Glossary definition of 'Dynamic Range Enhancement'

(DRE) Prism Sound DRE is a process designed for increasing the dynamic range of digital recordings when further post-processing is required. It requires an encode process on recording and a decode process on playback. It enables 20-bit dynamic range on 16-bit tracks or 24-bit dynamic range on 20-bit tracks.

Prism Sound DRE was devised as an encoding scheme for representing extended wordlengths on a 16-bit recorder or transmission channel, but without the need to sacrifice channels.

This requirement obviously means that precise data cannot be reconstituted under all circumstances. DRE works by ensuring that precise data IS reconstituted for small and moderate signal levels (up to about 20dB below peak) and that loss of data is optimally concealed above that point. This criterion was in response to existing sub-band ("perceptual") coding systems which have unsatisfactory small-signal performance. Subjectively, DRE allows 16-bit media (such as DAT or CD-R) to be used to make recordings indistinguishable from 20-bit recordings.

The ADA-8 and ADA-8XR also feature an extended version of DRE, optimised for use with 20-bit media. In view of this extension to the format, the original DRE for 16-bit media is now referred to as DRE₁₆, and the new extension for 20-bit media is known as DRE₂₀.

Note that DRE encoded data cannot be metered accurately at the recorder or transmission channel. Although the audio envelope is approximately maintained in the encoded data, levels are not as metered.