About FLV to MKV
FLV to MKV converts legacy Adobe Flash Video (.flv) files into modern MKV (Matroska) containers. FLV was the dominant online video format from 2005-2016 while Flash was alive — now that browsers have dropped Flash support entirely, FLV files are effectively unplayable in most modern software without conversion.
This tool remuxes the video and audio streams into MKV — usually without re-encoding, so the process is fast and quality-preserving. Use it to rescue old training videos, legacy Flash game recordings, archived webinars, or family videos from the Flash era.
Privacy first: Your files are processed using client-side JavaScript when possible. Files sent to our servers are encrypted with TLS and automatically deleted within 1 hour.
How to use FLV to MKV
Get the result you need in just three simple steps:
Upload your FLV
Drag and drop your .flv file onto the upload area. The tool inspects the video and audio codecs to decide whether to remux (fast, lossless) or transcode (slower, still lossless).
Automatic remux or transcode
If the FLV uses H.264/AAC (most FLVs from 2010+), the streams are remuxed straight into MKV — no quality loss, takes seconds. Older Sorenson Spark or VP6 video is transcoded to H.264 for compatibility.
Download the MKV
Get a clean .mkv playable in VLC, Media Player Classic, or any modern editor. Original video quality is preserved for remux cases.
Key Features
Smart remux vs transcode
Detects codec and picks the fastest lossless path. Most modern FLVs remux in under 10 seconds.
Preserves audio
AAC audio tracks are kept intact; MP3 audio is remuxed without re-encoding.
Handles legacy codecs
Sorenson Spark, VP6, and Nellymoser (obsolete FLV codecs) are transcoded to modern equivalents.
Modern container
MKV supports chapters, multiple audio tracks, and subtitles — future-proof for archival.
Common Use Cases
- Rescue old training videos, webinars, or lectures recorded in FLV.
- Convert Flash game recording (Fraps, Bandicam pre-2016) to a modern format.
- Migrate a legacy FLV archive to MKV for long-term storage.
- Prepare old FLV footage for use in a current video editor.
Security & Privacy
We take your data security seriously. Here's how we protect your files:
- TLS encryption: All file transfers are encrypted using industry-standard TLS 1.3 protocol.
- Auto-deletion: Uploaded files are automatically and permanently deleted from our servers within 1 hour.
- No access: We never read, analyze, or store the contents of your files.
- Browser processing: When possible, files are processed directly in your browser without being uploaded.