Step 1
Upload video
Upload your FLV video file to Sonix and select the language.
Add subtitles to FLV videos
Sonix automatically transcribes your FLV video and lets you add professional subtitles with customizable styling.
Auto-transcribe
Custom styling
Burn-in option
Audio
Video
DOCX
SRT/VTT
PDF
53+ Languages
10x
Faster than real-time
Add subtitles to FLV in minutes
99%
Accuracy rate
Industry-leading AI transcription
53+
Languages
Subtitles in any language
Custom
Styling
Fonts, colors, positioning
Add subtitles to FLV 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 FLV subtitles
Can Sonix add subtitles to FLV videos?
Yes! Upload your FLV 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 FLV 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.
The easiest way to add video subtitles
Auto-Transcribe
Upload your FLV 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 53+ languages from your original video.
More ways to work with FLV files
Other FLV conversions
Trusted by video creators
I love how easy and intuitive it is to use Sonix! I can now put my energy and focus on actual content, instead of going through the tedious and time consuming process of transcribing audio.
I thought it was absolutely amazing, flawless.
I need to produce very accurate transcripts and the initial transcripts Sonix produces are much better than competitors (I've used many others).
I tried 3 other tools online and I can say that sonix blows them out of the water. I was very impressed with the ease of use, the % of words correctly translated and how simple it ...
I am impressed by the almost perfect accuracy of the conversion and the speed by which the transcription was completed. Your web display is also impressive with clear and easy-to-u...
The experience is fantastic, the system is easy to use, and transcription quality in different languages is unbeatable. Sonix is the best system I've tried so far...and I know one ...
Sonix is easy to use. Ridiculously easy. And even though the accuracy wasn't perfect it saved several days in a typical transcription cycle and the hourly cost we usually pay.
I loovvvve that the audio is transcribed so quickly.
Add subtitles to FLV now
Try Sonix free with 30 minutes of transcription. No credit card required.
