Difference between revisions of "Frame"
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(Adapt text of framerate here) |
(→Types: Key frames and I-frames are effectively the same. A Quora answer claims a slight difference, but I cannot seem to find a secondary source confirming that statement) |
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A frame is a still image. Video is made up of many frames per second to create the illusion of movement.<br /> | A frame is a still image. Video is made up of many frames per second to create the illusion of movement.<br /> | ||
The number of frames to be displayed per unit of time is expressed in ''frames per second'' (fps) or ''Hertz'' (Hz). These are different terms for the same measurement. | The number of frames to be displayed per unit of time is expressed in ''frames per second'' (fps) or ''Hertz'' (Hz). These are different terms for the same measurement. | ||
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== Types == | == Types == | ||
{{Wikipedia|Video compression picture types#Summary|l1=Video compression picture types|Inter frame#Frame types|l2=Inter frame § Frame types}} | {{Wikipedia|Video compression picture types#Summary|l1=Video compression picture types|Inter frame#Frame types|l2=Inter frame § Frame types}} | ||
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| + | Key frames (keyframes) and I-frames are the same.<sup>[[#note_1|†]]</sup> | ||
Digital video compression techniques involve [[compression]] of frames: | Digital video compression techniques involve [[compression]] of frames: | ||
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;P-frame: ''''P'''redicted' from previous frame(s)'s picture | ;P-frame: ''''P'''redicted' from previous frame(s)'s picture | ||
;B-frame: ''''B'''i-predictive' or ''''B'''idirectional' calculated from surrounding frames's pictures. Can painlessly be skipped. | ;B-frame: ''''B'''i-predictive' or ''''B'''idirectional' calculated from surrounding frames's pictures. Can painlessly be skipped. | ||
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| + | ---- | ||
| + | <sup><span id="note_1">†</span></sup> <small>[https://www.quora.com/What-is-the-difference-between-an-I-Frame-and-a-Keyframe-in-video-encoding/answer/Keith-Winstein This Quora answer] says that although the terms are used interchangeably, a ''key frame'' is an ''I-frame'' with the property of being a point from which a decoder can start decoding</small> | ||
[[Category:Glossary]] | [[Category:Glossary]] | ||
Revision as of 06:39, 30 March 2019
A frame is a still image. Video is made up of many frames per second to create the illusion of movement.
The number of frames to be displayed per unit of time is expressed in frames per second (fps) or Hertz (Hz). These are different terms for the same measurement.
Types
Key frames (keyframes) and I-frames are the same.†
Digital video compression techniques involve compression of frames:
- I-frame
- A full 'Intra-coded picture'
- P-frame
- 'Predicted' from previous frame(s)'s picture
- B-frame
- 'Bi-predictive' or 'Bidirectional' calculated from surrounding frames's pictures. Can painlessly be skipped.
† This Quora answer says that although the terms are used interchangeably, a key frame is an I-frame with the property of being a point from which a decoder can start decoding
