Audio editing software

An audio production facility at An-Najah National University

Audio editing software is software which allows editing and generating of audio data. Audio editing software can be implemented completely or partly as library, as computer application, as Web application or as a loadable kernel module. Wave Editors are digital audio editors and there are many sources of software available to perform this function. Most can edit music, apply effects and filters, adjust stereo channels etc.

A digital audio workstation (DAW) can consist to a great part out of software. are usually software suites composed of many distinct software components, giving access to them through a unified graphical user interface using GTK+, Qt or some other library for the GUI widgets.

For use with music

Editors designed for use with music typically allow the user to do the following:

The ability to import and export various audio file formats for editing.
Record audio from one or more inputs and store recordings in the computer's memory as digital audio
Edit the start time, stop time, and duration of any sound on the audio timeline
Fade into or out of a clip (e.g. an S-fade out during applause after a performance), or between clips (e.g. crossfading between takes)
Mix multiple sound sources/tracks, combine them at various volume levels and pan from channel to channel to one or more output tracks
Apply simple or advanced effects or filters, including compression, expansion, flanging, reverb, audio noise reduction and equalization to change the audio
Playback sound (often after being mixed) that can be sent to one or more outputs, such as speakers, additional processors, or a recording medium
Conversion between different audio file formats, or between different sound quality levels

Typically these tasks can be performed in a manner that is non-linear. Audio editors may process the audio data non-destructively in real-time, or destructively as an "off-line" process, or a hybrid with some real-time effects and some off-line effects.

Comparison of destructive and real-time editing

Destructive editing modify the data of the original audio file, as opposed to just editing its playback parameters. Destructive editors are also known as "sample editors".

Destructive editing applies edits and processing directly to the audio data, changing the data immediately. If, for example, part of a track is deleted, the "deleted" audio data is immediately removed from that part of the track.

Real-time editing does not apply changes immediately, but applies edits and processing on the fly during playback. If, for example, part of a track is deleted, the "deleted" audio data is not actually removed from the track, but is hidden and will be skipped on playback.

Advantages of destructive editing

In graphical editors, all changes to the audio is usually visible immediately as the visible waveform is updated to match the audio data.
The number of effects that may be applied is virtually unlimited (though may be limited by disk space available for "undo" data).
Editing is usually precise down to exact sample intervals.
Effects may be applied to a precisely specified selected region.
Mixing down or exporting the edited audio is usually relatively quick as little additional processing is required.

Limitations of destructive editing

Once an effect has been applied, it cannot usually be changed. This is usually mitigated by the ability to "undo" the last performed action. Typically a destructive audio editor will maintain many levels of "undo history" so that multiple actions may be undone in the reverse order that they were applied.
Edits can only be undone in the reverse order that they were applied (undoing the most recent edit first).

Advantages of real-time editing

Effects can usually be adjusted during playback, or at any other time.
Edits may be undone or adjusted at any time in any order.
Multiple effects and edits may be 'stacked' so that they are applied to the audio as an effect chain.
A stack of effects may be changed so that effects are applied in a different order, or effects inserted or removed from the chain.
Some real-time editors support effect automation so that changes to effect parameters may be programmed to occur at specified times during audio playback.

Limitations of real-time editing

The waveform does not usually show the effect of processing until the audio has been mixed-down or "bounced" (rendered) to another track.
The number of effects that may be applied is limited by the available processing power of the computer or editing hardware. In some editors this may be mitigated by "freezing" the track (applying the effect stack destructively).
It is not usually possible to have an effect only on part of a track. To apply a real-time effect to part of a track usually required that the effect is set to turn on at one point and turn off at another.
In multi-track editors, if audio is copied or moved from one track to another, the audio in the new track may sound different from how it sounded in the original track as there may be different real-time effects in each track.
In some applications, mixing down or exporting the edited audio may be slow as all effects and processing needs to be applied.

For use with speech

Editors designed for use in speech research add the ability to make measurements and perform acoustic analyses such as extracting and displaying a fundamental frequency contour or spectrogram. They typically lack most or all of the effects of interest to musicians.