2 * This file is part of FFmpeg.
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.
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.
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
19 #include "libavutil/channel_layout.h"
20 #include "libavutil/ffmath.h"
21 #include "libavutil/opt.h"
26 typedef struct CrossfeedContext {
41 static int query_formats(AVFilterContext *ctx)
43 AVFilterFormats *formats = NULL;
44 AVFilterChannelLayouts *layout = NULL;
47 if ((ret = ff_add_format (&formats, AV_SAMPLE_FMT_DBL )) < 0 ||
48 (ret = ff_set_common_formats (ctx , formats )) < 0 ||
49 (ret = ff_add_channel_layout (&layout , AV_CH_LAYOUT_STEREO)) < 0 ||
50 (ret = ff_set_common_channel_layouts (ctx , layout )) < 0 ||
51 (ret = ff_set_common_samplerates (ctx , ff_all_samplerates())) < 0)
57 static int config_input(AVFilterLink *inlink)
59 AVFilterContext *ctx = inlink->dst;
60 CrossfeedContext *s = ctx->priv;
61 double A = ff_exp10(s->strength * -30 / 40);
62 double w0 = 2 * M_PI * (1. - s->range) * 2100 / inlink->sample_rate;
65 alpha = sin(w0) / 2 * sqrt(2 * (1 / 0.5 - 1) + 2);
67 s->a0 = (A + 1) + (A - 1) * cos(w0) + 2 * sqrt(A) * alpha;
68 s->a1 = -2 * ((A - 1) + (A + 1) * cos(w0));
69 s->a2 = (A + 1) + (A - 1) * cos(w0) - 2 * sqrt(A) * alpha;
70 s->b0 = A * ((A + 1) - (A - 1) * cos(w0) + 2 * sqrt(A) * alpha);
71 s->b1 = 2 * A * ((A - 1) - (A + 1) * cos(w0));
72 s->b2 = A * ((A + 1) - (A - 1) * cos(w0) - 2 * sqrt(A) * alpha);
83 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
85 AVFilterContext *ctx = inlink->dst;
86 AVFilterLink *outlink = ctx->outputs[0];
87 CrossfeedContext *s = ctx->priv;
88 const double *src = (const double *)in->data[0];
89 const double level_in = s->level_in;
90 const double level_out = s->level_out;
91 const double b0 = s->b0;
92 const double b1 = s->b1;
93 const double b2 = s->b2;
94 const double a1 = s->a1;
95 const double a2 = s->a2;
100 if (av_frame_is_writable(in)) {
103 out = ff_get_audio_buffer(outlink, in->nb_samples);
106 return AVERROR(ENOMEM);
108 av_frame_copy_props(out, in);
110 dst = (double *)out->data[0];
112 for (n = 0; n < out->nb_samples; n++, src += 2, dst += 2) {
113 double mid = (src[0] + src[1]) * level_in * .5;
114 double side = (src[0] - src[1]) * level_in * .5;
115 double oside = side * b0 + s->i1 * b1 + s->i2 * b2 - s->o1 * a1 - s->o2 * a2;
122 dst[0] = (mid + oside) * level_out;
123 dst[1] = (mid - oside) * level_out;
128 return ff_filter_frame(outlink, out);
131 #define OFFSET(x) offsetof(CrossfeedContext, x)
132 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
134 static const AVOption crossfeed_options[] = {
135 { "strength", "set crossfeed strength", OFFSET(strength), AV_OPT_TYPE_DOUBLE, {.dbl=.2}, 0, 1, FLAGS },
136 { "range", "set soundstage wideness", OFFSET(range), AV_OPT_TYPE_DOUBLE, {.dbl=.5}, 0, 1, FLAGS },
137 { "level_in", "set level in", OFFSET(level_in), AV_OPT_TYPE_DOUBLE, {.dbl=.9}, 0, 1, FLAGS },
138 { "level_out", "set level out", OFFSET(level_out), AV_OPT_TYPE_DOUBLE, {.dbl=1.}, 0, 1, FLAGS },
142 AVFILTER_DEFINE_CLASS(crossfeed);
144 static const AVFilterPad inputs[] = {
147 .type = AVMEDIA_TYPE_AUDIO,
148 .filter_frame = filter_frame,
149 .config_props = config_input,
154 static const AVFilterPad outputs[] = {
157 .type = AVMEDIA_TYPE_AUDIO,
162 AVFilter ff_af_crossfeed = {
164 .description = NULL_IF_CONFIG_SMALL("Apply headphone crossfeed filter."),
165 .query_formats = query_formats,
166 .priv_size = sizeof(CrossfeedContext),
167 .priv_class = &crossfeed_class,