Boundaries and events

The EMU-webApp has slightly different labeling mechanics compared with other annotation software. Compared to the usual click and drag of segment boundaries and event markers, the web application continuously tracks the movement of the mouse in levels containing time information, highlighting the boundary or event marker that is closest to it by coloring it blue. Figure displays this automatic boundary preselection.

Screenshot of segment level as displayed by the EMU-webApp with superimposed mouse cursor displaying the automatic boundary preselection of closest boundary (boundary marked blue).

Once a boundary or event is preselected, the user can perform various actions with it. She or he can, for example, grab a preselected boundary or event by holding down the SHIFT key and moving it to the desired position, or delete the current boundary or event by hitting the BACKSPACE key. Other actions that can be performed on preselected boundaries or events are:

• snap to closest boundary or event in level above (Keyboard Shortcut t),
• snap to closest boundary or event in level below (Keyboard Shortcut b), and
• snap to nearest zero crossing (Keyboard Shortcut x).

To add a new boundary or event to a level the user initially has to select the desired level she or he wishes to edit. This is achieved either by using the up and down cursor keys or by single-left-clicking on the desired level. The current preselected level is marked in a darker shade of gray, as is displayed in Figure .

Screenshot of two levels as displayed by the EMU-webApp, where the lower level is preselected (i.e., marked in a darker shade of gray).

To add a boundary to the currently selected level one first has to select a point in time either in the spectrogram or the oscillogram by single-left-clicking on the desired location. Hitting the enter/return key adds a new boundary or event to the preselected level at the selected time point. Selecting a stretch of time in the spectrogram or the oscillogram (left-click-and-drag) and hitting enter will add a segment (not a boundary) to a preselected segment level.

Segments and events

The EMU-webApp also allows segments and events to be preselected by single-left-clicking the desired item. The web application colors the preselected segments and events yellow to indicate their pre-selection as displayed in Figure .

Screenshot of level as displayed by the EMU-webApp, where the /@/ segment is currently preselected as it is marked yellow.

As with preselected boundaries or events the user can now perform multiple actions with these preselected items. She or he can, for example, edit the item’s label by hitting the enter/return key (which can also be achieved by double-left-clicking the item). Other actions that can be performed on preselected items are:

• Select next item in level (keyboard shortcut TAB),
• Select previous item in level (keyboard shortcut SHIFT plus TAB),
• Add time to selected item(s) end (keyboard shortcut +),
• Add time to selected item(s) start (keyboard shortcut SHIFT plus +),
• Remove time to selected item(s) end (keyboard shortcut -),
• Remove time to selected item(s) start (keyboard shortcut SHIFT plus -), and
• Move selected item(s) (hold down ALT Key and drag to desired position).

By right-clicking adjacent segment or events (keyboard shortcut SHIFT plus left or right cursor keys), it is possible to select multiple items at once.

Parallel labels in segments and events

If a level containing time information has multiple attribute definitions (i.e., multiple parallel labels per segment or event) the EMU-webApp automatically displays radio buttons underneath that level (see red square in Figure ) that allow the user to switch between the parallel labels. Figure displays a segment level with three attribute definitions.

Screenshot of segment level with three attribute definitions. The radio buttons that switch between the parallel labels are highlighted by a red square.

Legal labels

As mentioned in Section , an array of so-called legal labels can be defined for every level or, more specifically, for each attribute definition. The EMU-webApp enforces these legal labels by not allowing any other labels to be entered in the label editing text fields. If an illegal label is entered, the text field will turn red and the EMU-webApp will not permit this label to be saved.

Viewing the hierarchy

As mentioned in Section , pressing the show hierarchy button (keyboard shortcut h) in the top menu bar opens the hierarchy view modal window². As with most modal windows in the EMU-webApp, it can be closed by clicking on the close button, clicking the X circle icon in the top right hand corner of the modal or by hitting the ESCAPE key. By default, the hierarchy modal window displays a horizontal version of the hierarchy for a spatially economical visualization. As most people are more familiar with a vertical hierarchical annotation display, the hierarchy can be rotated by hitting the rotate by 90° button (keyboard shortcut r). Zooming in and out of the hierarchy can be achieved by using the mouse wheel, and moving through the hierarchy in time can be achieved by holding down the left mouse button and dragging the hierarchy in the desired direction. Figure shows the hierarchy modal window displaying the hierarchical annotation of a single path (Utterance -> Intonational -> Intermediate -> Word -> Syllable -> Phoneme -> Phonetic) through a multi-path hierarchy of the ae emuDB in its horizontal form.

Screenshot of the hierarchy modal window level displaying a path through the hierarchy of the ae emuDB in its horizontal form.

Selecting a path through the hierarchy

As more complex databases have multiple hierarchical paths through their hierarchical annotation structure (see Figure for an example of a multi-dimensional hierarchical annotation structure), the hierarchy modal offers a drop-down menu to choose the current path to be displayed. Area 2 in Figure marks the hierarchy path drop-down menu of the hierarchy modal.

Screenshot of top of hierarchy modal window of the EMU-webApp in which the area marked 1 shows the drop-down menus for selecting the parallel label for each level and area 2 marks the hierarchy path drop-down menu.

It is worth noting that only non-partial paths can be selected in the hierarchy path drop-down menu.

Selecting parallel labels in timeless levels

As timeless levels may also contain multiple parallel labels, the hierarchy path modal window provides a drop-down menu for each level to select which label or attribute definition is to be displayed. Area 1 of Figure displays these drop-down menus.

Adding a new item

The hierarchy modal window provides two methods for adding new annotation items to a level. This can either be achieved by pressing the blue and white + button next to the level’s name (which appends a new item to the end of the level) or by preselecting an annotation item (by hovering the mouse over it) and hitting either the n (insert new item before preselected item) or the m key (insert new item after preselected item).

Modifying an annotation item

An item’s context menu³ is opened by single-left-clicking its node. The resulting context menu displays a text area in which the label of the annotation item can be edited, a play button to play the audio section associated with the item and a collapse arrow button allowing the user to collapse the sub-tree beneath the current item. Collapsing a sub-tree can be useful for masking parts of the hierarchy while editing. A screenshot of the context menu is displayed in Figure .

Screenshot of the hierarchy modal window of the EMU-webApp displaying an annotation item’s context menu.

Adding a new link

Adding a new link between two items can be achieved by hovering the mouse over one of the two items, holding down the SHIFT key and moving the mouse cursor to the other item. A green dashed line indicates that the link to be added is valid, while a red dashed line indicates it is not. A link’s validity is dependent on the database’s configuration (i.e., if there is a link definition present and the type of link definition) as well as the non-crossing constraint that essentially implies that links are not allowed to cross each other. If the link is valid (i.e., a green dashed line is present), releasing the SHIFT key will add the link to the annotation.

Deleting an annotation item or a link

Items and links are deleted by initially preselecting them by hovering the mouse cursor over them. The preselected items are marked blue and preselected links yellow. A preselected link is removed by hitting BACKSPACE and a preselected item is deleted by hitting the y key. Deleting an item will also delete all links leading to and from it.