139 lines
4.5 KiB
C
139 lines
4.5 KiB
C
/*
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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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* @file
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* null audio source
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*/
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#include "libavutil/audioconvert.h"
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#include "libavutil/opt.h"
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#include "avfilter.h"
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#include "internal.h"
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typedef struct {
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const AVClass *class;
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char *channel_layout_str;
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int64_t channel_layout;
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char *sample_rate_str;
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int sample_rate;
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int nb_samples; ///< number of samples per requested frame
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int64_t pts;
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} ANullContext;
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#define OFFSET(x) offsetof(ANullContext, x)
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static const AVOption anullsrc_options[]= {
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{ "channel_layout", "set channel_layout", OFFSET(channel_layout_str), FF_OPT_TYPE_STRING, {.str = "stereo"}, 0, 0 },
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{ "cl", "set channel_layout", OFFSET(channel_layout_str), FF_OPT_TYPE_STRING, {.str = "stereo"}, 0, 0 },
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{ "sample_rate", "set sample rate", OFFSET(sample_rate_str) , FF_OPT_TYPE_STRING, {.str = "44100"}, 0, 0 },
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{ "r", "set sample rate", OFFSET(sample_rate_str) , FF_OPT_TYPE_STRING, {.str = "44100"}, 0, 0 },
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{ "nb_samples", "set the number of samples per requested frame", OFFSET(nb_samples), FF_OPT_TYPE_INT, {.dbl = 1024}, 0, INT_MAX },
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{ "n", "set the number of samples per requested frame", OFFSET(nb_samples), FF_OPT_TYPE_INT, {.dbl = 1024}, 0, INT_MAX },
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{ NULL },
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};
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static const char *anullsrc_get_name(void *ctx)
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{
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return "anullsrc";
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}
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static const AVClass anullsrc_class = {
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"ANullSrcContext",
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anullsrc_get_name,
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anullsrc_options
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};
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static int init(AVFilterContext *ctx, const char *args, void *opaque)
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{
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ANullContext *null = ctx->priv;
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int ret;
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null->class = &anullsrc_class;
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av_opt_set_defaults(null);
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if ((ret = (av_set_options_string(null, args, "=", ":"))) < 0) {
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av_log(ctx, AV_LOG_ERROR, "Error parsing options string: '%s'\n", args);
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return ret;
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}
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if ((ret = ff_parse_sample_rate(&null->sample_rate,
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null->sample_rate_str, ctx)) < 0)
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return ret;
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if ((ret = ff_parse_channel_layout(&null->channel_layout,
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null->channel_layout_str, ctx)) < 0)
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return ret;
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return 0;
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}
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static int config_props(AVFilterLink *outlink)
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{
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ANullContext *null = outlink->src->priv;
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char buf[128];
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int chans_nb;
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outlink->sample_rate = null->sample_rate;
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outlink->channel_layout = null->channel_layout;
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chans_nb = av_get_channel_layout_nb_channels(null->channel_layout);
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av_get_channel_layout_string(buf, sizeof(buf), chans_nb, null->channel_layout);
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av_log(outlink->src, AV_LOG_INFO,
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"sample_rate:%d channel_layout:'%s' nb_samples:%d\n",
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null->sample_rate, buf, null->nb_samples);
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return 0;
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}
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static int request_frame(AVFilterLink *outlink)
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{
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ANullContext *null = outlink->src->priv;
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AVFilterBufferRef *samplesref;
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samplesref =
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avfilter_get_audio_buffer(outlink, AV_PERM_WRITE, null->nb_samples);
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samplesref->pts = null->pts;
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samplesref->pos = -1;
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samplesref->audio->channel_layout = null->channel_layout;
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samplesref->audio->sample_rate = outlink->sample_rate;
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avfilter_filter_samples(outlink, avfilter_ref_buffer(samplesref, ~0));
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avfilter_unref_buffer(samplesref);
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null->pts += null->nb_samples;
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return 0;
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}
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AVFilter avfilter_asrc_anullsrc = {
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.name = "anullsrc",
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.description = NULL_IF_CONFIG_SMALL("Null audio source, return empty audio frames."),
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.init = init,
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.priv_size = sizeof(ANullContext),
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.inputs = (AVFilterPad[]) {{ .name = NULL}},
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.outputs = (AVFilterPad[]) {{ .name = "default",
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.type = AVMEDIA_TYPE_AUDIO,
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.config_props = config_props,
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.request_frame = request_frame, },
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{ .name = NULL}},
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};
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