WebSVN – Kolibri OS – Blame – /contrib/sdk/sources/ffmpeg/ffmpeg-2.8/libavcodec/iirfilter.c

Rev	Author	Line No.	Line
6147	serge	1	/*
		2	* IIR filter
		3	* Copyright (c) 2008 Konstantin Shishkov
		4	*
		5	* This file is part of FFmpeg.
		6	*
		7	* FFmpeg is free software; you can redistribute it and/or
		8	* modify it under the terms of the GNU Lesser General Public
		9	* License as published by the Free Software Foundation; either
		10	* version 2.1 of the License, or (at your option) any later version.
		11	*
		12	* FFmpeg is distributed in the hope that it will be useful,
		13	* but WITHOUT ANY WARRANTY; without even the implied warranty of
		14	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
		15	* Lesser General Public License for more details.
		16	*
		17	* You should have received a copy of the GNU Lesser General Public
		18	* License along with FFmpeg; if not, write to the Free Software
		19	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
		20	*/
		21
		22	/**
		23	* @file
		24	* different IIR filters implementation
		25	*/
		26
		27	#include "iirfilter.h"
		28	#include
		29	#include "libavutil/attributes.h"
		30	#include "libavutil/common.h"
		31
		32	/**
		33	* IIR filter global parameters
		34	*/
		35	typedef struct FFIIRFilterCoeffs{
		36	int order;
		37	float gain;
		38	int *cx;
		39	float *cy;
		40	}FFIIRFilterCoeffs;
		41
		42	/**
		43	* IIR filter state
		44	*/
		45	typedef struct FFIIRFilterState{
		46	float x[1];
		47	}FFIIRFilterState;
		48
		49	/// maximum supported filter order
		50	#define MAXORDER 30
		51
		52	static av_cold int butterworth_init_coeffs(void *avc,
		53	struct FFIIRFilterCoeffs *c,
		54	enum IIRFilterMode filt_mode,
		55	int order, float cutoff_ratio,
		56	float stopband)
		57	{
		58	int i, j;
		59	double wa;
		60	double p[MAXORDER + 1][2];
		61
		62	if (filt_mode != FF_FILTER_MODE_LOWPASS) {
		63	av_log(avc, AV_LOG_ERROR, "Butterworth filter currently only supports "
		64	"low-pass filter mode\n");
		65	return -1;
		66	}
		67	if (order & 1) {
		68	av_log(avc, AV_LOG_ERROR, "Butterworth filter currently only supports "
		69	"even filter orders\n");
		70	return -1;
		71	}
		72
		73	wa = 2 * tan(M_PI * 0.5 * cutoff_ratio);
		74
		75	c->cx[0] = 1;
		76	for(i = 1; i < (order >> 1) + 1; i++)
		77	c->cx[i] = c->cx[i - 1] * (order - i + 1LL) / i;
		78
		79	p[0][0] = 1.0;
		80	p[0][1] = 0.0;
		81	for(i = 1; i <= order; i++)
		82	p[i][0] = p[i][1] = 0.0;
		83	for(i = 0; i < order; i++){
		84	double zp[2];
		85	double th = (i + (order >> 1) + 0.5) * M_PI / order;
		86	double a_re, a_im, c_re, c_im;
		87	zp[0] = cos(th) * wa;
		88	zp[1] = sin(th) * wa;
		89	a_re = zp[0] + 2.0;
		90	c_re = zp[0] - 2.0;
		91	a_im =
		92	c_im = zp[1];
		93	zp[0] = (a_re * c_re + a_im * c_im) / (c_re * c_re + c_im * c_im);
		94	zp[1] = (a_im * c_re - a_re * c_im) / (c_re * c_re + c_im * c_im);
		95
		96	for(j = order; j >= 1; j--)
		97	{
		98	a_re = p[j][0];
		99	a_im = p[j][1];
		100	p[j][0] = a_rezp[0] - a_imzp[1] + p[j-1][0];
		101	p[j][1] = a_rezp[1] + a_imzp[0] + p[j-1][1];
		102	}
		103	a_re = p[0][0]zp[0] - p[0][1]zp[1];
		104	p[0][1] = p[0][0]zp[1] + p[0][1]zp[0];
		105	p[0][0] = a_re;
		106	}
		107	c->gain = p[order][0];
		108	for(i = 0; i < order; i++){
		109	c->gain += p[i][0];
		110	c->cy[i] = (-p[i][0] * p[order][0] + -p[i][1] * p[order][1]) /
		111	(p[order][0] * p[order][0] + p[order][1] * p[order][1]);
		112	}
		113	c->gain /= 1 << order;
		114
		115	return 0;
		116	}
		117
		118	static av_cold int biquad_init_coeffs(void avc, struct FFIIRFilterCoeffs c,
		119	enum IIRFilterMode filt_mode, int order,
		120	float cutoff_ratio, float stopband)
		121	{
		122	double cos_w0, sin_w0;
		123	double a0, x0, x1;
		124
		125	if (filt_mode != FF_FILTER_MODE_HIGHPASS &&
		126	filt_mode != FF_FILTER_MODE_LOWPASS) {
		127	av_log(avc, AV_LOG_ERROR, "Biquad filter currently only supports "
		128	"high-pass and low-pass filter modes\n");
		129	return -1;
		130	}
		131	if (order != 2) {
		132	av_log(avc, AV_LOG_ERROR, "Biquad filter must have order of 2\n");
		133	return -1;
		134	}
		135
		136	cos_w0 = cos(M_PI * cutoff_ratio);
		137	sin_w0 = sin(M_PI * cutoff_ratio);
		138
		139	a0 = 1.0 + (sin_w0 / 2.0);
		140
		141	if (filt_mode == FF_FILTER_MODE_HIGHPASS) {
		142	c->gain = ((1.0 + cos_w0) / 2.0) / a0;
		143	x0 = ((1.0 + cos_w0) / 2.0) / a0;
		144	x1 = (-(1.0 + cos_w0)) / a0;
		145	} else { // FF_FILTER_MODE_LOWPASS
		146	c->gain = ((1.0 - cos_w0) / 2.0) / a0;
		147	x0 = ((1.0 - cos_w0) / 2.0) / a0;
		148	x1 = (1.0 - cos_w0) / a0;
		149	}
		150	c->cy[0] = (-1.0 + (sin_w0 / 2.0)) / a0;
		151	c->cy[1] = (2.0 * cos_w0) / a0;
		152
		153	// divide by gain to make the x coeffs integers.
