Write video captions and choose their timing

Start with short captions

Watch your video and identify its important moments. A PDF table demo may only need “Select the table”, “Check the cells” and “Download the CSV”. Guide the viewer without covering the action. There is no speech recognition: type your own captions or import an existing SRT file.

Each caption accepts 240 characters. The MP4 supports up to four lines; text that does not fit the selected size and frame blocks creation instead of being silently cut. Shorten it or select a smaller size. Characters missing from the font are reported. You can still download an SRT even if the MP4 cannot reproduce a character.

Choose start and end times

1. Choose your video or try the three-second example.
2. Add text, position the player and use Start here and End here. Time fields also accept 5 or 00:05.000.
3. Use Show this text to check its appearance, then add the next caption.
4. Choose a shared position and size, create the MP4 and check before downloading.

Times refer to the imported video. If you added a two-second intro with another tool, import that complete video and include those two seconds in your timings. Start must precede end, and end must stay within the video. This first version does not allow overlapping captions. One caption ending at 8 seconds and another starting at 8 is valid.

Play, pause or move the slider to choose a moment. The preview follows playback: the selected caption only appears within its time range. Top, middle and bottom positions, and the three sizes, apply to all captions. White text on a dark background improves contrast but can cover an important button in a recording; check the gestures you want to show.

Keep the SRT and check the MP4

SRT is a text file containing start and end times. Download it for later editing, or import a UTF-8 SRT up to 200 KiB. Import accepts up to 50 captions of 240 characters, removes simple styling and validates timing before replacing the list. SRT does not save size or position and is not automatic transcription.

The MP4 has text burned into its images: it stays visible without another file and cannot be switched off in the player. Video is re-encoded to H.264 at 30 fps, so timing is applied to one-frame precision. The first audio track becomes stereo AAC. Other tracks, chapters and existing subtitles are omitted. Keep your original.

Video limits: 50 MiB, one minute, 1,920 pixels per side and 60 fps. Use H.264 MP4/MOV/M4V or VP8/VP9 WebM in standard 8-bit colour; HEVC and HDR are rejected. Output is limited to 64 MiB. A recent computer is recommended. Cancellation or a rejected file keeps the last successful download. Files stay in this tab: download the MP4 and SRT before closing, reloading or changing language.