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-rw-r--r--libavcodec/iirfilter.c164
-rw-r--r--libavcodec/iirfilter.h (renamed from libavcodec/lowpass.h)54
-rw-r--r--libavcodec/lowpass.c129
3 files changed, 201 insertions, 146 deletions
diff --git a/libavcodec/iirfilter.c b/libavcodec/iirfilter.c
new file mode 100644
index 0000000000..bcaa021b60
--- /dev/null
+++ b/libavcodec/iirfilter.c
@@ -0,0 +1,164 @@
+/*
+ * IIR filter
+ * Copyright (c) 2008 Konstantin Shishkov
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file iirfilter.c
+ * different IIR filters implementation
+ */
+
+#include "iirfilter.h"
+#include <complex.h>
+#include <math.h>
+
+/**
+ * IIR filter global parameters
+ */
+typedef struct FFIIRFilterCoeffs{
+ int order;
+ float gain;
+ int *cx;
+ float *cy;
+}FFIIRFilterCoeffs;
+
+/**
+ * IIR filter state
+ */
+typedef struct FFIIRFilterState{
+ float x[1];
+}FFIIRFilterState;
+
+/// maximum supported filter order
+#define MAXORDER 30
+
+struct FFIIRFilterCoeffs* ff_iir_filter_init_coeffs(enum IIRFilterType filt_type,
+ enum IIRFilterMode filt_mode,
+ int order, float cutoff_ratio,
+ float stopband, float ripple)
+{
+ int i, j, size;
+ FFIIRFilterCoeffs *c;
+ double wa;
+ complex p[MAXORDER + 1];
+
+ if(filt_type != FF_FILTER_TYPE_BUTTERWORTH || filt_mode != FF_FILTER_MODE_LOWPASS)
+ return NULL;
+ if(order <= 1 || (order & 1) || order > MAXORDER || cutoff_ratio >= 1.0)
+ return NULL;
+
+ c = av_malloc(sizeof(FFIIRFilterCoeffs));
+ c->cx = av_malloc(sizeof(c->cx[0]) * ((order >> 1) + 1));
+ c->cy = av_malloc(sizeof(c->cy[0]) * order);
+ c->order = order;
+
+ wa = 2 * tan(M_PI * 0.5 * cutoff_ratio);
+
+ c->cx[0] = 1;
+ for(i = 1; i < (order >> 1) + 1; i++)
+ c->cx[i] = c->cx[i - 1] * (order - i + 1LL) / i;
+
+ p[0] = 1.0;
+ for(i = 1; i <= order; i++)
+ p[i] = 0.0;
+ for(i = 0; i < order; i++){
+ complex zp;
+ double th = (i + (order >> 1) + 0.5) * M_PI / order;
+ zp = cexp(I*th) * wa;
+ zp = (zp + 2.0) / (zp - 2.0);
+
+ for(j = order; j >= 1; j--)
+ p[j] = zp*p[j] + p[j - 1];
+ p[0] *= zp;
+ }
+ c->gain = creal(p[order]);
+ for(i = 0; i < order; i++){
+ c->gain += creal(p[i]);
+ c->cy[i] = creal(-p[i] / p[order]);
+ }
+ c->gain /= 1 << order;
+
+ return c;
+}
+
+struct FFIIRFilterState* ff_iir_filter_init_state(int order)
+{
+ FFIIRFilterState* s = av_mallocz(sizeof(FFIIRFilterState) + sizeof(s->x[0]) * (order - 1));
+ return s;
+}
+
+#define FILTER(i0, i1, i2, i3) \
+ in = *src * 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; \
+ *dst = av_clip_int16(lrintf(res)); \
+ s->x[i0] = in; \
+ src += sstep; \
+ dst += dstep; \
+
+void ff_iir_filter(const struct FFIIRFilterCoeffs *c, struct FFIIRFilterState *s, int size, const int16_t *src, int sstep, int16_t *dst, int dstep)
+{
+ int i;
+
+ if(c->order == 4){
+ for(i = 0; i < size; i += 4){
+ float in, res;
+
+ FILTER(0, 1, 2, 3);
+ FILTER(1, 2, 3, 0);
+ FILTER(2, 3, 0, 1);
+ FILTER(3, 0, 1, 2);
+ }
+ }else{
+ for(i = 0; i < size; i++){
+ int j;
+ float in, res;
+ in = *src * 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];
+ *dst = av_clip_int16(lrintf(res));
+ s->x[c->order - 1] = in;
+ src += sstep;
+ dst += sstep;
+ }
+ }
+}
+
+void ff_iir_filter_free_state(struct FFIIRFilterState *state)
+{
+ av_free(state);
+}
+
+void ff_iir_filter_free_coeffs(struct FFIIRFilterCoeffs *coeffs)
+{
+ if(coeffs){
+ av_free(coeffs->cx);
+ av_free(coeffs->cy);
+ }
+ av_free(coeffs);
+}
+
diff --git a/libavcodec/lowpass.h b/libavcodec/iirfilter.h
index 6a77907746..ac948d8959 100644
--- a/libavcodec/lowpass.h
+++ b/libavcodec/iirfilter.h
@@ -1,5 +1,5 @@
/*
- * Lowpass IIR filter
+ * IIR filter
* Copyright (c) 2008 Konstantin Shishkov
*
* This file is part of FFmpeg.
