FFmpeg  4.4
asrc_anullsrc.c
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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 
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;
41  uint64_t channel_layout;
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 
65 
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 
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 
91  return ret;
92 
94 }
95 
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 
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 
132  {
133  .name = "default",
134  .type = AVMEDIA_TYPE_AUDIO,
135  .config_props = config_props,
136  },
137  { NULL }
138 };
139 
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,
148  .activate = activate,
149  .priv_class = &anullsrc_class,
150 };
static const AVFilterPad inputs[]
Definition: af_acontrast.c:193
static const AVFilterPad outputs[]
Definition: af_acontrast.c:203
static const AVOption anullsrc_options[]
Definition: asrc_anullsrc.c:52
static int query_formats(AVFilterContext *ctx)
Definition: asrc_anullsrc.c:82
#define FLAGS
Definition: asrc_anullsrc.c:50
AVFilter ff_asrc_anullsrc
AVFILTER_DEFINE_CLASS(anullsrc)
static int activate(AVFilterContext *ctx)
static av_cold int init(AVFilterContext *ctx)
Definition: asrc_anullsrc.c:66
static const AVFilterPad avfilter_asrc_anullsrc_outputs[]
#define OFFSET(x)
Definition: asrc_anullsrc.c:49
static av_cold int config_props(AVFilterLink *outlink)
Definition: asrc_anullsrc.c:96
#define av_cold
Definition: attributes.h:88
AVFrame * ff_get_audio_buffer(AVFilterLink *link, int nb_samples)
Request an audio samples buffer with a specific set of permissions.
Definition: audio.c:86
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1094
Main libavfilter public API header.
audio channel layout utility functions
#define FFMIN(a, b)
Definition: common.h:105
#define NULL
Definition: coverity.c:32
sample_rates
static void ff_outlink_set_status(AVFilterLink *link, int status, int64_t pts)
Set the status field of a link from the source filter.
Definition: filters.h:189
#define FFERROR_NOT_READY
Filters implementation helper functions.
Definition: filters.h:34
static int ff_outlink_frame_wanted(AVFilterLink *link)
Test if a frame is wanted on an output link.
Definition: filters.h:172
AVFilterFormats * ff_all_formats(enum AVMediaType type)
Return a list of all formats supported by FFmpeg for the given media type.
Definition: formats.c:345
int ff_parse_channel_layout(int64_t *ret, int *nret, const char *arg, void *log_ctx)
Parse a channel layout or a corresponding integer representation.
Definition: formats.c:644
int ff_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats)
A helper for query_formats() which sets all links to the same list of formats.
Definition: formats.c:587
AVFilterFormats * ff_make_format_list(const int *fmts)
Create a list of supported formats.
Definition: formats.c:286
int ff_parse_sample_rate(int *ret, const char *arg, void *log_ctx)
Parse a sample rate.
Definition: formats.c:632
AVFilterChannelLayouts * ff_make_format64_list(const int64_t *fmts)
Definition: formats.c:295
int ff_set_common_samplerates(AVFilterContext *ctx, AVFilterFormats *samplerates)
Definition: formats.c:575
int ff_set_common_channel_layouts(AVFilterContext *ctx, AVFilterChannelLayouts *channel_layouts)
A helper for query_formats() which sets all links to the same list of channel layouts/sample rates.
Definition: formats.c:568
@ AV_OPT_TYPE_DURATION
Definition: opt.h:239
@ AV_OPT_TYPE_INT
Definition: opt.h:225
@ AV_OPT_TYPE_STRING
Definition: opt.h:229
#define AVERROR_EOF
End of file.
Definition: error.h:55
#define AVERROR(e)
Definition: error.h:43
int64_t av_rescale(int64_t a, int64_t b, int64_t c)
Rescale a 64-bit integer with rounding to nearest.
Definition: mathematics.c:129
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
#define AV_TIME_BASE
Internal time base represented as integer.
Definition: avutil.h:254
common internal API header
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
AVOptions.
int64_t duration
Definition: asrc_anullsrc.c:44
uint64_t channel_layout
Definition: asrc_anullsrc.c:41
int nb_samples
number of samples per requested frame
Definition: asrc_anullsrc.c:45
char * channel_layout_str
Definition: asrc_anullsrc.c:40
char * sample_rate_str
Definition: asrc_anullsrc.c:42
Describe the class of an AVClass context structure.
Definition: log.h:67
An instance of a filter.
Definition: avfilter.h:341
void * priv
private data for use by the filter
Definition: avfilter.h:356
A filter pad used for either input or output.
Definition: internal.h:54
const char * name
Pad name.
Definition: internal.h:60
Filter definition.
Definition: avfilter.h:145
const char * name
Filter name.
Definition: avfilter.h:149
This structure describes decoded (raw) audio or video data.
Definition: frame.h:318
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:384
int64_t pts
Presentation timestamp in time_base units (time when frame should be shown to user).
Definition: frame.h:411
AVOption.
Definition: opt.h:248
int64_t duration
Definition: movenc.c:64
AVFormatContext * ctx
Definition: movenc.c:48