Add your MKV file
Drop one or more .mkv files onto the converter above, or browse for them. They load into browser memory only — nothing is uploaded, so there is no size-based pricing and no server queue.
MKV to FLV
Pulling the soundtrack out of a .mkv video into .flv audio keeps what you can hear and drops the picture entirely. Free, private, and validated — the file never leaves your browser.
Private for supported formats — processed in your browser
Runs on your deviceConvert supported files
Drop MKV files here
Batch files can each use a different output. Nothing uploads for local conversions.
Working inputs include camera RAW, browser-local audio/video, PDF, CBZ/CBR comics, office documents, ebooks, markup, 3D models, structured text, images, and archives.About converting Matroska video to Flash video
Pulling the soundtrack out of a .mkv video into .flv audio keeps what you can hear and drops the picture entirely. An .mkv file uses the Matroska container, an open format designed to hold an unlimited number of video, audio, and subtitle tracks in one file. Collectors of high-quality rips and archival copies favor .mkv because it keeps every language track, chapter marker, and font attachment together.
An .flv file is a Flash Video container, the format that powered most web video during the 2000s. YouTube, news sites, and early streaming platforms delivered .flv streams into the Flash Player plugin before HTML5 video replaced the whole stack. For this route the practical draw is very small container overhead and h.264/AAC content re-wraps to MP4 without any re-encoding — balanced against no mainstream player ships FLV support anymore, which is worth knowing before you commit a large batch.
Why convert MKV to FLV?
The usual reason to take .flv audio out of a .mkv file is that only the sound matters — a talk, interview, song, or podcast segment. Keeping the video stream would waste storage, and a dedicated audio file is easier to trim, tag, and play. On the source side, safari and iOS refuse the container outright; on the target side, the payoff is very small container overhead, which is exactly what you want for recovering clips downloaded during the Flash era.
MKV vs FLV at a glance
| Aspect | Matroska video (.mkv) | Flash video (.flv) |
|---|---|---|
| Format type | Container — quality depends on the codecs and settings inside | Container — quality depends on the codecs and settings inside |
| How it stores data | built on EBML, a binary XML-like structure that lets the container gain features without breaking older parsers | a simple sequence of tagged audio, video, and script packets designed for progressive download and RTMP streaming |
| Strongest at | archiving discs while preserving every audio track and subtitle stream | recovering clips downloaded during the Flash era |
| Weak spot | safari and iOS refuse the container outright | no mainstream player ships FLV support anymore |
| Metadata | matroska tags cover title, cast, and arbitrary key-value pairs, and the container can embed cover art and other files as attachments | an onMetaData script tag embeds duration, dimensions, and encoder details; there is no standard field set for titles or authorship |
Pick FLV as the output
Select .flv in the output menu next to each file. The menu only offers targets this engine can genuinely produce, so if FLV is selectable, the route is real and validated.
Convert on your device
Press Convert. A WebAssembly FFmpeg build demuxes the audio track and re-encodes it locally; the video stream is simply discarded.
Verify and download
Each result is signature-checked before the download unlocks, so a failed encode can never masquerade as a valid FLV file. Outputs keep the original filename with the .flv extension.
MKV to FLV questions, answered
Will converting MKV to FLV lose quality?
Since mkv is container-oriented and flv is container-oriented, the conversion preserves the source content exactly as stored; no additional compression pass is applied beyond what .flv itself requires.
Is it private to convert MKV files here?
Yes — the .mkv file is processed inside your browser tab and never uploaded. A WebAssembly FFmpeg build demuxes the audio track and re-encodes it locally; the video stream is simply discarded. Close the tab and the file is gone from memory.
Where will the FLV file work?
No current browser can play .flv, since the plugin that decoded it was removed from Chrome, Firefox, and Edge at the end of 2020. VLC and ffmpeg-based tools still read the format reliably, which is how old files get rescued into MP4.
Will the FLV file be bigger or smaller than my MKV?
Much smaller — the video stream is usually 80–95% of a .mkv file's weight, and it is discarded entirely. The remaining audio is re-encoded at the bitrate implied by your quality setting.
What happens to the metadata in my MKV file?
This converter strips container metadata deliberately (the FFmpeg command runs with metadata mapping disabled) so exported files do not leak recording details. In the source, matroska tags cover title, cast, and arbitrary key-value pairs, and the container can embed cover art and other files as attachments; none of it is transmitted anywhere because the file never leaves your browser.
Can I convert FLV back to MKV?
Yes — the reverse route exists as a separate tool. Bear in mind that round-tripping .mkv → .flv → .mkv is not a perfect undo when any lossy step is involved; keep your original if fidelity matters.