Using Sound Forge to create your own loops for ACID

by Gary Rebholz

It's a lot of fun to explore the vast collection of loops that you can find in the many loop libraries available from Sony Creative Software. And you can most often find something that works for what you're trying to accomplish in a composition. But there's a whole different layer of creativity to be experienced when you make, or cut, your own loops.

You can cut loops in a couple of different ways. You can cut them right inside ACID Pro software if you want to and sometimes that's a great way to accomplish the task, especially when you just want to create a quick loop and get on with your composition. But for those times when you want to cut several loops, you might find that the tools inside Sound Forge software make the job more efficient. In this article we'll take a look at the tools in Sound Forge 9 software that you can use to cut loops that work fantastically in ACID Pro software.

To get started, you can use Sound Forge software's recording capabilities to record some audio. Perhaps you want to create a bunch of loops from a lead guitar solo or a piano performance. Whatever you want to record, you can then use Sound Forge software to cut loops from the recorded performance.

You can also cut loops from an existing audio file. We'll follow that path in this article, so let's get started.

In Sound Forge software, click the Open button. In the Open dialog box, navigate to the file from which you want to cut your loops. Keep in mind that you need to own the copyrights or get permission from the owner of those rights in order to legally use the audio or any loops that you cut from it. I'm going to open a PCA file of a piece of music that I recorded using the multitrack tools in ACID Pro software.

Play your file. As it plays, poise your finger over the I key on your keyboard. When you reach a point at which you want to start your loop, press the I key. This marks an in point for a selection area in your file. The file continues to play. When you reach the point at which you want the loop to stop, click the Pause button. This stops playback and leaves the edit cursor at the point where you paused. Now, click the O key. This marks the out point of the selection area and, as Figure 1 shows, you can now see the selected area in the data window.

Figure 1

Select a portion of your file that you want to use as your loop.

Now that you've got the selection over the audio that you want to use for your loop, you'll need to verify that the section of the file you've selected will make a solid loop. You'll most likely need to tweak your selection so that it works flawlessly when you drop the loop into your ACID timeline.

A flawless loop is one that you can play repeatedly and never loose the beat. In other words, if it's a four-beat loop it lasts for exactly four beats. This is critical to creating loops that work in your ACID project. "Close enough" won't work, so the time you spend here tweaking the selection to be just exactly what it needs to be will be time that you won't later regret having spent.

As with many operations in Sound Forge software, you could approach the task of perfecting your selection in a number of different ways. I'll show you one technique, but I encourage you to explore other options once you get the idea of what we're trying to accomplish.

First, click the Loop Playback button if you're not already in Loop Playback mode. Notice that the loop region indicator above the timeline turns from gray to blue. Now, play the file and count along with the music. You should be able to readily determine whether the selection length does the job or not. If the file loops back and begins playing from the beginning of the selection before or after you count the appropriate beat, you'll be able to hear—and more likely feel—that something's wrong. Chances are, you could tighten your selection up a bit to make it work more effectively.

As the file continually loops through the selected area, try to determine which edge of the selection needs adjustment. Did you mark your in point late? Maybe your out point comes early. Once you decide upon the problem, drag that edge of the selected area to a more appropriate location.

You might have some difficulty in trying to find the perfect location for the selection edges. If so, use your mouse wheel or the Up Arrow key to zoom into your data window. The farther you zoom in, the easier it will be to find the proper in and out points and the finer adjustments you can make as you drag the selection edges left and right. You can also much more effectively identify the transients in your waveforms when you zoom in and that gives you valuable clues about where your selection edges should be. It might also help to maximize the data window to make the waveform as large as possible.

Keep tweaking your selection until you can count along perfectly with the music as it loops over and over.

Now that you have a solid loop selection, let's break out the ACID loop tools to help get the loop or loops you want. Choose Options | Preferences to open the Preferences dialog box. Click the Toolbars tab. In the Toolbars list, select the ACID Loop Creation Tools checkbox and click OK.

This opens the ACID Loop Creation Tools toolbar in a floating window. You can leave it floating freely if you want to, but I prefer to place mine in the main toolbar at the top of my window. To do that, drag the ACID Loop Creation Tools toolbar and drop it onto the main toolbar. As you can see in Figure 2, I like to position mine so that I have some space between my default tools and my ACID Loop Creation tools so that they stand out more effectively, but of course you can put them wherever you like them.

