FFmpeg
avio_reading.c
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1 /*
2  * Copyright (c) 2014 Stefano Sabatini
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a copy
5  * of this software and associated documentation files (the "Software"), to deal
6  * in the Software without restriction, including without limitation the rights
7  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
8  * copies of the Software, and to permit persons to whom the Software is
9  * furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice shall be included in
12  * all copies or substantial portions of the Software.
13  *
14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
17  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
19  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
20  * THE SOFTWARE.
21  */
22 
23 /**
24  * @file
25  * libavformat AVIOContext API example.
26  *
27  * Make libavformat demuxer access media content through a custom
28  * AVIOContext read callback.
29  * @example avio_reading.c
30  */
31 
32 #include <libavcodec/avcodec.h>
33 #include <libavformat/avformat.h>
34 #include <libavformat/avio.h>
35 #include <libavutil/file.h>
36 
37 struct buffer_data {
39  size_t size; ///< size left in the buffer
40 };
41 
42 static int read_packet(void *opaque, uint8_t *buf, int buf_size)
43 {
44  struct buffer_data *bd = (struct buffer_data *)opaque;
45  buf_size = FFMIN(buf_size, bd->size);
46 
47  if (!buf_size)
48  return AVERROR_EOF;
49  printf("ptr:%p size:%zu\n", bd->ptr, bd->size);
50 
51  /* copy internal buffer data to buf */
52  memcpy(buf, bd->ptr, buf_size);
53  bd->ptr += buf_size;
54  bd->size -= buf_size;
55 
56  return buf_size;
57 }
58 
59 int main(int argc, char *argv[])
60 {
62  AVIOContext *avio_ctx = NULL;
63  uint8_t *buffer = NULL, *avio_ctx_buffer = NULL;
64  size_t buffer_size, avio_ctx_buffer_size = 4096;
65  char *input_filename = NULL;
66  int ret = 0;
67  struct buffer_data bd = { 0 };
68 
69  if (argc != 2) {
70  fprintf(stderr, "usage: %s input_file\n"
71  "API example program to show how to read from a custom buffer "
72  "accessed through AVIOContext.\n", argv[0]);
73  return 1;
74  }
75  input_filename = argv[1];
76 
77  /* slurp file content into buffer */
78  ret = av_file_map(input_filename, &buffer, &buffer_size, 0, NULL);
79  if (ret < 0)
80  goto end;
81 
82  /* fill opaque structure used by the AVIOContext read callback */
83  bd.ptr = buffer;
84  bd.size = buffer_size;
85 
86  if (!(fmt_ctx = avformat_alloc_context())) {
87  ret = AVERROR(ENOMEM);
88  goto end;
89  }
90 
91  avio_ctx_buffer = av_malloc(avio_ctx_buffer_size);
92  if (!avio_ctx_buffer) {
93  ret = AVERROR(ENOMEM);
94  goto end;
95  }
96  avio_ctx = avio_alloc_context(avio_ctx_buffer, avio_ctx_buffer_size,
97  0, &bd, &read_packet, NULL, NULL);
98  if (!avio_ctx) {
99  ret = AVERROR(ENOMEM);
100  goto end;
101  }
102  fmt_ctx->pb = avio_ctx;
103 
104  ret = avformat_open_input(&fmt_ctx, NULL, NULL, NULL);
105  if (ret < 0) {
106  fprintf(stderr, "Could not open input\n");
107  goto end;
108  }
109 
110  ret = avformat_find_stream_info(fmt_ctx, NULL);
111  if (ret < 0) {
112  fprintf(stderr, "Could not find stream information\n");
113  goto end;
114  }
115 
116  av_dump_format(fmt_ctx, 0, input_filename, 0);
117 
118 end:
119  avformat_close_input(&fmt_ctx);
120  /* note: the internal buffer could have changed, and be != avio_ctx_buffer */
121  if (avio_ctx) {
122  av_freep(&avio_ctx->buffer);
123  av_freep(&avio_ctx);
124  }
125  av_file_unmap(buffer, buffer_size);
126 
127  if (ret < 0) {
128  fprintf(stderr, "Error occurred: %s\n", av_err2str(ret));
129  return 1;
130  }
131 
132  return 0;
133 }
#define NULL
Definition: coverity.c:32
Bytestream IO Context.
Definition: avio.h:161
Buffered I/O operations.
static AVFormatContext * fmt_ctx
unsigned char * buffer
Start of the buffer.
Definition: avio.h:226
Format I/O context.
Definition: avformat.h:1351
uint8_t
#define av_malloc(s)
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:90
AVFormatContext * avformat_alloc_context(void)
Allocate an AVFormatContext.
Definition: options.c:144
Misc file utilities.
#define AVERROR_EOF
End of file.
Definition: error.h:55
void av_dump_format(AVFormatContext *ic, int index, const char *url, int is_output)
Print detailed information about the input or output format, such as duration, bitrate, streams, container, programs, metadata, side data, codec and time base.
Definition: dump.c:563
AVIOContext * avio_alloc_context(unsigned char *buffer, int buffer_size, int write_flag, void *opaque, int(*read_packet)(void *opaque, uint8_t *buf, int buf_size), int(*write_packet)(void *opaque, uint8_t *buf, int buf_size), int64_t(*seek)(void *opaque, int64_t offset, int whence))
Allocate and initialize an AVIOContext for buffered I/O.
Definition: aviobuf.c:131
void av_file_unmap(uint8_t *bufptr, size_t size)
Unmap or free the buffer bufptr created by av_file_map().
Definition: file.c:139
int av_file_map(const char *filename, uint8_t **bufptr, size_t *size, int log_offset, void *log_ctx)
Read the file with name filename, and put its content in a newly allocated buffer or map it with mmap...
Definition: file.c:53
size_t size
size left in the buffer
Definition: avio_reading.c:39
#define FFMIN(a, b)
Definition: common.h:96
#define av_err2str(errnum)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition: error.h:119
uint8_t * ptr
Definition: avio_reading.c:38
static const char * input_filename
Definition: ffplay.c:311
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_reading.c:42
Libavcodec external API header.
AVIOContext * pb
I/O context.
Definition: avformat.h:1393
int main(int argc, char *argv[])
Definition: avio_reading.c:59
void * buf
Definition: avisynth_c.h:690
Main libavformat public API header.
int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
Read packets of a media file to get stream information.
Definition: utils.c:3564
void avformat_close_input(AVFormatContext **s)
Close an opened input AVFormatContext.
Definition: utils.c:4427
printf("static const uint8_t my_array[100] = {\n")
int avformat_open_input(AVFormatContext **ps, const char *url, AVInputFormat *fmt, AVDictionary **options)
Open an input stream and read the header.
Definition: utils.c:537
#define av_freep(p)
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
GLuint buffer
Definition: opengl_enc.c:102