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demuxing_decoding.c
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1 /*
2  * Copyright (c) 2012 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  * Demuxing and decoding example.
26  *
27  * Show how to use the libavformat and libavcodec API to demux and
28  * decode audio and video data.
29  * @example demuxing_decoding.c
30  */
31 
32 #include <libavutil/imgutils.h>
33 #include <libavutil/samplefmt.h>
34 #include <libavutil/timestamp.h>
35 #include <libavformat/avformat.h>
36 
37 static AVFormatContext *fmt_ctx = NULL;
39 static AVStream *video_stream = NULL, *audio_stream = NULL;
40 static const char *src_filename = NULL;
41 static const char *video_dst_filename = NULL;
42 static const char *audio_dst_filename = NULL;
43 static FILE *video_dst_file = NULL;
44 static FILE *audio_dst_file = NULL;
45 
46 static uint8_t *video_dst_data[4] = {NULL};
47 static int video_dst_linesize[4];
48 static int video_dst_bufsize;
49 
50 static int video_stream_idx = -1, audio_stream_idx = -1;
51 static AVFrame *frame = NULL;
52 static AVPacket pkt;
53 static int video_frame_count = 0;
54 static int audio_frame_count = 0;
55 
56 /* The different ways of decoding and managing data memory. You are not
57  * supposed to support all the modes in your application but pick the one most
58  * appropriate to your needs. Look for the use of api_mode in this example to
59  * see what are the differences of API usage between them */
60 enum {
61  API_MODE_OLD = 0, /* old method, deprecated */
62  API_MODE_NEW_API_REF_COUNT = 1, /* new method, using the frame reference counting */
63  API_MODE_NEW_API_NO_REF_COUNT = 2, /* new method, without reference counting */
64 };
65 
66 static int api_mode = API_MODE_OLD;
67 
68 static int decode_packet(int *got_frame, int cached)
69 {
70  int ret = 0;
71  int decoded = pkt.size;
72 
73  *got_frame = 0;
74 
75  if (pkt.stream_index == video_stream_idx) {
76  /* decode video frame */
77  ret = avcodec_decode_video2(video_dec_ctx, frame, got_frame, &pkt);
78  if (ret < 0) {
79  fprintf(stderr, "Error decoding video frame (%s)\n", av_err2str(ret));
80  return ret;
81  }
82 
83  if (*got_frame) {
84  printf("video_frame%s n:%d coded_n:%d pts:%s\n",
85  cached ? "(cached)" : "",
87  av_ts2timestr(frame->pts, &video_dec_ctx->time_base));
88 
89  /* copy decoded frame to destination buffer:
90  * this is required since rawvideo expects non aligned data */
92  (const uint8_t **)(frame->data), frame->linesize,
93  video_dec_ctx->pix_fmt, video_dec_ctx->width, video_dec_ctx->height);
94 
95  /* write to rawvideo file */
97  }
98  } else if (pkt.stream_index == audio_stream_idx) {
99  /* decode audio frame */
100  ret = avcodec_decode_audio4(audio_dec_ctx, frame, got_frame, &pkt);
101  if (ret < 0) {
102  fprintf(stderr, "Error decoding audio frame (%s)\n", av_err2str(ret));
103  return ret;
104  }
105  /* Some audio decoders decode only part of the packet, and have to be
106  * called again with the remainder of the packet data.
107  * Sample: fate-suite/lossless-audio/luckynight-partial.shn
108  * Also, some decoders might over-read the packet. */
109  decoded = FFMIN(ret, pkt.size);
110 
111  if (*got_frame) {
112  size_t unpadded_linesize = frame->nb_samples * av_get_bytes_per_sample(frame->format);
113  printf("audio_frame%s n:%d nb_samples:%d pts:%s\n",
114  cached ? "(cached)" : "",
115  audio_frame_count++, frame->nb_samples,
117 
118  /* Write the raw audio data samples of the first plane. This works
119  * fine for packed formats (e.g. AV_SAMPLE_FMT_S16). However,
120  * most audio decoders output planar audio, which uses a separate
121  * plane of audio samples for each channel (e.g. AV_SAMPLE_FMT_S16P).
122  * In other words, this code will write only the first audio channel
123  * in these cases.
