2.1 Sequences, Screens, Layers and Clips

Many different structures are used to organize media, cues, effects, etc. on the Timeline. Make sure you have a good understanding of what these structures do and how they are used. The following sections of the manual (from 2.1.1 to 2.5.4) provide information on how Sequences, Screens, Layers and Clips are used.

2.1.1 Sequences

A Sequence contains all of the Screens, Layers and Clips used in a project, and it provides a representation of the Show’s temporal structure. This is where you will organize and edit media, cues, effects, etc.

A project can have multiple Sequences, but you can only render one Sequence at a time (i.e. the Sequence that is currently selected). Additional Sequences can be used as editing bins to build specific segments of a Show or to hold alternative versions of it.

Select a Sequence

To select a Sequence:

  • Click on a Sequence tab to activate a specific Sequence and access its content.

Create a Sequence

There are three ways to create a new Sequence:

  • Click on the [+] button located to the right of the Sequence tabs; or

  • Press [Ctrl+T] with the Timeline module in focus; or

  • Select {File > Add sequence} from the Timeline menu bar.

Delete a Sequence

To delete a Sequence:

  1. [Right-click] on the tab linked to the Sequence you want to delete. This will give you access to its contextual menu.

  2. Select {Delete} from the contextual menu.

2.1.2 Screens

Any 3D object that was created or imported in the 3D Scene will become a Screen (with the notable exception of Decorative Objects). Screens are virtual structures that represent real-world projection screens. A Screen will coexist in the 3D Scene module (where it is created, then calibrated) and in the Timeline module. Each Screen has its own section of the Timeline, where you can create all of the Layers it will hold.

Create Screens

Screens are not created in the Timeline module per se. When a 3D object is added in the 3D Scene, TACHYON will automatically recognize it as a Screen. A newly created Screen will add its own section to the Timeline.

Collapse and Expand Screens

In order to collapse or expand a Screen click on the small triangle located beside the Screen’s name.

Add Screen Metadata

It is possible to add text metadata to a Screen by accessing the Screen Properties (see Section 5 Clip Properties in Chapter 4 Programming a Show). The metadata attached to a Screen can be used to show or hide specific Screens when executing a search command. For example, if you add text metadata such as “Aisle Screens” to some of the Screens as a way to identify them, you can easily find them when performing a search.

Screen Render Resolution

Screens have a render resolution. The render resolution represents the amount of pixels used to display images on a Screen. You can set a Screen’s render resolution by adjusting its width and height parameters in the Screen Properties (see Section 5 Clip Properties in Chapter 4 Programming a Show).

When determining a Screen’s resolution many different factors need to be taken into account: the Screen’s physical size, its ratio, the distance between its position and the audience, and the resolution of the media that will be displayed on it should be considered. The best practice when choosing resolution is to match the ratio of the Screen and the resolution of the media that will be displayed on it. Insufficient resolution will result in a pixelated image. Using a higher resolution than the media being displayed is a waste of computing resources.

Search for a Screen

A search box is located at the top of the Layers list. You can enter text in the box to filter out some of the Screens on the list.

Screens that remain visible in the Layers list will be the ones that match the name or metadata tag entered into the search box. Note that the names of the 3D objects from which the Screens originate are taken into account by the search box filter.

The Root

The Root can be thought of as an invisible Screen that holds various Clip types (see Section 2.2 Clip Types in Chapter 4 Programming a Show). These Clips are independent from any of the actual Screens created in the 3D Scene. Clips placed in the Root can be referenced by other Clips (such as Proxy Clips, Stack FX Clips,Virtual Projectors, etc.).

It is considered a best practice to place Cue Clips in the Root because by doing this they will appear at the top of all of the other Screens. Also, since the search box filter affects the visibility of the Screens but not the Root, Cues placed in the Root will always be visible.

2.1.3 Layers

Layers are represented as horizontal tracks in the Timeline. They can store many Clips horizontally. Layers can be stacked up vertically to create composited scenes. Layers are also useful when building real-time effects by combining multiple Stack FX Clips. They are also useful in contexts where automation relies on Cue Clips.

Unlike Adobe After Effects, TACHYON’s Layers can hold many clips.

