Source and Destination

The Source text boxes display the length of the current selection before processing in each of the listed formats. All the text boxes in both columns are constantly active, and a change made to one value is immediately reflected in the values displayed in the other text boxes.

The text boxes in the Destination column display and control the length of the selection after processing using the current settings. You can enter the length of the Destination file by double-clicking the appropriate text box in the Destination column. Type the number of samples in min:secs:msec format or type timecode values as start and end locations. All the Destination text boxes are constantly updated, and a change made to one value is immediately reflected in the values displayed in the other text boxes.

You can also enter a new tempo, bars:beats:ticks length, or time signature for regions that have tempo or Bars & Beats settings. This can be any region associated with a MIDI Metronome value (such as an overdub recorded to a MIDI click) or regions that have been processed with the Pro Tools Identify Beat command.

The Ratio slider lets you set the destination length in relation to the source length. Dragging the slider to the right increases the length of the destination file, and dragging the slider to the left decreases its length.

The controls below the bar line allow you to fine-tune the time compression and expansion process. They include the Crossfade, Min Pitch, and Accuracy sliders.

Crossfade

The Crossfade slider allows you to 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 are processing. 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 be sufficient for most applications; however, 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 40áHz to 1000áHz. By controlling the minimum pitch, you can focus the time compression and expansion process for maximum efficiency — it all depends on the audio's spectral shape.

This slider should be set 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.