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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 
39 static int width, height;
40 static enum AVPixelFormat pix_fmt;
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 pts:%s\n",
97  cached ? "(cached)" : "",
99  av_ts2timestr(frame->pts, &video_dec_ctx->time_base));
100 
101  /* copy decoded frame to destination buffer:
102  * this is required since rawvideo expects non aligned data */
104  (const uint8_t **)(frame->data), frame->linesize,
105  pix_fmt, width, height);
106 
107  /* write to rawvideo file */
109  }
110  } else if (pkt.stream_index == audio_stream_idx) {
111  /* decode audio frame */
112  ret = avcodec_decode_audio4(audio_dec_ctx, frame, got_frame, &pkt);
113  if (ret < 0) {
114  fprintf(stderr, "Error decoding audio frame (%s)\n", av_err2str(ret));
115  return ret;
116  }
117  /* Some audio decoders decode only part of the packet, and have to be
118  * called again with the remainder of the packet data.
119  * Sample: fate-suite/lossless-audio/luckynight-partial.shn
120  * Also, some decoders might over-read the packet. */
121  decoded = FFMIN(ret, pkt.size);
122 
123  if (*got_frame) {
124  size_t unpadded_linesize = frame->nb_samples * av_get_bytes_per_sample(frame->format);
125  printf("audio_frame%s n:%d nb_samples:%d pts:%s\n",
126  cached ? "(cached)" : "",
127  audio_frame_count++, frame->nb_samples,
129 
130  /* Write the raw audio data samples of the first plane. This works
131  * fine for packed formats (e.g. AV_SAMPLE_FMT_S16). However,
132  * most audio decoders output planar audio, which uses a separate
133  * plane of audio samples for each channel (e.g. AV_SAMPLE_FMT_S16P).
134  * In other words, this code will write only the first audio channel
135  * in these cases.
136  * You should use libswresample or libavfilter to convert the frame
137  * to packed data. */
138  fwrite(frame->extended_data[0], 1, unpadded_linesize, audio_dst_file);
139  }
140  }
141 
142  /* If we use frame reference counting, we own the data and need
143  * to de-reference it when we don't use it anymore */
144  if (*got_frame && refcount)
145  av_frame_unref(frame);
146 
147  return decoded;
148 }
149 
150 static int open_codec_context(int *stream_idx,
151  AVFormatContext *fmt_ctx, enum AVMediaType type)
152 {
153  int ret, stream_index;
154  AVStream *st;
156  AVCodec *dec = NULL;
158 
159  ret = av_find_best_stream(fmt_ctx, type, -1, -1, NULL, 0);
160  if (ret < 0) {
161  fprintf(stderr, "Could not find %s stream in input file '%s'\n",
163  return ret;
164  } else {
165  stream_index = ret;
166  st = fmt_ctx->streams[stream_index];
167 
168  /* find decoder for the stream */
169  dec_ctx = st->codec;
170  dec = avcodec_find_decoder(dec_ctx->codec_id);
171  if (!dec) {
172  fprintf(stderr, "Failed to find %s codec\n",
174  return AVERROR(EINVAL);
175  }
176 
177  /* Init the decoders, with or without reference counting */
178  av_dict_set(&opts, "refcounted_frames", refcount ? "1" : "0", 0);
179  if ((ret = avcodec_open2(dec_ctx, dec, &opts)) < 0) {
180  fprintf(stderr, "Failed to open %s codec\n",
182  return ret;
183  }
184  *stream_idx = stream_index;
185  }
186 
187  return 0;
188 }
189 
190 static int get_format_from_sample_fmt(const char **fmt,
191  enum AVSampleFormat sample_fmt)
192 {
193  int i;
194  struct sample_fmt_entry {
195  enum AVSampleFormat sample_fmt; const char *fmt_be, *fmt_le;
196  } sample_fmt_entries[] = {
197  { AV_SAMPLE_FMT_U8, "u8", "u8" },
198  { AV_SAMPLE_FMT_S16, "s16be", "s16le" },
199  { AV_SAMPLE_FMT_S32, "s32be", "s32le" },
200  { AV_SAMPLE_FMT_FLT, "f32be", "f32le" },
201  { AV_SAMPLE_FMT_DBL, "f64be", "f64le" },
202  };
203  *fmt = NULL;
204 
205  for (i = 0; i < FF_ARRAY_ELEMS(sample_fmt_entries); i++) {
206  struct sample_fmt_entry *entry = &sample_fmt_entries[i];
207  if (sample_fmt == entry->sample_fmt) {
208  *fmt = AV_NE(entry->fmt_be, entry->fmt_le);
209  return 0;
210  }
211  }
212 
213  fprintf(stderr,
214  "sample format %s is not supported as output format\n",
215  av_get_sample_fmt_name(sample_fmt));
216  return -1;
217 }
218 
219 int main (int argc, char **argv)
220 {
221  int ret = 0, got_frame;
222 
223  if (argc != 4 && argc != 5) {
224  fprintf(stderr, "usage: %s [-refcount] input_file video_output_file audio_output_file\n"
225  "API example program to show how to read frames from an input file.\n"
226  "This program reads frames from a file, decodes them, and writes decoded\n"
227  "video frames to a rawvideo file named video_output_file, and decoded\n"
228  "audio frames to a rawaudio file named audio_output_file.\n\n"
229  "If the -refcount option is specified, the program use the\n"
230  "reference counting frame system which allows keeping a copy of\n"
231  "the data for longer than one decode call.\n"
232  "\n", argv[0]);
233  exit(1);
234  }
235  if (argc == 5 && !strcmp(argv[1], "-refcount")) {
236  refcount = 1;
237  argv++;
238  }
239  src_filename = argv[1];
240  video_dst_filename = argv[2];
241  audio_dst_filename = argv[3];
242 
243  /* register all formats and codecs */
244  av_register_all();
245 
246  /* open input file, and allocate format context */
247  if (avformat_open_input(&fmt_ctx, src_filename, NULL, NULL) < 0) {
