/* * 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 "internal.h" typedef struct ANullContext {    const AVClass *class;    char   *channel_layout_str;    uint64_t channel_layout;    char   *sample_rate_str;    int     sample_rate;    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(channel_layout_str), AV_OPT_TYPE_STRING, {.str = "stereo"}, 0, 0, FLAGS },    { "cl",             "set channel_layout", OFFSET(channel_layout_str), AV_OPT_TYPE_STRING, {.str = "stereo"}, 0, 0, FLAGS },    { "sample_rate",    "set sample rate",    OFFSET(sample_rate_str)   , AV_OPT_TYPE_STRING, {.str = "44100"}, 0, 0, FLAGS },    { "r",              "set sample rate",    OFFSET(sample_rate_str)   , AV_OPT_TYPE_STRING, {.str = "44100"}, 0, 0, FLAGS },    { "nb_samples",     "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 0, INT_MAX, FLAGS },    { "n",              "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 0, INT_MAX, FLAGS },    { NULL }}; AVFILTER_DEFINE_CLASS(anullsrc); static av_cold int init(AVFilterContext *ctx){    ANullContext *null = ctx->priv;    int ret;     if ((ret = ff_parse_sample_rate(&null->sample_rate,                                     null->sample_rate_str, ctx)) < 0)        return ret;     if ((ret = ff_parse_channel_layout(&null->channel_layout, NULL,                                        null->channel_layout_str, ctx)) < 0)        return ret;     return 0;} static int query_formats(AVFilterContext *ctx){    ANullContext *null = ctx->priv;    int64_t chlayouts[] = { null->channel_layout, -1 };    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_channel_layouts (ctx, avfilter_make_format64_list (chlayouts         ))) < 0 ||        (ret = ff_set_common_samplerates     (ctx, ff_make_format_list         (sample_rates      ))) < 0)        return ret;     return 0;} static int config_props(AVFilterLink *outlink){    ANullContext *null = outlink->src->priv;    char buf[128];     av_get_channel_layout_string(buf, sizeof(buf), 0, null->channel_layout);    av_log(outlink->src, AV_LOG_VERBOSE,           "sample_rate:%d channel_layout:'%s' nb_samples:%d\n",           null->sample_rate, buf, null->nb_samples);     return 0;} static int request_frame(AVFilterLink *outlink){    int ret;    ANullContext *null = outlink->src->priv;    AVFrame *samplesref;     samplesref = ff_get_audio_buffer(outlink, null->nb_samples);    if (!samplesref)        return AVERROR(ENOMEM);     samplesref->pts = null->pts;     ret = ff_filter_frame(outlink, samplesref);    if (ret < 0)        return ret;     null->pts += null->nb_samples;    return ret;} static const AVFilterPad avfilter_asrc_anullsrc_outputs[] = {    {        .name          = "default",        .type          = AVMEDIA_TYPE_AUDIO,        .config_props  = config_props,        .request_frame = request_frame,    },    { NULL }}; AVFilter ff_asrc_anullsrc = {    .name          = "anullsrc",    .description   = NULL_IF_CONFIG_SMALL("Null audio source, return empty audio frames."),    .init          = init,    .query_formats = query_formats,    .priv_size     = sizeof(ANullContext),    .inputs        = NULL,    .outputs       = avfilter_asrc_anullsrc_outputs,    .priv_class    = &anullsrc_class,};