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Convert Matroska MKV video files to FLV for Flash-compatible players and legacy streaming platforms. ChangeThisFile uses FFmpeg on secure servers — no installation or signup needed.
By ChangeThisFile Team · Last updated: March 2026
ChangeThisFile converts Matroska to FLV using FFmpeg, a professional-grade multimedia framework, to transcode Matroska files to FLV format with optimized codec settings and quality preservation. Free with no signup required. Files are encrypted during transfer and automatically deleted from our servers after conversion.
Matroska vs FLV: Format Comparison
Key differences between the two formats
| Feature | MKV (Matroska) | FLV |
|---|---|---|
| Full Name | Matroska Video | Flash Video |
| Developer | Matroska.org | Adobe Systems |
| Open Standard | Yes | No (proprietary) |
| Video Codec | H.264, H.265, VP9, AV1, MPEG-4 | H.263, VP6, H.264 |
| Audio Codec | AAC, FLAC, AC-3, MP3, Vorbis | MP3, AAC, Nellymoser |
| Subtitle Tracks | Multiple formats supported | Not natively supported |
| Browser Support | Via HTML5 with plugin | Requires Flash Player |
| Streaming | HTTP, HLS, DASH | RTMP |
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 Matroska 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 Matroska 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 Matroska to FLV only when you cannot update the player itself.
Who Uses This Conversion
Tailored guidance for different workflows
Content Creators
- Convert Matroska footage to FLV for playback in software and devices that expect the FLV format
- Transform Matroska recordings to FLV to match the format an existing workflow or player requires
Video Editors
- Convert Matroska footage to FLV for importing into editing software like Premiere or DaVinci Resolve
- Transform Matroska project exports to FLV for client delivery or final distribution
Social Media Managers
- Convert Matroska videos to FLV for compatibility with legacy players or archival systems that use FLV
- Transform Matroska source files to FLV when a specific tool only accepts FLV input
How to Convert Matroska to FLV
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1
Upload Your MKV File
Click or drag to upload your Matroska MKV file. The upload is secured with HTTPS encryption to protect your content in transit.
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2
FFmpeg Converts to FLV
Our servers use FFmpeg to encode your MKV content into an FLV container with H.264 video and AAC audio for Flash-compatible playback.
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3
Download Your FLV
Download the finished FLV when conversion completes. Your original MKV file is permanently deleted from our servers immediately after.
Developers: convert via API →
Frequently Asked Questions
FLV is required for legacy Flash-based video platforms, RTMP streaming servers, and older video players that predate H.264 MP4 support. While Flash is deprecated, FLV archives and some platforms still require this format.
Yes. VLC, MPC-HC, and other modern media players support FLV playback without requiring Flash Player. Flash Player itself was discontinued by Adobe in 2020.
No. FLV does not support embedded subtitle tracks. You will need to burn subtitles into the video or manage them as separate files.
Only the primary audio track is converted to the FLV container. Multiple audio tracks in MKV are not supported in FLV format.
Both your uploaded MKV and the converted FLV are deleted from our servers automatically after your download completes.
Files up to 25MB (free tier; 100MB with eligible paid browser access) are supported. For larger MKV files, compress or trim the video beforehand.
Yes, FLV with H.264 encoding supports 720p and 1080p HD resolutions. The output maintains your source MKV resolution.
Yes, completely free. ChangeThisFile requires no payment, no account, and adds no watermarks.
The converted FLV uses H.264 video encoding with AAC audio, providing the best quality-to-size ratio for Flash-compatible delivery.
Only the primary video track is processed. MKV's multiple-track capability is not carried over to the FLV container.
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