Patterns and Loops

Patterns and Loops

You can quickly and easily sketch musical ideas in software like Kinetic and GarageBand thanks to their fluid use of pre-built, repeating musical components . You can then store, edit, and develop your sketches .

Patterns are chunks of MIDI data, and are played by a virtual instrument. Since patterns are stored as notes and rhythms , not as audio recordings, it's easy to change individual notes or radically change their sound by assigning them to a different instrument.


Loops are short audio recordings, often one, two, or four measures in length, that can be repeated seamlessly. You can adjust their tempo and pitch independently (though with some degradation in audio quality), but it's difficult to edit individual notes since you must digitally modify the original recording.


REX files combine some of the features of audio and MIDI. Each file contains a number of separate samples (usually single notes) that are played by a MIDI file. REX files require special playback software.


We'll look at two applications that represent simplified, "sketchpad" versions of professional workflows: Apple's GarageBand on the Mac and Cakewalk's Kinetic on Windows. Both applications are serious tools, even if they lack some of the bells and whistles of their higher-end counterparts. GarageBand uses a timeline approach, which is similar to full-blown studio Digital Audio Workstations (DAWs) like Logic, whereas Kinetic's "virtual hardware" approach reflects how DJs and remix artists work. Both programs can be integrated with pro apps if you decide you need features like score printing, surround sound, and editing features that these applications lack.

On the DVD: Expand your loop library with an exclusive free collection of loops from SmartLoops (www.smartloops.com), which includes Apple Loops for use with GarageBand and ACID loops for use with both GarageBand and Kinetic (along with many other programs). Also on the DVD you'll find tips for making the most of loops musically.


Is It a Pattern, or Is It a Loop?

Since editable MIDI patterns and audio loops function differently, the software must provide a way of distinguishing which is which. In GarageBand, audio is blue and MIDI is green, both in tracks and in loops. As in other applications, you'll also see that the two contain different kinds of data: audio is represented as a waveform, whereas MIDI is represented as note data ( Figure 5.1 ). In Kinetic, everything is a pattern unless it's specifically labeled as an audio loop.

Figure 5.1. MIDI note data as graphical bars (top) and audio data as a waveform (bottom) in GarageBand.


Pitch/Tempo Independence

In the days of analog tape, the only way to adjust pitch was to raise or lower the speed at which the tape moved. Any change in speed generated a change in pitch. With digital data, it's possible to manipulate pitch and tempo independently. You can adjust MIDI data to any tempo or pitch imaginable, and thanks to digital audio processing techniques, the pitch and tempo of audio can also be modified independently, though when the changes are large you'll probably hear changes in the character of the sound.

Specialized loop formats ease the audio pitch/time-shifting process by adding meta-information to the file, in one of several standard file formats (see the sidebar "Standard Loop Formats"). By storing original tempo information and markers to locate where beats begin ( Figure 5.2 ), these formats make adjustments more musically accurate and aurally satisfying . Instead of time-stretching the entire file at once, the audio software can stretch or manipulate beats individually. You can modify the tempo or pitch of the audio without this information, but it generally requires more manual labor for the best results.

Figure 5.2. Loop formats store the location of each beat for more accurate manipulation. Your software reads this information and adjusts automatically, like the beats stored in this Apple Loop.


Don't stretch too far: Changing the pitch or tempo of an audio loop by too great an amount can result in unpleasant audio effects. If you don't want those sounds, don't stretch the loop as far, or use a different loop. These effects aren't necessarily bad: in fact, some musicians have intentionally used the unusual sounds that result.


Standard Loop Formats

Applications like Sony Acid and Apple GarageBand helped popularize looping. But now many applicationsincluding all the major DAWs (see Chapter 2, "Choosing Your Tools")have integrated the technique. Some applications, such as Ableton Live, work fluidly with raw audio files in standard formats like WAV and AIFF. But specialized formats can help make looping more seamlessprovided your loops are prepped ahead of time, either by you or by a sample designer.

These specialized audio formats include metadata that stores information like key, original tempo, and the positions of beats ( Figure 5.3 ). Formats include:

Apple Loops: Audio in Apple Loops is stored in standard AIFF files, so the raw audio can be used by any application that can read AIFF, including PC software. Some Mac apps (like MOTU Digital Performer) can read beat locations from Apple Loops, and Apple's GarageBand and Logic can search through keywords, key, and tempo using the Loop Browser. You can create and edit Apple Loops using the free Apple Loops Utility included with Logic Pro or available for download at http://developer.apple.com/sdk/#AppleLoops.

ACID: Originally developed for the PC app Sony ACID, ACIDized files are now widely used on both the Mac and the PC. ACIDized files contain tempo, beat, and key information, but not keywords. Just as Apple Loops are AIFFs with additional information, ACID files use the standard WAV format, so even if your software doesn't natively support the ACID information, it can use the loop as a plain WAV.

REX: These audio files are created using ReCycle by Propellerhead. They are widely used on the Mac and the PC because of the flexibility of REX file slices, although the format doesn't contain keywords or key information.

Figure 5.3. Loop files store not only audio but meta information as well. An Apple Loop, shown here being edited in the Soundtrack Loop Utility (now called Apple Loop Utility), includes information like keywords, instrument type and genre , tempo, and key.

GarageBand is designed to work primarily with Apple Loops but it also supports the popular ACID format.

Kinetic's audio loops use the ACID format.


Musical Uses

Drum machines that emulated the patterns of rock drummers were among the first commercial pattern-based hardware. Hip-hop and so-called dance music seized on the unique, mechanical sounds they provided.

People often refer to loop-based music or pattern-based editing as though they're new forms of musicoften associating them solely with dance music and electronicabut the underlying concept isn't new at all. Musical traditions of all cultures use repetition and pattern.

By carefully stitching patterns and loops together and using variation, you can create pieces that sound more organic and musicalor, if you prefer, more mechanical and odd. Either way, there are endless musical possibilities.

We'll look at two ways people most commonly use loops and patterns. The first is to create a backing track for rehearsing, songwriting , or performing, letting the loops fill in for parts you can't play. The second is to build repetitive grooves for interactive dance music. Although we'll use GarageBand for the former and Kinetic for the latter, each is capable of both activities.

Quick start: Pros like Us3 producer Geoff Wilkinson use loops and samples to help develop ideas and get an initial groove, then replace them with recorded music.




Real World Digital Audio
Real World Digital Audio
ISBN: 0321304608
EAN: 2147483647
Year: 2006
Pages: 96
Authors: Peter Kirn

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