Convert FLV to MKV Online

About FLV (source)

FLV (Flash Video) was the standard for web video before HTML5. Flash Player is discontinued, so FLV files no longer play in browsers. FLV typically contains H.264 or VP6 with MP3 or AAC audio and survives mainly in old downloads.

Where FLV shows up:

• Recovered Flash-era website downloads
• Legacy streaming server archives
• Old live stream recordings
• Historical web media preservation

About MKV (target)

MKV (Matroska) is an open, highly flexible container built for archival and home theater use. It supports multiple video, audio, and subtitle tracks in one file, plus chapters and attachments. MKV is common for Blu-ray rips, anime fansubs, and Plex/Kodi libraries.

Where MKV is used:

• Blu-ray and DVD rips with commentary and multiple languages
• Anime and foreign films with soft subtitles
• Plex, Jellyfin, and Kodi media servers
• Preserving multiple audio tracks without splitting files

Converting FLV to MKV

Pros

• Keeps multiple audio and subtitle tracks in one file
• Open format with excellent Plex/Kodi support

Cons

• Not natively supported on iPhone or many TVs
• Social platforms often reject MKV uploads

Caveats

• FLV to MKV usually requires transcoding because legacy codecs do not fit the target container cleanly.
• FLV sources may use obsolete codecs or odd frame sizes. Verify aspect ratio after conversion - legacy pixel aspect ratios can look stretched.
• Muxara maps the primary video and audio streams. Extra subtitle or audio tracks may not carry over unless you choose subtitle handling in the converter settings.
• Uploads are processed on dedicated workers and deleted within 24 hours. For offline batch work, use the free Muxara Mac app.