In the early days of recording, engineers and sound designers faced an ongoing struggle to preserve audio fidelity. Capturing or playing back audio from an analogue recording medium would always add a certain amount of unwanted sonic artifacts and distortion to the signal, caused by the noise present in electrical circuitry. In fact, even the basic act of storing recorded audio on a format like magnetic tape would incur a degree of degradation over time.
In analog recording terms, this meant that almost any decision to edit, bounce or process an audio track had to be weighed up against a subsequent loss in fidelity. A practical solution emerged in the early 70s, when companies including Denon and the BBC pioneered the use of two·track digital audio recorders. In simple terms, digital audio is a method of representing an analogue audio signal as a series of 0s and 1s.
When an audio signal is converted into a digital representation, it can be copied, edited and moved around indefinitely within the digital realm without any inherent loss in fidelity. Actions such as changing an audio track's volume level can be performed digitally with generally imperceptible signal degradation which is only caused when digital values need to be rounded up or down during multiplication or division-and it also means that any process or edit can be reversed easily.
The digital revolution
The earliest digital audio devices were simple two-channel stereo recorders. However, as computer technology has progressed, the scope to do more within the digital realm has significantly broadened. Nowadays, a modem home computer can effectively play the role of an entire recording studio - mixing dozens of tracks together, enabling virtually unlimited processing and giving engineers the ability to edit tracks at a level of precision never possible on any analogue medium.
In this article we'll guide you through some of the fundamental ways in which digital audio has revolutionized the nature of modern music production, from multitrack audio recording and editing, through to various methods of processing and manipulation. We'll do this in both the software DAW and sampler. the latter being a supremely flexible and creative tool for digital audio recording and playback.
Linear audio vs sampling
In the software DAW (digital audio workstation), your audio files and recordings exist as raw data on your computer's hard disk and in its memory. This enables software developers to provide endlessly flexible and creative ways for you to arrange, edit and manipulate them.
As a digital audio file tends to involve quite a sizable chunk of data. and editing or manipulating it within a DAW is usually done via a scaled-down graphical representation of the audio's analogue waveform. Having audio tracks represented alongside each other graphically on a grid and timeline enables us to see where each instrument comes in and roughly what happens throughout Its progression. all in direct relation to the other audio tracks.
Digital audio represented in this manner is known as 'linear'. However, there's another approach to working directly with audio, called sampling. Using a sampler instrument plug-In typically involves importing one or more digital audio files directly Into it. from where it/they can be edited and manipulated. To play the audio files back, you trigger sounds with MIDI note events on your keyboard, then record (or draw) them into your arrangement.
While both approaches can be used somewhat interchangeably - many producers preferring one over the other - each offers its own advantages and limitations...
The long haul
Let's first get to grips with linear audio, which is almost always the best The linear audio functionality of DAWs such as Propellerhead's Record makes editing long recordings beautifully Intuitive choice when working with longer sections of sound -such as audio recordings of guitars, drums or vocal tracks - as it makes editing and positioning audio data very visual and intuitive. For example. by using your DAW's scissors tool, you can cut an audio track into two sections. whereupon any unwanted gaps or background noise can be trimmed out before rejoining the two sections into the final take.
To give another example, if you're working with a recorded drum track, you may want to make numerous tiny cuts and trim short bits of audio out to improve the timing and fix any sloppy hits captured in a take. With linear audio, this kind of editing tends to be very straightforward. as you can see all of your audio data represented visually in line with the rest of the arrangement.
Short but sweet
sampling, on the other hand, Is often the preferred method of working with shorter snippets of audio, particularly when you require some kind of performance variation during playback. For example, when using a single snare drum sample. you might want to trigger each hit at a slightly different volume level for authenticity.
One of the biggest creative benefits of sampling is that it enables audio files to be played back as MIDI instruments. A single bass note sample can be mapped across a MIDI keyboard, then played much like a synthesizer. It will respond to pitch changes by either slowing down or speeding up sample playback. can play for as long as a note's held (or not. if you prefer) and can be configured to respond to note velocity (how hard you hit the keys).
Samplers also enable you to set loop points in an audio file. whereby playback will continually cycle through a certain section of audio for as long as the note event triggering it is held. This enables you to turn a short bass or synth sample into a continuous tone. which can then be modified further by setting volume and filter envelopes - emulating the natural attack. decay and release of a performance instrument's volume and tone.
Whichever approach you'll end up favoring will most likely come down to how you prefer to think about music and audio - it's possible to construct melodies using short snippets of linear audio, aided by pitchshifting and volume envelopes, just as it's possible to work with long audio recordings being triggered from a sampler. Generally speaking, though, each situation will suggest one approach or the other.
Audio editing and processing
Working with digital audio in a DAW or audio editor gives you virtually unlimited scope when it comes to editing and processing. The audio channels in DAWs enable you to place and arrange all your audio tracks in relation to the timeline. Each channel generally corresponds to an individual mixer channel. too. on which track volume, panning and additional processing can be applied to everything on that channel.
Among the most common edits you're likely to perform are "cuts". Much in the same way an engineer could slice off bits of tape to remove unwanted noises or silence on a reel-to-reel recording, a digital audio editor enables you to select and remove unwanted bits of audio. You might do this to remove unnecessary silences on recordings - which would otherwise be taking up disk space or to ensure that the track or sample you're working on comes in at exactly the right moment.
