Motion JPEG [MJPEG or M-JPEG] is a video compression format in which each video frame or interlaced field of a digital video sequence [including video and metadata such as subtitles and closed captions] is separately compressed into a JPEG image. Originally developed for multimedia PC applications, MJPEG is now used by video capture devices such as digital cameras, IP cameras, webcams and non-linear video editing systems. It is supported by QuickTime Player, PlayStation Console and browsers such as Safari, Google Chrome and Mozilla Firefox. MJPEG was first used by QuickTime Player in the mid-1990s.
MJPEG is an intra-only compression scheme. Since frames are compressed independently of each other, MJPEG has lower processing and memory requirements for hardware devices. Therefore, the image quality of MJPEG is directly a function of the spatial complexity of each video frame. Frames with large smooth transitions or monotonous surfaces compress well and are more likely to retain their original detail with few visible compression artifacts. Frames with complex textures, fine curves and lines are ready to render DCT artifacts such as ringing, smudges and macroblocks. This makes MJPEG better than the interframe compression scheme, which does not accommodate fast motion between frames and requires more hardware to meet the memory requirements for interframe compression.
MJPEG is often used in nonlinear video editing systems. The desktop CPU is powerful enough to handle HD video, so no special hardware is needed, and they provide native random access to frames. MJPEG support is also common in video capture and editing devices, allowing easy sharing of files such as archiving and transcription.
Prior to the rise of MPEG-4 encoding in consumer devices recently, MJPEG's progressive scan format was widely used in the movie mode of digital still cameras, allowing video encoding and playback through integrated JPEG compression hardware, with only software modifications. The AMV video format is a modified version of MJPEG.
Many network-enabled cameras provide MJPEG streams that network clients can connect to. Mozilla and Webkit-based browsers themselves support viewing MJPEG streams. Some network-enabled cameras offer their own MJPEG interface as part of the normal feature set. For cameras that do not provide this feature on the unit, you can use the server to transcode the camera image into an MJPEG stream and then provide the stream to other network clients.
The MJPEG standard comes from a market adoption process rather than a standards body and therefore enjoys extensive customer support. Most major web browsers and video players provide native support, and the rest are available.
Orignal From: What is Motion JPEG (MJPEG or M-JPEG)?
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