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 typedef struct CrossfeedContext {
27 const AVClass *class;
28
29 double range;
30 double strength;
31 double slope;
32 double level_in;
33 double level_out;
34
35 double a0, a1, a2;
36 double b0, b1, b2;
37
38 double i1, i2;
39 double o1, o2;
40 } CrossfeedContext;
41
query_formats(AVFilterContext * ctx)42 static int query_formats(AVFilterContext *ctx)
43 {
44 AVFilterFormats *formats = NULL;
45 AVFilterChannelLayouts *layout = NULL;
46 int ret;
47
48 if ((ret = ff_add_format (&formats, AV_SAMPLE_FMT_DBL )) < 0 ||
49 (ret = ff_set_common_formats (ctx , formats )) < 0 ||
50 (ret = ff_add_channel_layout (&layout , AV_CH_LAYOUT_STEREO)) < 0 ||
51 (ret = ff_set_common_channel_layouts (ctx , layout )) < 0 ||
52 (ret = ff_set_common_samplerates (ctx , ff_all_samplerates())) < 0)
53 return ret;
54
55 return 0;
56 }
57
config_input(AVFilterLink * inlink)58 static int config_input(AVFilterLink *inlink)
59 {
60 AVFilterContext *ctx = inlink->dst;
61 CrossfeedContext *s = ctx->priv;
62 double A = ff_exp10(s->strength * -30 / 40);
63 double w0 = 2 * M_PI * (1. - s->range) * 2100 / inlink->sample_rate;
64 double alpha;
65
66 alpha = sin(w0) / 2 * sqrt((A + 1 / A) * (1 / s->slope - 1) + 2);
67
68 s->a0 = (A + 1) + (A - 1) * cos(w0) + 2 * sqrt(A) * alpha;
69 s->a1 = -2 * ((A - 1) + (A + 1) * cos(w0));
70 s->a2 = (A + 1) + (A - 1) * cos(w0) - 2 * sqrt(A) * alpha;
71 s->b0 = A * ((A + 1) - (A - 1) * cos(w0) + 2 * sqrt(A) * alpha);
72 s->b1 = 2 * A * ((A - 1) - (A + 1) * cos(w0));
73 s->b2 = A * ((A + 1) - (A - 1) * cos(w0) - 2 * sqrt(A) * alpha);
74
75 s->a1 /= s->a0;
76 s->a2 /= s->a0;
77 s->b0 /= s->a0;
78 s->b1 /= s->a0;
79 s->b2 /= s->a0;
80
81 return 0;
82 }
83
filter_frame(AVFilterLink * inlink,AVFrame * in)84 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
85 {
86 AVFilterContext *ctx = inlink->dst;
87 AVFilterLink *outlink = ctx->outputs[0];
88 CrossfeedContext *s = ctx->priv;
89 const double *src = (const double *)in->data[0];
90 const double level_in = s->level_in;
91 const double level_out = s->level_out;
92 const double b0 = s->b0;
93 const double b1 = s->b1;
94 const double b2 = s->b2;
95 const double a1 = s->a1;
96 const double a2 = s->a2;
97 AVFrame *out;
98 double *dst;
99 int n;
100
101 if (av_frame_is_writable(in)) {
102 out = in;
103 } else {
104 out = ff_get_audio_buffer(outlink, in->nb_samples);
105 if (!out) {
106 av_frame_free(&in);
107 return AVERROR(ENOMEM);
108 }
109 av_frame_copy_props(out, in);
110 }
111 dst = (double *)out->data[0];
112
113 for (n = 0; n < out->nb_samples; n++, src += 2, dst += 2) {
114 double mid = (src[0] + src[1]) * level_in * .5;
115 double side = (src[0] - src[1]) * level_in * .5;
116 double oside = side * b0 + s->i1 * b1 + s->i2 * b2 - s->o1 * a1 - s->o2 * a2;
117
118 s->i2 = s->i1;
119 s->i1 = side;
120 s->o2 = s->o1;
121 s->o1 = oside;
122
123 if (ctx->is_disabled) {
124 dst[0] = src[0];
125 dst[1] = src[1];
126 } else {
127 dst[0] = (mid + oside) * level_out;
128 dst[1] = (mid - oside) * level_out;
129 }
130 }
131
132 if (out != in)
133 av_frame_free(&in);
134 return ff_filter_frame(outlink, out);
135 }
136
process_command(AVFilterContext * ctx,const char * cmd,const char * args,char * res,int res_len,int flags)137 static int process_command(AVFilterContext *ctx, const char *cmd, const char *args,
138 char *res, int res_len, int flags)
139 {
140 int ret;
141
142 ret = ff_filter_process_command(ctx, cmd, args, res, res_len, flags);
143 if (ret < 0)
144 return ret;
145
146 return config_input(ctx->inputs[0]);
147 }
148
149 #define OFFSET(x) offsetof(CrossfeedContext, x)
150 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_RUNTIME_PARAM
151
152 static const AVOption crossfeed_options[] = {
153 { "strength", "set crossfeed strength", OFFSET(strength), AV_OPT_TYPE_DOUBLE, {.dbl=.2}, 0, 1, FLAGS },
154 { "range", "set soundstage wideness", OFFSET(range), AV_OPT_TYPE_DOUBLE, {.dbl=.5}, 0, 1, FLAGS },
155 { "slope", "set curve slope", OFFSET(slope), AV_OPT_TYPE_DOUBLE, {.dbl=.5}, .01, 1, FLAGS },
156 { "level_in", "set level in", OFFSET(level_in), AV_OPT_TYPE_DOUBLE, {.dbl=.9}, 0, 1, FLAGS },
157 { "level_out", "set level out", OFFSET(level_out), AV_OPT_TYPE_DOUBLE, {.dbl=1.}, 0, 1, FLAGS },
158 { NULL }
159 };
160
161 AVFILTER_DEFINE_CLASS(crossfeed);
162
163 static const AVFilterPad inputs[] = {
164 {
165 .name = "default",
166 .type = AVMEDIA_TYPE_AUDIO,
167 .filter_frame = filter_frame,
168 .config_props = config_input,
169 },
170 { NULL }
171 };
172
173 static const AVFilterPad outputs[] = {
174 {
175 .name = "default",
176 .type = AVMEDIA_TYPE_AUDIO,
177 },
178 { NULL }
179 };
180
181 AVFilter ff_af_crossfeed = {
182 .name = "crossfeed",
183 .description = NULL_IF_CONFIG_SMALL("Apply headphone crossfeed filter."),
184 .query_formats = query_formats,
185 .priv_size = sizeof(CrossfeedContext),
186 .priv_class = &crossfeed_class,
187 .inputs = inputs,
188 .outputs = outputs,
189 .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL,
190 .process_command = process_command,
191 };
192