manual/include/grid-controls.html

<img class="left" src="/images/toolbar-grid.png" alt="Editor toolbar's grid">

<p>
  Ardour's editor utilizes a <dfn>grid</dfn> to assist in the placement of regions
  on the timeline, or with editing functions that need to happen at a specific
  point in time. This <dfn>snapping</dfn> of the cursor and various objects to the
  grid can be toggled on or off, as does its behaviour, and grid units.
</p>

<h2>About Snapping</h2>

<p>
  There are two ways to think about aligning material to a grid. The first and
  most obvious one is where an object's position is clamped to grid lines. In
  Ardour, this is called <dfn>absolute snap</dfn> and is commonly used when
  working with sampled material where audio begins exactly at the beginning of a
  file, note or region.
</p>

<p>
  The second, <dfn>relative snap</dfn>, is used when an object's position relative
  to the grid lines is important. In music, this allows to move objects around
  without changing the "feel" (or timing) of a performance.
</p>

<p>
  Absolute snap is the default method of snapping in Ardour.
</p>

<p>
  While dragging objects, pressing the absolute snap modifier key(s) switches
  from absolute to relative snap.
</p>

<p>
  The snap can also be entirely disabled by using the snap modifier (see below).
</p>

<p>
  Note that in relative snap mode the reference point is taken to be the distance
  to the nearest grid line.
</p>

<p>
  Note also that when an object lies exactly on a grid line, there will be no
  difference between relative and absolute snap modes.
</p>

<p>
  The relative snap and snap modifiers (along with other modifier keys) may be set
  in <kbd class="menu">Edit &gt; Preferences &gt; User Interaction</kbd>
</p>

<p>
  For common use patterns, it is recommended to assign a unique key for one
  snap modifier and two keys for the other in such a way that they share an
  otherwise unused key. For example, the snap modifier may be chosen to be the
  <kbd class="mod2n"></kbd> key and the relative snap modifier to be the <kbd
  class="mod2n"></kbd> and <kbd class="mod4n"></kbd> keys.
</p>

<h2>Snap Modes</h2>

<p>
  Using the above modifications, Ardour supports three different modes of snapping
  to the grid:
</p>

<table class="dl">
  <tr><th><kbd class="menu">No Grid</kbd></th>
    <td>disables the grid. All objects move freely in this mode.</br>
    In <kbd class="menu">No Grid</kbd> mode, the grid may be temporarily activated
    by pressing the snap modifier (for absolute snap) or switch to relative snap
    by pressing the relative snap modifier.</td></tr>
  <tr><th><kbd class="menu">Grid</kbd></th>
    <td>activates normal snapping. All positions of objects snap to the grid. (See
    <a href="#gridunits">Grid Units</a> below to change the grid).
    Moving an object in "Grid"-mode, does not change its position until
    the mouse is far enough for the object to reach the next grid line.</br>
    To maintain an objects' position relative to the grid line, the "snap relative"
    modifier can be used. When holding down this
    modifier during a drag, the dragged object will jump while maintaining its
    original distance from the line.</br>
    New objects will always be created at grid
    points.</br>
    Holding down the snap modifier will disable the current grid
    setting and allow moving the object freely.</td></tr>
  <tr><th><kbd class="menu">Magnetic</kbd></th>
    <td>is a less strict type of snapping. Objects can still be moved to any
    position, but positions close to the relative or absolute grid points will snap.
    In order to move an object very close to a snap point, it may be necessary to
    zoom in to prevent snapping to that point, or to use the snap modifier to
    disable snap completely.</br> As with Grid mode, the snap modifier will disable
    snap completely while the absolute snap modifier will move the "notch" of
    Magnetic snap to the grid lines.</td></tr>
</table>

<h2>Syncing Regions to the Grid</h2>

<p>
  By default, a region's beginning will be used as the reference for both types of
  snapping, this behaviour can be changed by setting a <dfn>sync point</dfn>
  in the region, by selecting the region(s) and pressing <kbd>V</kbd>. This will set the
  sync point to the current <a href="@@edit-point-control">edit point</a>.
</p>

<h2 id="gridunits">Grid Units</h2>

<p>
  The selector next to the grid mode selector defines the size of the grid
  elements. The grid can be set to several different units:
</p>

<table class="dl">
  <tr><th><kbd class="menu">CD Frames</kbd></th>
  <td>A CD Frame is 1/75th of a second. Snapping to CD Frames (using absolute snap) can be used to avoid issues with CD track lengths.</td></tr>
  <tr><th><kbd class="menu">Timecode Frames/Seconds/Minutes</kbd></th>
  <td>The duration of a frame depends on the timecode settings for the session.</td></tr>
  <tr><th><kbd class="menu">Seconds/Minutes</kbd></th>
  <td>These are absolute time units, unaffected by sample rate or timecode settings</td></tr>
  <tr><th><kbd class="menu">Beats/N</kbd></th>
  <td>Set the grid to units of 1/N beats, where N can be 128, 64, 32, 16, 8, 7, 6, 5, 4, 3, 2. The duration of a grid unit will depend on the tempo and meter in effect at that point in the timeline.</td></tr>
  <tr><th><kbd class="menu">Beats</kbd></th>
  <td>Set the grid to whole beats. The duration of a grid unit will depend on the tempo and meter in effect at that point in the timeline.</td></tr>
  <tr><th><kbd class="menu">Bars</kbd></th>
  <td>Set the grid to whole bars. The duration of a grid unit will depend on the tempo and meter in effect at that point in the timeline.</td></tr>
  <tr><th><kbd class="menu">Markers</kbd></th>
  <td>The grid lines are the markers.</td></tr>
  <tr><th><kbd class="menu">Region Starts</kbd></th>
  <td>The grid lines are constructed from region start points (see below).</td></tr>
  <tr><th><kbd class="menu">Region Ends</kbd></th>
  <td>The grid lines are constructed from region end points (see below).</td></tr>
  <tr><th><kbd class="menu">Region Syncs</kbd></th>
  <td>The grid lines are constructed from region sync points.</td></tr>
  <tr><th><kbd class="menu">Region Bounds</kbd></th>
  <td>The grid lines are constructed from region start or end points.</td></tr>
</table>

<p>
  To use Region starts/ends/syncs/bounds as snap choices, it is necessary to have either:
</p>

<ul>
  <li><em>No</em> tracks selected, which means that Ardour snaps to regions on any
    track, or </li>
  <li>Several tracks selected, which means that Ardour only snaps to regions on
    those selected tracks.</li>
</ul>

<p>
  If items are moved on a track, and only the current track is selected, then
  snapping will only happen with other regions on the same track. This means
  that enabling <kbd class="menu">Edit &gt; Preferences &gt; Editor &gt; Link
  Selections of Regions and Tracks</kbd> will make the "Region" grid unit
  unusable. This option should not be used in conjunction with the use any of the
  Region grid units.
</p>