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Convert MP4 to FLV (Flash Video) for compatibility with legacy systems, older web video players, or applications that still use Flash-based video playback.
By ChangeThisFile Team · Last updated: March 2026
ChangeThisFile converts your MP4 video to Flash Video format using FFmpeg on our secure servers. Though FLV is a legacy format, some older streaming platforms and media workflows still require it. Files are auto-deleted after conversion, free to use with no signup needed.
MP4 vs FLV: Format Comparison
Key differences between the two formats
| Feature | MP4 | FLV |
|---|---|---|
| Technology | Modern MPEG-4 standard | Adobe Flash Video (legacy) |
| Codec | H.264, H.265 | H.263 or H.264 (Sorenson Spark) |
| Browser support | Universal native support | Requires Flash plugin (discontinued) |
| Streaming | HLS, DASH streaming | RTMP streaming (legacy) |
| File size | Efficient | Larger for equivalent quality |
| Use case | Modern web and devices | Legacy Flash systems only |
| Metadata | Rich metadata | Basic FLV metadata |
When to Convert
Common scenarios where this conversion is useful
Feeding a system that still requires FLV
If an older CMS, LMS, or RTMP server only accepts FLV uploads, convert your MP4 file to satisfy that requirement. For anything modern, MP4 is the better target.
Matching an existing Flash-era archive
When a video library is already stored as FLV from the Flash era, convert new MP4 files to FLV so the collection stays in one format. New archives should use MP4.
Older offline or embedded players
Some legacy desktop, kiosk, or embedded players were built around FLV and cannot read modern formats. Convert MP4 to FLV only when you cannot update the player itself.
Who Uses This Conversion
Tailored guidance for different workflows
Content Creators
- Convert MP4 footage to FLV for playback in software and devices that expect the FLV format
- Transform MP4 recordings to FLV to match the format an existing workflow or player requires
Video Editors
- Convert MP4 footage to FLV for importing into editing software like Premiere or DaVinci Resolve
- Transform MP4 project exports to FLV for client delivery or final distribution
Social Media Managers
- Convert MP4 videos to FLV for compatibility with legacy players or archival systems that use FLV
- Transform MP4 source files to FLV when a specific tool only accepts FLV input
How to Convert MP4 to FLV
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1
Upload your MP4 file
Drag and drop your .mp4 file onto the converter, or click to browse. The free tier accepts files up to 25MB; eligible paid browser access accepts up to 100MB.
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2
Server-side conversion
Your file is securely uploaded and re-encoded using FFmpeg into FLV format. Processing typically takes a few seconds.
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3
Download the result
Click Download to save your converted .flv file. The original and converted files are automatically deleted from our servers.
Developers: convert via API →
Frequently Asked Questions
No. Adobe Flash Player was discontinued in December 2020. Modern browsers no longer support FLV playback. Use FLV only for legacy systems that require it.
Some legacy enterprise systems, older LMS platforms, archived websites, and embedded hardware were built around Flash and have not been updated. FLV is needed to feed content into these systems.
FLV typically uses older, less efficient codecs than MP4. Re-encoding involves some quality trade-off. The output uses the best settings available for FLV.
Yes. Files are transferred over HTTPS and automatically deleted from our servers after conversion.
Yes. VLC Media Player supports FLV playback on all platforms.
The FLV output uses MP3 audio, which is compatible with most Flash-era players.
The free tier accepts files up to 25MB; eligible paid browser access accepts up to 100MB.
Yes, completely free. No signup or subscription required.
Yes. Use the FLV to MP4 converter on ChangeThisFile to convert in the reverse direction.
Most conversions complete in a few seconds. Longer videos may take up to a minute.
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