Split audio stream into several bands.
This filter splits audio stream into two or more frequency ranges. Summing all streams back will give flat output.
The filter accepts the following options:
split
Set split frequencies. Those must be positive and increasing.
order
Set filter order for each band split. This controls filter roll-off or steepness of filter transfer function. Available values are:
‘2nd’
12 dB per octave.
‘4th’
24 dB per octave.
‘6th’
36 dB per octave.
‘8th’
48 dB per octave.
‘10th’
60 dB per octave.
‘12th’
72 dB per octave.
‘14th’
84 dB per octave.
‘16th’
96 dB per octave.
‘18th’
108 dB per octave.
‘20th’
120 dB per octave.
Default is 4th.
level
Set input gain level. Allowed range is from 0 to 1. Default value is 1.
gains
Set output gain for each band. Default value is 1 for all bands.
precision
Set which precision to use when processing samples.
auto
Auto pick internal sample format depending on other filters.
float
Always use single-floating point precision sample format.
double
Always use double-floating point precision sample format.
Default value is auto.
标签：ffmpeg,format,Default,dB,per,filter,octave,acrossover From： https://www.cnblogs.com/sathcal/p/18539144