@@ -20,27 +20,48 @@
*/
/**
- * @file lowpass.h
- * lowpass filter interface
+ * @file iirfilter.h
+ * IIR filter interface
*/
-#ifndef FFMPEG_LOWPASS_H
-#define FFMPEG_LOWPASS_H
+#ifndef FFMPEG_IIRFILTER_H
+#define FFMPEG_IIRFILTER_H
#include "avcodec.h"
-struct FFLPFilterCoeffs;
-struct FFLPFilterState;
+struct FFIIRFilterCoeffs;
+struct FFIIRFilterState;
+
+enum IIRFilterType{
+ FF_FILTER_TYPE_BESSEL,
+ FF_FILTER_TYPE_BUTTERWORTH,
+ FF_FILTER_TYPE_CHEBYSHEV,
+ FF_FILTER_TYPE_ELLIPTIC,
+};
+
+enum IIRFilterMode{
+ FF_FILTER_MODE_LOWPASS,
+ FF_FILTER_MODE_HIGHPASS,
+ FF_FILTER_MODE_BANDPASS,
+ FF_FILTER_MODE_BANDSTOP,
+};
/**
* Initialize filter coefficients.
*
+ * @param filt_type filter type (e.g. Butterworth)
+ * @param filt_mode filter mode (e.g. lowpass)
* @param order filter order
* @param cutoff_ratio cutoff to input frequency ratio
+ * @param stopband stopband to input frequency ratio (used by bandpass and bandstop filter modes)
+ * @param ripple ripple factor (used only in Chebyshev filters)
*
* @return pointer to filter coefficients structure or NULL if filter cannot be created
*/
-const struct FFLPFilterCoeffs* ff_lowpass_filter_init_coeffs(int order, float cutoff_ratio);
+struct FFIIRFilterCoeffs* ff_iir_filter_init_coeffs(enum IIRFilterType filt_type,
+ enum IIRFilterMode filt_mode,
+ int order, float cutoff_ratio,
+ float stopband, float ripple);
/**
* Create new filter state.
@@ -49,23 +70,21 @@ const struct FFLPFilterCoeffs* ff_lowpass_filter_init_coeffs(int order, float cu
*
* @return pointer to new filter state or NULL if state creation fails
*/
-struct FFLPFilterState* ff_lowpass_filter_init_state(int order);
+struct FFIIRFilterState* ff_iir_filter_init_state(int order);
-#if 0 //enable with arbitrary order filter implementation, use av_free() for filter state only for now
/**
* Free filter coefficients.
*
- * @param coeffs pointer allocated with ff_lowpass_filter_init_coeffs()
+ * @param coeffs pointer allocated with ff_iir_filter_init_coeffs()
*/
-void ff_lowpass_filter_free_coeffs(struct FFLPFilterCoeffs *coeffs);
+void ff_iir_filter_free_coeffs(struct FFIIRFilterCoeffs *coeffs);
/**
* Free filter state.
*
- * @param state pointer allocated with ff_lowpass_filter_init_state()
+ * @param state pointer allocated with ff_iir_filter_init_state()
*/
-void ff_lowpass_filter_free_state(struct FFLPFilterState *state);
-#endif
+void ff_iir_filter_free_state(struct FFIIRFilterState *state);
/**
* Perform lowpass filtering on input samples.
@@ -78,6 +97,7 @@ void ff_lowpass_filter_free_state(struct FFLPFilterState *state);
* @param dst filtered samples (destination may be the same as input)
* @param dstep destination stride
*/
-void ff_lowpass_filter(const struct FFLPFilterCoeffs *coeffs, struct FFLPFilterState *state, int size, int16_t *src, int sstep, int16_t *dst, int dstep);
+void ff_iir_filter(const struct FFIIRFilterCoeffs *coeffs, struct FFIIRFilterState *state,
+ int size, const int16_t *src, int sstep, int16_t *dst, int dstep);
-#endif /* FFMPEG_LOWPASS_H */
+#endif /* FFMPEG_IIRFILTER_H */
diff --git a/libavcodec/lowpass.c b/libavcodec/lowpass.c
deleted file mode 100644
index 7159a1ee02..0000000000
--- a/libavcodec/lowpass.c
+++ /dev/null
@@ -1,129 +0,0 @@
-/*
- * Lowpass IIR filter
- * Copyright (c) 2008 Konstantin Shishkov
- *
- * This file is part of FFmpeg.