Figure 2

You can position the ACID Loop Creation toolbar anywhere on the main toolbar that you want to.

We'll skip the first couple of buttons in the toolbar for a moment and come back to them later. The next several buttons give you tools for changing your loop selection quickly. Click the Double Selection button. This doubles the size of your selection area so that if you had previously selected a one-measure loop, you now have a two-measure selection.

Click the Halve Selection button to make the selected area half its current size. You can use these two buttons to quickly test out what your loop would sound like if it were longer or shorter. Making the selection longer can also help you to determine whether you selected a good, solid loop or not.

Click the Shift Selection Left and Shift Selection Right buttons to change the position of the selection by the length of the selection. For example, say you have selected a one-measure area over measure 27 of a song. Click the Shift Selection Left button to move the selection so that it covers measure 26 instead. Now you can hear what a loop of that area sounds like. If you have a two-measure selection over measures 34 and 35, click the Shift Selection Right button to move the selection to include measures 36 and 37 instead.

The Rotate Audio button rearranges the audio in the file, so be careful because unlike the other buttons I've mentioned here, this one will actually edit your file—not just change your selection.

If you have nothing selected, the Rotate Audio button takes the first quarter of the file and moves it to the end of the file. If you have made a selection at the beginning of the file, it shifts the selected area to the end of the file. And finally, if you've selected the end of the file, it shifts the selection to the beginning of the file. Again, be careful with this button because with it you actually edit the audio in your file!

Click the Selection Grid Lines button to turn on grid lines. The lines can serve as a guide to line up with transients in your waveform as you tweak your selection. Click the button again to turn the grid lines off.

The box at the right end of the ACID loop Creation toolbar displays the selection's tempo as if the selection represents an entire composition. You can't change the value in that box directly, but it changes whenever you change the size of your selection, as you'll see next, when you provide Sound Forge with more information to use in calculating the tempo. You'll provide that information as part of the ACIDization process.

When you ACIDize a loop, you essentially stuff it full of the information that ACID Pro software uses to work its transposition and tempo matching magic. In other words, when you add the loop to an ACID Pro project, ACID Pro software uses the ACIDization information to ensure that the loop plays back at the tempo and key dictated by your ACID Pro project settings.

To start the ACIDization process, let's first break your selected loop out into its own data window. That way you'll ACIDize just the loop you want without having to worry about the rest of the file. To create a new data window that holds the looped section of this file, drag the selected area and drop it onto a blank area of the Sound Forge workspace. If you maximized the data window earlier, first click the Restore Down button so that you can see blank workspace area.

Now, click the Edit ACID Properties button. Figure 3 shows the Edit ACID Properties dialog.

Figure 3

Use the Edit ACID Properties dialog to specify what type of file you want to create for your loop. The file type you choose gives ACID Pro software important information about how to treat the file when you add it to the timeline.

Here you'll specify what type of file you want to create. Since we're creating a loop, select the Loop radio button. Now you need to know a little bit about your file. Choose the key in which your file was played from the Root note for transposing drop-down list. If you don't know what key it was originally played in, you'll have to do your best to figure it out. If the loop you're creating is a non-pitched instrument, like drums or a tambourine, set this to Don't transpose so that the pitch of the loop doesn't change when you change the ACID Pro project key.

Next, enter the number of beats in the loop into the Number of beats field. For instance, if you selected one measure of a composition in 4/4 time, enter 4 here. Now, click OK.

Next, click the Edit Tempo button. You'll let Sound Forge software calculate most of the information in this dialog box, but you may need to help a little. First, enter the number of beats in the selected area into the Selection length in beats fields. For example, if you selected eight beats worth of music, enter 8 into this field. Press the Tab key and notice that Sound Forge software recalculates the loop's tempo for you.

Next, enter the number of beats per measure into the Number of beats in a measure field. For example, if your song is in 4/4 time, it has four beats per every measure, so enter 4 into this field. Click OK.

Now, save the file as a WAV or PCA file. Sound Forge software stuffs all of this ACIDization information into the file and you're ready to use it in your next smash ACID Pro hit composition!

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