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Add subtitles to a video automatically

Readable captions in minutes, burned in or as SRT.

Upload a video and Onda writes the captions, splits them into readable lines and syncs them to the speech. Download an SRT or VTT file, or a new MP4 with the subtitles burned in.

Accepted formats
  • MP4
Export formats
  • SRT
  • VTT
  • MP4

50 free credits a month · no card needed

Drop an audio or video file MP3, WAV, M4A or MP4 · up to 2 hours

No file handy? Try a sample:

1 credit per minute of audio

How it works

  1. Upload the video

    Add an MP4 file up to 2 hours long. Onda extracts the audio and detects the spoken language.

  2. Review the captions

    Captions appear line by line, synced to the speech. Fix a word, merge or split a line, and choose a style: font, size, color and position.

  3. Export

    Download an SRT or VTT file to upload alongside your video, or render an MP4 with the captions burned in for social feeds.

Key facts

Try it now
Input
MP4 video, up to 2 hours
Languages
40+ for transcription, with subtitle translation
Export
SRT, VTT, or MP4 with burned-in captions
Line length
42 characters per line, 2 lines max by default
Layouts
16:9, 9:16 and 1:1
Turnaround
Captions in a few minutes, even for long videos

Why use it

  • Watched on mute

    Plenty of people scroll their feeds with the sound off. Burned-in captions keep them watching.

  • Readable by design

    Lines break at natural pauses and stay on screen long enough to be read, following common subtitling guidelines.

  • One video, many languages

    Translate the subtitles into any supported language and export one SRT per language with the same timing.

Questions and answers

What is the difference between an SRT file and burned-in subtitles?

An SRT or VTT file sits alongside the video: viewers can switch it on or off and platforms can index it. Burned-in captions are part of the picture, so they show everywhere, including feeds that autoplay on mute.

Can I translate the subtitles?

Yes. After transcription, choose one or more target languages; the timing is kept and each language exports as its own file.

Can I change the caption style?

Yes. Pick the font, size, color, background box and position, or highlight each word as it is spoken, which works well on short vertical videos.

Does it work with background music?

Yes, as long as the voice is clearly audible over the music. Song lyrics are not transcribed by default.

Which video formats are supported?

MP4 files up to 2 hours. If your video is in another format, export it as MP4 from your editing app or phone first.

All tools
  • Transcribe audio

    Speakers labeled, timestamps included, 40+ languages.

    Accepted formats: MP3 · WAV · M4A · MP4 · RSS Export formats: TXT · DOCX · SRT · VTT

  • Audiogram

    Turn your best minute into a video people watch.

    Accepted formats: MP3 · WAV · M4A · RSS Export formats: MP4

  • Trim audio

    Cut, fade and export in seconds, no software.

    Accepted formats: MP3 · WAV · M4A · MP4 Export formats: MP3 · WAV · M4A

Try it now

Readable captions in minutes, burned in or as SRT.

50 free credits a month · no card needed