FFmpeg  3.0.7
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 int width, height;
40 static enum AVPixelFormat pix_fmt;
41 static AVStream *video_stream = NULL, *audio_stream = NULL;
42 static const char *src_filename = NULL;
43 static const char *video_dst_filename = NULL;
44 static const char *audio_dst_filename = NULL;
45 static FILE *video_dst_file = NULL;
46 static FILE *audio_dst_file = NULL;
47 
48 static uint8_t *video_dst_data[4] = {NULL};
49 static int video_dst_linesize[4];
50 static int video_dst_bufsize;
51 
52 static int video_stream_idx = -1, audio_stream_idx = -1;
53 static AVFrame *frame = NULL;
54 static AVPacket pkt;
55 static int video_frame_count = 0;
56 static int audio_frame_count = 0;
57 
58 /* Enable or disable frame reference counting. You are not supposed to support
59  * both paths in your application but pick the one most appropriate to your
60  * needs. Look for the use of refcount in this example to see what are the
61  * differences of API usage between them. */
62 static int refcount = 0;
63 
64 static int decode_packet(int *got_frame, int cached)
65 {
66  int ret = 0;
67  int decoded = pkt.size;
68 
69  *got_frame = 0;
70 
71  if (pkt.stream_index == video_stream_idx) {
72  /* decode video frame */
73  ret = avcodec_decode_video2(video_dec_ctx, frame, got_frame, &pkt);
74  if (ret < 0) {
75  fprintf(stderr, "Error decoding video frame (%s)\n", av_err2str(ret));
76  return ret;
77  }
78 
79  if (*got_frame) {
80 
81  if (frame->width != width || frame->height != height ||
82  frame->format != pix_fmt) {
83  /* To handle this change, one could call av_image_alloc again and
84  * decode the following frames into another rawvideo file. */
85  fprintf(stderr, "Error: Width, height and pixel format have to be "
86  "constant in a rawvideo file, but the width, height or "
87  "pixel format of the input video changed:\n"
88  "old: width = %d, height = %d, format = %s\n"
89  "new: width = %d, height = %d, format = %s\n",
91  frame->width, frame->height,
92  av_get_pix_fmt_name(frame->format));
93  return -1;
94  }
95 
96  printf("video_frame%s n:%d coded_n:%d\n",
97  cached ? "(cached)" : "",
99 
100  /* copy decoded frame to destination buffer:
101  * this is required since rawvideo expects non aligned data */
103  (const uint8_t **)(frame->data), frame->linesize,
104  pix_fmt, width, height);
105 
106  /* write to rawvideo file */
108  }
109  } else if (pkt.stream_index == audio_stream_idx) {
110  /* decode audio frame */
111  ret = avcodec_decode_audio4(audio_dec_ctx, frame, got_frame, &pkt);
112  if (ret < 0) {
113  fprintf(stderr, "Error decoding audio frame (%s)\n", av_err2str(ret));
114  return ret;
115  }
116  /* Some audio decoders decode only part of the packet, and have to be
117  * called again with the remainder of the packet data.
118  * Sample: fate-suite/lossless-audio/luckynight-partial.shn
119  * Also, some decoders might over-read the packet. */
120  decoded = FFMIN(ret, pkt.size);
121 
122  if (*got_frame) {
123  size_t unpadded_linesize = frame->nb_samples * av_get_bytes_per_sample(frame->format);
124  printf("audio_frame%s n:%d nb_samples:%d pts:%s\n",
125  cached ? "(cached)" : "",
126  audio_frame_count++, frame->nb_samples,
128 
129  /* Write the raw audio data samples of the first plane. This works
130  * fine for packed formats (e.g. AV_SAMPLE_FMT_S16). However,
131  * most audio decoders output planar audio, which uses a separate
132  * plane of audio samples for each channel (e.g. AV_SAMPLE_FMT_S16P).
133  * In other words, this code will write only the first audio channel
134  * in these cases.
