yading@10: /*
yading@10:  * Copyright 2010 S.N. Hemanth Meenakshisundaram <smeenaks ucsd edu>
yading@10:  * Copyright 2010 Stefano Sabatini <stefano.sabatini-lala poste it>
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or
yading@10:  * modify it under the terms of the GNU Lesser General Public
yading@10:  * License as published by the Free Software Foundation; either
yading@10:  * version 2.1 of the License, or (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
yading@10:  * Lesser General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU Lesser General Public
yading@10:  * License along with FFmpeg; if not, write to the Free Software
yading@10:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
yading@10:  */
yading@10: 
yading@10: /**
yading@10:  * @file
yading@10:  * null audio source
yading@10:  */
yading@10: 
yading@10: #include <inttypes.h>
yading@10: #include <stdio.h>
yading@10: 
yading@10: #include "libavutil/channel_layout.h"
yading@10: #include "libavutil/internal.h"
yading@10: #include "libavutil/opt.h"
yading@10: #include "audio.h"
yading@10: #include "avfilter.h"
yading@10: #include "internal.h"
yading@10: 
yading@10: typedef struct {
yading@10:     const AVClass *class;
yading@10:     char   *channel_layout_str;
yading@10:     uint64_t channel_layout;
yading@10:     char   *sample_rate_str;
yading@10:     int     sample_rate;
yading@10:     int nb_samples;             ///< number of samples per requested frame
yading@10:     int64_t pts;
yading@10: } ANullContext;
yading@10: 
yading@10: #define OFFSET(x) offsetof(ANullContext, x)
yading@10: #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
yading@10: 
yading@10: static const AVOption anullsrc_options[]= {
yading@10:     { "channel_layout", "set channel_layout", OFFSET(channel_layout_str), AV_OPT_TYPE_STRING, {.str = "stereo"}, 0, 0, FLAGS },
yading@10:     { "cl",             "set channel_layout", OFFSET(channel_layout_str), AV_OPT_TYPE_STRING, {.str = "stereo"}, 0, 0, FLAGS },
yading@10:     { "sample_rate",    "set sample rate",    OFFSET(sample_rate_str)   , AV_OPT_TYPE_STRING, {.str = "44100"}, 0, 0, FLAGS },
yading@10:     { "r",              "set sample rate",    OFFSET(sample_rate_str)   , AV_OPT_TYPE_STRING, {.str = "44100"}, 0, 0, FLAGS },
yading@10:     { "nb_samples",     "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 0, INT_MAX, FLAGS },
yading@10:     { "n",              "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 0, INT_MAX, FLAGS },
yading@10:     { NULL },
yading@10: };
yading@10: 
yading@10: AVFILTER_DEFINE_CLASS(anullsrc);
yading@10: 
yading@10: static int init(AVFilterContext *ctx)
yading@10: {
yading@10:     ANullContext *null = ctx->priv;
yading@10:     int ret;
yading@10: 
yading@10:     if ((ret = ff_parse_sample_rate(&null->sample_rate,
yading@10:                                      null->sample_rate_str, ctx)) < 0)
yading@10:         return ret;
yading@10: 
yading@10:     if ((ret = ff_parse_channel_layout(&null->channel_layout,
yading@10:                                         null->channel_layout_str, ctx)) < 0)
yading@10:         return ret;
yading@10: 
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: static int query_formats(AVFilterContext *ctx)
yading@10: {
yading@10:     ANullContext *null = ctx->priv;
yading@10:     int64_t chlayouts[] = { null->channel_layout, -1 };
yading@10:     int sample_rates[] = { null->sample_rate, -1 };
yading@10: 
yading@10:     ff_set_common_formats        (ctx, ff_all_formats(AVMEDIA_TYPE_AUDIO));
yading@10:     ff_set_common_channel_layouts(ctx, avfilter_make_format64_list(chlayouts));
yading@10:     ff_set_common_samplerates    (ctx, ff_make_format_list(sample_rates));
yading@10: 
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: static int config_props(AVFilterLink *outlink)
yading@10: {
yading@10:     ANullContext *null = outlink->src->priv;
yading@10:     char buf[128];
yading@10: 
yading@10:     av_get_channel_layout_string(buf, sizeof(buf), 0, null->channel_layout);
yading@10:     av_log(outlink->src, AV_LOG_VERBOSE,
yading@10:            "sample_rate:%d channel_layout:'%s' nb_samples:%d\n",
yading@10:            null->sample_rate, buf, null->nb_samples);
yading@10: 
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: static int request_frame(AVFilterLink *outlink)
yading@10: {
yading@10:     int ret;
yading@10:     ANullContext *null = outlink->src->priv;
yading@10:     AVFrame *samplesref;
yading@10: 
yading@10:     samplesref = ff_get_audio_buffer(outlink, null->nb_samples);
yading@10:     if (!samplesref)
yading@10:         return AVERROR(ENOMEM);
yading@10: 
yading@10:     samplesref->pts = null->pts;
yading@10:     samplesref->channel_layout = null->channel_layout;
yading@10:     samplesref->sample_rate = outlink->sample_rate;
yading@10: 
yading@10:     ret = ff_filter_frame(outlink, av_frame_clone(samplesref));
yading@10:     av_frame_free(&samplesref);
yading@10:     if (ret < 0)
yading@10:         return ret;
yading@10: 
yading@10:     null->pts += null->nb_samples;
yading@10:     return ret;
yading@10: }
yading@10: 
yading@10: static const AVFilterPad avfilter_asrc_anullsrc_outputs[] = {
yading@10:     {
yading@10:         .name          = "default",
yading@10:         .type          = AVMEDIA_TYPE_AUDIO,
yading@10:         .config_props  = config_props,
yading@10:         .request_frame = request_frame,
yading@10:     },
yading@10:     { NULL }
yading@10: };
yading@10: 
yading@10: AVFilter avfilter_asrc_anullsrc = {
yading@10:     .name        = "anullsrc",
yading@10:     .description = NULL_IF_CONFIG_SMALL("Null audio source, return empty audio frames."),
yading@10: 
yading@10:     .init        = init,
yading@10:     .query_formats = query_formats,
yading@10:     .priv_size   = sizeof(ANullContext),
yading@10: 
yading@10:     .inputs      = NULL,
yading@10: 
yading@10:     .outputs     = avfilter_asrc_anullsrc_outputs,
yading@10:     .priv_class = &anullsrc_class,
yading@10: };