/* * 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" 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(const AVFilterContext *ctx,                         AVFilterFormatsConfig **cfg_in,                         AVFilterFormatsConfig **cfg_out){    const ANullContext *null = ctx->priv;    const AVChannelLayout chlayouts[] = { null->ch_layout, { 0 } };    int sample_rates[] = { null->sample_rate, -1 };    int ret;     ret = ff_set_common_samplerates_from_list2(ctx, cfg_in, cfg_out, sample_rates);    if (ret < 0)        return ret;     return ff_set_common_channel_layouts_from_list2(ctx, cfg_in, cfg_out, 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 FFFilter ff_asrc_anullsrc = {    .p.name        = "anullsrc",    .p.description = NULL_IF_CONFIG_SMALL("Null audio source, return empty audio frames."),    .p.priv_class  = &anullsrc_class,    .priv_size     = sizeof(ANullContext),    FILTER_OUTPUTS(avfilter_asrc_anullsrc_outputs),    FILTER_QUERY_FUNC2(query_formats),    .activate      = activate,};