2 Every Region has a fade-in and fade-out. By default, the region fade
3 is very short, and serves to de-click the transitions at the start and
4 end of the region. By adjusting the regions fade length, a more
5 gradual transition can be accomplished.
10 <dfn>Region fades</dfn> are possible at the beginning and end of
11 all audio regions. In object mode, a grip appears at the top left and
12 top right of an audio region when the cursor hovers over it. Placing
13 the cursor over the top of the grip displays the region fade cursor
14 tip. Click and drag the grip left or right in the timeline to
15 adjust the length of the fade.
21 <dfn>Crossfades</dfn> refer to the behavior when you want to make
22 a smooth transition (mix) from one audio region to another on the same
23 track. Historically, this was done by splicing 2 pieces of analog
24 tape together, and this concept was carried forward into digital
25 editing. Each track is a sequence of sound files (regions). If
26 two regions are butted against each other, there needs to be a method
27 to splice them smoothly together. The crossfade allows one region
28 to fade smoothly out, while the next region fades smoothly in, like 2
29 pieces of tape that have been cut at and angle, and overlapped.
32 But Ardour uses a more refined "layered" editing model, and
33 therefore it is possible for multiple regions to be stacked on a single
34 location with arbitrary overlaps between different layers. For
35 this reason, crossfades must be implemented differently. We can't
36 assume that a crossfade is an entitry that exists between 2 regions;
37 instead each region must have its own associated crossfades at each
38 end, and the topmost region must always crossfade down to the
39 underlying region(s), if any.
42 Ardour solves this problem by putting a crossfade at the beginning
43 and end of every region. The fades of the bottom-most region are
44 first rendered, and then each region is rendered on top of the one
45 below it, with fades at the end of each region providing a crossfade to
46 the region(s) beneath it.
49 It is important to understand that region fades <em>are</em> crossfades. When one region has
50 another region or multiple regions beneath its fade area, then you will
51 hear the topmost region fade-out be mirrored as a fade-in on the
52 underlying region(s). The grip for the topmost region will allow
53 changing the length and type of the crossfade into the underlying
54 region(s). In this way you can create a complicated series of
55 crossfades, and then layer another region atop the others, and fade
56 into a complicated series.
59 If a region doesn't have any region(s) under it, then the region is
60 crossfaded to silence; for convenience we call this a "fade"
61 rather than a crossfade.
67 To activate/deactivate or change the shape of a region's fadein or
68 fade-out, hover the cursor over the regionfade grip till the cursor tip
69 indicates region fade editing and context-click to bring up a context
70 menu. In the context menu there is a list of options for the
71 regionfade. <kbd class="menu">Activate/Deactivate</kbd> enables and
72 disables the regionfade.
75 Because each fade is also a crossfade, it has an inverse fade shape
76 for the audio beneath the fade. It is important to know how the
77 shapes differ, and which are most suitable for various editing tasks.
80 The different types of fades are:
83 <tr><th><kbd class="menu">Linear</kbd></th><td>A simple linear coefficient decrease, and its
84 mathematical inverse. A Linear fade starts attentuating quickly
85 and then cuts off even more abruptly at lower levels. When used
86 as a crossfade, the signals are each -6dB attenuated at the midpoint.
87 This is the correct crossfade to use with highly-correlated signals for
88 a smooth transition.</td></tr>
89 <tr><th><kbd class="menu">Constant Power</kbd></th><td>The constant power curve starts fading
90 slowly and then cuts off abruptly. When used as a crossfade
91 between 2 audio regions, the signals are symetrically attenuated, and
92 they each reach -3dB at the midpoint. This is the correct crossfade to
93 use when you want to splice audio in the general ( uncorrelated ) case.</td></tr>
94 <tr><th><kbd class="menu">Symmetric</kbd></th><td>The Symmetric fade starts slowly, then
95 attenuates significantly before transitioning to a slower fade-out near
96 the end of the fade. When used as a crossfade, the Symmetric
97 curve is not mathematically correct like the Equal Power or Linear
98 curves, but it provides a slower fade-out at low volumes. This is
99 sometimes useful when editing 2 entire music works together so that the
100 transition is more gradual.</td></tr>
101 <tr><th><kbd class="menu">Fast</kbd></th><td>The Fast curve is a linear decibel fade; It sounds
102 like a perfectly smooth fader or knob moved to silence. This shape is
103 excellent as a general-purpose fade-in. When used as a
104 crossfade, the inverse fade curve maintains constant power but is
105 therefore non-symmetric; so its use is limited to those cases where the
106 user finds it appropriate.</td></tr>
107 <tr><th><kbd class="menu">Slow</kbd></th><td>The Slow curve is a modified linear decibel fade.
108 The initial curve starts more gradually so that it has a less
109 abrupt transition near unity. After that, it sounds like a
110 perfectly smooth fader or knob moved to silence. This shape is excellent as
111 a general-purpose fade-out. When used as a crossfade, the
112 inverse fade curve maintains constant power but is therefore
113 non-symmetric; so its use is limited to those cases where the user
114 finds it appropriate.</td></tr>
118 Although these fade shapes serve specific purposes, you might find that
119 any of the shapes is usable in your situation. The final decision
120 is mostly an artistic choice.
124 These fade curves are developed to provide a range of common uses, and
125 are developed with the least possible amount of changes in the "slope"
126 of the line. This provides artifact-free crossfades. Some
127 DAWs provide complicated fade editors with parametric "spline" controls
128 of the fade curves. While it might be interesting to develop a
129 fade curve with a faster cutoff, the mathematical difference between
130 this and simply shortening the fade is vanishingly small; and the
131 amount of effort to shorten the fade is much easier than messing with a
132 crossfade editor dialog.