Convert FLV to WEBM
Convert FLV (Flash Video) files to WebM directly in your browser. FLV was the standard for streaming video before HTML5 killed Flash in 2020 — WebM with VP9/Opus is its modern, royalty-free replacement. No upload needed.
Drag 'n' drop files here, or
click to select files
.flv
Drop your files and click Convert to get WEBM
//when_to_use
When to Convert FLV to WEBM
- Modernizing FLV tutorial archives (Lynda.com / Adobe TV era) to WebM for embedding in current HTML5 LMS platforms
- Migrating FLV screencasts captured with Camtasia 5 / Jing to WebM for upload to Wikimedia Commons
- Converting FLV Flash gameplay recordings to WebM for posting on Mastodon (which prefers WebM)
- Re-encoding FLV community footage from Ustream / Justin.tv backups to WebM for Internet Archive preservation
- Preparing FLV recordings to WebM derivatives before publishing on a patent-sensitive academic media server
//comparison
FLV vs WEBM
| Property | FLV | WEBM |
|---|---|---|
| Container era | Flash streaming (2003-2020) | Modern HTML5 (2010+) |
| Video codec | H.264 or Sorenson H.263 | VP9 (royalty-free) |
| Audio codec | MP3 or AAC | Opus |
| Patent / royalty | Adobe + codec-dependent | Fully patent-free |
| Browser playback | Dead (Flash EOL 2020) | Universal modern browsers |
| Best for | Flash-era archives | HTML5, Wikimedia, Mastodon |
//how_it_works
How It Works
Drop your FLV files
Drag and drop or pick .flv files. First conversion loads FFmpeg WASM (~30MB).
FFmpeg decodes FLV
FFmpeg WASM parses FLV tag structure and decodes H.264 / Sorenson video and MP3 / AAC audio to raw frames and PCM.
Encode VP9 + Opus
Video is re-encoded with libvpx-vp9 at CRF 32 and audio with libopus at 128 kbps, then muxed into the WebM container.
Download WebM files
WebMs play natively in Chrome, Firefox, Edge, Safari 14+, and embed directly in HTML5 <video> tags without licensing concerns.
// under the hood
FLV (Flash Video) is Adobe's 2003 streaming container carrying H.264 / Sorenson H.263 video and MP3 / AAC audio. WebM is a restricted Matroska container carrying VP8/VP9/AV1 video and Vorbis/Opus audio. Our converter uses FFmpeg WASM to decode FLV streams, then re-encode with libvpx-vp9 at CRF 32 and libopus at 128 kbps, muxed into WebM/Matroska.
//faq
Frequently Asked Questions
- Why migrate FLV to WebM specifically?
- WebM is the patent-free HTML5 replacement for Flash. If you have FLV archives from the Flash era (2005-2020) and want them embeddable on Wikipedia/Wikimedia, Mastodon, Pixelfed, or any patent-sensitive site that mandates royalty-free codecs, WebM with VP9 + Opus is the canonical target. For non-royalty-free uses MP4 is also fine.
- Can the conversion stream-copy?
- Almost never. FLV typically contains H.264 or Sorenson Spark video with MP3 or AAC audio — none of which are WebM-compatible. We always re-encode to VP9 + Opus. Sorenson H.263 content (older FLVs) is also fully supported.
- How long does the encoding take?
- VP9 in FFmpeg WASM runs around 0.3-0.5x realtime on a modern laptop — a 5-minute FLV becomes a WebM in 10-15 minutes. Old low-res Flash content (240p tutorials, screencasts) is much faster, often realtime or better.
- What encoder settings do you use?
- VP9 video at CRF 32 (visually lossless web quality) and Opus audio at 128 kbps. Source resolution and framerate are preserved; common Flash-era 240p/360p/480p inputs come out compact and clean.
- Are my FLV files uploaded?
- No. FFmpeg WebAssembly runs everything in your browser tab. Old FLVs often hold rare or unreleased content — they stay local, which is the point.
//related_converters
Related Converters
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→Convert MKV to WEBM
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