Convert FLV to subtitles

Transform your FLV videos into professional subtitles in multiple formats. Make legacy Flash content accessible and modern with professional subtitles.

Free to start — no credit card required.See pricing

SRT & VTT
5-min turnaround
All platforms
FLV conversion guide

Create subtitles from FLV in 6 steps

  1. 1
    Create account~30 sec

    Sign up for a free Sonix trial with 30 free minutes.

  2. 2
    Upload file~1 min

    Upload your FLV file from your computer or cloud storage.

    44+ formats supported
  3. 3
    Select language~10 sec

    Select the language spoken in your file.

    54+ languages
  4. 4
    Auto-transcribe~5 min

    Sonix AI transcribes your FLV with word-level timestamps.

  5. 5
    Split subtitles~2 min

    Customize line length, duration, and subtitle breaks.

  6. 6
    Export~10 sec

    Download your subtitles as SRT or VTT files.

    30+ export formats
The FLV file format

Understanding FLV files

What is a FLV file?

Legacy Flash video format for web streaming

FLV files are also known as Flash Video Files. Most FLV files use Adobe Flash Player or Adobe Air to transmit audio/video over the Internet. Most embedded videos on the Internet are FLV files, but with the introduction of HTML5 videos, many streaming services have dropped usage of FLV files. You can sometimes see FLV files with a F4V file extension. FLV files aren’t as common now, but we still support them at Sonix.

Common uses for FLV files

  • Legacy web videos
  • Archived Flash content
  • Old streaming platforms
  • Legacy YouTube downloads
  • Archived web content
  • Old streaming sites

Who works with FLV files?

Digital archivists, e-learning teams, and media librarians maintaining Flash-era video libraries still work with FLV files, often while migrating old training courses, webinars, and news clips to modern formats. Researchers and journalists reviewing pre-2015 web footage also encounter FLV files in their source material.

FLV vs MP4: which should you use?

FLV is a legacy container tied to Adobe Flash Player, while MP4 is an open ISO standard supported natively by browsers, phones, and editing software. FLV files often use older codecs such as Sorenson Spark or On2 VP6, whereas MP4 typically pairs H.264 video with AAC audio. Choose MP4 for anything you plan to play, share, or edit today; FLV is mainly relevant when handling archived Flash-era content.

Convert MP4 to text
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Get your FLV subtitles in minutes
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Accuracy rate
Industry-leading AI for FLV files
53+
Languages
Subtitles in any language
30+
Export formats
SRT, VTT, FCPXML, and more
FLV conversion FAQ

FLV subtitles: frequently asked questions

What subtitle formats can I export from FLV?

Sonix exports FLV transcriptions to supported subtitle formats: SRT (universal), VTT (web), and TTML.

What's the best subtitle format for converting FLV to modern video?

SRT is most compatible when converting FLV to MP4 or other modern formats. Most video editors and players support SRT without issues.

How do I add subtitles to FLV for YouTube upload?

Convert your FLV to MP4, export SRT from Sonix, then either upload the SRT separately to YouTube or burn subtitles into the video before uploading.

Can I create styled subtitles from FLV recordings?

Use VTT captions with CSS in compatible web players, or burn subtitles into the video when you need fixed styling.

What format should I use for FLV subtitles on social media?

Most social platforms require burned-in subtitles. Convert FLV to MP4, export SRT from Sonix, then use video editing software to embed them permanently.

How do I sync subtitles with variable quality FLV?

Sonix timestamps are audio-based, ensuring accurate sync regardless of video encoding variations common in FLV files from different eras.

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.

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