[FFmpeg-user] For discussion: A better video notation.

[Mark Filipak (ffmpeg)]

On 02/04/2021 06:50 PM, Mark Filipak (ffmpeg) wrote:
> For discussion: A better video notation.
> 
> 24PPS at 23.9FPS         (aka "24p") Cinema (i.e. 24PPS) mastered at 23.9FPS, 0.1% slow.
> 24PPS at 23.9FPS         (aka "30i") Soft-telecined: cinema with 29.9FPS metadata, 0.1% slow.
> 24PPS at 25FPS           (aka "25i") Cinema with 25FPS metadata, 4% fast.
> 24PPS at 29.9FPS         (aka "30i") Hard-telecined: cinema converted to 29.9FPS, 0.1% slow.
> 25PPS at 25FPS           (aka "25i") Cinema interpolated to 25PPS, no speed up.
> 29.9PPS at 29.9FPS       (aka "30p") 29.9PPS video at 29.9FPS (some documentaries).
> 50SPS at 25FPS           (aka "25i") PAL broadcast TV interlaced to 25FPS.
> 50SPS+24PPS at 25FPS     (aka "25i") Mix of 50SPS at 25FPS & 24PPS at 25FPS (some "Making of" docs).
> 59.9SPS at 29.9FPS       (aka "30i") NTSC broadcast TV interlaced to 29.9FPS.
> 59.9SPS+24PPS at 29.9FPS (aka "30i") Mix of 59.9SPS at 29.9FPS & 24PPS at 29.9FPS (some "Making of" docs).
> IRREGULAR at 29.9FPS     (aka "30i") Having various frame/field repeats/discards with image loss.

I decided that using lower case was more readable. What do you think?

24pps at 23.9fps         (aka "24p") Cinema (i.e. 24pps) mastered at 23.9fps, 0.1% slow.
24pps at 23.9fps         (aka "30i") Soft-telecined: cinema with 29.9fps metadata, 0.1% slow.
24pps at 25fps           (aka "25i") Cinema with 25fps metadata, 4% fast.
24pps at 29.9fps         (aka "30i") Hard-telecined: cinema mastered at 29.9fps, 0.1% slow.
25pps at 25fps           (aka "25i") Cinema interpolated to 25pps, mastered at 25fps, no speed up.
29.9pps at 29.9fps       (aka "30p") 29.9pps video mastered at 29.9fps -- some documentaries.
50sps at 25fps           (aka "25i") PAL broadcast TV, scan-interlaced, mastered at 25fps.
50sps+24pps at 25fps     (aka "25i") Mix of 50sps at 25fps & 24pps at 25fps -- some "Making of" docs.
59.9sps at 29.9fps       (aka "30i") NTSC broadcast TV, scan-interlaced, mastered at 29.9fps.
59.9sps+24pps at 29.9fps (aka "30i") Mix of 59.9sps at 29.9fps & 24pps at 29.9fps -- some "Making of" docs.
irregular at 29.9fps     (aka "30i") Having various frame or field discards with temporal image loss.

This system is extensible to non-DVD/-BD transcodes (e.g. @59.9fps) but I'm a bit miffed by some 
DVDs that I've encountered.

For example, I have a couple of DVDs from Korea that are @29.9fps but get there via frame repeat, 
not via telecine -- of course the judder was awful until I fixed it.

24pps at 29.9fps doesn't fit such a case because the original 24fps can't be obtained via detelecine, 
but by dropping the repeated frame, instead. So I'm playing with such frame repeats by something 
like '24pps+6pps at 29.9fps'. Of course, that doesn't seem very intuitive, and novices will question 
it, at least at first. Perhaps '(24+6)pps at 29.9fps' expresses it better. Or maybe 
'6x(4+1)pps at 29.9fps' or maybe '6x(1-1-1-2)pps at 29.9fps'. Whatever, things get messy.

-- 
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And furthermore, my dog doesn't bite.
And furthermore, you provoked him.