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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\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,
151 {
152  int ret, stream_index;
153  AVStream *st;
154  AVCodec *dec = NULL;
156 
157  ret = av_find_best_stream(fmt_ctx, type, -1, -1, NULL, 0);
158  if (ret < 0) {
159  fprintf(stderr, "Could not find %s stream in input file '%s'\n",
161  return ret;
162  } else {
163  stream_index = ret;
164  st = fmt_ctx->streams[stream_index];
165 
166  /* find decoder for the stream */
168  if (!dec) {
169  fprintf(stderr, "Failed to find %s codec\n",
171  return AVERROR(EINVAL);
172  }
173 
174  /* Allocate a codec context for the decoder */
175  *dec_ctx = avcodec_alloc_context3(dec);
176  if (!*dec_ctx) {
177  fprintf(stderr, "Failed to allocate the %s codec context\n",
179  return AVERROR(ENOMEM);
180  }
181 
182  /* Copy codec parameters from input stream to output codec context */
183  if ((ret = avcodec_parameters_to_context(*dec_ctx, st->codecpar)) < 0) {
184  fprintf(stderr, "Failed to copy %s codec parameters to decoder context\n",
186  return ret;
187  }
188 
189  /* Init the decoders, with or without reference counting */
190  av_dict_set(&opts, "refcounted_frames", refcount ? "1" : "0", 0);
191  if ((ret = avcodec_open2(*dec_ctx, dec, &opts)) < 0) {
192  fprintf(stderr, "Failed to open %s codec\n",
194  return ret;
195  }
196  *stream_idx = stream_index;
197  }
198 
199  return 0;
200 }
201 
202 static int get_format_from_sample_fmt(const char **fmt,
203  enum AVSampleFormat sample_fmt)
204 {
205  int i;
206  struct sample_fmt_entry {
207  enum AVSampleFormat sample_fmt; const char *fmt_be, *fmt_le;
208  } sample_fmt_entries[] = {
209  { AV_SAMPLE_FMT_U8, "u8", "u8" },
210  { AV_SAMPLE_FMT_S16, "s16be", "s16le" },
211  { AV_SAMPLE_FMT_S32, "s32be", "s32le" },
212  { AV_SAMPLE_FMT_FLT, "f32be", "f32le" },
213  { AV_SAMPLE_FMT_DBL, "f64be", "f64le" },
214  };
215  *fmt = NULL;
216 
217  for (i = 0; i < FF_ARRAY_ELEMS(sample_fmt_entries); i++) {
218  struct sample_fmt_entry *entry = &sample_fmt_entries[i];
219  if (sample_fmt == entry->sample_fmt) {
220  *fmt = AV_NE(entry->fmt_be, entry->fmt_le);
221  return 0;
222  }
223  }
224 
225  fprintf(stderr,
226  "sample format %s is not supported as output format\n",
227  av_get_sample_fmt_name(sample_fmt));
228  return -1;
229 }
230 
231 int main (int argc, char **argv)
232 {
233  int ret = 0, got_frame;
234 
235  if (argc != 4 && argc != 5) {
236  fprintf(stderr, "usage: %s [-refcount] input_file video_output_file audio_output_file\n"
237  "API example program to show how to read frames from an input file.\n"
238  "This program reads frames from a file, decodes them, and writes decoded\n"
239  "video frames to a rawvideo file named video_output_file, and decoded\n"
240  "audio frames to a rawaudio file named audio_output_file.\n\n"
241  "If the -refcount option is specified, the program use the\n"
242  "reference counting frame system which allows keeping a copy of\n"
243  "the data for longer than one decode call.\n"
244  "\n", argv[0]);
245  exit(1);
246  }
247  if (argc == 5 && !strcmp(argv[1], "-refcount")) {
248  refcount = 1;
249  argv++;
250  }
251  src_filename = argv[1];
252  video_dst_filename = argv[2];
253  audio_dst_filename = argv[3];
254 
255  /* register all formats and codecs */
256  av_register_all();
257 
258  /* open input file, and allocate format context */
259  if (avformat_open_input(&fmt_ctx, src_filename, NULL, NULL) < 0) {
260  fprintf(stderr, "Could not open source file %s\n", src_filename);
261  exit(1);
262  }
263 
264  /* retrieve stream information */
265  if (avformat_find_stream_info(fmt_ctx, NULL) < 0) {
266  fprintf(stderr, "Could not find stream information\n");
