firequalizer


Apply FIR Equalization using arbitrary frequency response.

The filter accepts the following option:

'gain'

Set gain curve equation (in dB). The expression can contain variables:

'f'

the evaluated frequency

'sr'

sample rate

'ch'

channel number, set to 0 when multichannels evaluation is disabled

'chid'

channel id, see libavutil/channel_layout.h, set to the first channel id when multichannels evaluation is disabled

'chs'

number of channels

'chlayout'

channel_layout, see libavutil/channel_layout.h

and functions:

'gain_interpolate(f)'

interpolate gain on frequency f based on gain_entry

'cubic_interpolate(f)'

same as gain_interpolate, but smoother

This option is also available as command. Default is gain_interpolate(f).

'gain_entry'

Set gain entry for gain_interpolate function. The expression can contain functions:

'entry(f, g)'

store gain entry at frequency f with value g

This option is also available as command.

'delay'

Set filter delay in seconds. Higher value means more accurate. Default is 0.01.

'accuracy'

Set filter accuracy in Hz. Lower value means more accurate. Default is 5.

'wfunc'

Set window function. Acceptable values are:

'rectangular'

rectangular window, useful when gain curve is already smooth

'hann'

hann window (default)

'hamming'

hamming window

'blackman'

blackman window

'nuttall3'

3-terms continuous 1st derivative nuttall window

'mnuttall3'

minimum 3-terms discontinuous nuttall window

'nuttall'

4-terms continuous 1st derivative nuttall window

'bnuttall'

minimum 4-terms discontinuous nuttall (blackman-nuttall) window

'bharris'

blackman-harris window

'tukey'

tukey window

'fixed'

If enabled, use fixed number of audio samples. This improves speed when filtering with large delay. Default is disabled.

'multi'

Enable multichannels evaluation on gain. Default is disabled.

'zero_phase'

Enable zero phase mode by subtracting timestamp to compensate delay. Default is disabled.

'scale'

Set scale used by gain. Acceptable values are:

'linlin'

linear frequency, linear gain

'linlog'

linear frequency, logarithmic (in dB) gain (default)

'loglin'

logarithmic (in octave scale where 20 Hz is 0) frequency, linear gain

'loglog'

logarithmic frequency, logarithmic gain

'dumpfile'

Set file for dumping, suitable for gnuplot.

'dumpscale'

Set scale for dumpfile. Acceptable values are same with scale option. Default is linlog.

'fft2'

Enable 2-channel convolution using complex FFT. This improves speed significantly. Default is disabled.

'min_phase'

Enable minimum phase impulse response. Default is disabled.