[FFmpeg-user] Filter just the 1st audio channel of the input.

[Paul B Mahol]

On Wed, Feb 3, 2021 at 2:05 PM Marco Mircoli <nuvolablux at gmail.com> wrote:

> Hello,
>    wandering if it is possible to process just the 1st audio channel of an
> input.
> I don't know how many channels I will have as input, but I know that I have
> to process just the 1st and the others I have not to considerate.
>
> INPUT from mono to multichannel
> filters.....
> OUTPUT just one channel (mono)
>
> I've tried this but doesn't works
>
> ffmpeg -i FILE_FROM -map_channel 0.0.0 -af
> highpass=f=70,adeclick,loudnorm=I=-16.5:TP=-1.5:LRA=7 FILE_TO
>

you will need to extract each channel by channelsplit filter, and later
merge it with other filters.
This makes filtergraph description longer.
Some filters support processing only specific channel but most do not as it
does not make sense for such filters.


>
> Any suggest?
> Thanks.
> S.
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