1 /*
2 * This file is part of FFmpeg.
3 *
4 * FFmpeg is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
8 *
9 * FFmpeg is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
13 *
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with FFmpeg; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18
19 #include "libavutil/channel_layout.h"
20 #include "libavutil/ffmath.h"
21 #include "libavutil/opt.h"
22 #include "avfilter.h"
23 #include "audio.h"
24 #include "formats.h"
25
26 #define MAX_ORDER 30
27
28 typedef struct Coeffs {
29 double g;
30 double a1;
31 double b0, b1;
32 } Coeffs;
33
34 typedef struct ATiltContext {
35 const AVClass *class;
36
37 double freq;
38 double level;
39 double slope;
40 double width;
41 int order;
42
43 Coeffs coeffs[MAX_ORDER];
44
45 AVFrame *w;
46
47 int (*filter_channels)(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs);
48 } ATiltContext;
49
prewarp(double w,double T,double wp)50 static double prewarp(double w, double T, double wp)
51 {
52 return wp * tan(w * T * 0.5) / tan(wp * T * 0.5);
53 }
54
mz(int i,double w0,double r,double alpha)55 static double mz(int i, double w0, double r, double alpha)
56 {
57 return w0 * pow(r, -alpha + i);
58 }
59
mp(int i,double w0,double r)60 static double mp(int i, double w0, double r)
61 {
62 return w0 * pow(r, i);
63 }
64
mzh(int i,double T,double w0,double r,double alpha)65 static double mzh(int i, double T, double w0, double r, double alpha)
66 {
67 return prewarp(mz(i, w0, r, alpha), T, w0);
68 }
69
mph(int i,double T,double w0,double r)70 static double mph(int i, double T, double w0, double r)
71 {
72 return prewarp(mp(i, w0, r), T, w0);
73 }
74
set_tf1s(Coeffs * coeffs,double b1,double b0,double a0,double w1,double sr,double alpha)75 static void set_tf1s(Coeffs *coeffs, double b1, double b0, double a0,
76 double w1, double sr, double alpha)
77 {
78 double c = 1.0 / tan(w1 * 0.5 / sr);
79 double d = a0 + c;
80
81 coeffs->b1 = (b0 - b1 * c) / d;
82 coeffs->b0 = (b0 + b1 * c) / d;
83 coeffs->a1 = (a0 - c) / d;
84 coeffs->g = a0 / b0;
85 }
86
set_filter(AVFilterContext * ctx,int order,double sr,double f0,double bw,double alpha)87 static void set_filter(AVFilterContext *ctx,
88 int order, double sr, double f0,
89 double bw, double alpha)
90 {
91 ATiltContext *s = ctx->priv;
92 const double w0 = 2. * M_PI * f0;
93 const double f1 = f0 + bw;
94 const double w1 = 1.;
95 const double r = pow(f1 / f0, 1.0 / (order - 1.0));
96 const double T = 1. / sr;
97
98 for (int i = 0; i < order; i++) {
99 Coeffs *coeffs = &s->coeffs[i];
100
101 set_tf1s(coeffs, 1.0, mzh(i, T, w0, r, alpha), mph(i, T, w0, r),
102 w1, sr, alpha);
103 }
104 }
105
get_coeffs(AVFilterContext * ctx)106 static int get_coeffs(AVFilterContext *ctx)
107 {
108 ATiltContext *s = ctx->priv;
109 AVFilterLink *inlink = ctx->inputs[0];
110
111 set_filter(ctx, s->order, inlink->sample_rate, s->freq, s->width, s->slope);
112
113 return 0;
114 }
115
116 typedef struct ThreadData {
117 AVFrame *in, *out;
118 } ThreadData;
119
120 #define FILTER(name, type) \
121 static int filter_channels_## name(AVFilterContext *ctx, void *arg, \
122 int jobnr, int nb_jobs) \
123 { \
124 ATiltContext *s = ctx->priv; \
125 ThreadData *td = arg; \
126 AVFrame *out = td->out; \
127 AVFrame *in = td->in; \
128 const int start = (in->ch_layout.nb_channels * jobnr) / nb_jobs; \
129 const int end = (in->ch_layout.nb_channels * (jobnr+1)) / nb_jobs; \
130 const type level = s->level; \
131 \
132 for (int ch = start; ch < end; ch++) { \
133 const type *src = (const type *)in->extended_data[ch]; \
134 type *dst = (type *)out->extended_data[ch]; \
135 \
136 for (int b = 0; b < s->order; b++) { \
137 Coeffs *coeffs = &s->coeffs[b]; \
138 const type g = coeffs->g; \
139 const type a1 = coeffs->a1; \
140 const type b0 = coeffs->b0; \
