[FFmpeg-user] Cut part of a video, crop it and blackout parts of it

[Michael Koch]

Am 05.04.2021 um 11:58 schrieb Cecil Westerhof via ffmpeg-user:
> Michael Koch <astroelectronic at t-online.de> writes:
>
>> Am 05.04.2021 um 01:48 schrieb Cecil Westerhof via ffmpeg-user:
>>> I have to cut out a part of a video, crop it and blackout two parts.
>>> I do this with:
>>>       ffmpeg -y                                      \
>>>              -ss 00:19:49                            \
>>>              -i  2021-03-25ToastmastersClubAvond.mp4 \
>>>              -to 442                                 \
>>>              -vf "
>>>                   crop = 1440:1080:240:0
>>>                   ,
>>>                   drawbox=enable='between(t, 0, 2)'     :
>>>                      color     = black                  :
>>>                      w         = in_w                   :
>>>                      h         = in_h                   :
>>>                      thickness = fill
>>>                   ,
>>>                   drawbox=enable='between(t, 339, 342)' :
>>>                      color     = black                  :
>>>                      w         = in_w                   :
>>>                      h         = in_h                   :
>>>                      thickness = fill
>>>              "                                       \
>>>              -acodec copy                            \
>>>              -vcodec libx264                         \
>>>              -crf    23                              \
>>>              speechClean2.mp4
>>>
>>> The reason I do -to in the output is that in this way the metadata
>>> concerning the video length is less out of whack.
>>>
>>> I was wondering if this is a good way, or that it could be done
>>> better?
>>> Also, beside the timestamps the parameters for drawbox are the same.
>>> Is there a way that I do not have to repeat them?
>> drawbox=enable='bitor(between(t, 0, 2),between(t, 339, 342))'
> Works like a charm.
>
> Strange thing is that it seems to be much faster. About 20%. To much
> to be because of different load I think.
> But I am not complaining. ;-)

If you want to cover the whole frame size, you could also use this (for 
50% gray):
eq=enable='bitor(between(t, 0, 2),between(t, 339, 342))':contrast=0
or add :brightness=-0.5 if you want black.
It might be faster than drawbox.

Michael