c_weighting.h File Reference

C-weighting filter coefficients. More...

Go to the source code of this file.

Functions
aubio_filter_t *	new_aubio_filter_c_weighting (uint_t samplerate)
	create new C-design filter More...
uint_t	aubio_filter_set_c_weighting (aubio_filter_t *f, uint_t samplerate)
	set feedback and feedforward coefficients of a C-weighting filter More...

Detailed Description

C-weighting filter coefficients.

This file creates a C-weighting digital filter, which reduces low and high frequencies and enhance the middle ones to reflect the ability of the human hearing.

The implementation is based on the following standard:

• IEC/CD 1672: Electroacoustics-Sound Level Meters, IEC, Geneva, Nov. 1996, for A- and C-weighting filters.

See also:

• A-Weighting on Wikipedia
• Weighting filter on Wikipedia
• Christophe Couvreur's 'octave' toolbox

The coefficients in this file have been computed using Christophe Couvreur's scripts in octave 3.0 (debian package 1:3.0.5-6+b2 with octave-signal 1.0.9-1+b1 on i386), with

 [b, a] = cdsign(1/Fs) 

for various sampling frequencies (8000, 11025, 16000, 22050, 24000, 32000, 44100, 48000, 88200, 96000, and 192000 Hz).

The sampling frequency should normally be higher than 20kHz, but most common file sampling rates have been included for completeness.

Definition in file c_weighting.h.

Function Documentation

aubio_filter_set_c_weighting()

uint_t aubio_filter_set_c_weighting	(	aubio_filter_t *	f,
		uint_t	samplerate
	)

set feedback and feedforward coefficients of a C-weighting filter

Parameters

f	filter object to get coefficients from
samplerate	sampling frequency of the signal to filter. Should be one of 8000, 11025, 16000, 22050, 24000, 32000, 44100, 48000, 88200, 96000, and 192000 Hz

Examples:

temporal/test-c_weighting.c, and temporal/test-filter.c.

new_aubio_filter_c_weighting()

aubio_filter_t* new_aubio_filter_c_weighting

(

uint_t

samplerate

)

create new C-design filter

Parameters

samplerate

sampling frequency of the signal to filter. Should be one of 8000, 11025, 16000, 22050, 24000, 32000, 44100, 48000, 88200, 96000, and 192000 Hz

Returns

a new filter object

Examples:

temporal/test-c_weighting.c, and temporal/test-filter.c.