Being able to cut, copy and paste sections of audio also open up possibilities when it comes to rearranging tracks. For example, a single bar of recorded drums can be chopped up into a sequence of hits. which can then be pieced back together to create entirely new rhythms or add variations and embellishments to a regular beat.
Audio editors also enable you to timestretch and pitchshift tracks. The former involves changing the speed and duration of an audio file without affecting its pitch. For example, a slow beat can be sped up without changing the tone or tuning of the drums themselves.
Pitchshifting enables you to change the pitch without affecting the speed or duration of a sound it can be used when you want to change the key of a recorded track, to name but one use.
Lastly, fades can be used to bring a track in gradually or fade it out smoothly, while the 'reverse' function plays an audio track backwards. and is most commonly used as a special effect.
Samplers and sampling
The first affordable digital samplers revolutionized home music creation when they were released towards the end of the 80s, providing a whole new sonic paradigm for producers to exploit. A sampler can be used to lift sections - creatively or otherwise - out of other people's music, or it can be used to emulate instruments such as pianos, guitars and drum kits, by recording many notes and variations, and mapping them across the keyboard.
Today, a digital sampler can reside in your computer as a plug-in instrument. Popular soft samplers. like Native Instruments' Kontakt, offer a vast range of built-in audio processing and performance controls, enabling you to construct complex and highly expressive instruments from your source material. There's also a wide range of high quality sample libraries available on CD, DVD or via download, which typically comprise meticulously multisampled studio recordings of various instruments, along with often hundreds of performance patches.
When preparing a multisampled patch, the MIDI keyboard typically needs to be split up into various sections, with each one corresponding to a particular sample and/or set of playback parameters - including such things as start and end points. effects settings and volume envelopes. Setting up a multlsampled drum kit, for example, would normally involve splitting the keyboard up into a series of single notes, each corresponding to a particular drum hit. However. a multisampled piano may not require a separate sample for each note on the keyboard, so the keyboard can be split up into a number of short sections of perhaps four or five notes each, where each sample can be pitched up or down a few semitones without losing too much of the piano's natural quality.
Multisamples can also be divided based on other parameters, such as velocity. in such a case. a note played above a certain velocity may trigger a harder sounding piano sample, while a note played below a certain velocity may trigger a softer one. Many samplers also enable you to crossfade between two or more alternative recordings of a note, so that the transition from soft to loud sounds much more natural.
Unlike working with linear audio, a sampler plug-in typically sits on a MIDI channel, where rather than having sections of audio playing directly from your arrangement. MIDI notes are used to trigger the sounds of each key and its velocity.
Appetite for destruction
There's two ways in which a DAW or audio editor can process digital audio: it can either modify the samples in the audio file itself, or it can modify the way the samples are played back. The first of these methods is called 'destructive' editing, as it changes the samples themselves. For example, when you load an audio file into an editor and cut a section of silence out at the beginning, you've actually deleted a series of samples from the file, which will be gone for good as soon as you save the file.
'Non-destructive' editing involves changing the parameters or processes the computer employs when playing an audio file back. This can be illustrated by changing the start point for an audio clip in Ableton Live, which merely tells the software the point from which it should start playing the clip, without having to alter the audio file at all.
For convenience, and sometimes to save memory and resources, there are many situations in which destructive editing may be preferable- trimming unnecessary silence or noise from samples, applying CPU-intensive processes permanently, or when producing a master recording. The only drawback is that for every change you make to the source audio file, you're altering and losing information from it - which can sometimes result in subtle but cumulative losses in fidelity, as well as eventually being unable to track back and remove certain processes or edits once they're done.
When editing non-destructively, any processes are applied during playback. So, changing a track's volume or panning in a virtual mixer are examples of non-destructive editing, as is processing a sound with plug-ins.
Drum and instrument audio loops are a mainstay of computer-based music production. A loop is simply a recorded melody or rhythm pattern that can be played on repeat as part of a composition - drum loops are very popular, as they capture the natural characteristics of a live performance, which may be difficult to recreate or approximate when working with single-hit samples.
Loop slicing is a technique by which you rearrange and edit loops, while retaining their natural timing, as well as many of the other nuances of a live performance. For example, you may want to add playing variations to a drum loop, rearrange the beat completely, or change its timing to fit a different groove or tempo.
Not so long ago, loop slicing was done manually, by cutting your loop up Into a number of blocks that could then be re-sequenced in whatever order you liked-many modem genres, such as drum 'n' bass, evolved specifically from this technique. Nowadays, many DAWs and plug-ins offer automatic loop slicing facilities. This means the software can analyze an audio clip and find all of the points where it appears that notes or drum sounds begin. By chopping up the sample into a series of shorter samples at these points, the loop can easily be rearranged, and parts can be copied, repeated or removed completely to form radically different patterns.
Propellerhead's ReCycle was one of the first popular loop slicing applications. It works as a standalone application, enabling you to create sliced versions of audio files, ready to be imported into compatible sequencers, such as Cubase and Reason, where the slices can be loaded with their relative spacing (timing) intact, then edited and switched around to create interesting variations.
Newer versions of Steinberg's Cubase, amongst other DAWs, offer a similar form of loop-slicing that utilizes hit points. With this, any audio file can be imported and analyzed using hit-point detection, and once you're happy with the location of each hit, the file can be cut into slices.
Many dedicated loop-slicing plug-ins exist, too. FXpansion's Guru, Native Instruments' Kontakt, plus iZotope's iDrum and pHATmatik Pro all offer various forms of loop slicing and rearranging facilities, which you can use on any samples you like.
Read also about Digital Audio File Formats