Step 1
Upload video
Upload your MP4 video file to Sonix and select the language.
Add subtitles to MP4 videos
Sonix automatically transcribes your MP4 video and lets you add professional subtitles with customizable styling.
Free to start — no credit card required.See pricing
Auto-transcribe
Custom styling
Burn-in option
10x
Faster than real-time
Add subtitles to MP4 in minutes
99%
Accuracy rate
Industry-leading AI transcription
54+
Languages
Subtitles in any language
Custom
Styling
Fonts, colors, positioning
Add subtitles to MP4 in 4 steps
Step 2
Auto-transcribe
Sonix AI transcribes your video with word-level timestamps.
Step 3
Customize subtitles
Split subtitles, adjust timing, and customize fonts and colors.
Step 4
Export or burn-in
Download SRT/VTT files or burn subtitles directly into your video.
Everything about adding MP4 subtitles
Can Sonix add subtitles to MP4 videos?
Yes! Upload your MP4 video, and Sonix will transcribe it and let you add professional subtitles with customizable styling.
Can I burn subtitles into the video?
Yes! Sonix can permanently embed (burn-in) subtitles into your MP4 video with your choice of fonts, colors, and positioning.
What subtitle styles are available?
Customize fonts, colors, background boxes, positioning (top, center, bottom), and more for your burned-in subtitles.
Can I download subtitle files separately?
Yes! Export subtitles as SRT, VTT, or other formats to use with YouTube, Vimeo, or your video editor.
Can I translate subtitles to other languages?
Absolutely! Sonix can translate your subtitles into 54+ languages for multilingual videos.
How do I split subtitles correctly?
Sonix offers auto-split options for max characters per line, lines per caption, and max duration. Fine-tune manually if needed.
Do I need to extract the audio from an MP4 before transcribing it?
No. Because MP4 is a container that holds both video and audio streams, the audio track can be read directly from the file, so you can upload the video as is.
Why does my MP4 file play video but no sound?
The file may contain a video stream with no audio track, or its audio may use a codec your player does not support. Checking the file's stream details in a tool like VLC or re-exporting it with an AAC audio track usually resolves the issue.
The easiest way to add video subtitles
Auto-Transcribe
Upload your MP4 and get accurate subtitles automatically.
Custom Styling
Choose fonts, colors, and positioning for professional results.
Burn-in Option
Permanently embed subtitles into your video with one click.
Translate
Create subtitles in 54+ languages from your original video.
More ways to work with MP4 files
More ways to convert & transcribe
Jump straight to a related format, language, or tool — every link below is a real page.
Trusted by video creators
I'm very impressed about the accuracy. The transcript needs a little editing, but just minor correction. I think the interface is straightforward and user-friendly. I also like the audio-transcript matching playback functionality. I've been very deterred to use recording during my interviews because it takes a tremendous amount of time to transcribe.
I need to produce very accurate transcripts and the initial transcripts Sonix produces are much better than competitors (I've used many others).
Add subtitles to MP4 now
Try Sonix free with 30 minutes of transcription. No credit card required.
