Adjustable Fade

Peter 26Nov12: created this page as draft documentation for Adjustable Fade as preparation in case this new fade gets released in 2.0.3.

Use Adjustable Fade... to amplify the audio by a varying amount. This effect is a more advanced and versatile than Fade In and Fade Out in that it is not restricted to fading between silence and the original level but may fade from any amplification amount to any other. The "shape" of the fade can be selected to be linear or non-linear.
As with other Nyquist effects the settings will be "remembered" for the duration of the Audacity session but will revert to their default values when Audacity exits, so you may want to take note of any particularly useful fader curves that you create.

Accessed by: Effect > Adjustable Fade...

Peter 26Nov12: ToDo image will need to be replaced by the release version.

Fade Type

There are just two basic fade types available from this drop-down, either of which may be "Up" (from a low level to a higher level) or "Down" (from high level to a lower level).

1. Fade Up: provides a linear or simple curve fade up from a low gain setting to a higher gain setting.
2. Fade Down: provides a linear or simple curve fade down from a high gain setting to a lower gain setting.

A "simple" curve is one that curves in one direction only, for example the level may be changed slowly at first and progressively change more rapidly, or may change rapidly at the start of the fade and then gradually level out.

1. S-Curve Up: provides a "double" curve that bends one way and then the other. The level will rise gradually at first, then progressively more steeply toward the middle of the fade before gradually levelling out.
2. S-Curve Down: The level will fall gradually at first, then progressively more steeply toward the middle of the fade before gradually levelling out.

There is a detailed guide to fade types and their use on the Audacity wiki.

Peter 26Nov12: Further curve types may be added later - TBD.

Mid-fade Adjust

This slider control has a range of +/- 100 (default 0). It allows the shape of the fade that has been selected in the "Fade Type:" menu to be modified. Setting this control greater than zero will tend to push up the centre of fade, whereas negative values will tend to pull down the level in the middle of the fade.

• When used with "Fade Type: = Fade Up", a value of zero (default) will produce a linear fade.
  • Values greater than zero will cause the fade to rise more rapidly at first before levelling out to the higher amplification level.
  • Values less than zero will cause the fade to rise slowly at first then gradually rise more rapidly.
  • The further away from zero that this is set, the more curved the fade will be.
  • The mid fade amplification will never be less than the start of the fade or grater than the end of the fade.

• When used with "Fade Type: = Fade Down", a value of zero (default) will produce a linear fade.
  • Values greater than zero will cause the fade to fall gradually at first then progressively more steeply as it approached the final level.
  • Values less than zero will cause the fade to fall rapidly at first then progressively level out.
  • The further away from zero that this is set, the more curved the fade will be.
  • The mid fade amplification will never be greater than the start of the fade or less than the end of the fade.

• When used with "Fade Type: = S-Curve Up or S-Curve Down", half way through the fade the gain will be exactly half way between the starting point and end point.
  • With values greater than zero the fade will retain its "double curve" character but will be a bit higher at the mid point.
  • With values greater than zero the fade will retain its "double curve" character but will be a bit lower at the mid point.

Steve 26Nov12: illustrations may be required here.

Start/End as

This drop-down enables you to choose between percentage or dB as the units to be used in the Start and End gain parameter boxes below.

The obvious, most common / "standard", way to describe the gain levels is as "dB", however there were persistent arguments for using "% of original level", so this option has been included and set as the default.

The final two text boxes must contain one number each. They define the initial and final gain (amplification amount) of the fade. It is unimportant if this is entered with the initial gain in the fist of these text boxed and the final gain in the last, or the other way round as the direction of the fade is determined by the Fade Type: selection.

Start (or end)

Enables you to set the Start (or end) gain. If you are using percentage units a start value of 0 (silence), the default, will give you the start of a fade-in.

End (or start)

Enables you to set the End (or start) gain. If you are using percentage units a start value of 100 (unity gain, the original level), the default, will give you the final gain for a fade-in.

This effect is much easier to use in practice than it is to describe in words so do not be put off by the seeming-complexity of the controls that are available. A few minutes playing with various parameter settings will show you the various resultant fade curve shapes that you can create (a short generated sine wave is useful for this purpose).

Handy Presets

A number of fixed preset curve shapes are available from this drop-down selector: Linear, Exponential, Logarithmic, Rounded, Cosine and S-Curve.

Peter 6Dec12: ToDo image will need to be replaced by the release version.

Important: Selecting a preset curves will override all other parameter settings dialog box for this effect. To make the other parameters operable you will need to set "None Selected" from this drop-down.

• None Selected:
• Linear In:
• Linear Out:
• Exponential In:
• Exponential Out:
• Logarithmic In:
• Logarithmic:
• Rounded In:
• Rounded Out:
• Cosine In:
• Cosine Out:
• S-Curve In:
• S-Curve Out:

Example Settings

These settings assume that Start and End are set as "% of Original". Note that the order of the 'Start' and 'End' settings is unimportant.

Desired Effect	Fade Type	Mid Fade Adjust	Start (or End)	End (or start)
Linear fade-in from silence to original level	Fade Up	0	0	100
Linear fade-out from original level to silence	Fade Down	0	0	100
Linear fade from original level to half volume	Fade Down	0	50	100
Exponential fade-out similar to using the Envelope Tool	Fade Down	Less than 0	0	100
Fade-out for 'Equal Power' crossfade	Fade Down	+0.5	0	100
Fade-in for 'Equal Power' crossfade	Fade Up	+0.5	0	100
Similar to 'Pro Fade Out' effect	S-Curve Down	0	0	100
Smooth change from half volume to double volume	S-Curve Up	0	50	200

Links

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<  Back to: Wahwah

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Peter 27Nov12: These links will be needed if and when this effect is formally released and integrated in the Effect Menu