		154	// during filtering, the delay state will include the gain multiplication
		155	c->cx[0] = lrintf(x0 / c->gain);
		156	c->cx[1] = lrintf(x1 / c->gain);
		157
		158	return 0;
		159	}
		160
		161	av_cold struct FFIIRFilterCoeffs* ff_iir_filter_init_coeffs(void *avc,
		162	enum IIRFilterType filt_type,
		163	enum IIRFilterMode filt_mode,
		164	int order, float cutoff_ratio,
		165	float stopband, float ripple)
		166	{
		167	FFIIRFilterCoeffs *c;
		168	int ret = 0;
		169
		170	if (order <= 0 \|\| order > MAXORDER \|\| cutoff_ratio >= 1.0)
		171	return NULL;
		172
		173	FF_ALLOCZ_OR_GOTO(avc, c, sizeof(FFIIRFilterCoeffs),
		174	init_fail);
		175	FF_ALLOC_OR_GOTO (avc, c->cx, sizeof(c->cx[0]) * ((order >> 1) + 1),
		176	init_fail);
		177	FF_ALLOC_OR_GOTO (avc, c->cy, sizeof(c->cy[0]) * order,
		178	init_fail);
		179	c->order = order;
		180
		181	switch (filt_type) {
		182	case FF_FILTER_TYPE_BUTTERWORTH:
		183	ret = butterworth_init_coeffs(avc, c, filt_mode, order, cutoff_ratio,
		184	stopband);
		185	break;
		186	case FF_FILTER_TYPE_BIQUAD:
		187	ret = biquad_init_coeffs(avc, c, filt_mode, order, cutoff_ratio,
		188	stopband);
		189	break;
		190	default:
		191	av_log(avc, AV_LOG_ERROR, "filter type is not currently implemented\n");
		192	goto init_fail;
		193	}
		194
		195	if (!ret)
		196	return c;
		197
		198	init_fail:
		199	ff_iir_filter_free_coeffsp(&c);
		200	return NULL;
		201	}
		202
		203	av_cold struct FFIIRFilterState* ff_iir_filter_init_state(int order)
		204	{
		205	FFIIRFilterState* s = av_mallocz(sizeof(FFIIRFilterState) + sizeof(s->x[0]) * (order - 1));
		206	return s;
		207	}
		208
		209	#define CONV_S16(dest, source) dest = av_clip_int16(lrintf(source));
		210
		211	#define CONV_FLT(dest, source) dest = source;
		212
		213	#define FILTER_BW_O4_1(i0, i1, i2, i3, fmt) \
		214	in = src0 c->gain \
		215	+ c->cy[0]s->x[i0] + c->cy[1]s->x[i1] \
		216	+ c->cy[2]s->x[i2] + c->cy[3]s->x[i3]; \
		217	res = (s->x[i0] + in )*1 \
		218	+ (s->x[i1] + s->x[i3])*4 \
		219	+ s->x[i2] *6; \
		220	CONV_##fmt(*dst0, res) \
		221	s->x[i0] = in; \
		222	src0 += sstep; \
		223	dst0 += dstep;
		224
		225	#define FILTER_BW_O4(type, fmt) { \
		226	int i; \
		227	const type *src0 = src; \
		228	type *dst0 = dst; \
		229	for (i = 0; i < size; i += 4) { \
		230	float in, res; \
		231	FILTER_BW_O4_1(0, 1, 2, 3, fmt); \
		232	FILTER_BW_O4_1(1, 2, 3, 0, fmt); \
		233	FILTER_BW_O4_1(2, 3, 0, 1, fmt); \
		234	FILTER_BW_O4_1(3, 0, 1, 2, fmt); \
		235	} \
		236	}
		237
		238	#define FILTER_DIRECT_FORM_II(type, fmt) { \
		239	int i; \
		240	const type *src0 = src; \
		241	type *dst0 = dst; \
		242	for (i = 0; i < size; i++) { \
		243	int j; \
		244	float in, res; \
		245	in = src0 c->gain; \
		246	for(j = 0; j < c->order; j++) \
		247	in += c->cy[j] * s->x[j]; \
		248	res = s->x[0] + in + s->x[c->order >> 1] * c->cx[c->order >> 1]; \
		249	for(j = 1; j < c->order >> 1; j++) \
		250	res += (s->x[j] + s->x[c->order - j]) * c->cx[j]; \
