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 ASubBoostContext {
27 const AVClass *class;
28
29 double dry_gain;
30 double wet_gain;
31 double feedback;
32 double decay;
33 double delay;
34 double cutoff;
35 double slope;
36
37 double a0, a1, a2;
38 double b0, b1, b2;
39
40 int write_pos;
41 int buffer_samples;
42
43 AVFrame *i, *o;
44 AVFrame *buffer;
45 } ASubBoostContext;
46
query_formats(AVFilterContext * ctx)47 static int query_formats(AVFilterContext *ctx)
48 {
49 AVFilterFormats *formats = NULL;
50 AVFilterChannelLayouts *layouts = NULL;
51 static const enum AVSampleFormat sample_fmts[] = {
52 AV_SAMPLE_FMT_DBLP,
53 AV_SAMPLE_FMT_NONE
54 };
55 int ret;
56
57 formats = ff_make_format_list(sample_fmts);
58 if (!formats)
59 return AVERROR(ENOMEM);
60 ret = ff_set_common_formats(ctx, formats);
61 if (ret < 0)
62 return ret;
63
64 layouts = ff_all_channel_counts();
65 if (!layouts)
66 return AVERROR(ENOMEM);
67
68 ret = ff_set_common_channel_layouts(ctx, layouts);
69 if (ret < 0)
70 return ret;
71
72 formats = ff_all_samplerates();
73 return ff_set_common_samplerates(ctx, formats);
74 }
75
get_coeffs(AVFilterContext * ctx)76 static int get_coeffs(AVFilterContext *ctx)
77 {
78 ASubBoostContext *s = ctx->priv;
79 AVFilterLink *inlink = ctx->inputs[0];
80 double w0 = 2 * M_PI * s->cutoff / inlink->sample_rate;
81 double alpha = sin(w0) / 2 * sqrt(2. * (1. / s->slope - 1.) + 2.);
82
83 s->a0 = 1 + alpha;
84 s->a1 = -2 * cos(w0);
85 s->a2 = 1 - alpha;
86 s->b0 = (1 - cos(w0)) / 2;
87 s->b1 = 1 - cos(w0);
88 s->b2 = (1 - cos(w0)) / 2;
89
90 s->a1 /= s->a0;
91 s->a2 /= s->a0;
92 s->b0 /= s->a0;
93 s->b1 /= s->a0;
94 s->b2 /= s->a0;
95
96 s->buffer_samples = inlink->sample_rate * s->delay / 1000;
97
98 return 0;
99 }
100
config_input(AVFilterLink * inlink)101 static int config_input(AVFilterLink *inlink)
102 {
103 AVFilterContext *ctx = inlink->dst;
104 ASubBoostContext *s = ctx->priv;
105
106 s->buffer = ff_get_audio_buffer(inlink, inlink->sample_rate / 10);
107 s->i = ff_get_audio_buffer(inlink, 2);
108 s->o = ff_get_audio_buffer(inlink, 2);
109 if (!s->buffer || !s->i || !s->o)
110 return AVERROR(ENOMEM);
111
112 return get_coeffs(ctx);
113 }
114
filter_frame(AVFilterLink * inlink,AVFrame * in)115 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
116 {
117 AVFilterContext *ctx = inlink->dst;
118 AVFilterLink *outlink = ctx->outputs[0];
119 ASubBoostContext *s = ctx->priv;
120 const float wet = s->wet_gain, dry = s->dry_gain, feedback = s->feedback, decay = s->decay;
121 int write_pos;
122 AVFrame *out;
123
124 if (av_frame_is_writable(in)) {
125 out = in;
126 } else {
127 out = ff_get_audio_buffer(outlink, in->nb_samples);
128 if (!out) {
129 av_frame_free(&in);
130 return AVERROR(ENOMEM);
131 }
132 av_frame_copy_props(out, in);
133 }
134
135 for (int ch = 0; ch < in->channels; ch++) {
136 const double *src = (const double *)in->extended_data[ch];
137 double *dst = (double *)out->extended_data[ch];
138 double *buffer = (double *)s->buffer->extended_data[ch];