248  fprintf(stderr, "Could not open source file %s\n", src_filename);
249  exit(1);
250  }
251 
252  /* retrieve stream information */
253  if (avformat_find_stream_info(fmt_ctx, NULL) < 0) {
254  fprintf(stderr, "Could not find stream information\n");
255  exit(1);
256  }
257 
259  video_stream = fmt_ctx->streams[video_stream_idx];
260  video_dec_ctx = video_stream->codec;
261 
262  video_dst_file = fopen(video_dst_filename, "wb");
263  if (!video_dst_file) {
264  fprintf(stderr, "Could not open destination file %s\n", video_dst_filename);
265  ret = 1;
266  goto end;
267  }
268 
269  /* allocate image where the decoded image will be put */
270  width = video_dec_ctx->width;
271  height = video_dec_ctx->height;
272  pix_fmt = video_dec_ctx->pix_fmt;
274  width, height, pix_fmt, 1);
275  if (ret < 0) {
276  fprintf(stderr, "Could not allocate raw video buffer\n");
277  goto end;
278  }
279  video_dst_bufsize = ret;
280  }
281 
285  audio_dst_file = fopen(audio_dst_filename, "wb");
286  if (!audio_dst_file) {
287  fprintf(stderr, "Could not open destination file %s\n", audio_dst_filename);
288  ret = 1;
289  goto end;
290  }
291  }
292 
293  /* dump input information to stderr */
294  av_dump_format(fmt_ctx, 0, src_filename, 0);
295 
296  if (!audio_stream && !video_stream) {
297  fprintf(stderr, "Could not find audio or video stream in the input, aborting\n");
298  ret = 1;
299  goto end;
300  }
301 
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_packet_unref(&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",
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  av_frame_free(&frame);
381 
382  return ret < 0;
383 }
#define NULL
Definition: coverity.c:32
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
const char * fmt
Definition: avisynth_c.h:632
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...
Definition: imgutils.c:191
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
uint8_t
AV_SAMPLE_FMT_U8
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
Definition: frame.c:141
static int video_stream_idx
timestamp utils, mostly useful for debugging/logging purposes
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:90
#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.
Definition: samplefmt.c:110
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:480
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.
Definition: utils.c:3613
int avcodec_close(AVCodecContext *avctx)
Close a given AVCodecContext and free all the data associated with it (but not the AVCodecContext its...
Definition: utils.c:2529
int width
width and height of the video frame
Definition: frame.h:230
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.
Definition: utils.c:2091
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.
Definition: frame.c:154
#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
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.
Definition: samplefmt.c:47
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.
Definition: imgutils.c:302
AVCodecContext * codec
Codec context associated with this stream.
Definition: avformat.h:896
#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.
Definition: utils.c:2185
static int refcount
static const char * video_dst_filename
#define FF_ARRAY_ELEMS(a)
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
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.
Definition: utils.c:2629
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:545
GLint GLenum type
Definition: opengl_enc.c:105
int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags)
Set the given entry in *pm, overwriting an existing entry.
Definition: dict.c:69
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.
Definition: utils.c:1170
int av_read_frame(AVFormatContext *s, AVPacket *pkt)
Return the next frame of a stream.
Definition: utils.c:1509
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.
Definition: frame.c:474
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.
Definition: utils.c:79
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.
Definition: samplefmt.c:104
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.
Definition: samplefmt.c:73
int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
Read packets of a media file to get stream information.
Definition: utils.c:3139
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.
Definition: avpacket.c:33
void avformat_close_input(AVFormatContext **s)
Close an opened input AVFormatContext.
Definition: utils.c:3777
static int open_codec_context(int *stream_idx, AVFormatContext *fmt_ctx, enum AVMediaType type)
#define av_free(p)
int channels
number of audio channels
Definition: avcodec.h:2288
AVDictionary * opts
Definition: movenc-test.c:50
int avformat_open_input(AVFormatContext **ps, const char *url, AVInputFormat *fmt, AVDictionary **options)
Open an input stream and read the header.
Definition: utils.c:422
int height
Definition: frame.h:230
static int video_dst_bufsize
static int height
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.
Definition: pixdesc.c:2078
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.
Definition: allformats.c:51
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:235
static int width