267  exit(1);
268  }
269 
270  if (open_codec_context(&video_stream_idx, &video_dec_ctx, fmt_ctx, AVMEDIA_TYPE_VIDEO) >= 0) {
271  video_stream = fmt_ctx->streams[video_stream_idx];
272 
273  video_dst_file = fopen(video_dst_filename, "wb");
274  if (!video_dst_file) {
275  fprintf(stderr, "Could not open destination file %s\n", video_dst_filename);
276  ret = 1;
277  goto end;
278  }
279 
280  /* allocate image where the decoded image will be put */
281  width = video_dec_ctx->width;
282  height = video_dec_ctx->height;
283  pix_fmt = video_dec_ctx->pix_fmt;
285  width, height, pix_fmt, 1);
286  if (ret < 0) {
287  fprintf(stderr, "Could not allocate raw video buffer\n");
288  goto end;
289  }
290  video_dst_bufsize = ret;
291  }
292 
295  audio_dst_file = fopen(audio_dst_filename, "wb");
296  if (!audio_dst_file) {
297  fprintf(stderr, "Could not open destination file %s\n", audio_dst_filename);
298  ret = 1;
299  goto end;
300  }
301  }
302 
303  /* dump input information to stderr */
304  av_dump_format(fmt_ctx, 0, src_filename, 0);
305 
306  if (!audio_stream && !video_stream) {
307  fprintf(stderr, "Could not find audio or video stream in the input, aborting\n");
308  ret = 1;
309  goto end;
310  }
311 
312  frame = av_frame_alloc();
313  if (!frame) {
314  fprintf(stderr, "Could not allocate frame\n");
315  ret = AVERROR(ENOMEM);
316  goto end;
317  }
318 
319  /* initialize packet, set data to NULL, let the demuxer fill it */
320  av_init_packet(&pkt);
321  pkt.data = NULL;
322  pkt.size = 0;
323 
324  if (video_stream)
325  printf("Demuxing video from file '%s' into '%s'\n", src_filename, video_dst_filename);
326  if (audio_stream)
327  printf("Demuxing audio from file '%s' into '%s'\n", src_filename, audio_dst_filename);
328 
329  /* read frames from the file */
330  while (av_read_frame(fmt_ctx, &pkt) >= 0) {
331  AVPacket orig_pkt = pkt;
332  do {
333  ret = decode_packet(&got_frame, 0);
334  if (ret < 0)
335  break;
336  pkt.data += ret;
337  pkt.size -= ret;
338  } while (pkt.size > 0);
339  av_packet_unref(&orig_pkt);
340  }
341 
342  /* flush cached frames */
343  pkt.data = NULL;
344  pkt.size = 0;
345  do {
346  decode_packet(&got_frame, 1);
347  } while (got_frame);
348 
349  printf("Demuxing succeeded.\n");
350 
351  if (video_stream) {
352  printf("Play the output video file with the command:\n"
353  "ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n",
356  }
357 
358  if (audio_stream) {
360  int n_channels = audio_dec_ctx->channels;
361  const char *fmt;
362 
363  if (av_sample_fmt_is_planar(sfmt)) {
364  const char *packed = av_get_sample_fmt_name(sfmt);
365  printf("Warning: the sample format the decoder produced is planar "
366  "(%s). This example will output the first channel only.\n",
367  packed ? packed : "?");
368  sfmt = av_get_packed_sample_fmt(sfmt);
369  n_channels = 1;
370  }
371 
372  if ((ret = get_format_from_sample_fmt(&fmt, sfmt)) < 0)
373  goto end;
374 
375  printf("Play the output audio file with the command:\n"
376  "ffplay -f %s -ac %d -ar %d %s\n",
377  fmt, n_channels, audio_dec_ctx->sample_rate,
379  }
380 
381 end:
382  avcodec_free_context(&video_dec_ctx);
384  avformat_close_input(&fmt_ctx);
385  if (video_dst_file)
386  fclose(video_dst_file);
387  if (audio_dst_file)
388  fclose(audio_dst_file);
389  av_frame_free(&frame);
391 
392  return ret < 0;
393 }
#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:201
const char * fmt
Definition: avisynth_c.h:769
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:192
static AVFormatContext * fmt_ctx
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: avcodec.h:3838
int size
Definition: avcodec.h:1415
static int audio_frame_count
enum AVPixelFormat pix_fmt
Pixel format, see AV_PIX_FMT_xxx.
