[FFmpeg-user] Use concat filter with a fade
Michael Koch
astroelectronic at t-online.de
Tue Jun 14 17:34:41 EEST 2022
Am 14.06.2022 um 16:30 schrieb Cecil Westerhof via ffmpeg-user:
> Michael Koch <astroelectronic at t-online.de> writes:
>
>> Am 14.06.2022 um 15:33 schrieb Cecil Westerhof via ffmpeg-user:
>>> Michael Koch <astroelectronic at t-online.de> writes:
>>>
>>>> Am 14.06.2022 um 13:47 schrieb Cecil Westerhof via ffmpeg-user:
>>>>> Sometimes I have to cut parts out of a video. I now use for this (bash on Debian):
>>>>> ffmpeg -y \
>>>>> -ss ${videoStart} -to ${cutStart} -i ${inputFile} \
>>>>> -ss ${cutEnd} -to ${videoEnd} -i ${inputFile} \
>>>>> -vcodec libx264 \
>>>>> -crf 26 \
>>>>> -acodec libmp3lame -qscale:a 9 \
>>>>> -preset veryfast \
>>>>> -lavfi "concat=n=2:v=1:a=1" \
>>>>> -an ${outputFile}
>>>>>
>>>>> But the cut from one part to another is a bit abrupt. Is there a
>>>>> possibility to smooth it with something like a fade?
>>>> you can use the xfade filter. :
>>>> https://www.ffmpeg.org/ffmpeg-all.html#xfade
>>>> https://trac.ffmpeg.org/wiki/Xfade
>>> I am now using:
>>> offset=$((${cutStart} - ${videoStart} - ${duration}))
>>> xfade=xfade=transition=slideleft:duration=${duration}:offset=${offset}
>>> time ffmpeg -y \
>>> -ss ${videoStart} -to ${cutStart} -i ${inputFile} \
>>> -ss ${cutEnd} -to ${videoEnd} -i ${inputFile} \
>>> -vcodec libx264 \
>>> -crf 26 \
>>> -acodec libmp3lame -qscale:a 9 \
>>> -preset veryfast \
>>> -filter_complex ${xfade} \
>>> ${outputFile}
>>>
>>> But I have a major and minor problem.
>>> The major problem is that I do not have audio from the second part of
>>> the video.
>> Audio has its own filter: acrossfade
> This seems to work:
> xfade="xfade=transition=slideleft:duration=${duration}:offset=${offset};acrossfade=d=${duration}"
>
>
>>> The minor problem is that I have to calculate the offset. It would be
>>> nice if I could use -duration, but that does not work sadly.
>> As far as I know this isn't yet implemented.
> That sounds like it is going to be implemented. Or do I read to much
> in this sentence?
I really don't know.
Michael
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