Convert Flash Video (.flv) to Matroska Video (.mkv) online for free. Fast, secure video conversion with no watermarks or registration.
Conversion settings — add a file to adjust
Upload your .flv file by dragging it into the upload area or clicking to browse.
Choose your output settings. The default settings work great for most files.
Click Convert and download your .mkv file when it's ready.
FLV (Flash Video) is Adobe's proprietary streaming container with limited metadata and subtitle support. MKV (Matroska Video) is an open-standard container released in 2002, designed to hold an unlimited number of video, audio, subtitle, and metadata tracks in a single file. Named after Russian Matryoshka dolls, MKV supports virtually every codec ever created — H.264, H.265, VP9, AV1, FLAC, DTS, and hundreds more. Converting FLV to MKV preserves all content while upgrading to a far more capable container.
MKV is the preferred container for media archivists and power users because it supports every codec without the licensing restrictions of MP4. You can attach multiple audio tracks (different languages), multiple subtitle streams (SRT, SSA/ASS, PGS), chapter markers, fonts, and even attachments. MKV files play natively on VLC, mpv, Kodi, Plex, and most smart TVs, making it the most flexible container available.
When the FLV contains H.264 video and AAC audio, FFmpeg can remux directly to MKV without re-encoding — the codec streams are copied verbatim into the Matroska container. For FLV files with Sorenson Spark or VP6, re-encoding to H.264 or H.265 is performed. MKV's EBML (Extensible Binary Meta Language) structure supports per-stream language tags, chapter markers with named chapters, and embedded fonts for styled subtitles.
When remuxing (stream copy), quality is completely preserved — the operation is lossless and near-instantaneous. When re-encoding from older FLV codecs, H.264 or H.265 in MKV provides equivalent or better visual quality at similar bitrates. MKV itself introduces zero overhead — it is purely a container and does not affect codec-level quality.
| Device | FLV | MKV |
|---|---|---|
| Windows PC | Partial | Partial |
| macOS | Partial | Partial |
| iPhone/iPad | Partial | Partial |
| Android | Partial | Partial |
| Linux | Partial | Partial |
| Web Browser | No |
Resolution: 1920x1080
Bitrate: 8-12 Mbps
H.264 recommended for fast processing
Resolution: 1080x1080
Bitrate: 3.5 Mbps
Square or 9:16 for Reels
Resolution: 1080x1920
Bitrate: 4 Mbps
9:16 vertical, under 60s ideal
Resolution: 1280x720
Bitrate: 5 Mbps
Under 140s, 512MB max
Resolution: 960x540
Bitrate: 2 Mbps
16MB limit for standard, 64MB for document
Resolution: 1280x720
Bitrate: 4 Mbps
FLV to MKV conversion upgrades obsolete Flash content to the most capable open multimedia container available. Whether remuxing for archival or re-encoding for broader compatibility, MKV provides unmatched flexibility for multi-track, multi-subtitle media.
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Mọi trình duyệt, mọi thiết bị
| Tính năng | FLV | MKV |
|---|---|---|
| Tên đầy đủ | Flash Video | Matroska Video |
| Phần mở rộng | .flv | .mkv |
| Phù hợp nhất cho | Small file size | Multiple audio tracks |