Resuming work on removing 'you's. Adding a screenshot to the fade shapes.

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Ed Ward 2017-10-10 19:09:11 +02:00
parent 35203bc9d4
commit 2275c59de3
4 changed files with 84 additions and 84 deletions

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<p> <p>
Every Region has a fade-in and fade-out. By default, the region fade Every Region has a fade-in and fade-out. By default, the region fade
is very short, and serves to de-click the transitions at the start and is very short, and serves to de-click the transitions at the start and
end of the region. By adjusting the regions fade length, a more end of the region. By adjusting the regions fade length, a more
gradual transition can be accomplished. gradual transition can be accomplished.
</p> </p>
<h2>Region Fades</h2> <h2>Region Fades</h2>
<p> <p>
<dfn>Region fades</dfn> are possible at the beginning and end of <dfn>Region fades</dfn> are possible at the beginning and end of
all audio regions. In object mode, a grip appears at the top left and all audio regions. In object mode, a grip appears at the top left and
top right of an audio region when the cursor hovers over it. Placing top right of an audio region when the cursor hovers over it. Placing
the cursor over the top of the grip displays the region fade cursor the cursor over the top of the grip displays the region fade cursor
tip. Click and drag the grip left or right in the timeline to tip. Clicking and dragging the grip left or right in the timeline adjusts the
adjust the length of the fade. length of the fade.
</p> </p>
<h2>Crossfades</h2> <h2>Crossfades</h2>
<p> <p>
<dfn>Crossfades</dfn> refer to the behavior when you want to make <dfn>Crossfades</dfn> refer to the behavior of two audio regions transitionning
a smooth transition (mix) from one audio region to another on the same smoothly (mixing) from one to another on the same
track. Historically, this was done by splicing 2 pieces of analog track. Historically, this was done by splicing two pieces of analog
tape together, and this concept was carried forward into digital tape together, and this concept was carried forward into digital
editing. Each track is a sequence of sound files (regions). If editing. Each track is a sequence of sound files (regions). If
two regions are butted against each other, there needs to be a method two regions are butted against each other, there needs to be a method
to splice them smoothly together. The crossfade allows one region to splice them smoothly together. The crossfade allows one region
to fade smoothly out, while the next region fades smoothly in, like 2 to fade smoothly out, while the next region fades smoothly in, like two
pieces of tape that have been cut at and angle, and overlapped. pieces of tape that have been cut at and angle, and overlapped.
</p> </p>
<p> <p>
But Ardour uses a more refined "layered" editing model, and But Ardour uses a more refined "layered" editing model, and
therefore it is possible for multiple regions to be stacked on a single therefore it is possible for multiple regions to be stacked on a single
location with arbitrary overlaps between different layers. For location with arbitrary overlaps between different layers. For
this reason, crossfades must be implemented differently. We can't this reason, crossfades must be implemented differently. It can't be
assume that a crossfade is an entitry that exists between 2 regions; assumed that a crossfade is an entitry that exists between two regions;
instead each region must have its own associated crossfades at each instead each region must have its own associated crossfades at each
end, and the topmost region must always crossfade down to the end, and the topmost region must always crossfade down to the
underlying region(s), if any. underlying region(s), if any.
@ -46,29 +46,34 @@
the region(s) beneath it. the region(s) beneath it.
</p> </p>
<p> <p>
It is important to understand that region fades <em>are</em> crossfades. When one region has It is important to understand that region fades <em>are</em> crossfades.
another region or multiple regions beneath its fade area, then you will When one region has another region or multiple regions beneath its fade area,
hear the topmost region fade-out be mirrored as a fade-in on the then what will be heard is the topmost region fade-out mirrored as a fade-in
underlying region(s). The grip for the topmost region will allow on the underlying region(s). The grip for the topmost region will allow
changing the length and type of the crossfade into the underlying changing the length and type of the crossfade into the underlying
region(s). In this way you can create a complicated series of region(s). In this way complicated series of crossfades can be created, and
crossfades, and then layer another region atop the others, and fade then another region layered atop the others, and faded into a complicated
into a complicated series. series.
