# Play video, audio and playlists

Import media, prepare a preview and control room playback in TholusOS. Manage playlists, video ranges, background audio and the return to scheduled content.

Canonical: https://docs.theusualnext.com/en/tholusos/media-server/playback/
Updated: 2026-10-22
Publisher: the usual neXt

The TholusOS media server is organised around **Media library**, **Live control** and **Schedule**. The library holds your content, Live control prepares and operates room playback, and Schedule starts content at the times you choose. This guide covers manual playback, from importing a file to returning control to the schedule.

## Before you start

You need accessible media files, a licence that enables the functions you use, and a configured room output for projection. Preparing a video gives you a chance to check it before sending it to your audience.

For a new installation, begin with [Getting started](/en/tholusos/getting-started/). Confirm the projection setup for your venue. For a camera-calibrated or multi-projector installation, follow the [calibration guide](/en/tholusos/projection/calibration/). Check the image format too: rectangular video, fulldome fisheye and 360° panoramas need different settings, described in [Understanding immersive formats](/en/learn/fulldome-360/).

Connect the content drive before opening its files and keep it connected throughout the session. A thumbnail already displayed in the library does not establish that the source file is still accessible.

## Import and select your media

Use the **Import** menu to add video or audio to the library, then select the item you want to prepare. TholusOS organises these files in the content folder selected for your installation.

1. Open **Settings → Contents** and check the current folder. **Choose Folder…** selects another location; **Open** reveals the current folder in Finder.
2. In the app menu, choose **Import → Video…** or **Import → Audio…** and select your file.
3. Open **Media library** and select the Video or Audio tab. If you added files directly to the folder, use **Refresh content**.
4. Select an item to preview it. Choose **Prepare in Live control** from its context menu to prepare it in Live control.

The `videos` and `audio` folders are the usual locations for these media types. Importing takes care of placement in the library; keep the originals in your own archive as well.

Recognising a file extension and being able to play the file are separate checks. A listed file may contain an encoding that the Mac cannot read. Wait until the preview is ready before starting the session.

## Prepare a video and start room playback

In **Live control**, **Selected content** shows the item you are preparing and **Room output** shows the current output. **Start in room** begins playback; when content is already active, the action becomes **Replace room playback**.

1. Check the selected title and preview.
2. To start at a particular position, move the playhead in **Start position and in/out points**.
3. To play a segment, use **Mark In** and **Mark Out**, or enter the times in seconds. **Reset** restores the full range.
4. Check **Video output**, its selected display and the room status.
5. When the room is ready, select **Start in room**. Check **Room output** and the actual projection.

Playback starts at the current position within the In–Out range and finishes at the Out point you set. If the playhead is already at the end, playback starts at the beginning of the segment. The prepared preview is muted; use the mixer to set room audio levels.

The room-output switch controls whether the projection is shown. Turning it off keeps video, audio and scheduling running. Use the transport controls when you need to pause or stop playback.

If an experience or game is using the output, end that activity using its own controls before starting the video. Selecting another library item prepares it; selection alone does not release an occupied room output.

## Build a playlist

A playlist plays several videos in your chosen order and can include background audio. You can assemble one for the current session or save it in the library for reuse and scheduling.

1. In Media library, right-click a video and choose **Add to temporary playlist**.
2. Add the other videos. In the temporary playlist, drag items into order or use the move up and move down controls.
3. If you want a soundtrack, choose **Add background audio…**. This audio plays alongside the videos’ own sound.
4. Enable **Repeat** if the sequence should begin again when it ends.
5. Use **Save playlist…** to keep the order, soundtrack and repeat setting, or **Play playlist in room** when you are ready.

You can also use **Create Playlist** in Schedule for a saved playlist: choose its name, videos, order and background audio. **Ambient music only** mutes the videos’ sound. See [Scheduling content](/en/tholusos/media-server/scheduling/) to assign the playlist to a time slot.

A prepared playlist previews its first video. The start position and In–Out points apply to that first video when you start the prepared playlist; they do not trim every item in the sequence. Keep every video and the selected soundtrack accessible, including items that have not played yet.

## Control sound and playback

**Pause** and **Resume** control the active video, or background audio when no video is loaded. **Stop** ends media playback and stops background audio. **Next** appears for an active video playlist. The mixer gives **Video audio** and **Background audio** their own volume and mute controls.

Open **Audio mixer** from Live control. Check the track name and both channel levels before raising the volume. Background audio has its own play/pause button and can continue while the video is paused. **Video audio disabled by the playlist** means the playlist was configured to use background music only. When an experience controls background audio, use that experience’s controls.

Choosing the audio interface and speakers belongs to **Room** audio setup. The mixer changes levels; a disconnected device requires reconnecting it or choosing another output.

## Return to the schedule and troubleshoot

A manually started video or video playlist uses the override duration configured in **Settings → General**. You can hand control back sooner through **More controls → Return to schedule**. Starting a background audio file alone does not start this timed override.

Returning to the schedule checks what is due at the current time. **Stop** ends the current playback; use the dedicated return command to resume scheduled operation explicitly. A configured waiting video can cover periods with no active slot.

A manually started experience suspends scheduling until the operator returns to it explicitly, including after the experience ends. Its duration is independent of the video override timer. Follow the [session guide](/en/tholusos/schools/run-session/) for the experience’s own start and finish controls.

| Symptom | What to check |
| --- | --- |
| File unavailable | Reconnect its drive or import it again, then refresh the library. |
| Unsupported playback format | Check whether the preview becomes ready; try a version readable on the Mac. |
| Video ready but output occupied | Open the active experience or game and end its session before switching. |
| Image on the Mac but absent in the room | Check the room-output switch, selected display and [calibration](/en/tholusos/projection/calibration/). |
| No sound | Check the device, mute controls, levels and Ambient music only setting. |
| Schedule does not resume | Use Return to schedule, then check the slot, source file and feature access. |

For a step-by-step diagnosis and a support report, follow [Troubleshoot playback and sessions](/en/tholusos/settings/troubleshooting/).