[FFmpeg-user] Dim audio in parts where there is a lot of wind

[Michael Koch]

Am 02.06.2023 um 17:37 schrieb Cecil Westerhof via ffmpeg-user:
> Michael Koch <astroelectronic at t-online.de> writes:
>
>> Am 02.06.2023 um 08:39 schrieb Cecil Westerhof via ffmpeg-user:
>>> German Geraskin <german.geraskin at gmail.com> writes:
>>>
>>>>> I have videos where the audio is mostly reasonable good, but sometimes
>>>>> the wind creates havoc. Is there a way to dial the volume a good deal
>>>>> down for those parts only?
>>>>> It would be even better if that could be down in say half a second
>>>>> instead of at once.
>>>> Hi, Cecil
>>>>
>>>> You can use the volume audio filter.
>>>> Example for Linux version of ffmpeg:
>>>>
>>>>     -af volume=0.5:enable='between(t\,26.12\,28.64)'
>>>>
>>>> It means - set volume to 0.5 between 26.12 and 28.64 seconds.
>>> Thanks, I will try it out. I can do this several times?
>>> This is abrupt, there is no possibility to do it smooth?
>> I have added an example with start and stop ramps in chapter 3.5 of my book:
>> http://www.astro-electronic.de/FFmpeg_Book.pdf
>>
>> If someone finds a simpler solution, please let us know.
> This is abrupt. (It is better as nothing.) I would prefer it to slide
> to for example 25% and a the end slide back to 100%. Something like:
>      -                        -
>       -                      -
>        -                    -
>         -                  -
>          -                -
>           ----------------
>
> I understood I should do something with:
>      http://ffmpeg.org/ffmpeg-all.html#Expression-Evaluation

please download it again. It has ramps with 1.5 seconds duration. There 
was a bug in the first version. I uploaded a corrected version 10 
minutes later.

Michael