MJPEG to MKV Converter

Convert MJPEG to MKV Online

A raw .mjpeg dump from an IP camera, webcam or capture card is just JPEG frames written end to end — no container, no seek index, nothing that tells a player how long the recording is. Wrapping it into Matroska gives it a real timeline and an index, so it opens, scrubs and trims like an ordinary video file. You choose whether to re-encode the picture to H.264 for a compact file, or keep the intra-only MJPEG codec so every frame stays a self-contained image.

How to Convert MJPEG to MKV

1. Upload Your MJPEG File: Drag the .mjpeg onto the page or click "+ Add Files"; several captures can be queued in one pass. Uploads travel over an encrypted connection and convert on our servers.
2. Choose a Video Codec: The Video Codec list opens on H.264 for a small, widely playable MKV. Pick MJPEG to keep the intra-only coding, or work down the list — H.265, VP9, AV1, MPEG-4, Xvid and a dozen more are available.
3. Set File Compression, Video Resolution or Trim: File Compression starts on Quality Preset at Very High (Recommended), with Specific file size, Constant Bitrate, Variable Bitrate, Constant Quality and Constraint Quality alongside it. Video resolution keeps the source size unless you change it, and Trim → Time Range takes a Start time and Duration.
4. Convert and Download: Click Convert and save the .mkv. No sign-up, no watermark.

Choosing Between H.264 and MJPEG

What Changes When the Stream Is Wrapped

Frequently Asked Questions

Why does my converted MKV have no sound?

Because the source has none to give. A raw MJPEG elementary stream carries video frames and nothing else — IP cameras, webcams and machine-vision rigs that record MJPEG either capture no audio at all or write it to a separate file. The MKV therefore comes out picture-only. If you have a matching audio recording, it has to be muxed in as its own step; this converter works on the single stream you upload.

Can it just wrap the existing frames without re-encoding them?

No — the video is always re-encoded, even when you pick MJPEG as the output codec. That is worth stating plainly because "wrapping" sounds like a copy operation. Choosing MJPEG gets you the closest thing to the original: an intra-only re-encode where each frame remains a self-contained JPEG, with no interframe prediction introduced. Set a high quality level if fidelity matters, and keep the original .mjpeg if you need the untouched bytes.

Which codec should I actually pick?

Keep H.264 unless you have a reason not to. It plays on essentially every phone, TV and browser, and its interframe coding collapses the enormous redundancy in a fixed-camera scene, where consecutive frames are nearly identical and MJPEG stores each one in full. Switch to MJPEG when frame independence is the point — evidence, measurement, microscopy or any workflow that pulls individual frames back out later.

Why does the MKV report a different length than the recording?

Because the length is reconstructed, not read. A raw MJPEG has no timing information anywhere in it, so the frame count is divided by an assumed 25 fps to produce a duration. A camera running at 10 fps for a minute writes 600 frames, which becomes a 24-second MKV playing at two-and-a-half times real speed. The frames are all there and in order; only the clock is wrong. There is no frame-rate control on this page, so correcting the speed means re-timing the file in an editor afterwards.

Will the MKV play on my TV or older media player?

Usually, but Matroska is less universally supported in hardware than MP4 — some older smart TVs, set-top boxes and Windows Media Player builds do not read it. Desktop players handle it fine; VLC plays MKV everywhere. If a specific device refuses the file, MJPEG to MP4 produces the same H.264 video in the container with the broadest device support.

Should I choose MKV or MP4 for camera footage?

Choose MKV for archiving. It is an open, royalty-free container — now a Standards Track IETF specification, RFC 9559 — and it can later carry extra audio tracks, subtitles, chapters and attachments without repackaging. Choose MP4 when the file is going straight to a phone, a browser or a TV, where support is more universal. Both hold the same H.264 video, so the decision is about where the file needs to play.

Does the picture change during conversion?

Slightly, and deliberately, for compatibility. MJPEG frames are stored in JPEG full range, often with 4:4:4 or 4:2:2 chroma. We checked the output of a full-range capture through this pipeline: the H.264 track comes back as yuv420p at limited range on the High profile, which is what mainstream players and hardware decoders expect. In practice that means the levels are mapped correctly rather than clipped, and colour detail is subsampled to 4:2:0. If you need the original chroma sampling preserved, that is another argument for keeping the MJPEG codec, though 4:2:0 conversion still applies.

How do I keep only one incident out of a long recording?

Set Trim to Time Range and give it a Start time and a Duration, in seconds or as HH:MM:SS.sss. Remember the clock is the assumed 25 fps one described above, so work from frame numbers divided by 25 rather than real elapsed time. For repeated cutting of an already-converted file, Video Cutter handles it directly.

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

Files are uploaded over an encrypted connection, converted on our servers, and deleted automatically a few hours later. No sign-up, no watermark, and nothing is shared or made public — which matters when the upload is security-camera or clinical footage.