About MJPEG Files
Motion JPEG
Motion JPEG (MJPEG) is a video format where each frame is independently compressed as a JPEG image. This intraframe-only approach enables easy frame-accurate editing and is widely used in security cameras and digital camera video modes.
Family
Video Files
Extension
.mjpeg
MIME Type
video/x-motion-jpeg
Can Use As
HOW MJPEG
CAME TO BE.
Motion JPEG is the simplest approach to video: compress each frame independently as a full JPEG. No inter-frame prediction, no keyframe gaps — every frame is a complete standalone picture. M-JPEG was the video format inside QuickTime on early 1990s Macs and inside every digital camcorder’s "video mode" before MPEG-4 existed.
The trade-off is obvious: files are 3-5× larger than MPEG-2 for equivalent quality. The payoff: simple hardware, fast random access (any frame is a keyframe), and editability with no transcoding loss. That made M-JPEG the standard format of security cameras for two decades (an IP camera that can write JPEGs can trivially stream M-JPEG), Canon DSLR video capture pre-2008, and the default "low-CPU video" option on a thousand embedded boards. Even today, many IP-camera RTSP streams are M-JPEG — the codec that refuses to die because it’s too simple to kill.
CURIOSITIES &
TRIVIA.
Every frame in a Motion JPEG stream is a complete JPEG — rename the stream and any JPEG decoder handles frames one by one.
Security cameras and webcams have streamed M-JPEG for 25 years because it requires no inter-frame state.
Canon DSLRs from 2005-2008 recorded video as M-JPEG inside AVI containers — notoriously huge files.
Motion JPEG has no official standard — the convention predates formal standardization and varies subtly between implementations.
Modern IP cameras often offer both H.264 (bandwidth-efficient) and M-JPEG (simple, low-latency) streams side by side.
STRENGTHS &
LIMITATIONS.
Strengths
- Trivially simple — any JPEG decoder handles frames.
- Every frame is a keyframe — instant seek and edit.
- No inter-frame dependencies — recover from packet loss easily.
- Hardware cost is minimal — any JPEG decoder works.
- Lossless across edits — cutting and rejoining doesn't degrade quality.
Limitations
- 3-5× larger than MPEG-2; 8-10× larger than H.264 at comparable quality.
- No audio — requires a separate track.
- No standard container — appears inside AVI, MOV, MKV, MJPEG-over-HTTP.
- Obsolete for mass-market delivery.
Typical Sizes & Weights
1-min VGA webcam clip
40-80 MB
1-min 1080p IP camera stream
300-500 MB
Canon DSLR 720p video (1 min)
~550 MB
Technical Specifications
- MIME type
- video/x-motion-jpeg
- Extension
- .mjpeg, .mjpg
- Frame format
- Sequential JPEG (Baseline, usually 4:2:0)
- Typical containers
- AVI, MOV, MP4 (rare), raw stream
- Common in
- IP security cameras, USB webcams, scientific imaging
CONVERT FROM
MJPEG
CONVERT TO
MJPEG
Common Use Cases
Security cameras, IP cameras, webcam streams, frame-accurate video editing
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Frequently Asked Questions about MJPEG
Frequently Asked Questions
MJPEG (Motion JPEG) is a video container format that bundles one or more video streams, audio tracks, and optional subtitles into a single file. The container format determines how metadata is organised and which codecs can live inside; the visual quality itself depends on the codec (H.264, H.265, VP9, AV1) rather than the MJPEG wrapper. It is part of the video files family.
VLC, MPV and PotPlayer play nearly every MJPEG file on desktop. Browser support varies: modern Chromium, Firefox and Safari play common containers via the HTML5 <video> tag, but niche MJPEG variants may fail. If a device refuses your MJPEG, convert to MP4 with our MJPEG to MP4 converter for universal playback.
Upload your MJPEG to KaijuConverter and pick MP4, MOV, MKV, WebM, or any other target. Our pipeline uses FFmpeg under the hood and stream-copies when codecs are compatible (no quality loss) or transcodes at high-quality defaults otherwise. Conversion runs server-side; both files delete within two hours.
Only when the target requires re-encoding. If the codecs inside MJPEG match what the target container supports, FFmpeg stream-copies the streams and the output is bit-identical to the source. Transcoding uses transparent quality defaults (CRF 20–23 H.264) and produces output indistinguishable from the original at normal viewing distance.