aemphasis¶
The description in the official documentation:
Audio emphasis filter creates or restores material directly taken from LPs or emphased CDs with different filter curves. E.g. to store music on vinyl the signal has to be altered by a filter first to even out the disadvantages of this recording medium. Once the material is played back the inverse filter has to be applied to restore the distortion of the frequency response.
The filter accepts the following options:
level_in
Set input gain.
level_out
Set output gain.
mode
Set filter mode. For restoring material use
reproduction
mode, otherwise useproduction
mode. Default isreproduction
mode.type
Set filter type. Selects medium. Can be one of the following:
col
select Columbia.
emi
select EMI.
bsi
select BSI (78RPM).
riaa
select RIAA.
cd
select Compact Disc (CD).
50fm
select 50µs (FM).
75fm
select 75µs (FM).
50kf
select 50µs (FM-KF).
75kf
select 75µs (FM-KF).
[me@host: ~]$ # for restoring material:
[me@host: ~]$ ffmpeg -y -i input -filter_complex "aemphasis=mode=reproduction:type=cd" output
[me@host: ~]$ # otherwise:
[me@host: ~]$ ffmpeg -y -i input -filter_complex "aemphasis=mode=production:type=cd" output