Definition: avcodec.h:1711
static int open_codec_context(int *stream_idx, AVCodecContext **dec_ctx, AVFormatContext *fmt_ctx, enum AVMediaType type)
static AVStream * video_stream
attribute_deprecated 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: decode.c:833
static AVPacket pkt
static int audio_stream_idx
AVCodec.
Definition: avcodec.h:3365
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented...
Definition: avcodec.h:1624
Format I/O context.
Definition: avformat.h:1325
static FILE * audio_dst_file
enum AVSampleFormat sample_fmt
audio sample format
Definition: avcodec.h:2165
uint8_t
AV_SAMPLE_FMT_U8
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
Definition: frame.c:150
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:294
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1393
int avcodec_parameters_to_context(AVCodecContext *codec, const AVCodecParameters *par)
Fill the codec context based on the values from the supplied codec parameters.
Definition: utils.c:2306
static AVFrame * frame
uint8_t * data
Definition: avcodec.h:1414
static uint8_t * video_dst_data[4]
signed 32 bits
Definition: samplefmt.h:62
int av_sample_fmt_is_planar(enum AVSampleFormat sample_fmt)
Check if the sample format is planar.
Definition: samplefmt.c:112
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:555
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:4115
int width
Definition: frame.h:259
static int video_dst_linesize[4]
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:163
#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:49
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:386
AVDictionary * opts
Definition: movenc.c:50
#define FFMIN(a, b)
Definition: common.h:96
AVCodecContext * avcodec_alloc_context3(const AVCodec *codec)
Allocate an AVCodecContext and set its fields to default values.
Definition: options.c:157
int width
picture width / height.
Definition: avcodec.h:1674
#define av_err2str(errnum)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition: error.h:119
static int refcount
static const char * video_dst_filename
#define FF_ARRAY_ELEMS(a)
Stream structure.
Definition: avformat.h:872
int format
format of the frame, -1 if unknown or unset Values correspond to enum AVPixelFormat for video frames...
Definition: frame.h:274
int coded_picture_number
picture number in bitstream order
Definition: frame.h:315
attribute_deprecated 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: decode.c:826
AVSampleFormat
Audio sample formats.
Definition: samplefmt.h:58
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 sample_rate
samples per second
Definition: avcodec.h:2157
int linesize[AV_NUM_DATA_POINTERS]
For video, size in bytes of each picture line.
Definition: frame.h:232
int main(int argc, char **argv)
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 av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:590
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:70
static int get_format_from_sample_fmt(const char **fmt, enum AVSampleFormat sample_fmt)
AVMediaType
Definition: avutil.h:199
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:614
int av_read_frame(AVFormatContext *s, AVPacket *pkt)
Return the next frame of a stream.
Definition: utils.c:1712
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:510
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:76
uint8_t * data[AV_NUM_DATA_POINTERS]
pointer to the picture/channel planes.
Definition: frame.h:215
int av_get_bytes_per_sample(enum AVSampleFormat sample_fmt)
Return number of bytes per sample.
Definition: samplefmt.c:106
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:75
int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
Read packets of a media file to get stream information.
Definition: utils.c:3497
signed 16 bits
Definition: samplefmt.h:61
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:4350
#define av_free(p)
int channels
number of audio channels
Definition: avcodec.h:2158
int avformat_open_input(AVFormatContext **ps, const char *url, AVInputFormat *fmt, AVDictionary **options)
Open an input stream and read the header.
Definition: utils.c:515
int height
Definition: frame.h:259
static int video_dst_bufsize
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1014
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:2279
int stream_index
Definition: avcodec.h:1416
uint8_t ** extended_data
pointers to the data planes/channels.
Definition: frame.h:248
AVPixelFormat
Pixel format.
Definition: pixfmt.h:60
This structure stores compressed data.
Definition: avcodec.h:1391
void av_register_all(void)
Initialize libavformat and register all the muxers, demuxers and protocols.
Definition: allformats.c:395
int nb_samples
number of audio samples (per channel) described by this frame
Definition: frame.h:267
static int width