User manual

Core Avid Audio Plug-Ins
377
Time Shift (AudioSuite)
The Time Shift plug-in provides high quality time compression and expansion algorithms and
formant-correct pitch-shifting. Time Shift is ideal for music production, sound design, and post-
production applications. You can use it to manipulate audio loops for tempo matching or to transpose
vocal tracks using formant-correct pitch-shifting, or you can use it in audio postproduction for pullup
and pulldown conversions as well as for adjusting audio to specific time or SMPTE durations for
synchronization purposes.
The Time Shift plug-in has special parameters that let you enter time compression or expansion
values in different formats and edit the pitch shift parameters displayed in the plug-in window. Time
Shift plug-in controls are organized in four parts: Audio, Time, Formant/Transient, and Pitch.
Crossfade The Crossfade slider lets you manually adjust the crossfade length in milliseconds to
optimize performance of the Time Compression Expansion plug-in according to the type of
audio material you process. The Time Compression Expansion plug-in achieves length
modification by replicating or subtracting very small portions of audio material and very
quickly crossfading between these alterations in the waveform of the audio material.
Crossfade length essentially affects the amount of smoothing performed on audio material to
prevent audio artifacts such as clicks. In general, small narrow-range time (length) changes
require longer crossfades while larger changes in length require shorter crossfades. The
disadvantage of long crossfade times is that they smooth the signal, including any transients.
While this can be desirable for audio material such as vocals, it is not appropriate for
material with sharp transients such as drums or percussion.
The default setting for this parameter is Auto (leftmost position), in which crossfade times
are set automatically according to the percentage of change in length for the current process.
This setting should suffice for most applications, but you can use this slider to manually
adjust and optimize crossfade times, if necessary. For audio material with sharper attack
transients, use shorter crossfade times. For audio material with softer attack transients, use
longer crossfade times with a range in values of 1 to 200 ms.
Min Pitch The Min Pitch slider lets you select the minimum (lowest) pitch that is used in the plug-in’s
calculations during the time compression and expansion process. The slider has a range of
40 Hz to 1000 Hz. By controlling the minimum pitch, you can focus the time compression
and expansion process for maximum efficiency depending on the audio’s spectral shape.
Set this slider lower when you process bass guitar or another instrument with a similarly low
range. Set the min pitch higher when processing instruments such as snare drums, violins,
and other higher range instruments and sounds. Experiment with combinations of the other
fine-tune controls in relation to the Min Pitch slider.
Accuracy Use the Accuracy slider to prioritize the processing resources allocated to audio quality
(sound) or timing (rhythm). Dragging the slider toward sound generally results in better
sonic quality and fewer audio artifacts. Dragging the slider toward rhythm puts the emphasis
on keeping the tempo consistent. When working with loops, listen carefully and adjust
accuracy until you find the setting that keeps timing solid within the region. Start and end
times are precise, but the perception of beats might be “shuffled” if the Accuracy slider’s
rhythm setting is too low.
c
The smallest time ratio allowed for time compression and expansion is 0.25. The
largest time ratio allowed is 4.0.
n
Normalizing a selection before applying the Time Compression Expansion plug-in can
sometimes produce better-sounding results.
Parameter Description