[Ardour-Dev] Overlaps & crossfades

Paul Davis paul at linuxaudiosystems.com
Tue Dec 18 11:03:22 PST 2007

On Tue, 2007-12-18 at 06:56 +0000, John Emmas wrote:
> Sorry to keep pressing this point but I still need to know what is the
> significance of a "default" fade (within the context of an Ardour region).
> Following my last email I did some more experiments and I now realise that
> the behaviour of overlapping timeline fades is dependent upon whether the
> relevant regions are transparent or opaque.  However, I still don't know
> what the difference is between a fade and a default fade.
> Does the term "default" refer to the timing of the fade?  Or its profile?
> Or both?  Or neither?  Or is it something that's there for future expansion?
> Many years ago I worked on another DAW (AudioFile) which also had the
> concept of a default fade - but I don't want to make the mistake of assuming
> that Ardour's default fade fulfils the same purpose.  It would be better if
> I could find out what the *actual* purpose is.

Region fade in/out was created for one purpose and one purpose only: to
avoid clicks near region boundaries. The default fade is a length and
shape identified as a suitable for this purpose. The default fade is 64
samples long (or shorter if the region is less than 64 samples) and uses
a volumetrically linear gain ramp. 

Over time, users asked to be able to exert more control over the gain
envelope at the start & end of the region. There was already a way to do
this - the region gain envelope - but people found that too confusing or
hard to use. As a result, it is possible these days for users to change
the length and shape of the fade in/out, and indeed, for most users,
this is much more convenient than the region gain envelope. It ends up
satisfying most needs where no overlaps are involved.

Crossfades are 100% orthogonal to the fade in/fade out. They have no
relationship to each other in way whatsoever, other than both
representing a way to control gain near the start or end of 1 or more
regions. This may have been a design error, or not. The jury is still
out on that point.

In your use of Ardour, I would avoid any use of region transparency. No
other system that you can find offers this, and it confuses most users,
as it appears to have confused you. There is a reasonable chance that it
is a feature that will be removed from Ardour in the future.


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