Add Subtitles is the workstation tool for burning styled captions onto a short video. You bring in a video, get its spoken words turned into timed caption lines, fine-tune the wording and timing, pick and customize a caption style, watch it all in a live preview, then generate the final captioned video. It's for anyone who wants ready-to-post subtitled clips for social media without leaving the app.
What does Add Subtitles do?
It lets you put captions on a video in three steps: choose a video, build the caption lines (usually by extracting them straight from the video's audio), and style how those captions look. A live preview plays the video with your captions on top so you can see exactly what you'll get before you spend any credits generating the final file.
How do I add a video to caption?
You start with an empty workstation that shows two ways to bring in a video:
Select content — pick a video you already have, from your own library ("personal") or from the inspiration feed. You'll need to be signed in; if you're not, a sign-in prompt opens first.
Upload video — upload a video file from your device.
Once the video is ready, the uploader area is replaced by the captions and style editor, and your video appears in the preview.
What kind of video can I use? Are there limits?
Add Subtitles is built for short, caption-heavy clips — the uploader shows a hint recommending the video be under 1 minute. That's only a hint, though: the actual hard limit is 10 minutes, and a video longer than that is rejected with "We currently only support videos up to 10 minutes. Please select a shorter video." Upload a standard video file; if a file isn't accepted, the uploader will tell you.
How do I create the caption lines?
Open the Captions tab. When a video first loads, the app tries to read the spoken words automatically, and you'll see a loading indicator while it works. After that you have a list of caption lines you can edit. If the list is empty, you'll see two ways to fill it:
Extract subtitles from video — pulls the spoken words out of the video's audio and turns them into timed caption lines for you.
Add line — adds a single blank line you type yourself.
How do I edit the text of a caption?
Click into any caption line and type. Each line shows its start–end time at the top and the caption text below. There's a limit of 100 characters per line — typing past that simply stops. Empty lines show the placeholder "New text" until you fill them in.
How do I add, merge, or delete lines?
Add line — hover between two lines (or use the "Add line" button at the bottom of the list) to insert a new line at that spot. New lines also appear via the "+ Add line" control.
Merge — between any two adjacent lines (from the second line onward) you'll find a "Merge" control that joins that line into the one above it.
Delete / Update — each line has a "…" (more) button. It opens a small menu with Update (edit the line's timing) and Delete (remove the line).
How do I change when a caption appears (its timing)?
Click a line's time pill (the "0:00 - 0:00" label) or choose Update from its "…" menu. A small editor opens with a Start and End time, shown in seconds. You can:
Drag the two-handle slider to set the start and end together, or
Type exact values into the Start and End number boxes, or
Nudge each value up/down in 0.1-second steps with the little arrows.
The editor won't let a line overlap its neighbors — the earliest start is capped by the previous line's end, and the latest end is capped by the next line's start (or the end of the video). Click Confirm to save or Cancel to discard.
What's the empty state in the Captions tab?
If there are no caption lines yet, you'll see the tip: "No subtitles yet. Click above to add them and unlock full editing features." Add or extract at least one line to move forward — the style options and the Generate button both stay locked until you have captions.
How do I style my captions?
Switch to the Style tab. It shows a list of style presets (each a named look like a font + color combination). Tap a preset to apply it instantly to the live preview; the selected one is highlighted. Each preset also has an Update button that opens the full style editor so you can tweak every detail.
What can I change in the style editor?
The style editor (reached via Update on a preset, or "Edit presets") gives you a deep set of controls:
Name — preset names can be renamed (when the preset allows it). Names of 4 or more characters are accepted; names of 0–3 characters are rejected. (The in-app warning text reads "Style name must be at least 5 characters.", but 4-character names are actually allowed.)
Typography — font family, font size, and text color (with opacity).
Emphasis — bold, underline, and italic toggles.
Alignment — left, center, or right.
Letter case — leave as-is, ALL CAPS, Capitalized, or lowercase.
Spacing — line height and letter spacing sliders.
Position Y — slide the captions up or down the frame (shown as a percentage).
Text outline — turn on an outline and set its thickness (blur) and color.
Text shadow — turn on a drop shadow and set its blur, plus X/Y offset and color in the "more" panel.
Background — turn on a caption background, choose one of four shapes (line vs. whole-block, with square or rounded corners), and set its color.
Animation — turn on an effect and pick from Color Highlight, Karaoke, Float In, or Drop In. Color Highlight and Karaoke also let you choose a highlight color.
Random rotate lines — a playful toggle that slightly rotates each line at a random angle.
Anything you change updates the live preview right away.
How do I reset my style changes?
Inside the style editor there's a Reset button that returns the preset to its original look. Renaming a style shows a brief "Style name updated." confirmation when saved.
Can I preview the result before generating?
Yes — that's the whole point. A live preview plays your video with the current captions and style burned on. You can scrub the timeline, play/pause, mute/unmute, and open a full-screen preview. Editing text, timing, or any style control instantly reflects in the preview, so what you see is what you'll get.
What does it cost to generate?
Captioning is priced per second of video. Next to the Generate button you'll see a per-second rate (shown as "credits/s"), and the button itself shows the total for your video's length. The total scales with the video's duration, and the exact rate depends on your plan.
Why is the Generate button greyed out?
Generate stays disabled until all three of these are true:
Your model/output is ready,
A usable video source is loaded, and
You have at least one caption line.
If you click Generate with no captions, you'll see "Please provide at least one caption to generate subtitles." If the video source isn't available, you'll see "The video source is currently not available."
What happens while the video is loading?
The captions list shows a loading indicator while the app reads the audio, and the preview controls wait for the video data. If you try to play before it's ready, you'll get "Please wait for the video to load before playing." On mobile, opening the editor too early shows "Please wait for the video to load before editing."
What if my upload fails?
If an upload fails, the video area shows "Upload failed" with a Retry button — tap it to try the same file again. While a video is preparing, you'll see a "Preparing video..." status.
How do I remove the video and start over?
There's a delete (trash) button on the video preview. Removing the video clears the captions and style work and returns you to the Select content / Upload video chooser.
On mobile
The layout is stacked instead of side-by-side:
The video sits at the top with a reminder that "The video must be less than 1 minute." Tap Select to open a sheet with Select content and Upload video.
Below the video are two buttons, Style and Captions, that each open a bottom sheet for editing. If you open one before the video has finished loading, you'll be reminded to "Please provide a video to enable the full features of subtitle editing."
In the Captions sheet, an Edit / Save toggle in the corner switches between viewing and editing lines (with the same add/merge/delete and timing controls).
The per-second cost appears in the bottom bar, with the Generate button following the same rules as on desktop.