[FFmpeg-user] Decimation with ppsrc=1 malfunctions

Mark Filipak (ffmpeg) markfilipak at bog.us
Sun Dec 27 20:29:00 EET 2020

On 12/27/2020 07:30 AM, Carl Eugen Hoyos wrote:
>> Am 27.12.2020 um 12:19 schrieb Paul B Mahol <onemda at gmail.com>:
>> Do you know exact telecine pattern used in your samples?
> I don’t think the sample is telecined...

It must have been. Now, bear with me.
1, The original video was p24:
2, Later, it was telecined:
3, Later, a modulo-5 frame was dropped [1]:
4, Later, a modulo-4 frame was repeated:

[1] Dropping a frame in lieu of detelecine was a mistake. Perhaps the engineer was drunk.

>... or at least whatever was done with it can’t be undone (even the description confirms this)...

Ah! But it can be undone (sort of):
Decimate to:
Then synthesize a frame:
Then detelecine:

>... so this part of the discussion seems moot.

I agree. It's moot because it doesn't bear on why decimate=ppsrc=1 isn't working correctly.

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