different IIR filters implementation More...

#include "iirfilter.h"
#include <math.h>
#include "libavutil/common.h"

Data Structures
struct	FFIIRFilterCoeffs
	IIR filter global parameters. More...

struct	FFIIRFilterState
	IIR filter state. More...

Macros
#define	MAXORDER 30
	maximum supported filter order

#define	CONV_S16(dest, source) dest = av_clip_int16(lrintf(source));

#define	CONV_FLT(dest, source) dest = source;

#define	FILTER_BW_O4_1(i0, i1, i2, i3, fmt)

#define	FILTER_BW_O4(type, fmt)

#define	FILTER_DIRECT_FORM_II(type, fmt)

#define	FILTER_O2(type, fmt)

Functions
static int	butterworth_init_coeffs (void avc, struct FFIIRFilterCoeffs c, enum IIRFilterMode filt_mode, int order, float cutoff_ratio, float stopband)

static int	biquad_init_coeffs (void avc, struct FFIIRFilterCoeffs c, enum IIRFilterMode filt_mode, int order, float cutoff_ratio, float stopband)

av_cold struct FFIIRFilterCoeffs *	ff_iir_filter_init_coeffs (void *avc, enum IIRFilterType filt_type, enum IIRFilterMode filt_mode, int order, float cutoff_ratio, float stopband, float ripple)
	Initialize filter coefficients.

av_cold struct FFIIRFilterState *	ff_iir_filter_init_state (int order)
	Create new filter state.

void	ff_iir_filter (const struct FFIIRFilterCoeffs c, struct FFIIRFilterState s, int size, const int16_t src, int sstep, int16_t dst, int dstep)
	Perform IIR filtering on signed 16-bit input samples.

void	ff_iir_filter_flt (const struct FFIIRFilterCoeffs c, struct FFIIRFilterState s, int size, const float src, int sstep, float dst, int dstep)
	Perform IIR filtering on floating-point input samples.

av_cold void	ff_iir_filter_free_state (struct FFIIRFilterState *state)
	Free filter state.

av_cold void	ff_iir_filter_free_coeffs (struct FFIIRFilterCoeffs *coeffs)
	Free filter coefficients.

Detailed Description

different IIR filters implementation

Definition in file iirfilter.c.

Macro Definition Documentation

#define MAXORDER 30

maximum supported filter order

Definition at line 49 of file iirfilter.c.

Referenced by butterworth_init_coeffs(), and ff_iir_filter_init_coeffs().

#define CONV_S16	(	dest,
		source
	)	dest = av_clip_int16(lrintf(source));

Definition at line 207 of file iirfilter.c.

#define CONV_FLT	(	dest,
		source
	)	dest = source;

Definition at line 209 of file iirfilter.c.

#define FILTER_BW_O4_1	(	i0,
		i1,
		i2,
		i3,
		fmt
	)

Value:

in = *src0 * c->gain                            \
         + c->cy[0]*s->x[i0] + c->cy[1]*s->x[i1]    \
         + c->cy[2]*s->x[i2] + c->cy[3]*s->x[i3];   \
    res =  (s->x[i0] + in      )*1                  \
         + (s->x[i1] + s->x[i3])*4                  \
         +  s->x[i2]            *6;                 \
    CONV_##fmt(*dst0, res)                          \
    s->x[i0] = in;                                  \
    src0 += sstep;                                  \
    dst0 += dstep;

Definition at line 211 of file iirfilter.c.

#define FILTER_BW_O4	(	type,
		fmt
	)

Value:

{           \
    int i;                                  \
    const type *src0 = src;                 \
    type       *dst0 = dst;                 \
    for (i = 0; i < size; i += 4) {         \
        float in, res;                      \
        FILTER_BW_O4_1(0, 1, 2, 3, fmt);    \
        FILTER_BW_O4_1(1, 2, 3, 0, fmt);    \
        FILTER_BW_O4_1(2, 3, 0, 1, fmt);    \
        FILTER_BW_O4_1(3, 0, 1, 2, fmt);    \
    }                                       \
}

Definition at line 223 of file iirfilter.c.

Referenced by ff_iir_filter(), and ff_iir_filter_flt().

