to the grid. Typically, when starting a song from scratch, you'll manually set these values to what you want, then start recording MIDI and audio. When you create a new song, the tempo map starts off as a steady 120bpm 4/4 grid. In common with most music recording and sequencing packages, a Pro Tools song contains a tempo map, or bars-and-beats scale that measures musical time from left to right across your display.
Now it's time to look at the other side of the coin: extracting and using the tempo and timing of a recording. Last month we looked at using Pro Tools' Beat Detective tool for chopping up and quantising drum recordings. Selecting a kick drum track from which to derive a tempo map.