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The Keyframe Interval is set to 18 by default. How do I know if I should change this? I have Perceptually Lossless quality set. Will Blender adjust Keyframe Interval as needed or do I need to figure out what the best setting for my needs are? How do I figure out what is best for me needs?

EDIT: I am referring to the keyframe interval in the video encoding properties panel.

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  • $\begingroup$ Please use the edit link at the bottom of your post and clarify the contex for the question. Are you referring to keyframes for encoding video or what? $\endgroup$
    – user1853
    Commented May 18, 2019 at 22:39

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Assuming that you mean the keyframe interval in the video encoding properties panel (highlighted), this governs how often keyframes are written to the video stream. The default, 18, is one keyframe every 18 frames (or two-thirds of a second.)

As the tooltip states, there is a trade-off between file size and seekability. What this means is that when you seek through a file, the video cannot render correctly until the first keyframe -- this is the first frame of video data that is guaranteed to contain all pixels (the in between frames are "delta frames" and contain only partial information about what changed). So with fewer keyframes (with a large keyframe interval), when you skip through the video it will take longer for the video to "catch up" and start playing. However, because the keyframes do contain basically a whole screenshot, these frames take up more storage space. So if you have a small keyframe interval (lots of keyframes) then the resulting video file with be larger.

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    $\begingroup$ Thank you, slerfsterdn. It sounds like I can treat Keyframe Intervals just like the "old" GOP setting. YouTube recommends GOP be at half the FPS so I will use this recommendation to guide me in setting Keyframe Intervals. Thank you so much for your answer! $\endgroup$
    – user847
    Commented May 20, 2019 at 20:24

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