iZotope Radius is iZotope's offline time-stretching and pitch-shifting algorithm, designed for completely transparent operation on a wide variety of source material. Radius brings world class time-stretching and pitch-shifting to the selection based RX restoration platform, creating a powerful array of tools and algorithms for repairing audio.
Radius features two modes of operation, designed for completely transparent operation on a wide variety of source material.
Mix - Designed to work well with polyphonic material such as mixes with more than one instrument, as well as non-harmonic material such as drum loops or rhythmic audio.
Solo - Designed for monophonic pitched material such as a stringed instrument or human voice.
Quality (Mix mode only)- Controls the algorithm's processing quality
Stretch Ratio - Determines how much the resulting audio will be stretched in time. Values from %0-100 will cause the audio to speed up without affecting pitch, resulting in a shorter audio file. Values %100-800 will cause the audio to slow down without affecting pitch, giving you a longer audio file.
Pitch Shift - Controls the amount of pitch shifting up or down that will be performed to the audio.
Extended Parameters ("More")
Transient Sensitivity - determines the algorithms handling of transient material. Higher values will result in better preservation of individual transients after processing.
Adaptive Window Size (ms -Solo mode only) - adjusts the window size in milliseconds of radius' solo algorithm. If the adaptive window size is too small, you will hear a squeaking noise which sounds like the pitch of the audio is changing very rapidly. If the adaptive window size is too large then the sound will become grainy as you will begin to hear portions of it being repeated.
Pitch Coherence - controls the preservation of the natural timbre of the processed audio
Phase Coherence - preserves the phase coherence of the processed audio. High values will avoid phasiness in Radius's output at the expense of roughness (modulation) in processed polyphonic recordings.
Noise Generation - Helps to improve upon noisy material that can sound unnatural when processed. This control will generate noise instead of stretching the noise which is already present in the signal signal. Higher values of the noise generation parameter will cause Radius to generate noise more often at the expense of phase coherence.
Shift Formants - Causes radius to also shift the formants of the selected audio with the controls below when processing. Formant frequencies do not change when the pitch of the voice or instrument changes. When Radius performs pitch-shifting without Formant Correction, it will shift these resonant frequencies along with the rest of the audio. This can lead to an unnatural change in the way the audio is perceived.
Strength - Adjusts the strength of the formant correction
Shift - allows you to specify how much formant frequencies are shifted. Typically this control can be set to 0.0, which leaves the formant frequencies unshifted. Adjust this control to fine-tune the formant correction algorithm or for special effects.
Width - fine tunes the way that Radius detects formant frequencies. Smaller values of this control will offer more precise formant correction in the processed audio.