asrc_anullsrc.c
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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 
24 #include <inttypes.h>
25 #include <stdio.h>
26 
28 #include "libavutil/internal.h"
29 #include "avfilter.h"
30 #include "internal.h"
31 
32 typedef struct {
33  uint64_t channel_layout;
34  int64_t sample_rate;
35 } ANullContext;
36 
37 static int init(AVFilterContext *ctx, const char *args)
38 {
39  ANullContext *priv = ctx->priv;
40  char channel_layout_str[128] = "";
41 
42  priv->sample_rate = 44100;
44 
45  if (args)
46  sscanf(args, "%"PRId64":%s", &priv->sample_rate, channel_layout_str);
47 
48  if (priv->sample_rate < 0) {
49  av_log(ctx, AV_LOG_ERROR, "Invalid negative sample rate: %"PRId64"\n", priv->sample_rate);
50  return AVERROR(EINVAL);
51  }
52 
53  if (*channel_layout_str)
54  if (!(priv->channel_layout = av_get_channel_layout(channel_layout_str))
55  && sscanf(channel_layout_str, "%"PRId64, &priv->channel_layout) != 1) {
56  av_log(ctx, AV_LOG_ERROR, "Invalid value '%s' for channel layout\n",
57  channel_layout_str);
58  return AVERROR(EINVAL);
59  }
60 
61  return 0;
62 }
63 
64 static int config_props(AVFilterLink *outlink)
65 {
66  ANullContext *priv = outlink->src->priv;
67  char buf[128];
68  int chans_nb;
69 
70  outlink->sample_rate = priv->sample_rate;
71  outlink->channel_layout = priv->channel_layout;
72 
74  av_get_channel_layout_string(buf, sizeof(buf), chans_nb, priv->channel_layout);
75  av_log(outlink->src, AV_LOG_VERBOSE,
76  "sample_rate:%"PRId64 " channel_layout:%"PRId64 " channel_layout_description:'%s'\n",
77  priv->sample_rate, priv->channel_layout, buf);
78 
79  return 0;
80 }
81 
82 static int request_frame(AVFilterLink *link)
83 {
84  return -1;
85 }
86 
88  {
89  .name = "default",
90  .type = AVMEDIA_TYPE_AUDIO,
91  .config_props = config_props,
92  .request_frame = request_frame,
93  },
94  { NULL }
95 };
96 
98  .name = "anullsrc",
99  .description = NULL_IF_CONFIG_SMALL("Null audio source, never return audio frames."),
100 
101  .init = init,
102  .priv_size = sizeof(ANullContext),
103 
104  .inputs = NULL,
105 
106  .outputs = avfilter_asrc_anullsrc_outputs,
107 };