</p> </p>
<p> <p>
If a region doesn't have any region(s) under it, then the region is If a region doesn't have any region(s) under it, then the region is
crossfaded to silence; for convenience we call this a "fade" crossfaded to silence; for convenience this is called a "fade"
rather than a crossfade. rather than a crossfade.
</p> </p>
<h2>Fade Shapes</h2> <h2>Fade Shapes</h2>
<figure class=right>
<img src="/images/crossfade_menu.png">
<figcaption class=center>The fade shape context menu.</figcaption>
</figure>
<p> <p>
To activate/deactivate or change the shape of a region's fadein or To activate/deactivate or change the shape of a region's fadein or
fade-out, hover the cursor over the regionfade grip till the cursor tip fade-out, the cursor has to be hovered over the regionfade grip until the
indicates region fade editing and context-click to bring up a context cursor tip indicates region fade editing, then <kbd class="mouse">right</kbd>
menu. In the context menu there is a list of options for the clicked to bring up a context menu. In the context menu is a list of options
regionfade. <kbd class="menu">Activate/Deactivate</kbd> enables and for the regionfade. <kbd class="menu">Activate/Deactivate</kbd> enables and
disables the regionfade. disables the regionfade.
</p> </p>
<p> <p>
@ -80,44 +85,42 @@
The different types of fades are: The different types of fades are:
</p> </p>
<table class="dl"> <table class="dl">
<tr><th><kbd class="menu">Linear</kbd></th><td>A simple linear coefficient decrease, and its <tr><th><kbd class="menu">Linear</kbd></th><td>A simple linear coefficient
mathematical inverse. A Linear fade starts attentuating quickly decrease, and its mathematical inverse. A Linear fade starts attentuating
and then cuts off even more abruptly at lower levels. When used quickly and then cuts off even more abruptly at lower levels. When used as a
as a crossfade, the signals are each -6dB attenuated at the midpoint. crossfade, the signals are each -6dB attenuated at the midpoint. This is the
This is the correct crossfade to use with highly-correlated signals for correct crossfade to use with highly-correlated signals for a smooth
a smooth transition.</td></tr> transition.</td></tr>
<tr><th><kbd class="menu">Constant Power</kbd></th><td>The constant power curve starts fading <tr><th><kbd class="menu">Constant power</kbd></th><td>The constant power
slowly and then cuts off abruptly. When used as a crossfade curve starts fading slowly and then cuts off abruptly. When used as a
between 2 audio regions, the signals are symetrically attenuated, and crossfade between 2 audio regions, the signals are symetrically attenuated,
they each reach -3dB at the midpoint. This is the correct crossfade to and they each reach -3dB at the midpoint. This is the correct crossfade to
use when you want to splice audio in the general ( uncorrelated ) case.</td></tr> use when splicing audio in the general ( uncorrelated ) case.</td></tr>
<tr><th><kbd class="menu">Symmetric</kbd></th><td>The Symmetric fade starts slowly, then <tr><th><kbd class="menu">Symmetric</kbd></th><td>The Symmetric fade starts
attenuates significantly before transitioning to a slower fade-out near slowly, then attenuates significantly before transitioning to a slower
the end of the fade. When used as a crossfade, the Symmetric fade-out near the end of the fade. When used as a crossfade, the Symmetric
curve is not mathematically correct like the Equal Power or Linear curve is not mathematically correct like the Equal Power or Linear curves,
curves, but it provides a slower fade-out at low volumes. This is but it provides a slower fade-out at low volumes. This is sometimes useful
sometimes useful when editing 2 entire music works together so that the when editing 2 entire music works together so that the transition is more
transition is more gradual.</td></tr> gradual.</td></tr>
<tr><th><kbd class="menu">Fast</kbd></th><td>The Fast curve is a linear decibel fade; It sounds <tr><th><kbd class="menu">Slow</kbd></th><td>The Slow curve is a modified
like a perfectly smooth fader or knob moved to silence. This shape is linear decibel fade. The initial curve starts more gradually so that it has
