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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 "filters.h"
#include "formats.h"
#include "internal.h"
typedef struct ANullContext {
const AVClass *class;
AVChannelLayout ch_layout;
int sample_rate;
int64_t duration;
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(ch_layout), AV_OPT_TYPE_CHLAYOUT, {.str = "stereo"}, 0, 0, FLAGS },
{ "cl", "set channel_layout", OFFSET(ch_layout), AV_OPT_TYPE_CHLAYOUT, {.str = "stereo"}, 0, 0, FLAGS },
{ "sample_rate", "set sample rate", OFFSET(sample_rate) , AV_OPT_TYPE_INT, {.i64 = 44100}, 1, INT_MAX, FLAGS },
{ "r", "set sample rate", OFFSET(sample_rate) , AV_OPT_TYPE_INT, {.i64 = 44100}, 1, INT_MAX, FLAGS },
{ "nb_samples", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 1, UINT16_MAX, FLAGS },
{ "n", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 1, UINT16_MAX, FLAGS },
{ "duration", "set the audio duration", OFFSET(duration), AV_OPT_TYPE_DURATION, {.i64 = -1}, -1, INT64_MAX, FLAGS },
{ "d", "set the audio duration", OFFSET(duration), AV_OPT_TYPE_DURATION, {.i64 = -1}, -1, INT64_MAX, FLAGS },
{ NULL }
};
AVFILTER_DEFINE_CLASS(anullsrc);
static int query_formats(AVFilterContext *ctx)
{
ANullContext *null = ctx->priv;
const AVChannelLayout chlayouts[] = { null->ch_layout, { 0 } };
int sample_rates[] = { null->sample_rate, -1 };
int ret;
if ((ret = ff_set_common_formats (ctx, ff_all_formats (AVMEDIA_TYPE_AUDIO))) < 0 ||
(ret = ff_set_common_samplerates_from_list(ctx, sample_rates)) < 0)
return ret;
return ff_set_common_channel_layouts_from_list(ctx, chlayouts);
}
static av_cold int config_props(AVFilterLink *outlink)
{
ANullContext *null = outlink->src->priv;
if (null->duration >= 0)
null->duration = av_rescale(null->duration, null->sample_rate, AV_TIME_BASE);
return 0;
}
static int activate(AVFilterContext *ctx)
{
ANullContext *null = ctx->priv;
AVFilterLink *outlink = ctx->outputs[0];
if (null->duration >= 0 && null->pts >= null->duration) {
ff_outlink_set_status(outlink, AVERROR_EOF, null->pts);
return 0;
}
if (ff_outlink_frame_wanted(outlink)) {
AVFrame *samplesref = ff_get_audio_buffer(outlink, null->duration >= 0 ? FFMIN(null->nb_samples, null->duration - null->pts) : null->nb_samples);
if (!samplesref)
return AVERROR(ENOMEM);
samplesref->pts = null->pts;
null->pts += samplesref->nb_samples;
return ff_filter_frame(outlink, samplesref);
}
return FFERROR_NOT_READY;
}
static const AVFilterPad avfilter_asrc_anullsrc_outputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_AUDIO,
.config_props = config_props,
},
};
const AVFilter ff_asrc_anullsrc = {
.name = "anullsrc",
.description = NULL_IF_CONFIG_SMALL("Null audio source, return empty audio frames."),
.priv_size = sizeof(ANullContext),
.inputs = NULL,
FILTER_OUTPUTS(avfilter_asrc_anullsrc_outputs),
FILTER_QUERY_FUNC(query_formats),
.activate = activate,
.priv_class = &anullsrc_class,
};
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