FFmpeg
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 ANullContext {
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 
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,
147  .priv_class = &anullsrc_class,
148 };
ff_get_audio_buffer
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
ANullContext::pts
int64_t pts
Definition: asrc_anullsrc.c:44
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
opt.h
ff_make_format_list
AVFilterFormats * ff_make_format_list(const int *fmts)
Create a list of supported formats.
Definition: formats.c:283
anullsrc_options
static const AVOption anullsrc_options[]
Definition: asrc_anullsrc.c:50
ff_set_common_channel_layouts
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
ff_filter_frame
int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
Send a frame of data to the next filter.
Definition: avfilter.c:1080
av_frame_free
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:202
av_get_channel_layout_string
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.
Definition: channel_layout.c:211
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:295
AVFrame::pts
int64_t pts
Presentation timestamp in time_base units (time when frame should be shown to user).
Definition: frame.h:388
AVOption
AVOption.
Definition: opt.h:246
AVFILTER_DEFINE_CLASS
AVFILTER_DEFINE_CLASS(anullsrc)
ANullContext::nb_samples
int nb_samples
number of samples per requested frame
Definition: asrc_anullsrc.c:43
AV_LOG_VERBOSE
#define AV_LOG_VERBOSE
Detailed information.
Definition: log.h:192
AVFilter::name
const char * name
Filter name.
Definition: avfilter.h:148
AVFilterContext::priv
void * priv
private data for use by the filter
Definition: avfilter.h:353
ANullContext::channel_layout
uint64_t channel_layout
Definition: asrc_anullsrc.c:40
ff_all_formats
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
avfilter_asrc_anullsrc_outputs
static const AVFilterPad avfilter_asrc_anullsrc_outputs[]
Definition: asrc_anullsrc.c:129
AVFilterPad
A filter pad used for either input or output.
Definition: internal.h:54
init
static av_cold int init(AVFilterContext *ctx)
Definition: asrc_anullsrc.c:62
buf
void * buf
Definition: avisynth_c.h:766
av_cold
#define av_cold
Definition: attributes.h:84
ff_set_common_formats
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
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
outputs
static const AVFilterPad outputs[]
Definition: af_acontrast.c:203
ctx
AVFormatContext * ctx
Definition: movenc.c:48
av_frame_clone
AVFrame * av_frame_clone(const AVFrame *src)
Create a new frame that references the same data as src.
Definition: frame.c:540
AVClass
Describe the class of an AVClass context structure.
Definition: log.h:67
NULL
#define NULL
Definition: coverity.c:32
query_formats
static int query_formats(AVFilterContext *ctx)
Definition: asrc_anullsrc.c:78
ANullContext::channel_layout_str
char * channel_layout_str
Definition: asrc_anullsrc.c:39
inputs
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several inputs
Definition: filter_design.txt:243
request_frame
static int request_frame(AVFilterLink *outlink)
Definition: asrc_anullsrc.c:106
ff_asrc_anullsrc
AVFilter ff_asrc_anullsrc
Definition: asrc_anullsrc.c:139
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:188
ff_parse_channel_layout
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
AVFrame::sample_rate
int sample_rate
Sample rate of the audio data.
Definition: frame.h:467
AVFrame::channel_layout
uint64_t channel_layout
Channel layout of the audio data.
Definition: frame.h:472
sample_rates
sample_rates
Definition: ffmpeg_filter.c:191
internal.h
avfilter_make_format64_list
AVFilterChannelLayouts * avfilter_make_format64_list(const int64_t *fmts)
Definition: formats.c:303
internal.h
AVFilterPad::name
const char * name
Pad name.
Definition: internal.h:60
AVFilter
Filter definition.
Definition: avfilter.h:144
ret
ret
Definition: filter_design.txt:187
ANullContext::sample_rate_str
char * sample_rate_str
Definition: asrc_anullsrc.c:41
channel_layout.h
AV_OPT_TYPE_INT
@ AV_OPT_TYPE_INT
Definition: opt.h:223
ANullContext
Definition: asrc_anullsrc.c:37
avfilter.h
OFFSET
#define OFFSET(x)
Definition: asrc_anullsrc.c:47
AVFilterContext
An instance of a filter.
Definition: avfilter.h:338
audio.h
FLAGS
#define FLAGS
Definition: asrc_anullsrc.c:48
ANullContext::sample_rate
int sample_rate
Definition: asrc_anullsrc.c:42
config_props
static int config_props(AVFilterLink *outlink)
Definition: asrc_anullsrc.c:93
ff_parse_sample_rate
int ff_parse_sample_rate(int *ret, const char *arg, void *log_ctx)
Parse a sample rate.
Definition: formats.c:650
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
ff_set_common_samplerates
int ff_set_common_samplerates(AVFilterContext *ctx, AVFilterFormats *samplerates)
Definition: formats.c:556
AV_OPT_TYPE_STRING
@ AV_OPT_TYPE_STRING
Definition: opt.h:227