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7 <section id="sn-working-with-crossfades">
8 <title>Working with Crossfades</title>
10 Whenever you arrange any two audio regions so that they overlap in any
11 way, you create the potential for a
12 <link linkend="gt-crossfade">crossfade</link> between them: a smooth
13 transition from one region to the other. Crossfades in Ardour are
14 generated in realtime, and are not stored on disk. They are objects
15 within a playlist just like regions, except that the only way to create
16 a crossfade is by overlapping two regions, and the only way to remove a
17 crossfade is to move one or both of the regions so that they no longer
18 overlap. Note that crossfades are not always audible (they can be muted
19 and unmuted at will), and can be edited in a variety of ways. We think
20 of a crossfade as consisting of an overlap between two regions, plus two
21 gain control curves that control the volume of the incoming and outgoing
22 regions during the crossfade.
25 <section id="crossfade-types">
26 <title>Types of crossfades</title>
28 Ardour comes with two basic kinds of crossfades, termed
29 <emphasis>short crossfades</emphasis> and <emphasis>full
30 crossfades</emphasis> . A full crossfade is a transition between two
31 regions that spans the entire overlap between them. If the overlap is
32 2 seconds long, then the crossfade is 2 seconds long. A short
33 crossfade is a transition between two regions that lasts a fixed
34 amount of time and serves simply to avoid audio glitches at the
35 boundary of the two regions. The length of a short crossfade is a
36 session-wide parameter than can be set via the <emphasis>option
37 editor</emphasis> . The default is 15ms, and the length can vary from
38 1 milliseconds to 0.5 seconds. In the current version of Ardour, it is
39 not possible to change the length of a short becrossfade after it has
40 been created, but it is possible to change most short crossfades to a
41 full crossfade and vice versa. Full crossfades can have their length
42 altered by changing the extent of the overlap between the two regions.
46 Note that even though the absolute length of the crossfade is fixed,
47 crossfades can be <emphasis>edited</emphasis> with complete freedom,
48 allowing you change the effective length of a crossfade by altering
49 the shapes of the fade in and fade out curves.
53 <section id="crossfade-overlaps">
54 <title>Overlaps</title>
56 There are several different ways to overlap two regions, and they
57 result in different kinds of crossfades being placed at the boundaries
61 <section id="external-overlaps">
62 <title>External overlaps</title>
64 An "external" overlap occurs when a region starts within another
65 region, but extends beyond the other's end.
69 <imagedata fileref="images/overlaplaterhigher.png"/>
73 Overlaps like this will cause an xfade to be placed at the start of
74 the later region. Whether it is a full or short crossfade is
75 controlled by the current crossfade type preference. If short
76 crossfades have been chosen, the crossfade will last for the current
77 short crossfade duration; otherwise the full crossfade will last for
78 the entire overlap. The mute status of the crossfade will depend on
79 the current state of the "New crossfades are muted" setting.
83 In the example above, the later region is above the earlier one. It
84 is also possible to create an overlap where the earlier region is in
89 <imagedata fileref="images/overlapearlyhigher.png"/>
93 For an overlap of this type, the current crossfade type preference
94 affects the placement of the crossfade. If full crossfades have been
95 chosen, the crossfade will be placed at the start of the later
96 region and will last for the entire overlap. If short crossfades
97 have been chosen, the crossfade will start just before the end of
98 the earlier region and will last for the chosen short crossfade
99 duration. The mute status of the crossfade will depend on the
100 current state of the "New crossfades are muted" setting.
104 <section id="internal-overlaps">
105 <title>Internal overlaps</title>
107 An "internal" overlap occurs when the start and end of one region
108 both occur within the duration of another.
112 <imagedata fileref="images/internalhigheroverlap.png"/>
116 Overlaps of this type will cause two short crossfades to be place at
117 the start of the later region and close to its end. Both crossfades
118 will last for the current short crossfade duration, and are created
119 in an un-muted state. These crossfades <emphasis>cannot</emphasis>
120 be converted to full crossfades. It is important to realize that the
121 purpose of these two crossfades is a little different than those
122 created for the single-ended overlap cases above. They are created
123 solely to avoid audio glitches at the transitions between the two
124 regions, and are not intended to facilitate interesting crossfades
125 between the upper and lower region.
129 Notice that in the example above, the shorter region is above the
130 longer one. It is also possible to create the following type of
131 overlap, where the shorter region is below the longer one:
135 <imagedata fileref="images/internalloweroverlap.png"/>
139 Overlaps of this type will not cause any crossfades to be created.
140 The uppermost region will be audible throughout its duration; the
141 lowermost region will not be audible at all.
146 <section id="creating-crossfades">
147 <title>Creating Crossfades</title>
149 To create a crossfade between two regions, move them so that they
150 overlap. A crossfade is automatically created within the overlap
151 (possibly two, dependening on the type of overlap, as explained
152 above). Whether the crossfade is muted or not depends on two things:
158 if the current crossfade type is set to "Short", the new crossfade
159 will be created in an un-muted state
165 if the current crossfade type is set to "Full", the mute status of
166 the new crossfade is controlled from the <emphasis>option
167 editor</emphasis> on the "Layers&Fades" control panel. If "New
168 crossfades are unmuted", the new crossfade will be unmuted.
174 A muted crossfade is not directly visible in the editor window, but
175 can be accessed by context clicking within the overlap that it relates
176 to. An unmuted crossfade has a yellow background that covers the
177 entire overlap (to make its presence obvious at all times), and a pair
178 of visible curves that show the gain control curves for the fade.
179 These curves may not be visible at a particular zoom level, especially
180 for short crossfades.
184 <section id="editing-crossfades">
185 <title>Editing Crossfades</title>
187 To carry out operations on a crossfade, context click anywhere in the
188 overlap. For the short crossfades in the "internal" overlap case, you
189 will need to zoom in until the crossfade becomes visible, and then
190 context click on it. Each crossfade under the mouse pointer (there is
191 normally only one) will appear in the context menu, and will lead to a
192 submenu offering the following options:
198 Mute/Unmute the crossfade
210 change the crossfade from short to full or vice versa
216 The last option is not available for the short crossfades in the
217 "internal" overlap case.
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