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/*
* Copyright 2010 S.N. Hemanth Meenakshisundaram <smeenaks ucsd edu>
* Copyright 2010 Stefano Sabatini <stefano.sabatini-lala poste it>
*
* 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 <inttypes.h>
#include <stdio.h>
#include "libavutil/channel_layout.h"
#include "libavutil/internal.h"
#include "libavutil/opt.h"
#include "audio.h"
#include "avfilter.h"
#include "internal.h"
typedef struct {
const AVClass *class;
char *channel_layout_str;
uint64_t channel_layout;
char *sample_rate_str;
int sample_rate;
int nb_samples; ///< number of samples per requested frame
int64_t pts;
} ANullContext;
#define OFFSET(x) offsetof(ANullContext, x)
#define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
static const AVOption anullsrc_options[]= {
{ "channel_layout", "set channel_layout", OFFSET(channel_layout_str), AV_OPT_TYPE_STRING, {.str = "stereo"}, 0, 0, FLAGS },
{ "cl", "set channel_layout", OFFSET(channel_layout_str), AV_OPT_TYPE_STRING, {.str = "stereo"}, 0, 0, FLAGS },
{ "sample_rate", "set sample rate", OFFSET(sample_rate_str) , AV_OPT_TYPE_STRING, {.str = "44100"}, 0, 0, FLAGS },
{ "r", "set sample rate", OFFSET(sample_rate_str) , AV_OPT_TYPE_STRING, {.str = "44100"}, 0, 0, FLAGS },
{ "nb_samples", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 0, INT_MAX, FLAGS },
{ "n", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 0, INT_MAX, FLAGS },
{ NULL }
};
AVFILTER_DEFINE_CLASS(anullsrc);
static av_cold int init(AVFilterContext *ctx)
{
ANullContext *null = ctx->priv;
int ret;
if ((ret = ff_parse_sample_rate(&null->sample_rate,
null->sample_rate_str, ctx)) < 0)
return ret;
if ((ret = ff_parse_channel_layout(&null->channel_layout, NULL,
null->channel_layout_str, ctx)) < 0)
return ret;
return 0;
}
static int query_formats(AVFilterContext *ctx)
{
ANullContext *null = ctx->priv;
int64_t chlayouts[] = { null->channel_layout, -1 };
int sample_rates[] = { null->sample_rate, -1 };
ff_set_common_formats (ctx, ff_all_formats(AVMEDIA_TYPE_AUDIO));
ff_set_common_channel_layouts(ctx, avfilter_make_format64_list(chlayouts));
ff_set_common_samplerates (ctx, ff_make_format_list(sample_rates));
return 0;
}
static int config_props(AVFilterLink *outlink)
{
ANullContext *null = outlink->src->priv;
char buf[128];
av_get_channel_layout_string(buf, sizeof(buf), 0, null->channel_layout);
av_log(outlink->src, AV_LOG_VERBOSE,
"sample_rate:%d channel_layout:'%s' nb_samples:%d\n",
null->sample_rate, buf, null->nb_samples);
return 0;
}
static int request_frame(AVFilterLink *outlink)
{
int ret;
ANullContext *null = outlink->src->priv;
AVFrame *samplesref;
samplesref = ff_get_audio_buffer(outlink, null->nb_samples);
if (!samplesref)
return AVERROR(ENOMEM);
samplesref->pts = null->pts;
samplesref->channel_layout = null->channel_layout;
samplesref->sample_rate = outlink->sample_rate;
ret = ff_filter_frame(outlink, av_frame_clone(samplesref));
av_frame_free(&samplesref);
if (ret < 0)
return ret;
null->pts += null->nb_samples;
return ret;
}
static const AVFilterPad avfilter_asrc_anullsrc_outputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_AUDIO,
.config_props = config_props,
.request_frame = request_frame,
},
{ NULL }
};
AVFilter ff_asrc_anullsrc = {
.name = "anullsrc",
.description = NULL_IF_CONFIG_SMALL("Null audio source, return empty audio frames."),
.init = init,
.query_formats = query_formats,
.priv_size = sizeof(ANullContext),
.inputs = NULL,
.outputs = avfilter_asrc_anullsrc_outputs,
.priv_class = &anullsrc_class,
};
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