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/*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* null audio source
*/
#include "avfilter.h"
#include "libavutil/audioconvert.h"
typedef struct {
int64_t channel_layout;
int64_t sample_rate;
} ANullContext;
static int init(AVFilterContext *ctx, const char *args, void *opaque)
{
ANullContext *priv = ctx->priv;
char channel_layout_str[128] = "";
priv->sample_rate = 44100;
priv->channel_layout = AV_CH_LAYOUT_STEREO;
if (args)
sscanf(args, "%"PRId64":%s", &priv->sample_rate, channel_layout_str);
if (priv->sample_rate < 0) {
av_log(ctx, AV_LOG_ERROR, "Invalid negative sample rate: %"PRId64"\n", priv->sample_rate);
return AVERROR(EINVAL);
}
if (*channel_layout_str)
if (!(priv->channel_layout = av_get_channel_layout(channel_layout_str))
&& sscanf(channel_layout_str, "%"PRId64, &priv->channel_layout) != 1) {
av_log(ctx, AV_LOG_ERROR, "Invalid value '%s' for channel layout\n",
channel_layout_str);
return AVERROR(EINVAL);
}
return 0;
}
static int config_props(AVFilterLink *outlink)
{
ANullContext *priv = outlink->src->priv;
char buf[128];
int chans_nb;
outlink->sample_rate = priv->sample_rate;
outlink->channel_layout = priv->channel_layout;
chans_nb = av_get_channel_layout_nb_channels(priv->channel_layout);
av_get_channel_layout_string(buf, sizeof(buf), chans_nb, priv->channel_layout);
av_log(outlink->src, AV_LOG_INFO,
"sample_rate:%"PRId64 " channel_layout:%"PRId64 " channel_layout_description:'%s'\n",
priv->sample_rate, priv->channel_layout, buf);
return 0;
}
static int request_frame(AVFilterLink *link)
{
return -1;
}
AVFilter avfilter_asrc_anullsrc = {
.name = "anullsrc",
.description = NULL_IF_CONFIG_SMALL("Null audio source, never return audio frames."),
.init = init,
.priv_size = sizeof(ANullContext),
.inputs = (AVFilterPad[]) {{ .name = NULL}},
.outputs = (AVFilterPad[]) {{ .name = "default",
.type = AVMEDIA_TYPE_AUDIO,
.config_props = config_props,
.request_frame = request_frame, },
{ .name = NULL}},
};
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