excellent as a general-purpose fade-in. When used as a a less abrupt transition near unity. After that, it sounds like a perfectly
crossfade, the inverse fade curve maintains constant power but is smooth fader or knob moved to silence. This shape is excellent as a
therefore non-symmetric; so its use is limited to those cases where the general-purpose fade-out. When used as a crossfade, the inverse fade curve
user finds it appropriate.</td></tr> maintains constant power but is therefore non-symmetric; so its use is
<tr><th><kbd class="menu">Slow</kbd></th><td>The Slow curve is a modified linear decibel fade. limited to those cases where the user finds it appropriate.</td></tr>
The initial curve starts more gradually so that it has a less <tr><th><kbd class="menu">Fast</kbd></th><td>The Fast curve is a linear
abrupt transition near unity. After that, it sounds like a decibel fade; It sounds like a perfectly smooth fader or knob moved to
perfectly smooth fader or knob moved to silence. This shape is excellent as silence. This shape is excellent as a general-purpose fade-in. When used as
a general-purpose fade-out. When used as a crossfade, the a crossfade, the inverse fade curve maintains constant power but is
inverse fade curve maintains constant power but is therefore therefore non-symmetric; so its use is limited to those cases where the
non-symmetric; so its use is limited to those cases where the user user finds it appropriate.</td></tr>
finds it appropriate.</td></tr>
</table> </table>
<p> <p>
Although these fade shapes serve specific purposes, you might find that Although these fade shapes serve specific purposes, any of the shapes is
any of the shapes is usable in your situation. The final decision usable in any situation, so the final decision is mostly an artistic choice.
is mostly an artistic choice.
</p> </p>
<p> <p>
@ -131,4 +134,3 @@ finds it appropriate.</td></tr>
amount of effort to shorten the fade is much easier than messing with a amount of effort to shorten the fade is much easier than messing with a
crossfade editor dialog. crossfade editor dialog.
</p> </p>

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<figure class=right> <figure class=right>
<img src="/images/gain-envelope1.png" alt="Default gain envelope"> <img src="/images/gain-envelope1.png" alt="Default gain envelope">
<figcaption class=center>A typical gain envelope (green line).</figcaption> <figcaption>A gain envelope (in green).</figcaption>
</figure> </figure>
<p> <p>
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<p> <p>
The default gain curve, by itself, is not very useful; in order to have more The default gain curve, by itself, is not very useful; in order to have more
control over the shape of the gain envelope it is necessary to add extra control over the shape of the gain envelope it is necessary to add extra
control points. To add a control point to the envelope, click anywhere in the control points. Clicking anywhere in the region where there are no existing
region where there are no existing control points; it will appear <em>on the control points adds a control point to the envelope; it will appear <em>on the
line</em> at the X-axis of the mouse's current position in the region. line</em> at the X-axis of the mouse's current position in the region.
</p> </p>
<figure class=center> <figure class="center">
<img src="/images/gain-envelope2.png" alt="Complex gain envelope"> <img src="/images/gain-envelope2.png" alt="Complex gain envelope">
<figcaption class=center>A more complex gain envelope.</figcaption> <figcaption>A more complex gain envelope.</figcaption>
</figure> </figure>
<p> <p>
Once added, a control point can be <kbd class=mouse>Left</kbd> clicked and Once added, a control point can be <kbd class="mouse">Left</kbd> clicked and
dragged to the desired location. Hovering over a control point will show its dragged to the desired location. Hovering over a control point will show its
current level in dB. To remove a control point, <kbd class=mouse>Left</kbd> current level in dB. <kbd class="mouse">Left</kbd> clicking a control point
click it and press <kbd>Delete</kbd>, or <kbd class=mod3n></kbd><kbd and pressing <kbd>Delete</kbd>, or <kbd class="mod3 mouse">Right</kbd>
class=mouse>Right</kbd>-click on it. clicking a point deletes it.
