iirfilter.c File Reference

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

Go to the source code of this file.

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

Macros
#define	MAXORDER   30
	maximum supported filter order More...
#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 av_cold int	butterworth_init_coeffs (void *avc, struct FFIIRFilterCoeffs *c, enum IIRFilterMode filt_mode, int order, float cutoff_ratio, float stopband)
static av_cold 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. More...
av_cold struct FFIIRFilterState *	ff_iir_filter_init_state (int order)
	Create new filter state. More...
void	ff_iir_filter (const struct FFIIRFilterCoeffs *c, struct FFIIRFilterState *s, int size, const int16_t *src, ptrdiff_t sstep, int16_t *dst, ptrdiff_t dstep)
	Perform IIR filtering on signed 16-bit input samples. More...
static void	iir_filter_flt (const struct FFIIRFilterCoeffs *c, struct FFIIRFilterState *s, int size, const float *src, ptrdiff_t sstep, float *dst, ptrdiff_t dstep)
	Perform IIR filtering on floating-point input samples. More...
av_cold void	ff_iir_filter_free_statep (struct FFIIRFilterState **state)
	Free and zero filter state. More...
av_cold void	ff_iir_filter_free_coeffsp (struct FFIIRFilterCoeffs **coeffsp)
	Free filter coefficients. More...
void	ff_iir_filter_init (FFIIRFilterContext *f)
	Initialize FFIIRFilterContext. More...

Detailed Description

different IIR filters implementation

Definition in file iirfilter.c.

Macro Definition Documentation

MAXORDER

#define MAXORDER   30

maximum supported filter order

Definition at line 52 of file iirfilter.c.

CONV_S16

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

Definition at line 207 of file iirfilter.c.

CONV_FLT

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

Definition at line 209 of file iirfilter.c.

FILTER_BW_O4_1

#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.

FILTER_BW_O4

#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 225 of file iirfilter.c.

FILTER_DIRECT_FORM_II

#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 238 of file iirfilter.c.

FILTER_O2

#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 260 of file iirfilter.c.

Function Documentation

butterworth_init_coeffs()

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

static

Definition at line 54 of file iirfilter.c.

Referenced by ff_iir_filter_init_coeffs().

biquad_init_coeffs()

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

static

Definition at line 119 of file iirfilter.c.

Referenced by ff_iir_filter_init_coeffs().

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
	)

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 162 of file iirfilter.c.

Referenced by ff_psy_preprocess_init(), and main().

ff_iir_filter_init_state()

av_cold struct FFIIRFilterState* ff_iir_filter_init_state

(

int

order

)

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(), and main().

ff_iir_filter()

void ff_iir_filter	(	const struct FFIIRFilterCoeffs *	coeffs,
		struct FFIIRFilterState *	state,
		int	size,
		const int16_t *	src,
		ptrdiff_t	sstep,
		int16_t *	dst,
		ptrdiff_t	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 276 of file iirfilter.c.

Referenced by main().

iir_filter_flt()

static void iir_filter_flt ( const struct FFIIRFilterCoeffs *  c, struct FFIIRFilterState *  s, int  size, const float *  src, ptrdiff_t  sstep, float *  dst, ptrdiff_t  dstep  )

static

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

Definition at line 301 of file iirfilter.c.

Referenced by ff_iir_filter_init().

ff_iir_filter_free_statep()

av_cold void ff_iir_filter_free_statep

(

struct FFIIRFilterState **

state

)

Free and zero filter state.

Parameters

state

pointer to pointer allocated with ff_iir_filter_init_state()

Definition at line 315 of file iirfilter.c.

Referenced by ff_psy_preprocess_end(), and main().

ff_iir_filter_free_coeffsp()

av_cold void ff_iir_filter_free_coeffsp

(

struct FFIIRFilterCoeffs **

coeffs

)

Free filter coefficients.

Parameters

coeffs

pointer allocated with ff_iir_filter_init_coeffs()

Definition at line 320 of file iirfilter.c.

Referenced by ff_iir_filter_init_coeffs(), ff_psy_preprocess_end(), and main().

ff_iir_filter_init()

void ff_iir_filter_init

(

FFIIRFilterContext *

f

)

Initialize FFIIRFilterContext.

Definition at line 330 of file iirfilter.c.

Referenced by ff_psy_preprocess_init().