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/*
* Copyright (c) 2012 Michael Niedermayer
*
* 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
* audio pad filter.
*
* Based on af_aresample.c
*/
#include "libavutil/avstring.h"
#include "libavutil/channel_layout.h"
#include "libavutil/opt.h"
#include "libavutil/samplefmt.h"
#include "libavutil/avassert.h"
#include "avfilter.h"
#include "audio.h"
#include "internal.h"
typedef struct {
const AVClass *class;
int64_t next_pts;
int packet_size;
} APadContext;
#define OFFSET(x) offsetof(APadContext, x)
#define A AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
static const AVOption apad_options[] = {
{ "packet_size", "set silence packet size", OFFSET(packet_size), AV_OPT_TYPE_INT, { .i64 = 4096 }, 0, INT_MAX, A },
{ NULL },
};
AVFILTER_DEFINE_CLASS(apad);
static av_cold int init(AVFilterContext *ctx, const char *args)
{
int ret;
APadContext *apad = ctx->priv;
apad->class = &apad_class;
apad->next_pts = AV_NOPTS_VALUE;
av_opt_set_defaults(apad);
if ((ret = av_opt_set_from_string(apad, args, NULL, "=", ":")) < 0)
return ret;
av_opt_free(apad);
return 0;
}
static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *frame)
{
AVFilterContext *ctx = inlink->dst;
APadContext *apad = ctx->priv;
apad->next_pts = frame->pts + av_rescale_q(frame->audio->nb_samples, (AVRational){1, inlink->sample_rate}, inlink->time_base);
return ff_filter_frame(ctx->outputs[0], frame);
}
static int request_frame(AVFilterLink *outlink)
{
AVFilterContext *ctx = outlink->src;
APadContext *apad = ctx->priv;
int ret;
ret = ff_request_frame(ctx->inputs[0]);
if (ret == AVERROR_EOF) {
int n_out = apad->packet_size;
AVFilterBufferRef *outsamplesref = ff_get_audio_buffer(outlink, AV_PERM_WRITE, n_out);
if (!outsamplesref)
return AVERROR(ENOMEM);
av_assert0(outsamplesref->audio->sample_rate == outlink->sample_rate);
av_assert0(outsamplesref->audio->nb_samples == n_out);
av_samples_set_silence(outsamplesref->extended_data, 0,
n_out,
outsamplesref->audio->channels,
outsamplesref->format);
outsamplesref->pts = apad->next_pts;
if (apad->next_pts != AV_NOPTS_VALUE)
apad->next_pts += av_rescale_q(n_out, (AVRational){1, outlink->sample_rate}, outlink->time_base);
return ff_filter_frame(outlink, outsamplesref);
}
return ret;
}
static const AVFilterPad apad_inputs[] = {
{
.name = "default",
.type = AVMEDIA_TYPE_AUDIO,
.filter_frame = filter_frame,
.min_perms = AV_PERM_READ,
},
{ NULL },
};
static const AVFilterPad apad_outputs[] = {
{
.name = "default",
.request_frame = request_frame,
.type = AVMEDIA_TYPE_AUDIO,
},
{ NULL },
};
AVFilter avfilter_af_apad = {
.name = "apad",
.description = NULL_IF_CONFIG_SMALL("Pad audio with silence."),
.init = init,
.priv_size = sizeof(APadContext),
.inputs = apad_inputs,
.outputs = apad_outputs,
.priv_class = &apad_class,
};
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