Create New Layers

To create a new Layer:

  1. Select one of the Screens (or the Root) by clicking on its entry in the Layers list;

  2. Click on the [+] button located in the Master Layer panel.

The new Layer will be added at the bottom of the Layers list.

By pressing [Ctrl++] the new Layer will be inserted directly below the Layer that is currently selected.

A newly created Layer might not be immediately visible. You have to [Double-click] on the Screen or on the triangle found next to the Screen’s name in order to reveal the Layers stored inside it.

Reorganize the Layer Order

All Layers can be manipulated with the mouse in order to change their position in the Layers list:

  • [Click+Drag+Drop] any Layer to where you want it.

Layers can also be dragged from one Screen to another using the same method.

Layer Rendering Order

In TACHYON, the rendering order is organized sequentially, from top to bottom. This means the lowest item in the list will always be the last one rendered, and as a result it will be placed on top of the composition. This design applies to both the Timeline module (where compositing is done) and the 3D Scene list.

It is important to remember that the logic of TACHYON’s rendering order is the inverse of Adobe’s image compositing software.

2.1.4 Clips

A Clip is a container that can hold various time-based components such as media, cues, effects, etc. (see Section 2.2. Clip Types in Chapter 4 Programming a Show for a complete list of the Clip types and their description).

Clips are placed within Layers (which in turn are placed in Screens, or in the Root). Stacking Clips vertically in the Layers belonging to the same Screen (or in the Root) will allow the creation of visual compositions through Layer blending (see Section 4.3 Blending – Create Compositions in Chapter 4 Programming a Show).

Clips have a fixed duration defined by their borders. By default, the duration of the newly created Clip will match the duration of the whole project.

The Clip’s default duration can be changed by entering a new temporal value for Clips in the field located in the Timeline Default values window. To access the Timeline Default values window click on the General tab in the Settings module.

Add Clips

  • [Right-click] on any track on the Timeline (each Layer has a its own track) to open a contextual menu that contains the following options for adding new Clips (or use the dedicated shortcuts in the Timeline module):

  • Add Empty Clip [Ctrl+N]

  • Add Media Clip (Image, Video, Sound) [Ctrl+M]

  • Add FX Stack Clip [Ctrl+E]

  • Add Virtual Projector Clip [Ctrl+R]

  • Add Input Device Clip [Ctrl+I]

  • Add Cue Clip [Ctrl+U]

  • Add Proxy Clip [Ctrl+P]

  • [Drag+Drop] a media file from the File Manager module onto a track to create a new Media Clip.

  • [Drag+Drop] a cue from the Cue Editor module onto a track to create a new Cue Clip.

  • [Drag+Drop] a Live input from the I/O Manager module onto a track to create a new Live Input Clip.

Select a Single Clip

  • Click on a Clip to select it.

Select Multiple Clips

  • [Ctrl+Click] on Clips; or

  • Draw a selection square across the Layers to perform a group selection. (This only works if you draw the selection square within the tracks (identified by the lighter grey area.)

The selection square works across Screens.

Delete Clips

  • Select the Clips you want to delete and press the [Delete] key. A Confirmation Box will open to make sure you really want to delete the Clip. Click on the [Delete] key to delete the Clip.

Change Clip Type

Clip capacities (media playback, send a cue, etc.) are defined by their type (media, cue, effect, etc.). A Clip type is selected whenever a Clip is created.

You can also change a Clip type later on without affecting its duration or location in the Timeline by doing the following:

  • Select the Clip and then select an option from the Clip Type dropdown menu located in the Shared Clip Properties window section of the Timeline module.

The Clip type cannot be changed when multiple Clips are selected.

Change Clip Colors

  1. [Right-click] on a Clip (or a group of multi-selected Clips).

  2. Select {Change color} from the contextual menu. A color picker pop-up window will open. Choose the desired color and close the color picker.

Reset Clip Colors

  1. [Right-click] on a Clip (or a group of multi-selected Clips).

  2. Select {Reset color} from the contextual menu. The selected Clips will reset their color to the default specified in the Settings module.

Change a Clip Type Color

  1. Press [Alt+S] or select {System > Settings} to open the Settings module.

  2. Click on the General tab to access the Default Clip Colors list.

  3. Click on any of the Clip type buttons in the list to open a color picker pop-up window. Choose the desired color and close the color picker.

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