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

[Marco Mircoli]

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

Any suggest?
Thanks.
S.