af_channelsplit.c
Go to the documentation of this file.
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 
27 #include "libavutil/internal.h"
28 #include "libavutil/opt.h"
29 
30 #include "audio.h"
31 #include "avfilter.h"
32 #include "formats.h"
33 #include "internal.h"
34 
35 typedef struct ChannelSplitContext {
36  const AVClass *class;
37 
38  uint64_t channel_layout;
41 
42 #define OFFSET(x) offsetof(ChannelSplitContext, x)
43 #define A AV_OPT_FLAG_AUDIO_PARAM
44 static const AVOption options[] = {
45  { "channel_layout", "Input channel layout.", OFFSET(channel_layout_str), AV_OPT_TYPE_STRING, { .str = "stereo" }, .flags = A },
46  { NULL },
47 };
48 
49 static const AVClass channelsplit_class = {
50  .class_name = "channelsplit filter",
51  .item_name = av_default_item_name,
52  .option = options,
53  .version = LIBAVUTIL_VERSION_INT,
54 };
55 
56 static int init(AVFilterContext *ctx, const char *arg)
57 {
58  ChannelSplitContext *s = ctx->priv;
59  int nb_channels;
60  int ret = 0, i;
61 
64  if ((ret = av_set_options_string(s, arg, "=", ":")) < 0) {
65  av_log(ctx, AV_LOG_ERROR, "Error parsing options string '%s'.\n", arg);
66  return ret;
67  }
69  av_log(ctx, AV_LOG_ERROR, "Error parsing channel layout '%s'.\n",
71  ret = AVERROR(EINVAL);
72  goto fail;
73  }
74 
76  for (i = 0; i < nb_channels; i++) {
77  uint64_t channel = av_channel_layout_extract_channel(s->channel_layout, i);
78  AVFilterPad pad = { 0 };
79 
81  pad.name = av_get_channel_name(channel);
82 
83  ff_insert_outpad(ctx, i, &pad);
84  }
85 
86 fail:
87  av_opt_free(s);
88  return ret;
89 }
90 
92 {
93  ChannelSplitContext *s = ctx->priv;
94  AVFilterChannelLayouts *in_layouts = NULL;
95  int i;
96 
99 
100  ff_add_channel_layout(&in_layouts, s->channel_layout);
101  ff_channel_layouts_ref(in_layouts, &ctx->inputs[0]->out_channel_layouts);
102 
103  for (i = 0; i < ctx->nb_outputs; i++) {
104  AVFilterChannelLayouts *out_layouts = NULL;
105  uint64_t channel = av_channel_layout_extract_channel(s->channel_layout, i);
106 
107  ff_add_channel_layout(&out_layouts, channel);
108  ff_channel_layouts_ref(out_layouts, &ctx->outputs[i]->in_channel_layouts);
109  }
110 
111  return 0;
112 }
113 
114 static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *buf)
115 {
116  AVFilterContext *ctx = inlink->dst;
117  int i, ret = 0;
118 
119  for (i = 0; i < ctx->nb_outputs; i++) {
121 
122  if (!buf_out) {
123  ret = AVERROR(ENOMEM);
124  break;
125  }
126 
127  buf_out->data[0] = buf_out->extended_data[0] = buf_out->extended_data[i];
128  buf_out->audio->channel_layout =
130 
131  ret = ff_filter_frame(ctx->outputs[i], buf_out);
132  if (ret < 0)
133  break;
134  }
136  return ret;
137 }
138 
140  {
141  .name = "default",
142  .type = AVMEDIA_TYPE_AUDIO,
143  .filter_frame = filter_frame,
144  },
145  { NULL }
146 };
147 
149  .name = "channelsplit",
150  .description = NULL_IF_CONFIG_SMALL("Split audio into per-channel streams"),
151  .priv_size = sizeof(ChannelSplitContext),
152 
153  .init = init,
155 
156  .inputs = avfilter_af_channelsplit_inputs,
157  .outputs = NULL,
158 };