- *
- * FFmpeg is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * FFmpeg is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with FFmpeg; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-/**
- * @file lowpass.c
- * lowpass filter implementation
- */
-
-#include "lowpass.h"
-
-/**********************
- * TODO:
- * support filters with order != 4
- * calculate coefficients for filter instead of taking approximate ones from the table
- *********************/
-
-/** filter order */
-#define LOWPASS_FILTER_ORDER 4
-
-/**
- * IIR filter global parameters
- */
-typedef struct FFLPFilterCoeffs{
- float gain;
- float c[LOWPASS_FILTER_ORDER];
-}FFLPFilterCoeffs;
-
-/**
- * filter data for 4th order IIR lowpass Butterworth filter
- */
-static const FFLPFilterCoeffs lp_filter_coeffs[] = {
- { 9.398085e-01, { -0.0176648009, 0.0000000000, -0.4860288221, 0.0000000000 } },
- { 6.816645e-01, { -0.4646665999, -2.2127207402, -3.9912017501, -3.2380429984 } },
- { 4.998150e-01, { -0.2498216698, -1.3392807613, -2.7693097862, -2.6386277439 } },
- { 3.103469e-01, { -0.0965076902, -0.5977763360, -1.4972580903, -1.7740085241 } },
- { 2.346995e-01, { -0.0557639007, -0.3623690447, -1.0304538354, -1.3066051440 } },
- { 1.528432e-01, { -0.0261686639, -0.1473794606, -0.6204721225, -0.6514716536 } },
- { 6.917529e-02, { -0.0202414073, 0.0780167640, -0.5277442247, 0.3631641670 } },
- { 6.178391e-02, { -0.0223681543, 0.1069446609, -0.5615167033, 0.4883976841 } },
- { 5.298685e-02, { -0.0261686639, 0.1473794606, -0.6204721225, 0.6514716536 } },
- { 2.229030e-02, { -0.0647354087, 0.4172275190, -1.1412129810, 1.4320761385 } },
- { 1.693903e-02, { -0.0823177861, 0.5192354923, -1.3444768251, 1.6365345642 } },
- { 7.374053e-03, { -0.1481421788, 0.8650973862, -1.9894244796, 2.1544844308 } },
- { 5.541768e-03, { -0.1742301048, 0.9921936565, -2.2090801108, 2.3024482658 } },
-};
-
-/** cutoff ratios for lp_filter_data[] */
-static const float lp_cutoff_ratios[] = {
- 0.5000000000, 0.4535147392, 0.4166666667, 0.3628117914,
- 0.3333333333, 0.2916666667, 0.2267573696, 0.2187500000,
- 0.2083333333, 0.1587301587, 0.1458333333, 0.1133786848,
- 0.1041666667,
-};
-
-/**
- * IIR filter state
- */
-typedef struct FFLPFilterState{
- float x[LOWPASS_FILTER_ORDER];
-}FFLPFilterState;
-
-const struct FFLPFilterCoeffs* ff_lowpass_filter_init_coeffs(int order, float cutoff_ratio)
-{
- int i, size;
-
- //we can create only order-4 filters with cutoff ratio <= 0.5 for now
- if(order != LOWPASS_FILTER_ORDER) return NULL;
-
- size = sizeof(lp_cutoff_ratios) / sizeof(lp_cutoff_ratios[0]);
- if(cutoff_ratio > lp_cutoff_ratios[0])
- return NULL;
- for(i = 0; i < size; i++){
- if(cutoff_ratio >= lp_cutoff_ratios[i])
- break;
- }
- if(i == size)
- i = size - 1;
- return &lp_filter_coeffs[i];
-}
-
-struct FFLPFilterState* ff_lowpass_filter_init_state(int order)
-{
- if(order != LOWPASS_FILTER_ORDER) return NULL;
- return av_mallocz(sizeof(FFLPFilterState));
-}
-
-#define FILTER(i0, i1, i2, i3) \
- in = *src * c->gain \
- + c->c[0]*s->x[i0] + c->c[1]*s->x[i1] \
- + c->c[2]*s->x[i2] + c->c[3]*s->x[i3]; \
- res = (s->x[i0] + in )*1 \
- + (s->x[i1] + s->x[i3])*4 \
- + s->x[i2] *6; \
- *dst = av_clip_int16(lrintf(res)); \
- s->x[i0] = in; \
- src += sstep; \
- dst += dstep; \
-
-void ff_lowpass_filter(const struct FFLPFilterCoeffs *c, struct FFLPFilterState *s, int size, int16_t *src, int sstep, int16_t *dst, int dstep)
-{
- int i;
-
- for(i = 0; i < size; i += 4){
- float in, res;
-
- FILTER(0, 1, 2, 3);
- FILTER(1, 2, 3, 0);
- FILTER(2, 3, 0, 1);
- FILTER(3, 0, 1, 2);
- }
-}
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