Audio looping and sampling is popular in Rap, Funk and Hip-hop music. If you use a lot of drum loops or samples, and need a software audio editor that can handle pitch-shifting and tempo modifications, try ACID from Sonic Foundry.
ACID: $295, includes sample CD.
ACID PH-1: $95.00, "lite" version of ACID
Sonic Foundry
704 Williamson St.
Madison, WI 53791-8062
Tom Connell is a freelance composer and sound designer living in Baltimore.
He does mostly scoring work for a variety of clients, including Ogilvy
Worldwide and the Centers for Disease Control. He's been making noise on
PCs since the green-screen days - his bloodshot eyes and torn-out hair
prove it. He also plays a lot of guitar and is teaching himself the
rudiments of Web development. If you've got ideas or questions, contact him
at tconnell@qis.net.
If you make music on a PC, you've probably used loops to build and layer
tracks, especially if you're into techno, hiphop or other loop-heavy
genres. Whether you chop and loop your own samples or lift them from CD,
there's no shortage of raw material. But those killer drum, synth and
ambient sounds are all over the map in tempo and pitch. Inevitably, you'll
have to time-stretch those puppies so they'll correctly loop to your
project's tempo without pops and gaps, and pitch-shift them to match key.
Some audio editing programs (Sound Forge, Cool Edit) handle this pretty
well, as long as you don't stretch or shift too drastically. Bear in mind
that at the end of all this,if you decide to change your project's master
tempo by even 1 bpm, you'll have to start all over. That blows.
February 10, 1999
Sonic Foundry's ACID is a workable solution to all of the above headaches.
Billed as "a breakthrough loop-based music production tool" ACID definitely delivers: it's an intuitive, easy-to-use multi-track audio arranger
that lets you dispense with the hassle of painstakingly constructing and
contorting disparate audio to fit a project. ACID does it for you, smoothly
stretching, shifting and looping the audio you feed it to any tempo and
key. As long as your audio is loopable your tracks will be seamless.
Fortunately, you're not limited to looping - you can place audio samples as
discrete events. You can record audio tracks, too. But it's the currently
unmatched looping capability that dominates the package. Anyone
constructing sample-heavy grooves will put it right to work, but sound
designers, ambient and electronica artists, or game developers will also
find it useful. In fact, ACID's learning curve is so shallow that almost
anyone who can point and click can make music right out of the box.
The ACID window is divided into three main areas. Track view, the largest,
will look familiar to midi/audio sequencer jockeys. Audio events display as
clips, and clips are stacked as tracks. You have as many virtual tracks
available as your RAM and CPU can handle (best if you have at least a
200mhz CPU and 64MB RAM). A timeline, scalable to beats, measures, SMPTE
frames, or seconds, runs along the bottom. Standard transport controls
above, and the usual scroll bars and zoom buttons complete the work space.
The display is clean, with each audio clip a distinctive color and loop
boundaries clearly marked.
The Track List View gives you control over individual track volumes, pans
and effect sends (through a horizontal slider with a drop-down menu). You can mute or solo tracks, select output device and channel,and choose
whether your source audio will loop-to-tempo, play at its original tempo
and length (a "one-shot") or trigger from hard disk. You can also duplicate
or pitch-shift a track (two-octave range), or invoke an external audio
editor. The third window is selectable between a Windows Explorer-like
directory of your audio files (ACID only reads .wavs), an Edit Window
(displays current event's waveform - but it can't be edited), and a Mixer
and Effects Page where you can select Direct X plug-ins and route effects.
Click once on a file to auto-audition a looped preview at the current
project tempo and key (default is 120bpm, A). With large audio files you
may wait a few seconds while the file is "acidized" - optimized for more
accurate tempo and pitch shifting. Since you can change tempo and key in
real time while files are auditioning, it's quick and easy to settle in on
a good tempo, and just as easy to get wild. Will that slow-cookin' funk
loop still groove rammed up to 175 amphetamine-laced bpm? Even if it
sounds ridiculous it will only cost you a few seconds to find out.
If you like what you hear, click twice to load it to Track view, or simply
drag it over. Click and drag the Pencil tool right and you've created an
audio loop. The longer you drag along the timeline, the more times the loop
will repeat. Handy top and bottom notches on the audio clips mark the
boundaries of a looped region.
If you've already assembled your source audio files, a full-blown rough
project can be up and running in a few clicks and drags. But maybe you're
stalled at the drum track - get it playing in loop mode while you browse
through, say, your directory of bass grooves (of course, you've got all
your samples neatly indexed, right?). Quickly audition a few dozen against
your drum track until you find the one that locks. Load it up and move to
the next element. Goodbye, time-consuming trial and error. Hello, enhanced
creative flow.
Once your basic tracks are in order it's time to push them around. The
Pencil tool gets a good part of the job done - you can drag, drop and copy
clips and adjust clip boundaries by grabbing an edge and dragging in or
out. An Erase tool scrubs out unwanted audio, a Selection tool highlights
regions, and a Paint tool enables you to wipe across multiple tracks,
adding or erasing audio. Changing snap-to settings enables finer or
grosser tool control - options range from the default (the looped region
boundaries) to a 64th note.
With the Envelope Editing tool you can hand-draw volume, pan and effects
envelopes right on the audio clip. Unfortunately, there are no automatic
settings or dialog boxes to set up fades and cross-fades - you have to
hand-draw everything, which can be a bit tedious. Other than its superior
time and pitch shifting, ACID has no other on-board audio editing
capability. If you need to do some serious audio tweaking, invoke Sound
Forge or CoolEdit from within ACID, do your thing, and bring it back into
ACID.
Recording a track into ACID is straightforward. Click Record and an applet
pops up for setting levels and channels. ACID treats the recorded audio as a hard disk-based event - it won't loop the file - so your best use of
recording in ACID is probably to leaven the loopiness with a little
flesh-and-blood audio - a guitar solo, vocals, keyboard track to give
things a more human feel. When your project is done you mix down to a .wav
file.
The full version of ACID ships with a companion sample CD - split between
Sonic Foundry's "Essential Sounds" (a collection of basic grooves and
elements spanning a number of styles) and a selection of samples from SF's
"Loops For ACID" CD series which emphasizes techno, hiphop and ambient
styles (SF sells the full CD's for $39.00: the files are "optimized for
use within ACID"). You can download a free 30-day trial of ACID from Sonic
Foundry's website. It's full-featured but won't save files, and an
annoying message stops the fun every 5 minutes to remind you to register.
ACID is a serious professional tool for musicians and sound designers.
Right now, it rules on looping capability. It's also well-designed,
easy-to use and fun. It's an excellent application for anyone who would
rather use a PC than a dedicated sampler to work with audio files. Pair up
ACID with solid audio editing power from the likes of Cool Edit or Sound
Forge and you've got a powerful and flexible PC platform for music
development.
Although you can certainly slam together good-sounding standard grooves
with ACID, don't be afraid to push the envelope. Dying to hear Bulgarian
monks chant in perfect sync to a hyperactive drum 'n bass track? Do it.
Or forget the loops altogether: grab some audio snippets, ghostly voices,
ambient clouds, temple bells, and let a free-floating collage evolve. If
you've got a PC and some samples, your imagination is the only limit. ACID
won't get in your way.
