On 06-02-2019 12:57 AM, Christian Johannesen wrote:
It's my understanding that the -t option can be used before or after the
input file. I've found that its more accurate with some input files if I
place the option after the input file. However, this impacts the ability to
use the concat video filter to combine multiple clips. When I set the -t
duration after the input last input clip does not appear in the output file
after using the concat video filter. If move the -t duration before the
input, the concat video filter outputs both clips.
Thanks,
Chris
-t before input:
ffmpeg -y -ss 86.086 -t 4.004 -i countdownclock_720p2398_21min.mp4 -ss
1257.256 -t 4.004 -i countdownclock_720p2398_21min.mp4 -filter_complex
"[0:v:0][1:v:0]concat=n=2:v=1:a=0[concat_v]" -map "[concat_v]" -pix_fmt
yuv420p t_after_input.mp4
-ss and -t when used as output options, take effect *after* filtering,
so you're actually trimming the output from the concat filter.
Use the trim filters instead.
ffmpeg -y -i countdownclock_720p2398_21min.mp4 -filter_complex \
"[0]split=2[v1][v2];
[v1]trim=st=86.086:d=4.004,setpts=PTS-STARTPTS[v1];
[v2]trim=st=1257.256:d=4.004,setpts=PTS-STARTPTS[v2]; \
[v1][v2]concat=n=2:v=1:a=0,format=yuv420p" t_after_input.mp4
In this case, you can also use the select filter since you're working on
one input.
ffmpeg -y -i countdownclock_720p2398_21min.mp4 -vf
"select='between(t,86.086,86.086+4.004)+between(t,1257.256,1257.256+4.004)',setpts=PTS-STARTPTS
,format=yuv420p" t_after_input.mp4
Note that both these methods will be slower than input ss/t.
Gyan
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