FLV Compressor
Compress FLV files locally — no upload, no watermark, free. Output is universal H.264 MP4 that plays everywhere.
Recommended FFmpeg settings
FLV (Flash Video) was Adobe's video format for the Flash Player era, dominant from 2002-2010. Before HTML5 video, virtually all web video (early YouTube, Vimeo, news sites) was FLV. Flash was officially end-of-life'd on December 31, 2020 — modern browsers no longer support it. Any FLV file you encounter today is legacy content that needs modernization. This FLV compressor decodes FLV input and re-encodes to H.264 MP4 at CRF 26, typically reducing file size 50-80% while preserving quality acceptable for web and social media. The output is a universally-compatible MP4 file with AAC stereo audio and the +faststart flag for instant streaming playback across browsers, phones, tablets, and smart TVs. Compressing FLV before sharing means your video plays everywhere without compatibility headaches.
- 1Modernizing FLV to MP4 is essentially required for any current use. The original format is unsupported by every modern player.
- 2FLV files commonly contain codecs like Sorenson Spark (very old), VP6 (most FLV), or H.264 (FLV modernization attempt, 2007+). Audio is MP3 or AAC.
- 3Typical sources include Old YouTube videos downloaded before 2010, Pre-2010 video podcasts and screencasts, Educational content from the Flash e-learning era, and similar.
- 4Local processing means no upload bandwidth and no server storing your files.
- 5Free, no account, no watermark — compress unlimited videos.
- 6CRF 26 encoding is tuned specifically for typical FLV content profiles, preserving source quality.
Three steps, no account needed
From raw footage to shareable MP4 in seconds — all in your browser.
Upload your video
Drag-and-drop or click to browse. Files are processed locally — nothing is uploaded to any server.
Pick quality
Use the recommended preset or fine-tune CRF / resolution in advanced settings.
Download
Compression runs entirely in your browser. Grab your smaller MP4 in seconds — no account, no watermark.
Why people choose this compressor
Built for everyday use — fast, private, and free forever.
100% Browser-Based
Your video never leaves your device. No upload, no server-side processing, no privacy concerns.
No Watermark
Output is clean H.264 MP4 — no logos, no overlays, no time limits baked in.
Free & Unlimited
No sign-up, no credit card, no daily cap. Compress as many videos as you need.
Fast FFmpeg Engine
Powered by FFmpeg compiled to WebAssembly — the same engine professionals use, now in your browser.
Universal MP4 Output
Output is H.264 + AAC in an MP4 container — plays everywhere, uploads everywhere.
Cross-Platform
Works on Windows, macOS, Linux, iOS, and Android — any modern browser.
Who uses this tool
Old YouTube videos downloaded before 2010
Modernize old youtube videos downloaded before 2010 to universal H.264 MP4 without quality loss beyond the unavoidable CRF-based compression.
Pre-2010 video podcasts and screencasts
Modernize pre-2010 video podcasts and screencasts to universal H.264 MP4 without quality loss beyond the unavoidable CRF-based compression.
Educational content from the Flash e-learning era
Modernize educational content from the flash e-learning era to universal H.264 MP4 without quality loss beyond the unavoidable CRF-based compression.
Legacy corporate training videos
Modernize legacy corporate training videos to universal H.264 MP4 without quality loss beyond the unavoidable CRF-based compression.
Frequently asked questions
The tool decodes your FLV file and re-encodes the video stream to H.264 with Constant Rate Factor (CRF) compression. Audio is converted to AAC. The result is wrapped in an MP4 container for universal compatibility. Typical size reduction is 50-80% for FLV sources, depending on the original codec and bitrate.
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