24 to 23.976 by decimating

[doctorm]

I have a source video that is fake 24 fps. Every 1000 frames the 1001st is a duplicate.

I haven't fully decided if that's worth fixing or not, but is there a good decimation method for doing that?

My best guess was
TDecimate(Mode=0,cycleR=1,cycle=1001)

Seems like that would be a terrible idea though... and slow.

[poisondeathray]

If the pattern is repeating without deviation, you can use DeleteEvery(1001,1000) from the ApplyEvery plugin. It would be much faster than TDecimate (because DeleteEvery is not performing an analysis, it's "blindly" deleting the offset value)

DeleteEvery adjusts the FPS, but does not affect audio. So you would need to slow the audio from 24/1 to 24000/1001

[doctorm]

Doesn't something like DeleteEvery cause the number of frame to shift as it works? I'd thought about creating something like that, but if frame 501,1502 ,2503, 3504, and 4505 are duplicates, doesn't deleting those frames move the duplicates? So they would become 501, 1501, 2501, 3501, 4501, etc.? Which would actually be pretty easy to delete now that I look at the math.

Btw, tested "TDecimate(Mode=0,cycleR=1,cycle=1001)" and it's slow and faulty.

[VoodooFX]

I would use SelectRangeEvery, that shouldn't affect the timeline.

DeleteEvery adjusts the FPS, but does not affect audio. So you would need to slow the audio

I never used it, are you sure that it affects the timeline?

[doctorm]

No. Sorry. Too low on sleep with stupid crazy thinkin' going on. I suppose if I re-encoded it again and again deleting one frame each time that would happen.
I'll try DeleteEvery when I get a chance.

[poisondeathray]

I would use SelectRangeEvery, that shouldn't affect the timeline.

DeleteEvery adjusts the FPS, but does not affect audio. So you would need to slow the audio

I never used it, are you sure that it affects the timeline?

DeleteEvery uses the original framenumbering for the timeline and does not shift as it works. You can verify with blankclip and showframenumber

blankclip(10000, fps=23.976).AssumeFPS(24000,1001)
showframenumber()
changefps(24) #24/1 fps with duplicates @ framenumbers 1001,1002, 2002,2003,  3003,3004
Trim(1,0) #24/1 fps with duplicates @ framenumbers 1000,1001, 2001,2002,  3002,3003
DeleteEvery(1001,1000)
#works ok

SelectRangeEvery works too in that example, and a better suggestion because it only relies on internal functions. It's also very fast. It affects the audio by default

SelectRangeEvery(1001,1000,0, audio=false)

Not sure if audio=true or false would be better. Probably audio=false is better. If you delete 1 frame duration of audio every 1001 frames, there might be audio glitches. So I would slow audio down separately too

[VoodooFX]

SelectRangeEvery works too in that example, and a better suggestion because it only relies on internal functions. It's also very fast. It affects the audio by default

SelectRangeEvery(1001,1000,0, audio=false)

Not sure if audio=true or false would be better. Probably audio=false is better. If you delete 1 frame duration of audio every 1001 frames, there might be audio glitches. So I would slow audio down separately too

You don't need to do anything with audio as SelectRangeEvery doesn't affect video duration.

[dannyboy48888]

Changefps("ntsc_film") the duration will stay the same and the judder if any will be uniform

[doctorm]

The audio function doesn't matter either way, the audio is separate and will be synced later.

[Luke M]

The audio will remain in sync, you don't need to touch it.