Working with Tempo and Audio Regions

Earlier in this lesson, you saw that the Anchor point ties an Audio Region to Logic's time grid. This is particularly important for situations where you must change your song's timing, such as when you're changing tempo.

1.	Press the spacebar to start playback.
2.	Double-click the tempo setting and change the song's tempo to 110 bpm. Notice that the Kick and Snare hits keep the correct timing, but the HH Region sounds completely off! This is because the Kick and Snare Regions are single hits, and the Anchors in these Regions tie them to the correct place in Logic's time grid, even when you change the tempo. The HH Region, on the other hand, is an entire loop with just one Anchor point. Unfortunately, as you slow down the playback tempo, this Region begins to play too quickly relative to the other Audio Regions in the song. But guess what? There's a quick and easy way to fix that.
3.	Set the tempo back to 120 bpm.
4.	From the toolbox, grab the Scissors tool.
5.	Hold down the Option key, and click the Scissors tool at exactly 1 1 3 1 (the beginning of the second eighth note of the bar). The HH Region is divided into eight equal sections. Pressing the Option key while slicing Objects is a great way to create several equal-size Regions out of one large Region. In this situation it is an ideal edit because there is a single hihat hit on each eighth note. Consequently, you have now created eight individual Regions, each with its own Anchor.
6.	Next, change the tempo back to 110 bpm. Because the HH Region has been divided into eight smaller Regions, and each of these smaller Regions has its own Anchor, the HH track now keeps time with the rest of the song. In fact, you can now change the tempo to anything you'd like and the HH will always play in time.
7.	Press the spacebar to stop playback.
8.	Over in the Audio window, notice that a bunch of new Regions have been created for the HH.aif file. Zoom out of the audio window to see all of the HH Regions, if necessary.
9.	Close the Audio window.

Adjusting Tempos to Regions

These days more than ever, music is based on sample loops. Unfortunately, you won't always know the bpm of the loop you're using, and that makes it hard to set your song's tempo or integrate the loop into the song. Thankfully, Logic provides an automatic way to set the bpm based on the length of an Audio Region, and it's called the "Adjust Tempo using Region Length and Locators" function. Let's import the 1-Bar Conga.aif loop and see how this function works. To import this loop we will use a trick you haven't seen yet, so follow the first few steps closely.

1.	From the Arrange window's toolbox, grab the Pencil tool.
2.	Press Shift and click the Pencil tool on the Audio 4 track at exactly 1 1 1 1. Shiftclicking the Pencil tool in the Arrange area causes the Open file dialog to appear.
3.	Navigate to the Lesson 4 Project Files > Audio Files, then select the 1-Bar Conga.aif file, and click Open. The file is added to Track 4 at 1 1 1 1. As you can see, the 1-Bar Conga.aif file is not quite one bar long at the song's current tempo of 110 bpm. Consequently, you can tell it must use a faster bpm. But how much faster? Let's find out.
4.	Make sure the 1-Bar Conga Region is selected.
5.	In the Bar Ruler, make sure that the one-bar Cycle range is enabled. As you saw in Lesson 3, the Cycle mode always cycles from the left to the right locators. With a one-bar Cycle range enabled, you can be sure the left and right locators are exactly one bar apart. This is important as you do the following step.
6.	Choose Options > Tempo > Adjust Tempo using Region Length and Locators (T). A dialog pops up to ask if you want to change the tempo of the entire song (globally) or if you want to create a tempo change for only the part of the song covered by the 1-Bar Conga Region (in this case, only one bar). If you choose Create, only one bar of your song will have its tempo changed to match the tempo of the 1-Bar Conga Region. All the other parts of the song will stay at their current tempo. If you choose Globally, the tempo changes for the entire song.
7.	Click the Globally button. The song's tempo changes to 114.0001 bpm. Why? Well, the Region is exactly one bar long, and the song's left and right locators are exactly one bar apart. When you adjust the tempo of the song using the "Adjust Tempo using Region Length and Locators" function, Logic looks at the length of the Region (one bar) and the distance between the left and right locators (also one bar) and makes them exactly the same. However, 114.0001 bpm is a strange tempo indeed! Perhaps there's a better option for matching the tempo of this Region to the tempo of the song.
8.	Press Cmd-Z to undo the tempo change. The song's tempo reverts to 110 bpm.

Adjusting Regions to Tempos

In the previous exercise you discovered that the 1-Bar Conga Region's tempo was approximately 114 bpm, but your song currently uses a tempo of 110 bpm. To resolve this difference in tempos, you must use a process called timestretching to change the 1-Bar Conga Region to match your song's tempo.

In the old days of audio design, this was a timeconsuming task that took a bit of trial and error using the Time and Pitch Machine, located in the Sample Editor's Digital Factory. But with Logic 7, this task is now easily and quickly accomplished right in the Arrange window using the new Adjust Region Length to Locators function.

But first things first: You are about to change the timing of an audio file. Before doing so, you must choose a Time Machine algorithm that suits the aural content of the file.

1.	From the Arrange window's local menus, choose Audio > Time Machine Algorithm > Beats Only. The Conga line is just a rhythmic pattern, with no pitch or melody, so Beats Only is an appropriate Time Machine algorithm choice. However, there are six Time Machine algorithms on offer, each particularly suited to a certain type of audio material. Selecting the correct algorithm will help you avoid introducing unwanted artifacts into your audio file. The available algorithms include: Version 5 The tried and trusted algorithm used in Logic 5. Any material A universal algorithm that produces acceptable results for almost any type of audio material. The best default algorithm choice. Monophonic The best one for mono vocal, brass, woodwind, or other mono Audio Regions. Pads The setting for Audio Regions with a lot of harmonic content (such as choirs, strings sections, or synth swells). Rhythmic The algorithm for steady rhythmic instrumental recordings (including synth stabs, rhythmic pianos, or guitar loops). Beats Only One that perfectly maintains the timing of percussive material; should be used with drum loops. With the correct Time Machine algorithm selected, it's time to adjust the tempo of the 1-Bar Conga Region.
2.	From the Arrange window's local menu bar, choose Audio > Adjust Region Length to Locators. TIP Adjusting Objects to tempos relies on the Region being a perfect loop. You may need to use the Sample window to trim your Audio Regions to the correct length before performing this function. Logic quickly processes the Region, and timestretches it. However, Logic may not have adjusted the actual Region boundary to match the new length. No problem, just grab the bottom right corner of the Region and stretch it out.
3.	Grab the bottom right corner of the 1-Bar Conga Region and drag right until it covers exactly one bar.
4.	Press the spacebar to start playback. The Conga loop plays in time with your song. In the next lesson you will discover another great way to work with the tempo of audio files: Apple Loops! In fact, you'll reinsert this Conga loop as an Apple Loop, so let's clear it out of the Arrange window for now.
5.	Make sure the 1-Bar Conga Region is selected and press the Delete key to remove it from the song.