[FFmpeg-user] Multiple parts of a video

Cecil Westerhof Cecil at decebal.nl
Tue May 31 21:27:05 EEST 2022

Michael Koch <astroelectronic at t-online.de> writes:

> Am 31.05.2022 um 18:43 schrieb Cecil Westerhof via ffmpeg-user:
>> Michael Koch <astroelectronic at t-online.de> writes:
>>> I have a short example in chapter 2.57 of my book:
>>> http://www.astro-electronic.de/FFmpeg_Book.pdf
>> Just to make sure I understand it, I should do something like:
>>      ffmpeg -ss %S1% -t %L1% -i %I1%     \
>>             -ss %S2% -t %L2% -i %I1%     \
>>             -ss %S3% -t %L3% -i %I1%     \
>>             -lavfi "concat=n=3:v=1:a=0"  \
>>             -an %OUT%
>> But if I understand it well, this works on the iframes, would it not
>> be better (but longer) to use:
>>      ffmpeg -i %I1% -ss %S1% -t %L1%     \
>>             -i %I1% -ss %S2% -t %L2%     \
>>             -i %I1% -ss %S3% -t %L3%     \
>>             -lavfi "concat=n=3:v=1:a=0"  \
>>             -an %OUT%
> I think that won't work. If you write the options after the input file,
> then they are applied to the next input file, and the options in the 
> third line are applied to the output file.
> The concat filter does also work with audio. I just didn't need audio in
> my example.

But if you put them before the input file they are not precise, but
work on the iframe level. This can give quit extensive differences. (I
was bitten by that in the past.) Or is that not the case in this
specific scenario?

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

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