# Key Concepts Before diving into the tutorials, it helps to understand the core building blocks of Exaplay 3. This page introduces the terms and ideas you will encounter throughout the documentation. ## Screens & Outputs A **Screen** is the fundamental canvas in Exaplay 3. Each screen maps to a physical display output — a projector, LED wall, or monitor. When you create a screen, you give it a name, choose which display output it uses, and set a resolution. You can have as many screens as your GPU supports. Each screen gets its own composition with independent layers and timelines. ::: tip Think of a screen as a "virtual projector" — it has a resolution, a position, and its own stack of content. Even if you only have one monitor, you can still create multiple screens for pre-programming. ::: ## Compositions & Layers Every screen contains a **Composition** — the visual scene that gets rendered to that screen. A composition is built from **layers** stacked on top of each other, similar to layers in Photoshop or After Effects. * **Layer 1** (bottom) might be a background video loop. * **Layer 2** could be a title graphic with transparency. * **Layer 3** might be a live NDI camera feed. Each layer can hold a video, image, colour, live input (NDI / Spout), or a test pattern. You control each layer's position, scale, opacity, blend mode, and transitions independently. ## Timeline The **Timeline** is where you arrange media clips in time. Each layer appears as a horizontal track, and you drag media clips onto these tracks to set when they appear, how long they play, and how they transition. Key timeline concepts: * **Playhead** — The vertical line that shows the current playback position. * **Clips** — Coloured blocks on a track representing a media file or input. * **In/Out points** — The start and end of each clip on the timeline. * **Transitions** — Crossfades or cuts between clips on the same track. * **Loop** — A clip or the entire timeline can loop indefinitely. ## Cue List A **Cue List** provides operator-driven control. Instead of everything being driven by a continuous timeline, cue lists let you define named actions (cues) that trigger on demand — by clicking a button, pressing a hotkey, or receiving an external command. Common cue actions include: * **Go to timecode** — Jump the timeline to a specific position. * **Play / Pause / Stop** — Control transport. * **Load composition** — Switch to a different visual scene. * **Fire sequence** — Trigger a chain of timed events. Cue lists are essential for live shows where an operator controls the pacing. ## Transport Controls The **Transport** bar sits at the bottom of the editor and controls playback: | Control | Shortcut | Description | | ---------- | -------- | ---------------------------------------- | | ▶ Play | `Space` | Start playback from the current position | | ⏸ Pause | `Space` | Pause at the current frame | | ⏹ Stop | `Escape` | Stop and return to the beginning | | ⏮ Previous | `←` | Jump to previous cue or clip boundary | | ⏭ Next | `→` | Jump to next cue or clip boundary | ## Inspector Panel The **Inspector** is the properties panel on the right side of the editor. When you select a clip, layer, or screen, the Inspector shows all of its editable properties — position, scale, opacity, loop settings, transitions, effects, and more. The Inspector changes contextually: select a clip and it shows clip properties; select a screen and it shows output settings. ## File Browser The **File Browser** panel at the bottom of the interface is your media library. Point it at a folder on your computer, and it displays thumbnails for all supported media files. Drag files from the browser onto the timeline or directly onto a screen to add them to your composition. Supported formats include: * **Video:** MP4, MOV, AVI, MKV, HAP, HAP Q, HAP Alpha, NotchLC, ProRes * **Image:** PNG, JPEG, BMP, TIFF, TGA, SVG * **Audio:** WAV, MP3, AAC, FLAC ## Show Mode vs Edit Mode Exaplay 3 has two operational states: * **Edit Mode** (default) — The full editor is visible. Output windows may or may not be active. Use this mode to build and prepare your show. * **Show Mode** — Output windows go fullscreen on their assigned displays. The editor remains available for control but the audience only sees the rendered output. Toggle with **Shift+Escape** or the show-mode button in the header. ::: info Show Mode is what you activate for the actual performance. It hides the UI from the audience displays and ensures outputs run at maximum performance. ::: ## Projects (.vpp Files) All your work is saved as a `.vpp` project file. A project stores: * Screen definitions and output assignments * Compositions with all layers, clips, and timelines * Cue lists and cue definitions * Inspector settings (transitions, effects, keyframes) * System configuration (audio routing, network settings) Media files are **referenced by path**, not embedded. Keep your media folder alongside the `.vpp` file for portability. ## What's Next? Now that you know the vocabulary, continue with the tutorials: * [Quick Start Tutorial](/v3/getting-started/quick-start.md) — Play your first video in 5 minutes * [Your First Project](/v3/getting-started/first-project.md) — Build a multi-screen show with cues --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.exaplay.one/v3/getting-started/key-concepts.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. 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