		251	for(j = 0; j < c->order - 1; j++) \
		252	s->x[j] = s->x[j + 1]; \
		253	CONV_##fmt(*dst0, res) \
		254	s->x[c->order - 1] = in; \
		255	src0 += sstep; \
		256	dst0 += dstep; \
		257	} \
		258	}
		259
		260	#define FILTER_O2(type, fmt) { \
		261	int i; \
		262	const type *src0 = src; \
		263	type *dst0 = dst; \
		264	for (i = 0; i < size; i++) { \
		265	float in = src0 c->gain + \
		266	s->x[0] * c->cy[0] + \
		267	s->x[1] * c->cy[1]; \
		268	CONV_##fmt(dst0, s->x[0] + in + s->x[1] c->cx[1]) \
		269	s->x[0] = s->x[1]; \
		270	s->x[1] = in; \
		271	src0 += sstep; \
		272	dst0 += dstep; \
		273	} \
		274	}
		275
		276	void ff_iir_filter(const struct FFIIRFilterCoeffs *c,
		277	struct FFIIRFilterState *s, int size,
		278	const int16_t src, int sstep, int16_t dst, int dstep)
		279	{
		280	if (c->order == 2) {
		281	FILTER_O2(int16_t, S16)
		282	} else if (c->order == 4) {
		283	FILTER_BW_O4(int16_t, S16)
		284	} else {
		285	FILTER_DIRECT_FORM_II(int16_t, S16)
		286	}
		287	}
		288
		289	void ff_iir_filter_flt(const struct FFIIRFilterCoeffs *c,
		290	struct FFIIRFilterState *s, int size,
		291	const float src, int sstep, float dst, int dstep)
		292	{
		293	if (c->order == 2) {
		294	FILTER_O2(float, FLT)
		295	} else if (c->order == 4) {
		296	FILTER_BW_O4(float, FLT)
		297	} else {
		298	FILTER_DIRECT_FORM_II(float, FLT)
		299	}
		300	}
		301
		302	av_cold void ff_iir_filter_free_statep(struct FFIIRFilterState **state)
		303	{
		304	av_freep(state);
		305	}
		306
		307	av_cold void ff_iir_filter_free_coeffsp(struct FFIIRFilterCoeffs **coeffsp)
		308	{
		309	struct FFIIRFilterCoeffs coeffs = coeffsp;
		310	if(coeffs){
		311	av_freep(&coeffs->cx);
		312	av_freep(&coeffs->cy);
		313	}
		314	av_freep(coeffsp);
		315	}
		316
		317	void ff_iir_filter_init(FFIIRFilterContext *f) {
		318	f->filter_flt = ff_iir_filter_flt;
		319
		320	if (HAVE_MIPSFPU)
		321	ff_iir_filter_init_mips(f);
		322	}
		323
		324	#ifdef TEST
		325	#include
		326
		327	#define FILT_ORDER 4
		328	#define SIZE 1024
		329	int main(void)
		330	{
		331	struct FFIIRFilterCoeffs *fcoeffs = NULL;
		332	struct FFIIRFilterState *fstate = NULL;
		333	float cutoff_coeff = 0.4;
		334	int16_t x[SIZE], y[SIZE];
		335	int i;
		336
		337	fcoeffs = ff_iir_filter_init_coeffs(NULL, FF_FILTER_TYPE_BUTTERWORTH,
		338	FF_FILTER_MODE_LOWPASS, FILT_ORDER,
		339	cutoff_coeff, 0.0, 0.0);
		340	fstate = ff_iir_filter_init_state(FILT_ORDER);
		341
		342	for (i = 0; i < SIZE; i++) {
		343	x[i] = lrint(0.75 * INT16_MAX * sin(0.5M_PIi*i/SIZE));
		344	}
		345
		346	ff_iir_filter(fcoeffs, fstate, SIZE, x, 1, y, 1);
		347
		348	for (i = 0; i < SIZE; i++)
		349	printf("%6d %6d\n", x[i], y[i]);
		350
		351	ff_iir_filter_free_coeffsp(&fcoeffs);
		352	ff_iir_filter_free_statep(&fstate);
		353	return 0;
		354	}
		355	#endif /* TEST */

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(root)/contrib/sdk/sources/ffmpeg/ffmpeg-2.8/libavcodec/iirfilter.c @ 7195 – Rev 6147