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decode_video.c
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1 /*
2  * Copyright (c) 2001 Fabrice Bellard
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  * video decoding with libavcodec API example
26  *
27  * @example decode_video.c
28  */
29 
30 #include <stdio.h>
31 #include <stdlib.h>
32 #include <string.h>
33 
34 #include <libavcodec/avcodec.h>
35 
36 #define INBUF_SIZE 4096
37 
38 static void pgm_save(unsigned char *buf, int wrap, int xsize, int ysize,
39  char *filename)
40 {
41  FILE *f;
42  int i;
43 
44  f = fopen(filename,"w");
45  fprintf(f, "P5\n%d %d\n%d\n", xsize, ysize, 255);
46  for (i = 0; i < ysize; i++)
47  fwrite(buf + i * wrap, 1, xsize, f);
48  fclose(f);
49 }
50 
52  const char *filename)
53 {
54  char buf[1024];
55  int ret;
56 
57  ret = avcodec_send_packet(dec_ctx, pkt);
58  if (ret < 0) {
59  fprintf(stderr, "Error sending a packet for decoding\n");
60  exit(1);
61  }
62 
63  while (ret >= 0) {
64  ret = avcodec_receive_frame(dec_ctx, frame);
65  if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
66  return;
67  else if (ret < 0) {
68  fprintf(stderr, "Error during decoding\n");
69  exit(1);
70  }
71 
72  printf("saving frame %3d\n", dec_ctx->frame_number);
73  fflush(stdout);
74 
75  /* the picture is allocated by the decoder. no need to
76  free it */
77  snprintf(buf, sizeof(buf), "%s-%d", filename, dec_ctx->frame_number);
78  pgm_save(frame->data[0], frame->linesize[0],
79  frame->width, frame->height, buf);
80  }
81 }
82 
83 int main(int argc, char **argv)
84 {
85  const char *filename, *outfilename;
86  const AVCodec *codec;
87  AVCodecParserContext *parser;
89  FILE *f;
90  AVFrame *frame;
92  uint8_t *data;
93  size_t data_size;
94  int ret;
95  AVPacket *pkt;
96 
97  if (argc <= 2) {
98  fprintf(stderr, "Usage: %s <input file> <output file>\n", argv[0]);
99  exit(0);
100  }
101  filename = argv[1];
102  outfilename = argv[2];
103 
105 
106  pkt = av_packet_alloc();
107  if (!pkt)
108  exit(1);
109 
110  /* set end of buffer to 0 (this ensures that no overreading happens for damaged MPEG streams) */
111  memset(inbuf + INBUF_SIZE, 0, AV_INPUT_BUFFER_PADDING_SIZE);
112 
113  /* find the MPEG-1 video decoder */
115  if (!codec) {
116  fprintf(stderr, "Codec not found\n");
117  exit(1);
118  }
119 
120  parser = av_parser_init(codec->id);
121  if (!parser) {
122  fprintf(stderr, "parser not found\n");
123  exit(1);
124  }
125 
126  c = avcodec_alloc_context3(codec);
127  if (!c) {
128  fprintf(stderr, "Could not allocate video codec context\n");
129  exit(1);
130  }
131 
132  /* For some codecs, such as msmpeg4 and mpeg4, width and height
133  MUST be initialized there because this information is not
134  available in the bitstream. */
135 
136  /* open it */
137  if (avcodec_open2(c, codec, NULL) < 0) {
138  fprintf(stderr, "Could not open codec\n");
139  exit(1);
140  }
141 
142  f = fopen(filename, "rb");
143  if (!f) {
144  fprintf(stderr, "Could not open %s\n", filename);
145  exit(1);
146  }
147 
148  frame = av_frame_alloc();
149  if (!frame) {
150  fprintf(stderr, "Could not allocate video frame\n");
151  exit(1);
152  }
153 
154  while (!feof(f)) {
155  /* read raw data from the input file */
156  data_size = fread(inbuf, 1, INBUF_SIZE, f);
157  if (!data_size)
158  break;
159 
160  /* use the parser to split the data into frames */
161  data = inbuf;
162  while (data_size > 0) {
163  ret = av_parser_parse2(parser, c, &pkt->data, &pkt->size,
164  data, data_size, AV_NOPTS_VALUE, AV_NOPTS_VALUE, 0);
165  if (ret < 0) {
166  fprintf(stderr, "Error while parsing\n");
167  exit(1);
168  }
169  data += ret;
170  data_size -= ret;
171 
172  if (pkt->size)
173  decode(c, frame, pkt, outfilename);
174  }
175  }
176 
177  /* flush the decoder */
178  decode(c, frame, NULL, outfilename);
179 
180  fclose(f);
181 
182  av_parser_close(parser);
184  av_frame_free(&frame);
185  av_packet_free(&pkt);
186 
187  return 0;
188 }
#define NULL
Definition: coverity.c:32
#define INBUF_SIZE
Definition: decode_video.c:36
This structure describes decoded (raw) audio or video data.
