Multimedia Glossary List

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Glossary: M

M1V, M2V
MPEG-1 or MPEG-2 video elemantary stream(no audio). Also called M1V for MPEG-1 video and M2V for MPEG-2 video.

Matroska, MKV
A new video and audio container format similiar to AVI but with several new features like support for OGG audio, Variable Framerate Video.

.mkv : Generally video files, as well those containing audio ( movies ) or video only. For more info, see http://www.matroska.org

MJPEG
Moving JPEG. A moving image which is made by storing each frame of a moving picture sequence in JPEG compression, then decompressing and displaying each frame at rapid speed to show the moving picture.M-JPEG does not use interframe coding as MPEG does. Sometimes called Motion JPEG.

MOV
QuickTime Content (.mov, .qt) - a file format developed by Apple Computer to create, edit, publish, and view multimedia files. QuickTime supports video, animation, graphics, 3D and virtual reality (VR).

MPEG
Moving Pictures Expert Group. A working group of ISO/IEC in charge of the development of standards for coded representation of digital audio and video.

MPEG is not an acronym for any standard, it is the acronym for the group who develops these standards! For various standards, take a look at MPEG-1 or MPEG-2, MPEG-4.

MPEG-1
Audio and video compression format developed by MPEG group back in 1993. Official description: Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s.

MPEG-1 is the video format that has had some extremely popular spin-offs and sideproducts, most notably MP3 and VideoCD.

MPEG-1's compression method is based on re-using the existing framematerial and using psychological and physical limitations of human senses. MPEG-1 video compression method tries to use previous frame's information in order to reduce the amount of information the current frame requires. Also, the audio encoding uses something that's called psychoacoustics -- basically compression removes the high and low frequencies a normal human ear cannot hear.

MPEG-2
A video standard developed by MPEG group. MPEG-2 is not a successor for MPEG-1, but an addition instead -- both of these formats have their own purposes in life; MPEG-1 is meant for medium-bandwidth usage and MPEG-2 is meant for high-bandwidth/broadband usage. Most commonly MPEG-2 is used in digital TVs, DVD-Videos and in SVCDs.

MPEG-4
MPEG-4 is one of the latest (audio and video) compression method standardized by MPEG group, designed specially for low-bandwidth (less than 1.5MBit/sec bitrate) video/audio encoding purposes.

Probably the best-known MPEG-4 video encoders are called DivX and XviD, which both are nowadays fully standard-compliant MPEG-4 encoders.

It should be noted that unlike MPEG-1 and MPEG-2, the MPEG-4's predecessors, MPEG-4 itself isn't just one unified encoding mechanism, but rather a group name for several flavors of video and audio encoding methods that share certain same characteristics. These "flavors" are often referred either as "profiles" or "layers" in MPEG-4 compression scheme and each new profile should be backwards compliant to the older, "lower" versions of MPEG-4 in terms of playback capability.

The most common MPEG-4 layers that XviD and DivX both use extensively are called simple profile and advanced simple profile. After those two standardized video encoding layers, MPEG-4 group has standardized several new layers -- most important ones are h263+ (which is used widely in mobile phone's, dubbed as 3GP) and h.264 (often also called as AVC).