libavfilter/asrc_anullsrc.c

   1 /*
   2  * Copyright 2010 S.N. Hemanth Meenakshisundaram <smeenaks ucsd edu>
   3  * Copyright 2010 Stefano Sabatini <stefano.sabatini-lala poste it>
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /**
  23  * @file
  24  * null audio source
  25  */
  26
  27 #include <inttypes.h>
  28 #include <stdio.h>
  29
  30 #include "libavutil/channel_layout.h"
  31 #include "libavutil/internal.h"
  32 #include "libavutil/opt.h"
  33 #include "audio.h"
  34 #include "avfilter.h"
  35 #include "filters.h"
  36 #include "formats.h"
  37
  38 typedef struct ANullContext {
  39     const AVClass *class;
  40     AVChannelLayout ch_layout;
  41     int     sample_rate;
  42     int64_t duration;
  43     int nb_samples;             ///< number of samples per requested frame
  44     int64_t pts;
  45 } ANullContext;
  46
  47 #define OFFSET(x) offsetof(ANullContext, x)
  48 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
  49
  50 static const AVOption anullsrc_options[]= {
  51     { "channel_layout", "set channel_layout", OFFSET(ch_layout), AV_OPT_TYPE_CHLAYOUT, {.str = "stereo"}, 0, 0, FLAGS },
  52     { "cl",             "set channel_layout", OFFSET(ch_layout), AV_OPT_TYPE_CHLAYOUT, {.str = "stereo"}, 0, 0, FLAGS },
  53     { "sample_rate",    "set sample rate",    OFFSET(sample_rate)   , AV_OPT_TYPE_INT, {.i64 = 44100}, 1, INT_MAX, FLAGS },
  54     { "r",              "set sample rate",    OFFSET(sample_rate)   , AV_OPT_TYPE_INT, {.i64 = 44100}, 1, INT_MAX, FLAGS },
  55     { "nb_samples",     "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 1, UINT16_MAX, FLAGS },
  56     { "n",              "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 1, UINT16_MAX, FLAGS },
  57     { "duration",       "set the audio duration",                        OFFSET(duration),   AV_OPT_TYPE_DURATION, {.i64 = -1}, -1, INT64_MAX, FLAGS },
  58     { "d",              "set the audio duration",                        OFFSET(duration),   AV_OPT_TYPE_DURATION, {.i64 = -1}, -1, INT64_MAX, FLAGS },
  59     { NULL }
  60 };
  61
  62 AVFILTER_DEFINE_CLASS(anullsrc);
  63
  64 static int query_formats(const AVFilterContext *ctx,
  65                          AVFilterFormatsConfig **cfg_in,
  66                          AVFilterFormatsConfig **cfg_out)
  67 {
  68     const ANullContext *null = ctx->priv;
  69     const AVChannelLayout chlayouts[] = { null->ch_layout, { 0 } };
  70     int sample_rates[] = { null->sample_rate, -1 };
  71     int ret;
  72
  73     ret = ff_set_common_samplerates_from_list2(ctx, cfg_in, cfg_out, sample_rates);
  74     if (ret < 0)
  75         return ret;
  76
  77     return ff_set_common_channel_layouts_from_list2(ctx, cfg_in, cfg_out, chlayouts);
  78 }
  79
  80 static av_cold int config_props(AVFilterLink *outlink)
  81 {
  82     ANullContext *null = outlink->src->priv;
  83
  84     if (null->duration >= 0)
  85         null->duration = av_rescale(null->duration, null->sample_rate, AV_TIME_BASE);
  86
  87     return 0;
  88 }
  89
  90 static int activate(AVFilterContext *ctx)
  91 {
  92     ANullContext *null = ctx->priv;
  93     AVFilterLink *outlink = ctx->outputs[0];
  94
  95     if (null->duration >= 0 && null->pts >= null->duration) {
  96         ff_outlink_set_status(outlink, AVERROR_EOF, null->pts);
  97         return 0;
  98     }
  99
 100     if (ff_outlink_frame_wanted(outlink)) {
 101         AVFrame *samplesref = ff_get_audio_buffer(outlink, null->duration >= 0 ? FFMIN(null->nb_samples, null->duration - null->pts) : null->nb_samples);
 102
 103         if (!samplesref)
 104             return AVERROR(ENOMEM);
 105
 106         samplesref->pts = null->pts;
 107         null->pts += samplesref->nb_samples;
 108
 109         return ff_filter_frame(outlink, samplesref);
 110     }
 111
 112     return FFERROR_NOT_READY;
 113 }
 114
 115 static const AVFilterPad avfilter_asrc_anullsrc_outputs[] = {
 116     {
 117         .name          = "default",
 118         .type          = AVMEDIA_TYPE_AUDIO,
 119         .config_props  = config_props,
 120     },
 121 };
 122
 123 const FFFilter ff_asrc_anullsrc = {
 124     .p.name        = "anullsrc",
 125     .p.description = NULL_IF_CONFIG_SMALL("Null audio source, return empty audio frames."),
 126     .p.priv_class  = &anullsrc_class,
 127     .priv_size     = sizeof(ANullContext),
 128     FILTER_OUTPUTS(avfilter_asrc_anullsrc_outputs),
 129     FILTER_QUERY_FUNC2(query_formats),
 130     .activate      = activate,
 131 };