Miles Sound System SDK 7.2a

AIL_quick_set_low_pass_cut_off

The function AIL_quick_set_low_pass_cut_off applies a low-pass filter to the digital audio sample.

void AIL_quick_set_low_pass_cut_off(
  HAUDIO audio,
  F32 cut_off
);

In Parameters

audio

specifies the audio handle that you wish to control (must be a digital handle).

cut_off

specifies the low-pass filter cutoff frequency. The range is 0.0 to 1.0, given as a fraction of the sample's Nyquist rate (which is half the sample rate). For example, if you have a 44100 Hz sample, then the Nyquist rate is 22050 Hz. If you then set a 0.5 cutoff factor, only frequencies under 11025 Hz will be perceived at close to their full amplitude.

Note that the original Xbox's low-pass filter hardware is limited to 30 Hz to 8000 Hz.

Discussion

This function allows you to set a low-pass filter on any digital sample (whether uncompressed or compressed). A low-pass filter attenuates frequencies above the cutoff frequency.

The default low-pass cutoff is 1.0 (allowing all frequencies to pass).

There is almost no CPU hit at all with this filter. There is no CPU hit at all on the original Xbox, but the hardware low-pass filter only supports frequencies from 30 to 8000 Hz.

Group: Quick Integration Services
Related Basic Types: F32, HAUDIO, void