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
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