124  * You should use libswresample or libavfilter to convert the frame
125  * to packed data. */
126  fwrite(frame->extended_data[0], 1, unpadded_linesize, audio_dst_file);
127  }
128  }
129 
130  /* If we use the new API with reference counting, we own the data and need
131  * to de-reference it when we don't use it anymore */
132  if (*got_frame && api_mode == API_MODE_NEW_API_REF_COUNT)
133  av_frame_unref(frame);
134 
135  return decoded;
136 }
137 
138 static int open_codec_context(int *stream_idx,
139  AVFormatContext *fmt_ctx, enum AVMediaType type)
140 {
141  int ret;
142  AVStream *st;
143  AVCodecContext *dec_ctx = NULL;
144  AVCodec *dec = NULL;
145  AVDictionary *opts = NULL;
146 
147  ret = av_find_best_stream(fmt_ctx, type, -1, -1, NULL, 0);
148  if (ret < 0) {
149  fprintf(stderr, "Could not find %s stream in input file '%s'\n",
151  return ret;
152  } else {
153  *stream_idx = ret;
154  st = fmt_ctx->streams[*stream_idx];
155 
156  /* find decoder for the stream */
157  dec_ctx = st->codec;
158  dec = avcodec_find_decoder(dec_ctx->codec_id);
159  if (!dec) {
160  fprintf(stderr, "Failed to find %s codec\n",
162  return AVERROR(EINVAL);
163  }
164 
165  /* Init the decoders, with or without reference counting */
167  av_dict_set(&opts, "refcounted_frames", "1", 0);
168  if ((ret = avcodec_open2(dec_ctx, dec, &opts)) < 0) {
169  fprintf(stderr, "Failed to open %s codec\n",
171  return ret;
172  }
173  }
174 
175  return 0;
176 }
177 
178 static int get_format_from_sample_fmt(const char **fmt,
179  enum AVSampleFormat sample_fmt)
180 {
181  int i;
182  struct sample_fmt_entry {
183  enum AVSampleFormat sample_fmt; const char *fmt_be, *fmt_le;
184  } sample_fmt_entries[] = {
185  { AV_SAMPLE_FMT_U8, "u8", "u8" },
186  { AV_SAMPLE_FMT_S16, "s16be", "s16le" },
187  { AV_SAMPLE_FMT_S32, "s32be", "s32le" },
188  { AV_SAMPLE_FMT_FLT, "f32be", "f32le" },
189  { AV_SAMPLE_FMT_DBL, "f64be", "f64le" },
190  };
191  *fmt = NULL;
192 
193  for (i = 0; i < FF_ARRAY_ELEMS(sample_fmt_entries); i++) {
194  struct sample_fmt_entry *entry = &sample_fmt_entries[i];
195  if (sample_fmt == entry->sample_fmt) {
196  *fmt = AV_NE(entry->fmt_be, entry->fmt_le);
197  return 0;
198  }
199  }
200 
201  fprintf(stderr,
202  "sample format %s is not supported as output format\n",
203  av_get_sample_fmt_name(sample_fmt));
204  return -1;
205 }
206 
207 int main (int argc, char **argv)
208 {
209  int ret = 0, got_frame;
210 
211  if (argc != 4 && argc != 5) {
212  fprintf(stderr, "usage: %s [-refcount=<old|new_norefcount|new_refcount>] "
213  "input_file video_output_file audio_output_file\n"
214  "API example program to show how to read frames from an input file.\n"
215  "This program reads frames from a file, decodes them, and writes decoded\n"
216  "video frames to a rawvideo file named video_output_file, and decoded\n"
217  "audio frames to a rawaudio file named audio_output_file.\n\n"
218  "If the -refcount option is specified, the program use the\n"
219  "reference counting frame system which allows keeping a copy of\n"
220  "the data for longer than one decode call. If unset, it's using\n"
221  "the classic old method.\n"
222  "\n", argv[0]);
223  exit(1);
224  }
225  if (argc == 5) {
226  const char *mode = argv[1] + strlen("-refcount=");
227  if (!strcmp(mode, "old")) api_mode = API_MODE_OLD;
228  else if (!strcmp(mode, "new_norefcount")) api_mode = API_MODE_NEW_API_NO_REF_COUNT;
229  else if (!strcmp(mode, "new_refcount")) api_mode = API_MODE_NEW_API_REF_COUNT;
230  else {
231  fprintf(stderr, "unknow mode '%s'\n", mode);
232  exit(1);
233  }
234  argv++;
235  }
236  src_filename = argv[1];
237  video_dst_filename = argv[2];
238  audio_dst_filename = argv[3];
239 
240  /* register all formats and codecs */
241  av_register_all();
242 
243  /* open input file, and allocate format context */
244  if (avformat_open_input(&fmt_ctx, src_filename, NULL, NULL) < 0) {
