lavfi: add channelsplit audio filter.
[libav.git] / libavfilter / af_channelsplit.c
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d6251368
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1/*
2 * This file is part of Libav.
3 *
4 * Libav 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 * Libav 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 Libav; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17 */
18
19/**
20 * @file
21 * Channel split filter
22 *
23 * Split an audio stream into per-channel streams.
24 */
25
26#include "libavutil/audioconvert.h"
27#include "libavutil/opt.h"
28
29#include "audio.h"
30#include "avfilter.h"
31#include "formats.h"
32#include "internal.h"
33
34typedef struct ChannelSplitContext {
35 const AVClass *class;
36
37 uint64_t channel_layout;
38 char *channel_layout_str;
39} ChannelSplitContext;
40
41#define OFFSET(x) offsetof(ChannelSplitContext, x)
42#define A AV_OPT_FLAG_AUDIO_PARAM
43static const AVOption options[] = {
44 { "channel_layout", "Input channel layout.", OFFSET(channel_layout_str), AV_OPT_TYPE_STRING, { .str = "stereo" }, .flags = A },
45 { NULL },
46};
47
48static const AVClass channelsplit_class = {
49 .class_name = "channelsplit filter",
50 .item_name = av_default_item_name,
51 .option = options,
52 .version = LIBAVUTIL_VERSION_INT,
53};
54
55static int init(AVFilterContext *ctx, const char *arg, void *opaque)
56{
57 ChannelSplitContext *s = ctx->priv;
58 int nb_channels;
59 int ret = 0, i;
60
61 s->class = &channelsplit_class;
62 av_opt_set_defaults(s);
63 if ((ret = av_set_options_string(s, arg, "=", ":")) < 0) {
64 av_log(ctx, AV_LOG_ERROR, "Error parsing options string '%s'.\n", arg);
65 return ret;
66 }
67 if (!(s->channel_layout = av_get_channel_layout(s->channel_layout_str))) {
68 av_log(ctx, AV_LOG_ERROR, "Error parsing channel layout '%s'.\n",
69 s->channel_layout_str);
70 ret = AVERROR(EINVAL);
71 goto fail;
72 }
73
74 nb_channels = av_get_channel_layout_nb_channels(s->channel_layout);
75 for (i = 0; i < nb_channels; i++) {
76 uint64_t channel = av_channel_layout_extract_channel(s->channel_layout, i);
77 AVFilterPad pad = { 0 };
78
79 pad.type = AVMEDIA_TYPE_AUDIO;
80 pad.name = av_get_channel_name(channel);
81
82 ff_insert_outpad(ctx, i, &pad);
83 }
84
85fail:
86 av_opt_free(s);
87 return ret;
88}
89
90static int query_formats(AVFilterContext *ctx)
91{
92 ChannelSplitContext *s = ctx->priv;
93 AVFilterChannelLayouts *in_layouts = NULL;
94 int i;
95
96 ff_set_common_formats (ctx, ff_planar_sample_fmts());
97 ff_set_common_samplerates(ctx, ff_all_samplerates());
98
99 ff_add_channel_layout(&in_layouts, s->channel_layout);
100 ff_channel_layouts_ref(in_layouts, &ctx->inputs[0]->out_channel_layouts);
101
102 for (i = 0; i < ctx->output_count; i++) {
103 AVFilterChannelLayouts *out_layouts = NULL;
104 uint64_t channel = av_channel_layout_extract_channel(s->channel_layout, i);
105
106 ff_add_channel_layout(&out_layouts, channel);
107 ff_channel_layouts_ref(out_layouts, &ctx->outputs[i]->in_channel_layouts);
108 }
109
110 return 0;
111}
112
113static void filter_samples(AVFilterLink *inlink, AVFilterBufferRef *buf)
114{
115 AVFilterContext *ctx = inlink->dst;
116 int i;
117
118 for (i = 0; i < ctx->output_count; i++) {
119 AVFilterBufferRef *buf_out = avfilter_ref_buffer(buf, ~AV_PERM_WRITE);
120
121 if (!buf_out)
122 return;
123
124 buf_out->data[0] = buf_out->extended_data[0] = buf_out->extended_data[i];
125 buf_out->audio->channel_layout =
126 av_channel_layout_extract_channel(buf->audio->channel_layout, i);
127
128 ff_filter_samples(ctx->outputs[i], buf_out);
129 }
130 avfilter_unref_buffer(buf);
131}
132
133AVFilter avfilter_af_channelsplit = {
134 .name = "channelsplit",
135 .description = NULL_IF_CONFIG_SMALL("Split audio into per-channel streams"),
136 .priv_size = sizeof(ChannelSplitContext),
137
138 .init = init,
139 .query_formats = query_formats,
140
141 .inputs = (const AVFilterPad[]){{ .name = "default",
142 .type = AVMEDIA_TYPE_AUDIO,
143 .filter_samples = filter_samples, },
144 { NULL }},
145 .outputs = (const AVFilterPad[]){{ NULL }},
146};