2 * Copyright (C) 2012 VLC authors and VideoLAN
3 * Author : Sukrit Sangwan < sukritsangwan at gmail dot com >
5 * This file is part of FFmpeg.
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.
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.
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
22 #include "libavutil/channel_layout.h"
23 #include "libavutil/opt.h"
28 typedef struct StereoWidenContext {
41 #define OFFSET(x) offsetof(StereoWidenContext, x)
42 #define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
44 static const AVOption stereowiden_options[] = {
45 { "delay", "set delay time", OFFSET(delay), AV_OPT_TYPE_FLOAT, {.dbl=20}, 1, 100, A },
46 { "feedback", "set feedback gain", OFFSET(feedback), AV_OPT_TYPE_FLOAT, {.dbl=.3}, 0, 0.9, A },
47 { "crossfeed", "set cross feed", OFFSET(crossfeed), AV_OPT_TYPE_FLOAT, {.dbl=.3}, 0, 0.8, A },
48 { "drymix", "set dry-mix", OFFSET(drymix), AV_OPT_TYPE_FLOAT, {.dbl=.8}, 0, 1.0, A },
52 AVFILTER_DEFINE_CLASS(stereowiden);
54 static int query_formats(AVFilterContext *ctx)
56 AVFilterFormats *formats = NULL;
57 AVFilterChannelLayouts *layout = NULL;
60 if ((ret = ff_add_format (&formats, AV_SAMPLE_FMT_FLT )) < 0 ||
61 (ret = ff_set_common_formats (ctx , formats )) < 0 ||
62 (ret = ff_add_channel_layout (&layout , AV_CH_LAYOUT_STEREO)) < 0 ||
63 (ret = ff_set_common_channel_layouts (ctx , layout )) < 0)
66 formats = ff_all_samplerates();
67 return ff_set_common_samplerates(ctx, formats);
70 static int config_input(AVFilterLink *inlink)
72 AVFilterContext *ctx = inlink->dst;
73 StereoWidenContext *s = ctx->priv;
75 s->length = s->delay * inlink->sample_rate / 1000;
77 s->buffer = av_calloc(s->length, sizeof(*s->buffer));
79 return AVERROR(ENOMEM);
85 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
87 AVFilterContext *ctx = inlink->dst;
88 AVFilterLink *outlink = ctx->outputs[0];
89 StereoWidenContext *s = ctx->priv;
90 const float *src = (const float *)in->data[0];
91 const float drymix = s->drymix;
92 const float crossfeed = s->crossfeed;
93 const float feedback = s->feedback;
98 if (av_frame_is_writable(in)) {
101 out = ff_get_audio_buffer(outlink, in->nb_samples);
104 return AVERROR(ENOMEM);
106 av_frame_copy_props(out, in);
108 dst = (float *)out->data[0];
110 for (n = 0; n < in->nb_samples; n++, src += 2, dst += 2, s->cur += 2) {
111 const float left = src[0], right = src[1];
113 if (s->cur == s->buffer + s->length)
116 dst[0] = drymix * left - crossfeed * right - feedback * s->cur[1];
117 dst[1] = drymix * right - crossfeed * left - feedback * s->cur[0];
125 return ff_filter_frame(outlink, out);
128 static av_cold void uninit(AVFilterContext *ctx)
130 StereoWidenContext *s = ctx->priv;
132 av_freep(&s->buffer);
135 static const AVFilterPad inputs[] = {
138 .type = AVMEDIA_TYPE_AUDIO,
139 .filter_frame = filter_frame,
140 .config_props = config_input,
145 static const AVFilterPad outputs[] = {
148 .type = AVMEDIA_TYPE_AUDIO,
153 AVFilter ff_af_stereowiden = {
154 .name = "stereowiden",
155 .description = NULL_IF_CONFIG_SMALL("Apply stereo widening effect."),
156 .query_formats = query_formats,
157 .priv_size = sizeof(StereoWidenContext),
158 .priv_class = &stereowiden_class,