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.
Free to start — no credit card required.See pricing
Auto-transcribe
Custom styling
Burn-in option
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 55+ 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.
Why won't my FLV file play on my computer?
FLV was designed for Adobe Flash Player, which was discontinued at the end of 2020, so modern browsers and many media players no longer support it. Players such as VLC can still open FLV files, or you can convert them to MP4 for broader compatibility.
Do I need to convert FLV to MP4 before transcribing?
No, FLV files can be uploaded directly for transcription. Converting to MP4 is only needed if you also want the video to play in modern browsers or editing software.
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 54+ languages from your original video.
More ways to work with FLV 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'd give Sonix a 10 mainly due to the accuracy.
Your product is amazing, I love so many features including the video capture on the side, ability to change the transcript as you go, highlighting, downloading audio files... SEARCHING TRANSCRIPTS
Add subtitles to FLV now
Try Sonix free with 30 minutes of transcription. No credit card required.
