The Digital Audio Software Environment

Last updated: 05 February 2009
Published in: Digitising analogue media | Creating new digital media |
Tags: audio |

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Summary

At first glance the interface of your digital audio software (DAS) can be somewhat intimidating. This document breaks down the main components of the software environment and introduce you to their functions and features.

Tracks and channels

The terms tracks and channels relate to their analogue counterparts, the tracks of a tape and the channels found on a mixing desk. Essentially, within DAS the two are same thing.

Tracks are added and used in the edit/arrange window to host audio regions in the arrangement. These tracks correspond to the channels of the mixer, should your DAS host one.

DAS commonly has up to three environments for working in:

• Arrange Window
• Sample editor
• Mixer

Arrange Window

The arrange window is found in all multi-track audio editors, and is provided to align and control the sequence of different audio regions in the time domain.

Audio files are displayed against a global timeline (left to right) that is commonly displayed along the top of the window from left to right. The timeline can display the number of samples in time, the time from a start position of zero, or as beats and bars defined by the specified tempo in a musical arrangement.

Audio files are arranged in tracks vertically as shown in diagram 1 below. During playback, a vertical bar moves along the timeline indicating where the position of playback is relative to the audio files. In diagram 1 this is positioned at the start of bar 3.

AUDIO FILE of diagram 1.

Diagram 1

Arrange window

The main feature of the arrange window is the ability to position and reposition audio regions anywhere in the time domain. In diagram 1 regions are represented as blue blocks which start and end at specific positions. These blocks can be dragged and repositioned along the time line, as desired.

Example:

You have three separate audio files you wish to piece together for a final production.

They each contain:

1. A spoken word lecture
2. A sound effect to be positioned at a particular time
3. An extension to the lecture to be added at the end

The edit window allows you to align all three files so that they come in at the right place in time.

Sample editor

In some software the actual editing of audio files is done within a sample editor separate from the edit window, but in other cases editing is done directly within the edit window.

The sample editor provides extreme close up analysis of a wave file for specific editing functions which is separate from the other audio files within the edit window.

Files are imported into the sample editor by an ‘import' function that is built in to the DAS.

Example:

You have a digitised file of a vinyl record being played which contains clicks and pops as a result from scratched on the record, which you would like to remove.

A sample editor provides an environment where close up analysis of the wave file is provided along with tools for selecting and removing the clicks and pops.

Mixer window

Some DAEs come with a built in mixer facility. The mixer has vertical ‘channels' which correspond to the audio tracks in the edit window. It is especially convenient for when you may be working with multiple tracks at once, or ‘multi-track arrangements'. The vertical audio faders allows you to ‘mix' the tracks together by setting the volume levels of each track so that track can be heard clearly and that one track is not drowning out another. In diagram 2 there are seven audio channels that have their decibel levels displayed next to the fader controls.

Diagram 2

The mixer window

Transport controls

Similar to the buttons on a Hi-Fi player, an mp3 player or any other audio playback device, the transport panel contains the basic functions you would expect to find when working with audio.

It can often be pain accessing the transport controls with a computer mouse so a common shortcut is to use the keyboards space bar which activates the play and stop buttons remotely.

Transport panel

Some transport panels contain more features and displays for more advanced controls of your project.

Signal Routing

The mixer in diagram 2 has a number of routing options for each channel within a project. The concept of audio routing can be a confusing matter and may be overkill for a lot of editing projects. However it can be time and processing power efficient when it is used correctly.

Audio buses and auxiliary sends can be used to group sounds to send to effects or other processors internal or external to the DAE. Each software package has its own unique way of handling audio routing internally, and some packages provide more options than others. An effective example of using routing could be when you wish to apply a similar effect, for example reverberation, to more than channel within your project. Instead of applying the same instance of effect to each individual channel, it may be possible to route all the desired channels to one new channel (an audio bus) with the volume levels individually determined. From here one instance of the effect can be applied to the bus, covering all the designated channels, thus considerably reducing the processing power being used.

Diagram 4

a)                                  b)                                  c)

4a Shows an audio channel, labelled Guitar 7, which has it's signal split to Bus 1 as well as the main mix output (Output 1 - 2). Aux 1 channel takes the input of Bus1 and also outputs to the main mix. The Guitar 7 channel in 4b sends the output signal not to the main mix output but to Bus 1 where again Aux 1 channel routes this signal to the main mix output.

Using Plug-ins

Software plug-ins are based on hardware processors which manipulate sound waves. They can be split into two groups.

1. Effects - such as reverb, delay or distortion
2. Dynamic Processors - such as equalisation, compression or expansion

These units can be applied to an individual channel, a bus or auxiliary channel, or even across the master channel.

Plug-ins act as a unit which sound enters and then exits. The changes applied as the sound passes through the plug-in are dependent on the parameters set by the user.

The more advanced DAEs host plug-ins which can process and output audio while it is being played in the edit window, which makes it easier for altering the parameters during playback to the desired effect of the listener. On the other hand, some of the more basic DAEs only allow for offline processing with plug-ins. That is, the plug-ins parameters are set, then the file is processed (changed) according to those settings and then placed back in the edit window. This way it is impossible to tweak the parameters during playback and a trial and error approach is adopted.

Most plug-ins have factory presets built-in. This allows the inexperienced user to pick a preset based on their needs and make adjustments as they see fit.

For more information about using digital processing techniques please see the advice documents about applying digital effects and signal processing.

Diagram 5

An example of a plug-in included with the audio software package Reaper

Last updated: 05 February 2009
Published in: Digitising analogue media | Creating new digital media |
Tags: audio |

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