FFmpeg
utils.c
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1 /*
2  * This file is part of FFmpeg.
3  *
4  * FFmpeg is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU Lesser General Public
6  * License as published by the Free Software Foundation; either
7  * version 2.1 of the License, or (at your option) any later version.
8  *
9  * FFmpeg is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * Lesser General Public License for more details.
13  *
14  * You should have received a copy of the GNU Lesser General Public
15  * License along with FFmpeg; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
17  */
18 
19 #include "internal.h"
20 #include "libavutil/opt.h"
21 #include "libavformat/avformat.h"
22 
24 {
26  int ret = 0;
27 
28  *avctx = NULL;
29  if (!iformat && !format)
30  return AVERROR(EINVAL);
31  if (!(s = avformat_alloc_context()))
32  return AVERROR(ENOMEM);
33 
34  if (!iformat)
37  ret = AVERROR(EINVAL);
38  goto error;
39  }
40  s->iformat = iformat;
41  if (s->iformat->priv_data_size > 0) {
42  s->priv_data = av_mallocz(s->iformat->priv_data_size);
43  if (!s->priv_data) {
44  ret = AVERROR(ENOMEM);
45  goto error;
46  }
47  if (s->iformat->priv_class) {
48  *(const AVClass**)s->priv_data= s->iformat->priv_class;
49  av_opt_set_defaults(s->priv_data);
50  }
51  } else
52  s->priv_data = NULL;
53 
54  *avctx = s;
55  return 0;
56  error:
58  return ret;
59 }
error
static void error(const char *err)
Definition: target_bsf_fuzzer.c:31
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
AV_IS_INPUT_DEVICE
#define AV_IS_INPUT_DEVICE(category)
Definition: log.h:49
av_opt_set_defaults
void av_opt_set_defaults(void *s)
Set the values of all AVOption fields to their default values.
Definition: opt.c:1364
AVInputFormat
Definition: avformat.h:643
s
#define s(width, name)
Definition: cbs_vp9.c:257
AVFormatContext
Format I/O context.
Definition: avformat.h:1193
AVClass
Describe the class of an AVClass context structure.
Definition: log.h:66
NULL
#define NULL
Definition: coverity.c:32
internal.h
ff_alloc_input_device_context
int ff_alloc_input_device_context(AVFormatContext **avctx, const AVInputFormat *iformat, const char *format)
Definition: utils.c:23
avformat_alloc_context
AVFormatContext * avformat_alloc_context(void)
Allocate an AVFormatContext.
Definition: options.c:154
AVClass::category
AVClassCategory category
Category used for visualization (like color) This is only set if the category is equal for all object...
Definition: log.h:114
format
ofilter format
Definition: ffmpeg_filter.c:172
iformat
static const AVInputFormat * iformat
Definition: ffprobe.c:266
av_mallocz
void * av_mallocz(size_t size)
Allocate a memory block with alignment suitable for all memory accesses (including vectors if availab...
Definition: mem.c:263
ret
ret
Definition: filter_design.txt:187
avformat.h
avformat_free_context
void avformat_free_context(AVFormatContext *s)
Free an AVFormatContext and all its streams.
Definition: utils.c:680
av_find_input_format
const AVInputFormat * av_find_input_format(const char *short_name)
Find AVInputFormat based on the short name of the input format.
Definition: format.c:118
AVInputFormat::priv_class
const AVClass * priv_class
AVClass for the private context.
Definition: avformat.h:673