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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 "internal.h"
36 
37 typedef struct {
38  const AVClass *class;
40  uint64_t channel_layout;
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(channel_layout_str), AV_OPT_TYPE_STRING, {.str = "stereo"}, 0, 0, FLAGS },
52  { "cl", "set channel_layout", OFFSET(channel_layout_str), AV_OPT_TYPE_STRING, {.str = "stereo"}, 0, 0, FLAGS },
53  { "sample_rate", "set sample rate", OFFSET(sample_rate_str) , AV_OPT_TYPE_STRING, {.str = "44100"}, 0, 0, FLAGS },
54  { "r", "set sample rate", OFFSET(sample_rate_str) , AV_OPT_TYPE_STRING, {.str = "44100"}, 0, 0, FLAGS },
55  { "nb_samples", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 0, INT_MAX, FLAGS },
56  { "n", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64 = 1024}, 0, INT_MAX, FLAGS },
57  { NULL }
58 };
59 
60 AVFILTER_DEFINE_CLASS(anullsrc);
61 
63 {
64  ANullContext *null = ctx->priv;
65  int ret;
66 
67  if ((ret = ff_parse_sample_rate(&null->sample_rate,
68  null->sample_rate_str, ctx)) < 0)
69  return ret;
70 
71  if ((ret = ff_parse_channel_layout(&null->channel_layout, NULL,
72  null->channel_layout_str, ctx)) < 0)
73  return ret;
74 
75  return 0;
76 }
77 
79 {
80  ANullContext *null = ctx->priv;
81  int64_t chlayouts[] = { null->channel_layout, -1 };
82  int sample_rates[] = { null->sample_rate, -1 };
83  int ret;
84 
85  if ((ret = ff_set_common_formats (ctx, ff_all_formats (AVMEDIA_TYPE_AUDIO))) < 0 ||
86  (ret = ff_set_common_channel_layouts (ctx, avfilter_make_format64_list (chlayouts ))) < 0 ||
87  (ret = ff_set_common_samplerates (ctx, ff_make_format_list (sample_rates ))) < 0)
88  return ret;
89 
90  return 0;
91 }
92 
93 static int config_props(AVFilterLink *outlink)
94 {
95  ANullContext *null = outlink->src->priv;
96  char buf[128];
97 
98  av_get_channel_layout_string(buf, sizeof(buf), 0, null->channel_layout);
99  av_log(outlink->src, AV_LOG_VERBOSE,
100  "sample_rate:%d channel_layout:'%s' nb_samples:%d\n",
101  null->sample_rate, buf, null->nb_samples);
102 
103  return 0;
104 }
105 
106 static int request_frame(AVFilterLink *outlink)
107 {
108  int ret;
109  ANullContext *null = outlink->src->priv;
110  AVFrame *samplesref;
111 
112  samplesref = ff_get_audio_buffer(outlink, null->nb_samples);
113  if (!samplesref)
114  return AVERROR(ENOMEM);
115 
116  samplesref->pts = null->pts;
117  samplesref->channel_layout = null->channel_layout;
118  samplesref->sample_rate = outlink->sample_rate;
119 
120  ret = ff_filter_frame(outlink, av_frame_clone(samplesref));
121  av_frame_free(&samplesref);
122  if (ret < 0)
123  return ret;
124 
125  null->pts += null->nb_samples;
126  return ret;
127 }
128 
130  {
131  .name = "default",
132  .type = AVMEDIA_TYPE_AUDIO,
133  .config_props = config_props,
134  .request_frame = request_frame,
135  },
136  { NULL }
137 };
138 
140  .name = "anullsrc",
141  .description = NULL_IF_CONFIG_SMALL("Null audio source, return empty audio frames."),
142  .init = init,
143  .query_formats = query_formats,
144  .priv_size = sizeof(ANullContext),
145  .inputs = NULL,
146  .outputs = avfilter_asrc_anullsrc_outputs,
147  .priv_class = &anullsrc_class,
148 };
#define NULL
Definition: coverity.c:32
int ff_set_common_channel_layouts(AVFilterContext *ctx, AVFilterChannelLayouts *layouts)
A helper for query_formats() which sets all links to the same list of channel layouts/sample rates...
