Defines | |
#define | FE2_FILTER_LOWPASS |
Filter name for use with Flix2_AddFilter(). | |
#define | FE2_LOWPASS_Q |
Filter parameter for shape constant ("Q" coefficient). | |
#define | FE2_LOWPASS_CUTOFF |
Filter parameter for cutoff frequency. |
The lowpass audio filter is a filter to attenuate sounds in the audio track that are higher than the cutoff frequency. In other words, low frequencies are passed by the filter, and high frequencies are stopped.
Example Usage:
sc = Flix2_AddFilter(&filter, flix, FE2_FILTER_LOWPASS); // Cut off frequencies above 10khz if(sc == ON2_OK) sc = Flix2_FilterSetParam(filter, FE2_LOWPASS_CUTOFF, 10000.0);
Additional References:
Cookbook formulae for audio EQ biquad filter coefficients by Robert Bristow-Johnson
#define FE2_FILTER_LOWPASS |
Filter name for use with Flix2_AddFilter().
#define FE2_LOWPASS_CUTOFF |
Filter parameter for cutoff frequency.
This is the filter's "corner" frequency. Components of the sound track with frequencies higher 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 sampling rate of the produced file (5512.5/11025/22050 for sample rates Hertz11025/Hertz22050/Hertz44100 respectively).
#define FE2_LOWPASS_Q |
Filter parameter for shape constant ("Q" coefficient).
The Q coefficient controls the "shape" of the filter. In general, higher numbers mean a sharper response curve. The default value is 0.707, and should be appropriate in most cases. If you feel the default value is inadequate, iterative experimentation is the best way to select a new value. Alternatively, a mathematical description of this filter is linked in the references above.