Definition: frame.h:201
ptrdiff_t const GLvoid * data
Definition: opengl_enc.c:101
static void pgm_save(unsigned char *buf, int wrap, int xsize, int ysize, char *filename)
Definition: decode_video.c:38
int size
Definition: avcodec.h:1415
int main(int argc, char **argv)
Definition: decode_video.c:83
static AVPacket pkt
void avcodec_register_all(void)
Register all the codecs, parsers and bitstream filters which were enabled at configuration time...
Definition: allcodecs.c:664
AVCodec.
Definition: avcodec.h:3365
void av_packet_free(AVPacket **pkt)
Free the packet, if the packet is reference counted, it will be unreferenced first.
Definition: avpacket.c:62
uint8_t
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
Definition: frame.c:150
static AVFrame * frame
uint8_t * data
Definition: avcodec.h:1414
#define AVERROR_EOF
End of file.
Definition: error.h:55
enum AVCodecID id
Definition: avcodec.h:3379
int width
Definition: frame.h:259
#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:163
int avcodec_receive_frame(AVCodecContext *avctx, AVFrame *frame)
Return decoded output data from a decoder.
Definition: decode.c:709
#define wrap(func)
Definition: neontest.h:65
static void decode(AVCodecContext *dec_ctx, AVFrame *frame, AVPacket *pkt, const char *filename)
Definition: decode_video.c:51
AVCodecContext * avcodec_alloc_context3(const AVCodec *codec)
Allocate an AVCodecContext and set its fields to default values.
Definition: options.c:157
int av_parser_parse2(AVCodecParserContext *s, AVCodecContext *avctx, uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size, int64_t pts, int64_t dts, int64_t pos)
Parse a packet.
Definition: parser.c:137
void av_parser_close(AVCodecParserContext *s)
Definition: parser.c:241
int avcodec_send_packet(AVCodecContext *avctx, const AVPacket *avpkt)
Supply raw packet data as input to a decoder.
Definition: decode.c:642
AVCodecParserContext * av_parser_init(int codec_id)
Definition: parser.c:52
Libavcodec external API header.
void avcodec_free_context(AVCodecContext **avctx)
Free the codec context and everything associated with it and write NULL to the provided pointer...
Definition: options.c:172
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:232
main external API structure.
Definition: avcodec.h:1502
AVCodec * avcodec_find_decoder(enum AVCodecID id)
Find a registered decoder with a matching codec ID.
Definition: utils.c:1251
void * buf
Definition: avisynth_c.h:690
int avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **options)
Initialize the AVCodecContext to use the given AVCodec.
Definition: utils.c:614
#define snprintf
Definition: snprintf.h:34
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:215
static double c[64]
static AVCodecContext * dec_ctx
#define AV_INPUT_BUFFER_PADDING_SIZE
Required number of additionally allocated bytes at the end of the input bitstream for decoding...
Definition: avcodec.h:770
AVPacket * av_packet_alloc(void)
Allocate an AVPacket and set its fields to default values.
Definition: avpacket.c:51
int frame_number
Frame counter, set by libavcodec.
Definition: avcodec.h:2188
int height
Definition: frame.h:259
This structure stores compressed data.
Definition: avcodec.h:1391
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248