245  fprintf(stderr, "Could not open source file %s\n", src_filename);
246  exit(1);
247  }
248 
249  /* retrieve stream information */
250  if (avformat_find_stream_info(fmt_ctx, NULL) < 0) {
251  fprintf(stderr, "Could not find stream information\n");
252  exit(1);
253  }
254 
256  video_stream = fmt_ctx->streams[video_stream_idx];
257  video_dec_ctx = video_stream->codec;
258 
259  video_dst_file = fopen(video_dst_filename, "wb");
260  if (!video_dst_file) {
261  fprintf(stderr, "Could not open destination file %s\n", video_dst_filename);
262  ret = 1;
263  goto end;
264  }
265 
266  /* allocate image where the decoded image will be put */
268  video_dec_ctx->width, video_dec_ctx->height,
269  video_dec_ctx->pix_fmt, 1);
270  if (ret < 0) {
271  fprintf(stderr, "Could not allocate raw video buffer\n");
272  goto end;
273  }
275  }
276 
280  audio_dst_file = fopen(audio_dst_filename, "wb");
281  if (!audio_dst_file) {
282  fprintf(stderr, "Could not open destination file %s\n", audio_dst_filename);
283  ret = 1;
284  goto end;
285  }
286  }
287 
288  /* dump input information to stderr */
289  av_dump_format(fmt_ctx, 0, src_filename, 0);
290 
291  if (!audio_stream && !video_stream) {
292  fprintf(stderr, "Could not find audio or video stream in the input, aborting\n");
293  ret = 1;
294  goto end;
295  }
296 
297  /* When using the new API, you need to use the libavutil/frame.h API, while
298  * the classic frame management is available in libavcodec */
299  if (api_mode == API_MODE_OLD)
300  frame = avcodec_alloc_frame();
301  else
302  frame = av_frame_alloc();
303  if (!frame) {
304  fprintf(stderr, "Could not allocate frame\n");
305  ret = AVERROR(ENOMEM);
306  goto end;
307  }
308 
309  /* initialize packet, set data to NULL, let the demuxer fill it */
310  av_init_packet(&pkt);
311  pkt.data = NULL;
312  pkt.size = 0;
313 
314  if (video_stream)
315  printf("Demuxing video from file '%s' into '%s'\n", src_filename, video_dst_filename);
316  if (audio_stream)
317  printf("Demuxing audio from file '%s' into '%s'\n", src_filename, audio_dst_filename);
318 
319  /* read frames from the file */
320  while (av_read_frame(fmt_ctx, &pkt) >= 0) {
321  AVPacket orig_pkt = pkt;
322  do {
323  ret = decode_packet(&got_frame, 0);
324  if (ret < 0)
325  break;
326  pkt.data += ret;
327  pkt.size -= ret;
328  } while (pkt.size > 0);
329  av_free_packet(&orig_pkt);
330  }
331 
332  /* flush cached frames */
333  pkt.data = NULL;
334  pkt.size = 0;
335  do {
336  decode_packet(&got_frame, 1);
337  } while (got_frame);
338 
339  printf("Demuxing succeeded.\n");
340 
341  if (video_stream) {
342  printf("Play the output video file with the command:\n"
343  "ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",
344  av_get_pix_fmt_name(video_dec_ctx->pix_fmt), video_dec_ctx->width, video_dec_ctx->height,
346  }
347 
348  if (audio_stream) {
350  int n_channels = audio_dec_ctx->channels;
351  const char *fmt;
352 
353  if (av_sample_fmt_is_planar(sfmt)) {
354  const char *packed = av_get_sample_fmt_name(sfmt);
355  printf("Warning: the sample format the decoder produced is planar "
356  "(%s). This example will output the first channel only.\n",
357  packed ? packed : "?");
358  sfmt = av_get_packed_sample_fmt(sfmt);
359  n_channels = 1;
360  }
361 
362  if ((ret = get_format_from_sample_fmt(&fmt, sfmt)) < 0)
363  goto end;
364 
365  printf("Play the output audio file with the command:\n"
366  "ffplay -f %s -ac %d -ar %d %s\n",
367  fmt, n_channels, audio_dec_ctx->sample_rate,
369  }
370 
371 end:
372  avcodec_close(video_dec_ctx);
374  avformat_close_input(&fmt_ctx);
375  if (video_dst_file)
376  fclose(video_dst_file);
377  if (audio_dst_file)
378  fclose(audio_dst_file);
379  if (api_mode == API_MODE_OLD)
380  avcodec_free_frame(&frame);
381  else
382  av_frame_free(&frame);
384 
385  return ret < 0;
386 }