135  * You should use libswresample or libavfilter to convert the frame
136  * to packed data. */
137  fwrite(frame->extended_data[0], 1, unpadded_linesize, audio_dst_file);
138  }
139  }
140 
141  /* If we use frame reference counting, we own the data and need
142  * to de-reference it when we don't use it anymore */
143  if (*got_frame && refcount)
144  av_frame_unref(frame);
145 
146  return decoded;
147 }
148 
149 static int open_codec_context(int *stream_idx,
150  AVFormatContext *fmt_ctx, enum AVMediaType type)
151 {
152  int ret, stream_index;
153  AVStream *st;
154  AVCodecContext *dec_ctx = NULL;
155  AVCodec *dec = NULL;
156  AVDictionary *opts = NULL;
157 
158  ret = av_find_best_stream(fmt_ctx, type, -1, -1, NULL, 0);
159  if (ret < 0) {
160  fprintf(stderr, "Could not find %s stream in input file '%s'\n",
162  return ret;
163  } else {
164  stream_index = ret;
165  st = fmt_ctx->streams[stream_index];
166 
167  /* find decoder for the stream */
168  dec_ctx = st->codec;
169  dec = avcodec_find_decoder(dec_ctx->codec_id);
170  if (!dec) {
171  fprintf(stderr, "Failed to find %s codec\n",
173  return AVERROR(EINVAL);
174  }
175 
176  /* Init the decoders, with or without reference counting */
177  av_dict_set(&opts, "refcounted_frames", refcount ? "1" : "0", 0);
178  if ((ret = avcodec_open2(dec_ctx, dec, &opts)) < 0) {
179  fprintf(stderr, "Failed to open %s codec\n",
181  return ret;
182  }
183  *stream_idx = stream_index;
184  }
185 
186  return 0;
187 }
188 
189 static int get_format_from_sample_fmt(const char **fmt,
190  enum AVSampleFormat sample_fmt)
191 {
192  int i;
193  struct sample_fmt_entry {
194  enum AVSampleFormat sample_fmt; const char *fmt_be, *fmt_le;
195  } sample_fmt_entries[] = {
196  { AV_SAMPLE_FMT_U8, "u8", "u8" },
197  { AV_SAMPLE_FMT_S16, "s16be", "s16le" },
198  { AV_SAMPLE_FMT_S32, "s32be", "s32le" },
199  { AV_SAMPLE_FMT_FLT, "f32be", "f32le" },
200  { AV_SAMPLE_FMT_DBL, "f64be", "f64le" },
201  };
202  *fmt = NULL;
203 
204  for (i = 0; i < FF_ARRAY_ELEMS(sample_fmt_entries); i++) {
205  struct sample_fmt_entry *entry = &sample_fmt_entries[i];
206  if (sample_fmt == entry->sample_fmt) {
207  *fmt = AV_NE(entry->fmt_be, entry->fmt_le);
208  return 0;
209  }
210  }
211 
212  fprintf(stderr,
213  "sample format %s is not supported as output format\n",
214  av_get_sample_fmt_name(sample_fmt));
215  return -1;
216 }
217 
218 int main (int argc, char **argv)
219 {
220  int ret = 0, got_frame;
221 
222  if (argc != 4 && argc != 5) {
223  fprintf(stderr, "usage: %s [-refcount] input_file video_output_file audio_output_file\n"
224  "API example program to show how to read frames from an input file.\n"
225  "This program reads frames from a file, decodes them, and writes decoded\n"
226  "video frames to a rawvideo file named video_output_file, and decoded\n"
227  "audio frames to a rawaudio file named audio_output_file.\n\n"
228  "If the -refcount option is specified, the program use the\n"
229  "reference counting frame system which allows keeping a copy of\n"
230  "the data for longer than one decode call.\n"
231  "\n", argv[0]);
232  exit(1);
233  }
234  if (argc == 5 && !strcmp(argv[1], "-refcount")) {
235  refcount = 1;
236  argv++;
237  }
238  src_filename = argv[1];
239  video_dst_filename = argv[2];
240  audio_dst_filename = argv[3];
241 
242  /* register all formats and codecs */
243  av_register_all();
244 
245  /* open input file, and allocate format context */
246  if (avformat_open_input(&fmt_ctx, src_filename, NULL, NULL) < 0) {
247  fprintf(stderr, "Could not open source file %s\n", src_filename);
248  exit(1);
249  }
250 
251  /* retrieve stream information */
252  if (avformat_find_stream_info(fmt_ctx, NULL) < 0) {
253  fprintf(stderr, "Could not find stream information\n");
254  exit(1);
255  }
256 
258  video_stream = fmt_ctx->streams[video_stream_idx];
259  video_dec_ctx = video_stream->codec;
260 
261  video_dst_file = fopen(video_dst_filename, "wb");
262  if (!video_dst_file) {
263  fprintf(stderr, "Could not open destination file %s\n", video_dst_filename);
264  ret = 1;
265  goto end;
266  }
267 
268  /* allocate image where the decoded image will be put */
269  width = video_dec_ctx->width;
270  height = video_dec_ctx->height;
271  pix_fmt = video_dec_ctx->pix_fmt;
