Add Subtitles to Video
Burn SRT or VTT subtitles into a video as permanent text overlay
Transitions add processing time and may slightly increase file size.
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Subtitles are no longer optional — they're expected. Viewers watch video on mute in public spaces, accessibility standards require captions for professional content, and search engines can index subtitle text to improve discoverability. Add Subtitles burns an SRT or VTT subtitle file directly into your video as a permanent text overlay, so the captions appear on every platform without depending on the player to support external subtitle tracks.
This is called "hardcoding" or "open captions" — the text becomes part of the picture. It's the right choice for social media clips, training videos, and any delivery target where you can't guarantee the player will render an external subtitle file correctly.
How to Add Subtitles to a Video Online
- 1
Upload your video
Drop any MP4, MOV, WebM, AVI, or MKV file onto the page. Files up to 50 MB are supported.
- 2
Upload your subtitle file
Upload a subtitle file in SRT or VTT format. The timing must match your video's duration.
- 3
Download your subtitled video
Click Add Subtitles. FileCrank burns the subtitles permanently into the video frames. Files are deleted within 1 hour.
How Subtitle Burning Works
SRT and VTT files are plain-text documents that map timecodes to text strings. Burning them into video requires rendering each subtitle as styled text onto the corresponding frames during the video encode pass. FFmpeg's `subtitles` filter handles this: it parses the subtitle file, uses libass (the Advanced SubStation Alpha renderer) to lay out and style the text, and composites it onto each frame before encoding.
Font face, size, color, border, and vertical position can all be configured. The text is rendered at the video's native resolution so it stays crisp on high-DPI displays. Because this involves re-encoding the entire video, processing time is proportional to clip length and resolution — a one-minute 1080p clip typically takes 20–60 seconds in WebAssembly.
Why Use FileCrank to Add Subtitles?
- ✓ Supports SRT and VTT subtitle formats.
- ✓ Subtitles are burned in (hardcoded) — visible on any player, no special track support needed.
- ✓ Subtitle file is fully validated before processing to prevent injection errors.
- ✓ No watermarks, no signup, completely free.
- ✓ Files are processed securely and deleted within 1 hour.
Recursos e Especificações
Frequently Asked Questions
What subtitle formats are supported?
SRT (SubRip Text) and VTT (WebVTT) subtitle files are supported. The subtitle file must be UTF-8 encoded.
Are the subtitles permanent?
Yes. FileCrank burns the subtitles into the video frames (hardcoded subtitles). They cannot be turned off during playback. For removable subtitles, you would need a video editor that supports subtitle tracks.
My subtitle file has special characters — will they display correctly?
UTF-8 characters including accents, Arabic, Chinese, Japanese, and other scripts should display correctly as long as your SRT/VTT file is saved in UTF-8 encoding.
Does the subtitle timing need to match the video?
Yes. Make sure your subtitle file is timed to match the video. If the video has been trimmed or speed-changed, adjust the subtitle timestamps accordingly.
Hardcoded Subtitles vs. Soft Subtitle Tracks
Soft subtitle tracks (embedded as a separate stream in MKV or MP4) are more flexible — viewers can toggle them on or off — but many players, particularly on mobile and social platforms, ignore them entirely. Hardcoded subtitles are always visible, always styled correctly, and require nothing from the player. Use soft tracks for archival or streaming service delivery; use burned-in subtitles for distribution anywhere else.
Related Tools
FileCrank Add Subtitles burns SRT or VTT subtitle files permanently into video frames. Subtitle file is validated before processing. Supports all common video formats. Free, no signup, files deleted within 1 hour.
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