[FFmpeg-user] "More than 1000 frames duplicated" when converting JPGs to video

[Eduard B]

Thank you!

On Sun, Jun 27, 2021 at 9:26 AM Gyan Doshi <ffmpeg at gyani.pro> wrote:

>
>
> On 2021-06-27 11:43, Eduard B wrote:
> > Hi list,
> >
> > I am using ffmpeg to convert a large set of timelapse still frames (JPGs)
> > captured by my surveillance camera to a video. Using x265 library to make
> > the file smaller. The particular batch I have tested has 14401 JPG files
> in
> > a folder (one image captured every 6 seconds).
> >
> > Command is:
> > ffmpeg -i /mnt/user/cctv/mjwVb9pFuK/8sHGyfFGu6_timelapse/$(date -d "-1
> > days" '+%Y-%m-%d')/%06d.jpg -c:v libx265 -preset medium -crf 20 -r 30
> -c:a
> > aac -b:a 128k /mnt/user/cctv/mjwVb9pFuK/8sHGyfFGu6_timelapse/$(date -d
> "-1
> > days" '+%Y-%m-%d')_x265_correct.mp4
> >
> > I wanted to convert to a 30 FPS video, the command I have been using,
> which
> > works, converts the files to a video, however it complains about
> duplicate
> > frames. While investigating, I have realized the final duplicate frames
> > count has 2880 frames, which is 1/5 of the total amount of still images.
> > Seems to me that the encoder assumes the input is recorded at 25 FPS and
> > tries to convert it to a video which has the same length, but with 30
> FPS.
> > However, the input is a series of still images with no frame rate.
> >
> > I have changed the command to a similar one, using 25 FPS frame rate
> > parameter value instead, and the complaint about duplicate frames is
> gone.
> > This means I would need to explicitly tell the encoder the input is using
> > 30 FPS, rather than the default assumption of 25. I have been looking at
> > the "--fps" option, however documentation says "YUV only", I'm not sure
> > it's applicable.
>
> For image sequence inputs, use the framerate option.
>
>      ffmpeg -framerate 30 -i ...
>
> Regards,
> Gyan
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