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  1. /*
  2.  * This file is part of FFmpeg.
  3.  *
  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.
  8.  *
  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.
  13.  *
  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
  17.  */
  18.  
  19. /**
  20.  * @file
  21.  * Channel split filter
  22.  *
  23.  * Split an audio stream into per-channel streams.
  24.  */
  25.  
  26. #include "libavutil/attributes.h"
  27. #include "libavutil/channel_layout.h"
  28. #include "libavutil/internal.h"
  29. #include "libavutil/opt.h"
  30.  
  31. #include "audio.h"
  32. #include "avfilter.h"
  33. #include "formats.h"
  34. #include "internal.h"
  35.  
  36. typedef struct ChannelSplitContext {
  37.     const AVClass *class;
  38.  
  39.     uint64_t channel_layout;
  40.     char    *channel_layout_str;
  41. } ChannelSplitContext;
  42.  
  43. #define OFFSET(x) offsetof(ChannelSplitContext, x)
  44. #define A AV_OPT_FLAG_AUDIO_PARAM
  45. #define F AV_OPT_FLAG_FILTERING_PARAM
  46. static const AVOption channelsplit_options[] = {
  47.     { "channel_layout", "Input channel layout.", OFFSET(channel_layout_str), AV_OPT_TYPE_STRING, { .str = "stereo" }, .flags = A|F },
  48.     { NULL }
  49. };
  50.  
  51. AVFILTER_DEFINE_CLASS(channelsplit);
  52.  
  53. static av_cold int init(AVFilterContext *ctx)
  54. {
  55.     ChannelSplitContext *s = ctx->priv;
  56.     int nb_channels;
  57.     int ret = 0, i;
  58.  
  59.     if (!(s->channel_layout = av_get_channel_layout(s->channel_layout_str))) {
  60.         av_log(ctx, AV_LOG_ERROR, "Error parsing channel layout '%s'.\n",
  61.                s->channel_layout_str);
  62.         ret = AVERROR(EINVAL);
  63.         goto fail;
  64.     }
  65.  
  66.     nb_channels = av_get_channel_layout_nb_channels(s->channel_layout);
  67.     for (i = 0; i < nb_channels; i++) {
  68.         uint64_t channel = av_channel_layout_extract_channel(s->channel_layout, i);
  69.         AVFilterPad pad  = { 0 };
  70.  
  71.         pad.type = AVMEDIA_TYPE_AUDIO;
  72.         pad.name = av_get_channel_name(channel);
  73.  
  74.         ff_insert_outpad(ctx, i, &pad);
  75.     }
  76.  
  77. fail:
  78.     return ret;
  79. }
  80.  
  81. static int query_formats(AVFilterContext *ctx)
  82. {
  83.     ChannelSplitContext *s = ctx->priv;
  84.     AVFilterChannelLayouts *in_layouts = NULL;
  85.     int i;
  86.  
  87.     ff_set_common_formats    (ctx, ff_planar_sample_fmts());
  88.     ff_set_common_samplerates(ctx, ff_all_samplerates());
  89.  
  90.     ff_add_channel_layout(&in_layouts, s->channel_layout);
  91.     ff_channel_layouts_ref(in_layouts, &ctx->inputs[0]->out_channel_layouts);
  92.  
  93.     for (i = 0; i < ctx->nb_outputs; i++) {
  94.         AVFilterChannelLayouts *out_layouts = NULL;
  95.         uint64_t channel = av_channel_layout_extract_channel(s->channel_layout, i);
  96.  
  97.         ff_add_channel_layout(&out_layouts, channel);
  98.         ff_channel_layouts_ref(out_layouts, &ctx->outputs[i]->in_channel_layouts);
  99.     }
  100.  
  101.     return 0;
  102. }
  103.  
  104. static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
  105. {
  106.     AVFilterContext *ctx = inlink->dst;
  107.     int i, ret = 0;
  108.  
  109.     for (i = 0; i < ctx->nb_outputs; i++) {
  110.         AVFrame *buf_out = av_frame_clone(buf);
  111.  
  112.         if (!buf_out) {
  113.             ret = AVERROR(ENOMEM);
  114.             break;
  115.         }
  116.  
  117.         buf_out->data[0] = buf_out->extended_data[0] = buf_out->extended_data[i];
  118.         buf_out->channel_layout =
  119.             av_channel_layout_extract_channel(buf->channel_layout, i);
  120.         av_frame_set_channels(buf_out, 1);
  121.  
  122.         ret = ff_filter_frame(ctx->outputs[i], buf_out);
  123.         if (ret < 0)
  124.             break;
  125.     }
  126.     av_frame_free(&buf);
  127.     return ret;
  128. }
  129.  
  130. static const AVFilterPad avfilter_af_channelsplit_inputs[] = {
  131.     {
  132.         .name         = "default",
  133.         .type         = AVMEDIA_TYPE_AUDIO,
  134.         .filter_frame = filter_frame,
  135.     },
  136.     { NULL }
  137. };
  138.  
  139. AVFilter avfilter_af_channelsplit = {
  140.     .name           = "channelsplit",
  141.     .description    = NULL_IF_CONFIG_SMALL("Split audio into per-channel streams."),
  142.     .priv_size      = sizeof(ChannelSplitContext),
  143.     .priv_class     = &channelsplit_class,
  144.     .init           = init,
  145.     .query_formats  = query_formats,
  146.     .inputs         = avfilter_af_channelsplit_inputs,
  147.     .outputs        = NULL,
  148.     .flags          = AVFILTER_FLAG_DYNAMIC_OUTPUTS,
  149. };
  150.