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

[Cecil Westerhof]

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?

I started the crf with 16, then 20 and lastly 23.

The input file has:
    Stream #0:1(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 2070 kb/s, 25 fps, 25 tbr, 30k tbn, 60k tbc (default)

With crf 16 I get:
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1440x1080, 5541 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)

With crf 20 I get:
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1440x1080, 3538 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)

And with crf 23 I get:
    Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1440x1080, 2444 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default)

So to me it seems that the crf value is still to high. Is there a way
to use the kb/s to calculate the crf value to use?

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof