Google Flix Engine Linux Reference Manual - Manual (Page 120)

114 Flix Engine Linux Module Documentation
5.28 Highpass
5.28.1 Detailed Description
The highpass audio filter is a filter to attenuate sounds in the audio track that are lower than the cutoff
frequency. In other words, high frequencies are passed by the filter, and low frequencies are stopped.
Example Usage:
sc = Flix2_AddFilter(&filter, flix, FE2_FILTER_HIGHPASS);
// Cut off frequencies below 2khz
if(sc == ON2_OK)
sc = Flix2_FilterSetParam(filter, FE2_HIGHPASS_CUTOFF, 2000.0);
Additional References:
Cookbook formulae for audio EQ biquad filter coefficients by Robert
Bristow-Johnson
Defines
• #define FE2_FILTER_HIGHPASS
Filter name for use with Flix2_AddFilter() .
• #define FE2_HIGHPASS_Q
Filter parameter for shape constant ("Q" coefficient).
• #define FE2_HIGHPASS_CUTOFF
Filter parameter for cutoff frequency.
5.28.2 Define Documentation
5.28.2.1 #define FE2_FILTER_HIGHPASS
Filter name for use with Flix2_AddFilter() .
Definition at line 46 of file highpass.h.
5.28.2.2 #define FE2_HIGHPASS_CUTOFF
Filter parameter for cutoff frequency.
This is the filter’s "corner" frequency. Components of the sound track with frequencies lower than this
frequency will be attenuated. If very precise control of the cutoff frequency is required, note that the
response of the filter at this frequency is -3db. Note that the maximum frequency is always half of the sam-
pling rate of the produced file (5512.5/11025/22050 for sample rates
Hertz11025 / Hertz22050 / Hertz44100
respectively).
Definition at line 69 of file highpass.h.
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