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This filter pads an audio stream with silence It can together with -shortest be used to extend audio streams to the same length as video. Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
117 lines
3.3 KiB
C
117 lines
3.3 KiB
C
/*
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* Copyright (c) 2012 Michael Niedermayer
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*
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* This file is part of FFmpeg.
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*
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*/
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/**
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* @file
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* audio pad filter.
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*
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* Based on af_aresample.c
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*/
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#include "libavutil/avstring.h"
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#include "libavutil/channel_layout.h"
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#include "libavutil/opt.h"
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#include "libavutil/samplefmt.h"
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#include "libavutil/avassert.h"
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#include "avfilter.h"
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#include "audio.h"
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#include "internal.h"
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typedef struct {
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int64_t next_pts;
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} APadContext;
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static av_cold int init(AVFilterContext *ctx, const char *args)
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{
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APadContext *apad = ctx->priv;
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apad->next_pts = AV_NOPTS_VALUE;
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return 0;
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}
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static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *frame)
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{
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AVFilterContext *ctx = inlink->dst;
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APadContext *apad = ctx->priv;
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apad->next_pts = frame->pts + av_rescale_q(frame->audio->nb_samples, (AVRational){1, inlink->sample_rate}, inlink->time_base);
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return ff_filter_frame(ctx->outputs[0], frame);
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}
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static int request_frame(AVFilterLink *outlink)
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{
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AVFilterContext *ctx = outlink->src;
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APadContext *apad = ctx->priv;
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int ret;
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ret = ff_request_frame(ctx->inputs[0]);
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if (ret == AVERROR_EOF) {
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int n_out = 4096;
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AVFilterBufferRef *outsamplesref = ff_get_audio_buffer(outlink, AV_PERM_WRITE, n_out);
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if (!outsamplesref)
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return AVERROR(ENOMEM);
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av_assert0(outsamplesref->audio->sample_rate == outlink->sample_rate);
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av_assert0(outsamplesref->audio->nb_samples == n_out);
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av_samples_set_silence(outsamplesref->extended_data, 0,
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n_out,
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outsamplesref->audio->channels,
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outsamplesref->format);
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outsamplesref->pts = apad->next_pts;
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if (apad->next_pts != AV_NOPTS_VALUE)
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apad->next_pts += av_rescale_q(n_out, (AVRational){1, outlink->sample_rate}, outlink->time_base);
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return ff_filter_frame(outlink, outsamplesref);
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}
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return ret;
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}
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static const AVFilterPad apad_inputs[] = {
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{
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.name = "default",
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.type = AVMEDIA_TYPE_AUDIO,
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.filter_frame = filter_frame,
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.min_perms = AV_PERM_READ,
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},
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{ NULL },
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};
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static const AVFilterPad apad_outputs[] = {
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{
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.name = "default",
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.request_frame = request_frame,
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.type = AVMEDIA_TYPE_AUDIO,
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},
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{ NULL },
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};
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AVFilter avfilter_af_apad = {
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.name = "apad",
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.description = NULL_IF_CONFIG_SMALL("Pad audio with silence."),
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.init = init,
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.priv_size = sizeof(APadContext),
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.inputs = apad_inputs,
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.outputs = apad_outputs,
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};
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