Content requirements

What the platform accepts and refuses, and the sizing, sound and caption behavior that decides how content looks on a real screen.

These are enforced on upload. A file outside them is refused with an error rather than accepted and left to fail on the screen.

Images — JPEG, PNG, GIF, WebP, up to 25 MB per file.
Video — MP4, WebM, up to 100 MB per file. 100 MB is a platform ceiling, not a preference: the upload passes through our API, and larger request bodies are rejected upstream before they reach us. For anything longer or larger, host it on YouTube or Vimeo and add it as an embed.
Files are checked by content, not by name. Renaming .txt to .png does not work — the file’s actual format is inspected and must match its type.
PDFs are imported as images. Upload a PDF and each page is converted to an image in your browser, then added as a playlist named after the file (up to 50 pages). The conversion happens on your computer, so a very long PDF on an older machine takes a moment. Pages are scaled to fit a 16:9 screen — portrait pages show bars down the sides. To change a page later, edit the source and re-import.
Audio is not supported. The player renders images, video, web embeds and PDF-page images only, so an audio upload is refused rather than silently charged against your storage and then playing nothing.
YouTube and Vimeo are added by URL under Add Embed — pick the matching type and paste the link. They are not uploaded and use no storage, so the file-size limits above do not apply to them. Other sites can be embedded as Web Page, but many block it with X-Frame-Options.

Not enforced — content outside these still plays, it just looks better inside them.

Design for 1920 × 1080 (16:9 landscape), and do not exceed it by much.
Match your screen’s aspect ratio. Content is scaled to fit and centered, never cropped — a mismatch shows bars down the sides.
Uploaded video always plays muted.
Do not rely on audio. Put the message on screen.
YouTube and Vimeo embeds have a sound toggle, but most devices ignore it and play muted. The video still plays; only the audio is conditional. Desktop Chrome and Chromium allow sound with --autoplay-policy=no-user-gesture-required; smart-TV browsers do not.
Captions work within each platform’s limits. On YouTube, switching them on always works and switching them off may not. On Vimeo, off is reliable and on works only if the video’s owner uploaded a caption file. The dashboard warns when captions cannot be enabled. For full control, upload an MP4 instead of embedding.
Google Slides embeds may render blank in DuckDuckGo and Brave. Use Fire TV/Silk, Chrome, or Safari for screens showing Slides.
MP4 (H.264) is the safest video format. WebM is accepted and plays on most devices.