273  width, height, pix_fmt, 1);
274  if (ret < 0) {
275  fprintf(stderr, "Could not allocate raw video buffer\n");
276  goto end;
277  }
278  video_dst_bufsize = ret;
279  }
280 
284  audio_dst_file = fopen(audio_dst_filename, "wb");
285  if (!audio_dst_file) {
286  fprintf(stderr, "Could not open destination file %s\n", audio_dst_filename);
287  ret = 1;
288  goto end;
289  }
290  }
291 
292  /* dump input information to stderr */
293  av_dump_format(fmt_ctx, 0, src_filename, 0);
294 
295  if (!audio_stream && !video_stream) {
296  fprintf(stderr, "Could not find audio or video stream in the input, aborting\n");
297  ret = 1;
298  goto end;
299  }
300 
301  frame = av_frame_alloc();
302  if (!frame) {
303  fprintf(stderr, "Could not allocate frame\n");
304  ret = AVERROR(ENOMEM);
305  goto end;
306  }
307 
308  /* initialize packet, set data to NULL, let the demuxer fill it */
309  av_init_packet(&pkt);
310  pkt.data = NULL;
311  pkt.size = 0;
312 
313  if (video_stream)
314  printf("Demuxing video from file '%s' into '%s'\n", src_filename, video_dst_filename);
315  if (audio_stream)
316  printf("Demuxing audio from file '%s' into '%s'\n", src_filename, audio_dst_filename);
317 
318  /* read frames from the file */
319  while (av_read_frame(fmt_ctx, &pkt) >= 0) {
320  AVPacket orig_pkt = pkt;
321  do {
322  ret = decode_packet(&got_frame, 0);
323  if (ret < 0)
324  break;
325  pkt.data += ret;
326  pkt.size -= ret;
327  } while (pkt.size > 0);
328  av_packet_unref(&orig_pkt);
329  }
330 
331  /* flush cached frames */
332  pkt.data = NULL;
333  pkt.size = 0;
334  do {
335  decode_packet(&got_frame, 1);
336  } while (got_frame);
337 
338  printf("Demuxing succeeded.\n");
339 
340  if (video_stream) {
341  printf("Play the output video file with the command:\n"
342  "ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",
345  }
346 
347  if (audio_stream) {
349  int n_channels = audio_dec_ctx->channels;
350  const char *fmt;
351 
352  if (av_sample_fmt_is_planar(sfmt)) {
353  const char *packed = av_get_sample_fmt_name(sfmt);
354  printf("Warning: the sample format the decoder produced is planar "
355  "(%s). This example will output the first channel only.\n",
356  packed ? packed : "?");
357  sfmt = av_get_packed_sample_fmt(sfmt);
358  n_channels = 1;
359  }
360 
361  if ((ret = get_format_from_sample_fmt(&fmt, sfmt)) < 0)
362  goto end;
363 
364  printf("Play the output audio file with the command:\n"
365  "ffplay -f %s -ac %d -ar %d %s\n",
366  fmt, n_channels, audio_dec_ctx->sample_rate,
368  }
369 
370 end:
371  avcodec_close(video_dec_ctx);
373  avformat_close_input(&fmt_ctx);
374  if (video_dst_file)
375  fclose(video_dst_file);
376  if (audio_dst_file)
377  fclose(audio_dst_file);
378  av_frame_free(&frame);
380 
381  return ret < 0;
382 }
static int decode_packet(int *got_frame, int cached)
static enum AVPixelFormat pix_fmt
This structure describes decoded (raw) audio or video data.
Definition: frame.h:181
misc image utilities
int av_image_alloc(uint8_t *pointers[4], int linesizes[4], int w, int h, enum AVPixelFormat pix_fmt, int align)
Allocate an image with size w and h and pixel format pix_fmt, and fill pointers and linesizes accordi...
static AVFormatContext * fmt_ctx
int size
Definition: avcodec.h:1468
static int audio_frame_count
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1752
static AVStream * video_stream
static AVPacket pkt
static int audio_stream_idx
AVCodec.
Definition: avcodec.h:3392
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented...
Definition: avcodec.h:1661
Format I/O context.
Definition: avformat.h:1314
static FILE * audio_dst_file
enum AVSampleFormat sample_fmt
audio sample format
Definition: avcodec.h:2295
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
static int video_stream_idx
timestamp utils, mostly useful for debugging/logging purposes
#define AV_NE(be, le)
Definition: common.h:50
int64_t pts
Presentation timestamp in time_base units (time when frame should be shown to user).
Definition: frame.h:262
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1382
static AVFrame * frame
uint8_t * data
Definition: avcodec.h:1467
static uint8_t * video_dst_data[4]
signed 32 bits
Definition: samplefmt.h:63
int av_sample_fmt_is_planar(enum AVSampleFormat sample_fmt)
Check if the sample format is planar.