</p> </p>

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<table class="dl"> <table class="dl">
<tr><th>Systems using JACK 1, versions 0.124 or later</th> <tr><th>Systems using JACK 1, versions 0.124 or later</th>
<td>On these systems, simply start JACK with the <code>-X alsa_midi</code> <td>On these systems, JACK must be started with the <code>-X alsa_midi</code>
server argument. To support legacy control applications, the <code>-X server argument. To support legacy control applications, the <code>-X
seq</code> argument to the ALSA backend of JACK can also be used to get the seq</code> argument to the ALSA backend of JACK can also be used to get the
exact same results.</td></tr> exact same results.</td></tr>
<tr><th>All others</th> <tr><th>All others</th>
<td>Use a2jmidid to act as a bridge between ALSA MIDI and JACK. Do not use <td>Using a2jmidid acts as a bridge between ALSA MIDI and JACK. The <code>-X seq</code>
the <code>-X seq</code> or <code>-X raw</code> arguments&mdash;the timing and or <code>-X raw</code> arguments should <em>not</em> be used&mdash;the timing and
performance of these options is unacceptable.</td></tr> performance of these options is unacceptable.</td></tr>
</table> </table>
@ -26,28 +26,28 @@
<p> <p>
First it must be ensured that there is no ALSA sequencer support enabled in First it must be ensured that there is no ALSA sequencer support enabled in
JACK. To check that, open QJackCtl's <kbd class="menu">Setup</kbd> window. JACK. To check that, one must open QJackCtl's <kbd class="menu">Setup</kbd> window
Set <kbd class="menu">Settings &gt; MIDI Driver</kbd> to <kbd and set <kbd class="menu">Settings &gt; MIDI Driver</kbd> to <kbd
class="input">none</kbd>. Then uncheck the <kbd class="optoff">Misc &gt; class="input">none</kbd>, then uncheck the <kbd class="optoff">Misc &gt;
Enable ALSA Sequencer support</kbd> option. Now restart the jack server Enable ALSA Sequencer support</kbd> option. The jack server must then be restarted
before going on. before going on.
</p> </p>
<h3>Check for a2jmidid availability</h3> <h3>Checking for a2jmidid availability</h3>
<p> <p>
Next, check whether a2jmidid is already installed. After starting the JACK Next, it must be checked whether a2jmidid is already installed. This is done
server, go to the command line and type: by starting the JACK server, then going to the command line and typing:
</p> </p>
<kbd class="cmd lin">a2jmidid -e</kbd> <kbd class="cmd lin">a2jmidid -e</kbd>
<p> <p>
If a2jmidid does not exist, install it with the software manager of the If a2jmidid does not exist, it must be installed with the software manager of the
Linux distribution in use and try again. Linux distribution in use until this command responds.
</p> </p>
<h2>Check available MIDI ports</h2> <h2>Checking available MIDI ports</h2>
<p> <p>
If JACK is correctly configured for MIDI, then the MIDI ports should appear If JACK is correctly configured for MIDI, then the MIDI ports should appear
@ -62,12 +62,11 @@
</p> </p>
<ul> <ul>
<li>If a newer version of JACK 1 is in use, just make sure the <code>-X <li>If a newer version of JACK 1 is in use, by just making sure the <code>-X
alsa_midi</code> or <code>-X seq</code> options are enabled for whatever alsa_midi</code> or <code>-X seq</code> options are enabled for whatever
technique is being used to start JACK.</li> technique is being used to start JACK.</li>
<li>For other versions of JACK, add <code>a2jmidid -e &amp;</code> as an <li>For other versions of JACK, by adding <code>a2jmidid -e &amp;</code> as an
"after start-up" script in the <kbd class="menu">Setup &gt; Options</kbd> tab "after start-up" script in the <kbd class="menu">Setup &gt; Options</kbd> tab
of QJackCtl, so that it is started automatically whenever JACK is of QJackCtl, so that it is started automatically whenever JACK is
started.</li> started.</li>
</ul> </ul>

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