1 /*
2 * Copyright (C) 2012 VLC authors and VideoLAN
3 * Author : Sukrit Sangwan < sukritsangwan at gmail dot com >
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #include "libavutil/channel_layout.h"
23 #include "libavutil/opt.h"
24 #include "avfilter.h"
25 #include "audio.h"
26 #include "formats.h"
27
28 typedef struct StereoWidenContext {
29 const AVClass *class;
30
31 float delay;
32 float feedback;
33 float crossfeed;
34 float drymix;
35
36 float *buffer;
37 float *cur;
38 int length;
39 } StereoWidenContext;
40
41 #define OFFSET(x) offsetof(StereoWidenContext, x)
42 #define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
43 #define AT AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_RUNTIME_PARAM
44
45 static const AVOption stereowiden_options[] = {
46 { "delay", "set delay time", OFFSET(delay), AV_OPT_TYPE_FLOAT, {.dbl=20}, 1, 100, A },
47 { "feedback", "set feedback gain", OFFSET(feedback), AV_OPT_TYPE_FLOAT, {.dbl=.3}, 0, 0.9, AT },
48 { "crossfeed", "set cross feed", OFFSET(crossfeed), AV_OPT_TYPE_FLOAT, {.dbl=.3}, 0, 0.8, AT },
49 { "drymix", "set dry-mix", OFFSET(drymix), AV_OPT_TYPE_FLOAT, {.dbl=.8}, 0, 1.0, AT },
50 { NULL }
51 };
52
53 AVFILTER_DEFINE_CLASS(stereowiden);
54
query_formats(AVFilterContext * ctx)55 static int query_formats(AVFilterContext *ctx)
56 {
57 AVFilterFormats *formats = NULL;
58 AVFilterChannelLayouts *layout = NULL;
59 int ret;
60
61 if ((ret = ff_add_format (&formats, AV_SAMPLE_FMT_FLT )) < 0 ||
62 (ret = ff_set_common_formats (ctx , formats )) < 0 ||
63 (ret = ff_add_channel_layout (&layout , &(AVChannelLayout)AV_CHANNEL_LAYOUT_STEREO)) < 0 ||
64 (ret = ff_set_common_channel_layouts (ctx , layout )) < 0)
65 return ret;
66
67 return ff_set_common_all_samplerates(ctx);
68 }
69
config_input(AVFilterLink * inlink)70 static int config_input(AVFilterLink *inlink)
71 {
72 AVFilterContext *ctx = inlink->dst;
73 StereoWidenContext *s = ctx->priv;
74
75 s->length = s->delay * inlink->sample_rate / 1000;
76 s->length *= 2;
77 if (s->length == 0)
78 return AVERROR(EINVAL);
79 s->buffer = av_calloc(s->length, sizeof(*s->buffer));
80 if (!s->buffer)
81 return AVERROR(ENOMEM);
82 s->cur = s->buffer;
83
84 return 0;
85 }
86
filter_frame(AVFilterLink * inlink,AVFrame * in)87 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
88 {
89 AVFilterContext *ctx = inlink->dst;
90 AVFilterLink *outlink = ctx->outputs[0];
91 StereoWidenContext *s = ctx->priv;
92 const float *src = (const float *)in->data[0];
93 const float drymix = s->drymix;
94 const float crossfeed = s->crossfeed;
95 const float feedback = s->feedback;
96 AVFrame *out;
97 float *dst;
98 int n;
99
100 if (av_frame_is_writable(in)) {
101 out = in;
102 } else {
103 out = ff_get_audio_buffer(outlink, in->nb_samples);
104 if (!out) {
105 av_frame_free(&in);
106 return AVERROR(ENOMEM);
107 }
108 av_frame_copy_props(out, in);
109 }
110 dst = (float *)out->data[0];
111
112 for (n = 0; n < in->nb_samples; n++, src += 2, dst += 2, s->cur += 2) {
113 const float left = src[0], right = src[1];
114
115 if (s->cur == s->buffer + s->length)
116 s->cur = s->buffer;
117
118 if (ctx->is_disabled) {
119 dst[0] = left;
120 dst[1] = right;
121 } else {
122 dst[0] = drymix * left - crossfeed * right - feedback * s->cur[1];
123 dst[1] = drymix * right - crossfeed * left - feedback * s->cur[0];
124 }
125
126 s->cur[0] = left;
127 s->cur[1] = right;
128 }
129
130 if (out != in)
131 av_frame_free(&in);
132 return ff_filter_frame(outlink, out);
133 }
134
uninit(AVFilterContext * ctx)135 static av_cold void uninit(AVFilterContext *ctx)
136 {
137 StereoWidenContext *s = ctx->priv;
138
139 av_freep(&s->buffer);
140 }
141
142 static const AVFilterPad inputs[] = {
143 {
144 .name = "default",
145 .type = AVMEDIA_TYPE_AUDIO,
146 .filter_frame = filter_frame,
147 .config_props = config_input,
148 },
149 };
150
151 static const AVFilterPad outputs[] = {
152 {
153 .name = "default",
154 .type = AVMEDIA_TYPE_AUDIO,
155 },
156 };
157
158 const AVFilter ff_af_stereowiden = {
159 .name = "stereowiden",
160 .description = NULL_IF_CONFIG_SMALL("Apply stereo widening effect."),
161 .priv_size = sizeof(StereoWidenContext),
162 .priv_class = &stereowiden_class,
163 .uninit = uninit,
164 FILTER_INPUTS(inputs),
165 FILTER_OUTPUTS(outputs),
166 FILTER_QUERY_FUNC(query_formats),
167 .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_INTERNAL,
168 .process_command = ff_filter_process_command,
169 };
170