Difference between revisions of "Frame"
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(NTSC is actually 29.97 frames per second, not 30; mention 2:3 pulldown) |
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| − | Video is stored in "[[frame]]s", which are snapshot images of a moving picture. These are typically captured (and shown) at a fixed rate, for example, 24 frames per second (fps). Television in the US is | + | Video is stored in "[[frame]]s", which are snapshot images of a moving picture. These are typically captured (and shown) at a fixed rate, for example, 24 frames per second (fps). Television in the US, under the [[NTSC]] standard, is 29.97 frames per second.<ref>[http://www.andrewduncan.ws/Timecodes/Timecodes.html Time codes]</ref> |
| − | Old-fashioned movies, such as World War I [[newsreel]]s, were shot at a slower frame rate (such as 16 frames per second). When these are added into a modern 24 fps movie, often they are played at the same frame rate, which speeds everything up noticeably. It is possible, of course, to program a computer to play frames at a [[variable rate]], so that the old 16 fps footage would appear at normal speed, and even 24 fps movies could play at 24 frames per second, but to save money or development time, this is rarely done. It seems to be easier to convert 24 fps to | + | Old-fashioned movies, such as World War I [[newsreel]]s, were shot at a slower frame rate (such as 16 frames per second). When these are added into a modern 24 fps movie, often they are played at the same frame rate, which speeds everything up noticeably. It is possible, of course, to program a computer to play frames at a [[variable rate]], so that the old 16 fps footage would appear at normal speed, and even 24 fps movies could play at 24 frames per second, but to save money or development time, this is rarely done. It seems to be easier to convert 24 fps to 29.97 fps by playing one frame twice and and the next frame 3 times. This is done using a process named 2:3 pulldown.<ref>[http://www.zerocut.com/tech/pulldown.html Pulldown Explained]</ref> |
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| + | ==References== | ||
| + | <references/> | ||
[[Category:Television]] | [[Category:Television]] | ||
Revision as of 15:15, March 12, 2008
Video is stored in "frames", which are snapshot images of a moving picture. These are typically captured (and shown) at a fixed rate, for example, 24 frames per second (fps). Television in the US, under the NTSC standard, is 29.97 frames per second.[1]
Old-fashioned movies, such as World War I newsreels, were shot at a slower frame rate (such as 16 frames per second). When these are added into a modern 24 fps movie, often they are played at the same frame rate, which speeds everything up noticeably. It is possible, of course, to program a computer to play frames at a variable rate, so that the old 16 fps footage would appear at normal speed, and even 24 fps movies could play at 24 frames per second, but to save money or development time, this is rarely done. It seems to be easier to convert 24 fps to 29.97 fps by playing one frame twice and and the next frame 3 times. This is done using a process named 2:3 pulldown.[2]