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Three types of pictures (or frames) are used in video compression: I, P, and B frames. An I‑frame (intra-coded picture) is a complete image, like a JPG or BMP image file. A P‑frame (Predicted picture) holds only the changes in the image from a previous frame. For example, in a scene where a car moves across a stationary background, only the ...
This process, dubbed "matting" or "pulling a matte," is most commonly used to separate the foreground and background elements of an image, and these images are often individual frames of a video file. In case of video, matting methods can use temporal relations as additional information. Compositing techniques are a relatively simple way of ...
The following is a simplistic illustrated explanation of how motion compensation works. Two successive frames were captured from the movie Elephants Dream.As can be seen from the images, the bottom (motion compensated) difference between two frames contains significantly less detail than the prior images, and thus compresses much better than the rest.
A fundamental property of B-frames is that they can be dropped without affecting the correct decoding of other frames. D frame (DC direct coded picture) – serves as a fast-access representation of a frame for loss robustness or fast-forward. D frames are only used in MPEG-1 video. An I frame indicates the beginning of a GOP.
M-JPEG is an intraframe-only compression scheme (compared with the more computationally intensive technique of interframe prediction).Whereas modern interframe video formats, such as MPEG1, MPEG2 and H.264/MPEG-4 AVC, achieve real-world compression ratios of 1:50 or better, M-JPEG's lack of interframe prediction limits its efficiency to 1:20 or lower, depending on the tolerance to spatial ...
SMPTE timecode (/ ˈ s ɪ m p t iː / or / ˈ s ɪ m t iː /) is a set of cooperating standards to label individual frames of video or film with a timecode. The system is defined by the Society of Motion Picture and Television Engineers in the SMPTE 12M specification. SMPTE revised the standard in 2008, turning it into a two-part document ...
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The frame is also sometimes used as a unit of time, so that a momentary event might be said to last six frames, the actual duration of which depends on the frame rate of the system, which varies according to the video or film standard in use. In North America and Japan, 30 frames per second (fps) is the broadcast standard, with 24 frames/s now ...