Peter 14Nov12: created this page. ToDo Ready for editorial review and merciless editing.

Once Steve's Wiki page on fading is published I would anticipate that we would link to it from this page.
Gale: 14Nov12: It's a bit bare bones, and mostly duplication of the Effects page (apart from the images). Is there any more we can say? Something about what fades may be useful for? If/when we get Adjustable Fade shipped, would it go here? I am not sure it would. Perhaps this page should be for "automatic" fades?
- How about an image of Cross Fade after mixing, to show what we mean by equal volume after the mix?
- I can't see the point repeating the tips box both here and on the Effects page. I would suggest only having it here, if we want this page.
Peter 15Nov12: Yes it is a little bare bones, but I was deeply conscious that this is the Manual and that thus here we need basically state what the commands do rather than how to effectively use them (in line with the documentation of the other effects). Use of the fade commands is complex tutorial material and I was intending to point this page at Steve's nascent tutorial on Steve's use of fades tutorial (which is currently under development in the Wiki but could IMO earn a useful place as a tutorial in the manual).
- Personally I find it useful to see the images of the various fades together on this page for easy visual comparison and I would hope that other readers would find that similarly useful. I was careful to keep the images and fades visually constant to facilitate such comparison.
- I have added an "After Cross Fade" image as you suggested - though I'm not entirely convinced of its utility here (see comments above re tutorial material).
- I agree that it's not worth repeating the note box on Effect Menu and here, so I have commented it out there for now. The note box here has slightly more information than the Effect Menu one - one extra bullet point.
- I would also anticipate that if and when Steve's adjustable fade is released then it would have a page of documentation to itself and that this page here would have a link to it with brief explanatory text.

Linear Fades

These basic fades apply a fade to the selected audio, so that the amplitude changes gradually from the original amplitude at the start of the selection down to silence at the end of the selection. The shape of the fade is linear. The rapidity of the fade-out depends entirely on the length of the selection it is applied to.

Fade Out

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Typically a fade out would be applied over a longish audio selection, from one or two up to about ten seconds or so.

Fade In

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Gale: Then why not an image of a fade in with a shorter selection than fade out? It lets people see the difference the selection length makes.

Peter 17Nov12: I thought long and hard about this before I constrcted the images. I finally decided that the most important thing on this page was to document the effects themselves rather than their usage (that to me is tutorial material as in Steve's emerging Steve's use of fades a referenced above) - accordingly I wanted the users to be able to directly visually compare the fade shapes. Note too that there is actually no timeline/timebase in the images,so the fade length is not specified directly in the image.
- Gale: Not a big deal, but I am not entirely convinced. "Unlike fading out a fade in is normally applied over a very short audio selection (less than a second)" is surely itself "tutorial material" (and is "less than a second" correct?). I agree it's good to let users compare like with like, but if you choose to introduce the comment about what the fade in is used for, it's confusing to then have the selections the same apparent length, timeline or not. Maybe have an additional image to show the difference the length of selection makes?

Example of a linear fade in applied to a constant frequency and amplitude sine wave.

Gale 19Nov12: ToDo "Exponentially" below needs to link to a Glossary item when we have one, otherwise it's meaningless.

Unlike fading out, a fade in is normally applied over a very short audio selection (less than a second). You may get an improved result by applying a fade in to the same audio selection three times (which effectively gives an exponentially curved fade in).

Cross Fades

Despite the names these effects do not do an automatic cross-fade between two tracks or clips. Instead they apply a curve that is different from the one used by the Fade Out effect. The curve used is one that will result in equal volume throughout the fade once the faded in and faded out regions are mixed.

Cross Fade Out

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Cross Fade In

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After a Cross Fade

If the two waveforms above (Cross Fade In and Out) then an equal volume section of audio would result as below. The example is untypical as we have used a constant frequency and amplitude sine wave to illustrate the fades - normal audio would appear more spiky.

Example of a constant frequency and amplitude sine wave after cross-fading.

Fade In/Out tips:

By repeating a fade in, the audio will remain quiet for longer then rise more rapidly to the original level. Similarly, repeating a fade out will cause the level to initially drop more rapidly then tail off at a lower level. As with other effects, the fade may be repeated as required by pressing CTRL + R.
For a more customizable exponential fade in or fade out, use the Envelope Tool on Tools Toolbar.
When cross-fading, fade in the first two-thirds of the overlapping audio that is beginning, and fade out the last two-thirds of the overlapping audio that is coming to an end. Two-thirds is a guideline rather than a rule, but helps to keep the level of audio constant through the fade. Alternatively, cross-fade using the two Cross Fade effects, selecting the entire overlap.
Typically fade-outs are applied over a longer period (up to ten seconds) whereas typical fade-ins are much shorter (less tha a second).

Gale 01Jan13: Probably we should not have a "Muscial Fades" (plural) section until we have Pro Fade Out released on Wiki (or in 2.0.x).

Musical Fades

These fades apply a more musical fade to the selected audio, giving a more pleasing (more "professional") sounding result.

Studio Fade Out

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ToDo-1 Gale 01Jan13: This is confusing. Which of the mirrored S or 1/2 period curves does it use, when? Or are they the same thing?

Produces a smooth and musical sounding fade out. A mirrored S-curve or 1/2 period cosine is used for the volume and a linear ramp for the low pass filter (from 22050 Hz down to 100 Hz). This makes it fade out the higher frequencies a little quicker than the lower frequencies. It gives it a "going off into the distance" type of sound rather than sounding like a "mechanical" fade out. This technique has found usage in the recording industry for CD or LP tracks.