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.
int av_find_best_stream(AVFormatContext *ic, enum AVMediaType type, int wanted_stream_nb, int related_stream, AVCodec **decoder_ret, int flags)
Find the "best" stream in the file.
int avcodec_close(AVCodecContext *avctx)
Close a given AVCodecContext and free all the data associated with it (but not the AVCodecContext its...
int width
width and height of the video frame
Definition: frame.h:230
void av_free(void *ptr)
Free a memory block which has been allocated with av_malloc(z)() or av_realloc(). ...
static int video_dst_linesize[4]
int avcodec_decode_video2(AVCodecContext *avctx, AVFrame *picture, int *got_picture_ptr, const AVPacket *avpkt)
Decode the video frame of size avpkt->size from avpkt->data into picture.
static const char * audio_dst_filename
#define AVERROR(e)
Definition: error.h:43
static AVStream * audio_stream
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
#define av_ts2timestr(ts, tb)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition: timestamp.h:76
static AVCodecContext * video_dec_ctx
struct AVDictionary AVDictionary
Definition: dict.h:91
const char * av_get_sample_fmt_name(enum AVSampleFormat sample_fmt)
Return the name of sample_fmt, or NULL if sample_fmt is not recognized.
void av_image_copy(uint8_t *dst_data[4], int dst_linesizes[4], const uint8_t *src_data[4], const int src_linesizes[4], enum AVPixelFormat pix_fmt, int width, int height)
Copy image in src_data to dst_data.
AVCodecContext * codec
Codec context associated with this stream.
Definition: avformat.h:896
unsigned 8 bits
Definition: samplefmt.h:61
#define FFMIN(a, b)
Definition: common.h:96
int width
picture width / height.
Definition: avcodec.h:1711
#define av_err2str(errnum)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition: error.h:119
int avcodec_decode_audio4(AVCodecContext *avctx, AVFrame *frame, int *got_frame_ptr, const AVPacket *avpkt)
Decode the audio frame of size avpkt->size from avpkt->data into frame.
static int refcount
static const char * video_dst_filename
Stream structure.
Definition: avformat.h:877
int format
format of the frame, -1 if unknown or unset Values correspond to enum AVPixelFormat for video frames...
Definition: frame.h:242
#define FF_ARRAY_ELEMS(a)
Definition: common.h:100
int coded_picture_number
picture number in bitstream order
Definition: frame.h:279
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:59
enum AVCodecID codec_id
Definition: avcodec.h:1549
int sample_rate
samples per second
Definition: avcodec.h:2287
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:209
int main(int argc, char **argv)
main external API structure.
Definition: avcodec.h:1532
AVCodec * avcodec_find_decoder(enum AVCodecID id)
Find a registered decoder with a matching codec ID.
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags)
Set the given entry in *pm, overwriting an existing entry.
static int get_format_from_sample_fmt(const char **fmt, enum AVSampleFormat sample_fmt)
AVMediaType
Definition: avutil.h:191
static const char * src_filename
int avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **options)
Initialize the AVCodecContext to use the given AVCodec.
int av_read_frame(AVFormatContext *s, AVPacket *pkt)
Return the next frame of a stream.
static AVCodecContext * audio_dec_ctx
static int video_frame_count
void av_frame_unref(AVFrame *frame)
Unreference all the buffers referenced by frame and reset the frame fields.
const char * av_get_media_type_string(enum AVMediaType media_type)
Return a string describing the media_type enum, NULL if media_type is unknown.
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:192
int av_get_bytes_per_sample(enum AVSampleFormat sample_fmt)
Return number of bytes per sample.
Main libavformat public API header.
enum AVSampleFormat av_get_packed_sample_fmt(enum AVSampleFormat sample_fmt)
Get the packed alternative form of the given sample format.
int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
Read packets of a media file to get stream information.
signed 16 bits
Definition: samplefmt.h:62
static AVCodecContext * dec_ctx
static FILE * video_dst_file
void av_init_packet(AVPacket *pkt)
Initialize optional fields of a packet with default values.
void avformat_close_input(AVFormatContext **s)
Close an opened input AVFormatContext.
static int open_codec_context(int *stream_idx, AVFormatContext *fmt_ctx, enum AVMediaType type)
int channels
number of audio channels
Definition: avcodec.h:2288
const char * av_get_pix_fmt_name(enum AVPixelFormat pix_fmt)
Return the short name for a pixel format, NULL in case pix_fmt is unknown.
int avformat_open_input(AVFormatContext **ps, const char *url, AVInputFormat *fmt, AVDictionary **options)
Open an input stream and read the header.
int height
Definition: frame.h:230
static int video_dst_bufsize
static int height
int stream_index
Definition: avcodec.h:1469
uint8_t ** extended_data
pointers to the data planes/channels.
Definition: frame.h:225
AVPixelFormat
Pixel format.
Definition: pixfmt.h:61
This structure stores compressed data.
Definition: avcodec.h:1444
void av_register_all(void)
Initialize libavformat and register all the muxers, demuxers and protocols.
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:235
static int width