[FFmpeg-user] video fps filter problem

Carl Eugen Hoyos ceffmpeg at gmail.com
Wed Aug 15 01:49:37 EEST 2018

> Am 14.08.2018 um 11:42 schrieb 홍석진 <ssokjin.hong at navercorp.com>:
> ​Hi.
>> I have something to discuss with you about vf_fps.c in FFmpeg 4.
>> When I tried to encode a video which has only one video frame, a encoded video (result) had no video stream.
> I used video fps filter to adjust fps from 25 to 12 (ffmpeg argument fps=fps=12.0000000000).
>> I know that vf_fps.c was newly rewritten in FFmpeg 4.
> I tried to analyze vf_fps.c source code and finally realized that fps filter remove frame few conditions as below
> /* There are two conditions where we want to drop a frame:
> * - If we have two buffered frames and the second frame is acceptable
> * as the next output frame, then drop the first buffered frame.
> * - If we have status (EOF) set, drop frames when we hit the
> * status timestamp. */​
> In that case, video frame of my video contents can't be passed to ff_filter_frame function because this video contents has only one frame.
>> So, I wonder if I should think of this video as unusual. Because when I use FFmpeg 3, encoded result video has video stream.

Please provide the input file.

Thank you, Carl Eugen

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