Editing Dynamic range compression (section)

=== Compressors ===

As far as the compressors are concerned, the authors performed two processing sessions, using a fast attack (0.5&nbsp;ms) in one case, and a slow attack (50&nbsp;ms) in the other. Make-up gain is deactivated, but the resulting file is normalized.

Set with a fast attack, the tested compressors had the following influence on the signal:
* slight increase of RMS power,
* slight increase of EBU R 128 loudness,
* decrease of crest factor,
* decrease of EBU R 128 LRA,
* slight decrease of clipped sample density.

In other words, fast-attack compressors increase both physical and perceptual levels, but only slightly. They decrease the density of clipped samples, and decrease both crest factor and macro-dynamics.

Set with a slow attack, the tested compressors had the following influence on the signal:
* decrease of RMS power,
* decrease of EBU R 128 loudness,
* no influence on crest factor,
* decrease of EBU R 128 LRA,
* no influence on clipped sample density.

In other words, slow-attack compressors decrease both physical and perceptual levels, decrease macro-dynamics, but have no influence on crest factor and clipped sample density.