#define FILTER_DIRECT_FORM_II	(	type,
		fmt
	)

Value:

{                                  \
    int i;                                                                  \
    const type *src0 = src;                                                 \
    type       *dst0 = dst;                                                 \
    for (i = 0; i < size; i++) {                                            \
        int j;                                                              \
        float in, res;                                                      \
        in = *src0 * c->gain;                                               \
        for(j = 0; j < c->order; j++)                                       \
            in += c->cy[j] * s->x[j];                                       \
        res = s->x[0] + in + s->x[c->order >> 1] * c->cx[c->order >> 1];    \
        for(j = 1; j < c->order >> 1; j++)                                  \
            res += (s->x[j] + s->x[c->order - j]) * c->cx[j];               \
        for(j = 0; j < c->order - 1; j++)                                   \
            s->x[j] = s->x[j + 1];                                          \
        CONV_##fmt(*dst0, res)                                              \
        s->x[c->order - 1] = in;                                            \
        src0 += sstep;                                                      \
        dst0 += dstep;                                                      \
    }                                                                       \
}

Definition at line 236 of file iirfilter.c.

Referenced by ff_iir_filter(), and ff_iir_filter_flt().

#define FILTER_O2	(	type,
		fmt
	)

Value:

{                                              \
    int i;                                                                  \
    const type *src0 = src;                                                 \
    type       *dst0 = dst;                                                 \
    for (i = 0; i < size; i++) {                                            \
        float in = *src0   * c->gain  +                                     \
                   s->x[0] * c->cy[0] +                                     \
                   s->x[1] * c->cy[1];                                      \
        CONV_##fmt(*dst0, s->x[0] + in + s->x[1] * c->cx[1])                \
        s->x[0] = s->x[1];                                                  \
        s->x[1] = in;                                                       \
        src0 += sstep;                                                      \
        dst0 += dstep;                                                      \
    }                                                                       \
}

Definition at line 258 of file iirfilter.c.

Referenced by ff_iir_filter(), and ff_iir_filter_flt().

Function Documentation

static int butterworth_init_coeffs	(	void *	avc,
		struct FFIIRFilterCoeffs *	c,
		enum IIRFilterMode	filt_mode,
		int	order,
		float	cutoff_ratio,
		float	stopband
	)

static

Definition at line 51 of file iirfilter.c.

Referenced by ff_iir_filter_init_coeffs().

static int biquad_init_coeffs	(	void *	avc,
		struct FFIIRFilterCoeffs *	c,
		enum IIRFilterMode	filt_mode,
		int	order,
		float	cutoff_ratio,
		float	stopband
	)

static

Definition at line 116 of file iirfilter.c.

Referenced by ff_iir_filter_init_coeffs().

av_cold struct FFIIRFilterCoeffs* ff_iir_filter_init_coeffs	(	void *	avc,
		enum IIRFilterType	filt_type,
		enum IIRFilterMode	filt_mode,
		int	order,
		float	cutoff_ratio,
		float	stopband,
		float	ripple
	)

read

Initialize filter coefficients.

Parameters

avc	a pointer to an arbitrary struct of which the first field is a pointer to an AVClass struct
filt_type	filter type (e.g. Butterworth)
filt_mode	filter mode (e.g. lowpass)
order	filter order
cutoff_ratio	cutoff to input frequency ratio
stopband	stopband to input frequency ratio (used by bandpass and bandstop filter modes)
ripple	ripple factor (used only in Chebyshev filters)

Returns: pointer to filter coefficients structure or NULL if filter cannot be created

Definition at line 159 of file iirfilter.c.

Referenced by ff_psy_preprocess_init().

av_cold struct FFIIRFilterState* ff_iir_filter_init_state ( int order )

read

Create new filter state.

Parameters

order filter order

Returns: pointer to new filter state or NULL if state creation fails

Definition at line 201 of file iirfilter.c.

Referenced by ff_psy_preprocess_init().

void ff_iir_filter	(	const struct FFIIRFilterCoeffs *	coeffs,
		struct FFIIRFilterState *	state,
		int	size,
		const int16_t *	src,
		int	sstep,
		int16_t *	dst,
		int	dstep
	)

Perform IIR filtering on signed 16-bit input samples.

Parameters

coeffs	pointer to filter coefficients
state	pointer to filter state
size	input length
src	source samples
sstep	source stride
dst	filtered samples (destination may be the same as input)
dstep	destination stride

Definition at line 274 of file iirfilter.c.

void ff_iir_filter_flt	(	const struct FFIIRFilterCoeffs *	coeffs,
		struct FFIIRFilterState *	state,
		int	size,
		const float *	src,
		int	sstep,
		float *	dst,
		int	dstep
	)

Perform IIR filtering on floating-point input samples.

Parameters

coeffs	pointer to filter coefficients
state	pointer to filter state
size	input length
src	source samples
sstep	source stride
dst	filtered samples (destination may be the same as input)
dstep	destination stride