139 double *ix = (double *)s->i->extended_data[ch];
140 double *ox = (double *)s->o->extended_data[ch];
141
142 write_pos = s->write_pos;
143 for (int n = 0; n < in->nb_samples; n++) {
144 double out_sample;
145
146 out_sample = src[n] * s->b0 + ix[0] * s->b1 + ix[1] * s->b2 - ox[0] * s->a1 - ox[1] * s->a2;
147 ix[1] = ix[0];
148 ix[0] = src[n];
149 ox[1] = ox[0];
150 ox[0] = out_sample;
151
152 buffer[write_pos] = buffer[write_pos] * decay + out_sample * feedback;
153 dst[n] = src[n] * dry + buffer[write_pos] * wet;
154
155 if (++write_pos >= s->buffer_samples)
156 write_pos = 0;
157 }
158 }
159
160 s->write_pos = write_pos;
161
162 if (out != in)
163 av_frame_free(&in);
164 return ff_filter_frame(outlink, out);
165 }
166
uninit(AVFilterContext * ctx)167 static av_cold void uninit(AVFilterContext *ctx)
168 {
169 ASubBoostContext *s = ctx->priv;
170
171 av_frame_free(&s->buffer);
172 av_frame_free(&s->i);
173 av_frame_free(&s->o);
174 }
175
process_command(AVFilterContext * ctx,const char * cmd,const char * args,char * res,int res_len,int flags)176 static int process_command(AVFilterContext *ctx, const char *cmd, const char *args,
177 char *res, int res_len, int flags)
178 {
179 int ret;
180
181 ret = ff_filter_process_command(ctx, cmd, args, res, res_len, flags);
182 if (ret < 0)
183 return ret;
184
185 return get_coeffs(ctx);
186 }
187
188 #define OFFSET(x) offsetof(ASubBoostContext, x)
189 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_RUNTIME_PARAM
190
191 static const AVOption asubboost_options[] = {
192 { "dry", "set dry gain", OFFSET(dry_gain), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 1, FLAGS },
193 { "wet", "set wet gain", OFFSET(wet_gain), AV_OPT_TYPE_DOUBLE, {.dbl=0.8}, 0, 1, FLAGS },
194 { "decay", "set decay", OFFSET(decay), AV_OPT_TYPE_DOUBLE, {.dbl=0.7}, 0, 1, FLAGS },
195 { "feedback", "set feedback", OFFSET(feedback), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0, 1, FLAGS },
196 { "cutoff", "set cutoff", OFFSET(cutoff), AV_OPT_TYPE_DOUBLE, {.dbl=100}, 50, 900, FLAGS },
197 { "slope", "set slope", OFFSET(slope), AV_OPT_TYPE_DOUBLE, {.dbl=0.5}, 0.0001, 1, FLAGS },
198 { "delay", "set delay", OFFSET(delay), AV_OPT_TYPE_DOUBLE, {.dbl=20}, 1, 100, FLAGS },
199 { NULL }
200 };
201
202 AVFILTER_DEFINE_CLASS(asubboost);
203
204 static const AVFilterPad inputs[] = {
205 {
206 .name = "default",
207 .type = AVMEDIA_TYPE_AUDIO,
208 .filter_frame = filter_frame,
209 .config_props = config_input,
210 },
211 { NULL }
212 };
213
214 static const AVFilterPad outputs[] = {
215 {
216 .name = "default",
217 .type = AVMEDIA_TYPE_AUDIO,
218 },
219 { NULL }
220 };
221
222 AVFilter ff_af_asubboost = {
223 .name = "asubboost",
224 .description = NULL_IF_CONFIG_SMALL("Boost subwoofer frequencies."),
225 .query_formats = query_formats,
226 .priv_size = sizeof(ASubBoostContext),
227 .priv_class = &asubboost_class,
228 .uninit = uninit,
229 .inputs = inputs,
230 .outputs = outputs,
231 .process_command = process_command,
232 };
233