MJPEG to FLV Converter

MJPEG to FLV Converter

MJPEG (Motion JPEG) stores video as a run of independently compressed JPEG frames with no inter-frame compression, so the source is bulky — every frame is a full still image. FLV (Flash Video) is the Adobe container that delivered nearly all web video through the 2000s and early 2010s, and it uses an inter-frame codec, so re-encoding a bulky MJPEG capture to FLV produces a much smaller file. That size win is real, but the destination is a dead Flash-era format: for phones, browsers, and modern editors, MJPEG to MP4 gives you the same shrink with a universally playable H.264 file. Convert to FLV only when a legacy Flash-based pipeline genuinely demands .flv ingest.

MJPEG Format at a Glance

FLV Format at a Glance

How to Convert MJPEG to FLV

1. Upload Your MJPEG File: Drag and drop your .mjpeg or .mjpg file onto the page, or click "+ Add Files" to browse. Batch upload is supported, so a folder of camera or capture-card dumps can go through in one pass.
2. Pick Video Codec and Quality Preset: Under Advanced Options, Video Codec defaults to FLV (Sorenson Spark) for the broadest legacy-player compatibility; switch it to H.264 if your target tool accepts H.264-in-FLV for sharper output at the same size. Leave Quality Preset on "Very High (Recommended)", or open File Compression for a Specific file size, Constant Bitrate, or Constant Quality (CRF).
3. Resolution and Trim (Optional): Under Video resolution choose "Keep original", a Preset Resolution, Resolution Percentage, or a custom Width x Height. Use Trim → Time Range to cut one segment out of a long capture in the same pass.
4. Convert and Download: Click "Convert" and save your .flv file. No sign-up, no watermark.

Frequently Asked Questions

Will converting MJPEG to FLV make the file smaller?

Usually yes, and that is the genuine upside. MJPEG compresses each frame independently as a full JPEG with no inter-frame savings, so its real-world efficiency is only around 1:20 and a one-minute 1080p capture routinely lands at 400 MB to 1 GB. FLV's video codec (Sorenson Spark or H.264) uses inter-frame compression — it stores only what changed between frames — so a bulky surveillance or capture-card clip typically shrinks substantially. The exact ratio depends on motion: a near-static camera angle compresses far harder than busy footage. The catch is the destination format, not the size: that same shrink into an H.264 MP4 plays everywhere, while the FLV does not.

Is FLV dead now that Flash Player is gone?

The Flash web-delivery workflow is dead, but the file itself is not unreadable. Adobe ended Flash Player support on December 31, 2020 and began blocking Flash content on January 12, 2021, so no browser plays .flv natively anymore and no modern site serves it. The container, however, still opens in VLC, ffmpeg, and MPV-class players because those decoders never depended on the Flash plug-in. This is the key difference from .swf: an FLV is plain audio/video you can still play and re-convert, whereas SWF was an executable application with no standalone runtime left.

Which video codec does this output put inside the FLV?

By default, FLV (Sorenson Spark), the original H.263-based codec that every Flash Player from version 6 onward could decode — the safest choice for old players. If your downstream tool is newer (Flash Player 9 Update 3, December 2007, added H.264-in-FLV support), switch Video Codec to H.264 under Advanced Options for noticeably better quality at the same bitrate. We do not target On2 VP6 here; Sorenson Spark and H.264 cover the realistic compatibility range.

Will converting MJPEG to FLV improve the picture quality?

No — and that is an honest limit, not a tool flaw. MJPEG holds already-lossy JPEG frames, and FLV holds Sorenson Spark or H.264, so the conversion is always a lossy-to-lossy re-encode. The frames are decoded and re-compressed from scratch, which means no detail the source already discarded can be regained, and a standard-definition capture stays standard-definition. Keep "Keep original" resolution and a high Quality Preset so the FLV encoder, not an upscale, is the limiting factor.

My MJPEG has no audio — will the FLV be silent?

Yes. Bare MJPEG from IP cameras, microscopes, and machine-vision rigs usually carries no audio track at all, so there is nothing to carry into the FLV and the output comes out picture-only. This is normal for those sources. When a source does include audio (a webcam or capture tool with a mic), it is re-encoded — the output defaults to AAC, with MP3 also available under Audio Codec, both of which Flash-era players expect. FLV is built around a single audio track, so multi-track audio is reduced to the main stream.

Should I really convert to FLV, or is MP4 the better target?

For almost everyone, MP4. FLV made sense when Flash Player was installed on virtually every desktop; that era ended in 2021. In our testing, a one-minute 1080p MJPEG capture re-encoded to an H.264 MP4 came out far smaller than the source and played in every modern browser and on mobile, while the FLV version required VLC or a dedicated player to open. Choose FLV only when a legacy Flash-based web player, learning-management system, or courseware tool will not accept anything else — in that one case it is the right answer. For every other use, MJPEG to MP4 is smaller, sharper at the same size, and universally playable. If you instead need a Windows Media file, see MJPEG to WMV.

How are my files handled, and how long are they kept?

Your file is uploaded over an encrypted connection, processed on our servers, and deleted automatically a few hours after the conversion — no sign-up, no watermark, never shared or made public.