FLV to WebM Converter

How to Convert FLV to WebM Online

1. Upload Your FLV File: Drag and drop or click "Add Files" to select FLV files. Old YouTube downloads, archived Flash-era web videos, screen captures from streaming sites, and recorded webinars all work. Batch is supported.
2. Pick a Codec and Quality: Default is VP9 (Google's modern web video codec). Choose AV1 for the smallest output on modern devices, or VP8 for legacy compatibility. Set a quality preset (Highest → Lowest), target a percentage of the original size or an exact size in MB, or fine-tune with CRF (VP9: 18 = visually lossless, 30 = default for web, 36 = small).
3. Resize or Trim: Pick a resolution preset (1080p / 720p / 480p / 360p), enter custom width × height, scale by percentage, or trim using start time + duration in HH:MM:SS.sss format. Old FLV files often benefit from being downscaled to 480p / 360p — that's typically their native resolution.
4. Convert and Download: Click Convert. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours — no sign-up, no watermark, never shared.

Why Convert FLV to WebM?

FLV (Flash Video) was the dominant web video format from 2003 to about 2015 — the format YouTube, Vimeo, and most streaming sites used during the Flash era. Adobe officially discontinued Flash Player in December 2020, and modern browsers no longer support it. FLV files are essentially stranded — playable only with VLC, archived Flash plugins, or specialty converters. WebM is the modern open-source web video format, designed for HTML5 <video>. Common reasons to convert FLV → WebM:

• Recovering Flash-era video archives — YouTube downloads from 2008-2014, lecture recordings from old e-learning platforms, archived webinars, and corporate training videos saved as FLV during the Flash era. Converting brings them into a format that plays in current browsers.
• HTML5 <video> embedding — FLV doesn't play in any modern browser. WebM plays in Chrome, Firefox, Edge, Opera, and Safari 14.1+ via <source type="video/webm">.
• Smaller files for the same visual quality — Modern VP9 / AV1 codecs are 50-70% more efficient than FLV's typical Sorenson H.263 or VP6 codecs. A 100 MB FLV often becomes a 30-50 MB WebM with no visible quality loss.
• Royalty-free codec for commercial use — WebM (VP8 / VP9 / AV1) has no licensing fees. Useful for republishing old content commercially without legacy codec licensing concerns.
• Self-hosting on a personal site — Convert old FLV recordings to WebM for self-hosted streaming on a portfolio, archive site, or blog.
• Fixing playback issues — Modern players often fail on old FLVs (audio desync, missing codecs, partial corruption). Re-encoding to WebM normalizes the file and resolves most playback issues.

FLV vs WebM — Format Comparison

Codec Choice for the WebM Output

Frequently Asked Questions

Why won't my FLV play anymore?

Adobe Flash Player was officially end-of-life on December 31, 2020. All major browsers (Chrome, Firefox, Edge, Safari) removed Flash support in early 2021. Standalone Flash projector apps still exist for offline use, but the format is effectively dead on the modern web. Converting FLV → WebM (or FLV to MP4) gets the content into a format that plays anywhere in 2026.

Will I lose quality converting FLV to WebM?

A small re-encoding loss is unavoidable since FLV's older codecs (Sorenson H.263, VP6) and WebM's VP9 / AV1 are different. At CRF 18-22 the difference is invisible — and often the WebM looks subjectively better than the original FLV at much smaller file size, because modern codecs handle the same content more efficiently. Old FLVs were typically encoded at low bitrates, so quality is capped by the source.

Will Safari users be able to play the WebM?

Safari 14.1+ (macOS Big Sur and later, iOS 14.5+) supports WebM with VP9. For older Safari, embed both formats in your <video> tag — WebM first, MP4 fallback second. See FLV to MP4 for the fallback file.

Should I pick VP9, AV1, or VP8?

VP9 for almost everything — universal modern browser support, fast server-based conversion. AV1 for archival when you want the smallest possible files and don't mind slower encoding. VP8 only for very old Android devices or extreme legacy compatibility.

Can I batch convert old FLV files?

Yes — drop in folders of FLV files. They convert in parallel withon our servers and download individually or as a single ZIP. Useful for modernizing an archive of old YouTube downloads or Flash-era recordings.

Can I trim or cut while converting?

Yes. Use the trim section to enter a start time and duration. Both accept seconds (12.5) or HH:MM:SS.sss format (00:01:30.500). Trim first to skip dead air, advertising bumpers, or test patterns common in old web video.

Will the audio survive?

Yes. FLV's MP3 / AAC / Nellymoser / Speex audio is decoded and re-encoded to Opus (default for WebM) or Vorbis. Quality is preserved at typical bitrates. Speech-codec audio (Nellymoser, Speex) sometimes sounds slightly different after re-encoding to Opus — usually clearer.

What if my FLV is corrupted?

Many old FLVs have minor corruption from incomplete downloads or interrupted streaming captures. The conversion can sometimes fix mild issues by re-encoding cleanly from the start. For severely corrupted FLVs, try a tool like FixFLV first, or use VLC's "Save as" feature to repair, then convert the repaired file.