141 const type b1 = coeffs->b1; \
142 type *w = ((type *)s->w->extended_data[ch]) + b * 2; \
143 \
144 for (int n = 0; n < in->nb_samples; n++) { \
145 type sain = b ? dst[n] : src[n] * level; \
146 type saout = sain * b0 + w[0] * b1 - w[1] * a1; \
147 \
148 w[0] = sain; \
149 w[1] = saout; \
150 \
151 dst[n] = saout * g; \
152 } \
153 } \
154 } \
155 \
156 return 0; \
157 }
158
FILTER(fltp,float)159 FILTER(fltp, float)
160 FILTER(dblp, double)
161
162 static int config_input(AVFilterLink *inlink)
163 {
164 AVFilterContext *ctx = inlink->dst;
165 ATiltContext *s = ctx->priv;
166
167 switch (inlink->format) {
168 case AV_SAMPLE_FMT_FLTP: s->filter_channels = filter_channels_fltp; break;
169 case AV_SAMPLE_FMT_DBLP: s->filter_channels = filter_channels_dblp; break;
170 }
171
172 s->w = ff_get_audio_buffer(inlink, 2 * MAX_ORDER);
173 if (!s->w)
174 return AVERROR(ENOMEM);
175
176 return get_coeffs(ctx);
177 }
178
filter_frame(AVFilterLink * inlink,AVFrame * in)179 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
180 {
181 AVFilterContext *ctx = inlink->dst;
182 ATiltContext *s = ctx->priv;
183 AVFilterLink *outlink = ctx->outputs[0];
184 ThreadData td;
185 AVFrame *out;
186
187 if (av_frame_is_writable(in)) {
188 out = in;
189 } else {
190 out = ff_get_audio_buffer(outlink, in->nb_samples);
191 if (!out) {
192 av_frame_free(&in);
193 return AVERROR(ENOMEM);
194 }
195 av_frame_copy_props(out, in);
196 }
197
198 td.in = in; td.out = out;
199 ff_filter_execute(ctx, s->filter_channels, &td, NULL, FFMIN(inlink->ch_layout.nb_channels,
200 ff_filter_get_nb_threads(ctx)));
201
202 if (out != in)
203 av_frame_free(&in);
204 return ff_filter_frame(outlink, out);
205 }
206
process_command(AVFilterContext * ctx,const char * cmd,const char * args,char * res,int res_len,int flags)207 static int process_command(AVFilterContext *ctx, const char *cmd, const char *args,
208 char *res, int res_len, int flags)
209 {
210 int ret;
211
212 ret = ff_filter_process_command(ctx, cmd, args, res, res_len, flags);
213 if (ret < 0)
214 return ret;
215
216 return get_coeffs(ctx);
217 }
218
uninit(AVFilterContext * ctx)219 static av_cold void uninit(AVFilterContext *ctx)
220 {
221 ATiltContext *s = ctx->priv;
222
223 av_frame_free(&s->w);
224 }
225
226 #define OFFSET(x) offsetof(ATiltContext, x)
227 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_RUNTIME_PARAM
228
229 static const AVOption atilt_options[] = {
230 { "freq", "set central frequency",OFFSET(freq), AV_OPT_TYPE_DOUBLE, {.dbl=10000}, 20, 192000, FLAGS },
231 { "slope", "set filter slope", OFFSET(slope), AV_OPT_TYPE_DOUBLE, {.dbl=0}, -1, 1, FLAGS },
232 { "width", "set filter width", OFFSET(width), AV_OPT_TYPE_DOUBLE, {.dbl=1000}, 100, 10000, FLAGS },
233 { "order", "set filter order", OFFSET(order), AV_OPT_TYPE_INT, {.i64=5}, 2,MAX_ORDER, FLAGS },
234 { "level", "set input level", OFFSET(level), AV_OPT_TYPE_DOUBLE, {.dbl=1.}, 0., 4., FLAGS },
235 { NULL }
236 };
237
238 AVFILTER_DEFINE_CLASS(atilt);
239
240 static const AVFilterPad inputs[] = {
241 {
242 .name = "default",
243 .type = AVMEDIA_TYPE_AUDIO,
244 .filter_frame = filter_frame,
245 .config_props = config_input,
246 },
247 };
248
249 static const AVFilterPad outputs[] = {
250 {
251 .name = "default",
252 .type = AVMEDIA_TYPE_AUDIO,
253 },
254 };
255
256 const AVFilter ff_af_atilt = {
257 .name = "atilt",
258 .description = NULL_IF_CONFIG_SMALL("Apply spectral tilt to audio."),
259 .priv_size = sizeof(ATiltContext),
260 .priv_class = &atilt_class,
261 .uninit = uninit,
262 FILTER_INPUTS(inputs),
263 FILTER_OUTPUTS(outputs),
264 FILTER_SAMPLEFMTS(AV_SAMPLE_FMT_FLTP, AV_SAMPLE_FMT_DBLP),
265 .process_command = process_command,
266 .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC |
267 AVFILTER_FLAG_SLICE_THREADS,
268 };
269