Definition: formats.c:549
This structure describes decoded (raw) audio or video data.
Definition: frame.h:184
AVOption.
Definition: opt.h:245
char * channel_layout_str
Definition: asrc_anullsrc.c:39
Main libavfilter public API header.
#define OFFSET(x)
Definition: asrc_anullsrc.c:47
AVFilterFormats * ff_make_format_list(const int *fmts)
Create a list of supported formats.
Definition: formats.c:283
const char * name
Pad name.
Definition: internal.h:59
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1189
#define av_cold
Definition: attributes.h:82
AVOptions.
int64_t pts
Presentation timestamp in time_base units (time when frame should be shown to user).
Definition: frame.h:268
#define AV_LOG_VERBOSE
Detailed information.
Definition: log.h:192
#define av_log(a,...)
static int config_props(AVFilterLink *outlink)
Definition: asrc_anullsrc.c:93
AVFilterFormats * ff_all_formats(enum AVMediaType type)
Return a list of all formats supported by FFmpeg for the given media type.
Definition: formats.c:350
A filter pad used for either input or output.
Definition: internal.h:53
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:568
AVFrame * ff_get_audio_buffer(AVFilterLink *link, int nb_samples)
Request an audio samples buffer with a specific set of permissions.
Definition: audio.c:65
#define AVERROR(e)
Definition: error.h:43
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:154
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:176
AVFilter ff_asrc_anullsrc
void * priv
private data for use by the filter
Definition: avfilter.h:322
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:662
int nb_samples
number of samples per requested frame
Definition: asrc_anullsrc.c:43
static const int sample_rates[]
Definition: dcaenc.h:32
uint64_t channel_layout
Channel layout of the audio data.
Definition: frame.h:349
common internal API header
audio channel layout utility functions
AVFormatContext * ctx
Definition: movenc.c:48
static const AVFilterPad outputs[]
Definition: af_afftfilt.c:386
AVFrame * av_frame_clone(const AVFrame *src)
Create a new frame that references the same data as src.
Definition: frame.c:472
void av_get_channel_layout_string(char *buf, int buf_size, int nb_channels, uint64_t channel_layout)
Return a description of a channel layout.
static const AVFilterPad inputs[]
Definition: af_afftfilt.c:376
#define FLAGS
Definition: asrc_anullsrc.c:48
AVFilterChannelLayouts * avfilter_make_format64_list(const int64_t *fmts)
Definition: formats.c:303
static const AVFilterPad avfilter_asrc_anullsrc_outputs[]
static int query_formats(AVFilterContext *ctx)
Definition: asrc_anullsrc.c:78
uint64_t channel_layout
Definition: asrc_anullsrc.c:40
void * buf
Definition: avisynth_c.h:690
Describe the class of an AVClass context structure.
Definition: log.h:67
int sample_rate
Sample rate of the audio data.
Definition: frame.h:344
Filter definition.
Definition: avfilter.h:144
const char * name
Filter name.
Definition: avfilter.h:148
static const AVOption anullsrc_options[]
Definition: asrc_anullsrc.c:50
static int request_frame(AVFilterLink *outlink)
AVFILTER_DEFINE_CLASS(anullsrc)
int ff_parse_sample_rate(int *ret, const char *arg, void *log_ctx)
Parse a sample rate.
Definition: formats.c:650
static av_cold int init(AVFilterContext *ctx)
Definition: asrc_anullsrc.c:62
An instance of a filter.
Definition: avfilter.h:307
internal API functions
int ff_set_common_samplerates(AVFilterContext *ctx, AVFilterFormats *samplerates)
Definition: formats.c:556
char * sample_rate_str
Definition: asrc_anullsrc.c:41