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 "internal.h"
37
38 typedef struct ANullContext {
39 const AVClass *class;
40 char *channel_layout_str;
41 uint64_t channel_layout;
42 char *sample_rate_str;
43 int sample_rate;
44 int64_t duration;
45 int nb_samples; ///< number of samples per requested frame
46 int64_t pts;
47 } ANullContext;
48
49 #define OFFSET(x) offsetof(ANullContext, x)
50 #define FLAGS AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
51
52 static const AVOption anullsrc_options[]= {
53 { "channel_layout", "set channel_layout", OFFSET(channel_layout_str), AV_OPT_TYPE_STRING, {.str = "stereo"}, 0, 0, FLAGS },
54 { "cl", "set channel_layout", OFFSET(channel_layout_str), AV_OPT_TYPE_STRING, {.str = "stereo"}, 0, 0, FLAGS },
55 { "sample_rate", "set sample rate", OFFSET(sample_rate_str) , AV_OPT_TYPE_STRING, {.str = "44100"}, 0, 0, FLAGS },
56 { "r", "set sample rate", OFFSET(sample_rate_str) , AV_OPT_TYPE_STRING, {.str = "44100"}, 0, 0, FLAGS },
57 { "nb_samples", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 1, UINT16_MAX, FLAGS },
58 { "n", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 1, UINT16_MAX, FLAGS },
59 { "duration", "set the audio duration", OFFSET(duration), AV_OPT_TYPE_DURATION, {.i64 = -1}, -1, INT64_MAX, FLAGS },
60 { "d", "set the audio duration", OFFSET(duration), AV_OPT_TYPE_DURATION, {.i64 = -1}, -1, INT64_MAX, FLAGS },
61 { NULL }
62 };
63
64 AVFILTER_DEFINE_CLASS(anullsrc);
65
init(AVFilterContext * ctx)66 static av_cold int init(AVFilterContext *ctx)
67 {
68 ANullContext *null = ctx->priv;
69 int ret;
70
71 if ((ret = ff_parse_sample_rate(&null->sample_rate,
72 null->sample_rate_str, ctx)) < 0)
73 return ret;
74
75 if ((ret = ff_parse_channel_layout(&null->channel_layout, NULL,
76 null->channel_layout_str, ctx)) < 0)
77 return ret;
78
79 return 0;
80 }
81
query_formats(AVFilterContext * ctx)82 static int query_formats(AVFilterContext *ctx)
83 {
84 ANullContext *null = ctx->priv;
85 int64_t chlayouts[] = { null->channel_layout, -1 };
86 int sample_rates[] = { null->sample_rate, -1 };
87 int ret;
88
89 if ((ret = ff_set_common_formats (ctx, ff_all_formats (AVMEDIA_TYPE_AUDIO))) < 0 ||
90 (ret = ff_set_common_samplerates (ctx, ff_make_format_list (sample_rates ))) < 0)
91 return ret;
92
93 return ff_set_common_channel_layouts(ctx, ff_make_format64_list(chlayouts));
94 }
95
config_props(AVFilterLink * outlink)96 static av_cold int config_props(AVFilterLink *outlink)
97 {
98 ANullContext *null = outlink->src->priv;
99
100 if (null->duration >= 0)
101 null->duration = av_rescale(null->duration, null->sample_rate, AV_TIME_BASE);
102
103 return 0;
104 }
105
activate(AVFilterContext * ctx)106 static int activate(AVFilterContext *ctx)
107 {
108 ANullContext *null = ctx->priv;
109 AVFilterLink *outlink = ctx->outputs[0];
110
111 if (null->duration >= 0 && null->pts >= null->duration) {
112 ff_outlink_set_status(outlink, AVERROR_EOF, null->pts);
113 return 0;
114 }
115
116 if (ff_outlink_frame_wanted(outlink)) {
117 AVFrame *samplesref = ff_get_audio_buffer(outlink, null->duration >= 0 ? FFMIN(null->nb_samples, null->duration - null->pts) : null->nb_samples);
118
119 if (!samplesref)
120 return AVERROR(ENOMEM);
121
122 samplesref->pts = null->pts;
123 null->pts += samplesref->nb_samples;
124
125 return ff_filter_frame(outlink, samplesref);
126 }
127
128 return FFERROR_NOT_READY;
129 }
130
131 static const AVFilterPad avfilter_asrc_anullsrc_outputs[] = {
132 {
133 .name = "default",
134 .type = AVMEDIA_TYPE_AUDIO,
135 .config_props = config_props,
136 },
137 { NULL }
138 };
139
140 AVFilter ff_asrc_anullsrc = {
141 .name = "anullsrc",
142 .description = NULL_IF_CONFIG_SMALL("Null audio source, return empty audio frames."),
143 .init = init,
144 .query_formats = query_formats,
145 .priv_size = sizeof(ANullContext),
146 .inputs = NULL,
147 .outputs = avfilter_asrc_anullsrc_outputs,
148 .activate = activate,
149 .priv_class = &anullsrc_class,
150 };
151