FFmpeg  5.1.2
remuxing.c
Go to the documentation of this file.
1 /*
2  * Copyright (c) 2013 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  * libavformat/libavcodec demuxing and muxing API example.
26  *
27  * Remux streams from one container format to another.
28  * @example remuxing.c
29  */
30 
31 #include <libavutil/timestamp.h>
32 #include <libavformat/avformat.h>
33 
34 static void log_packet(const AVFormatContext *fmt_ctx, const AVPacket *pkt, const char *tag)
35 {
37 
38  printf("%s: pts:%s pts_time:%s dts:%s dts_time:%s duration:%s duration_time:%s stream_index:%d\n",
39  tag,
40  av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, time_base),
41  av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, time_base),
43  pkt->stream_index);
44 }
45 
46 int main(int argc, char **argv)
47 {
48  const AVOutputFormat *ofmt = NULL;
49  AVFormatContext *ifmt_ctx = NULL, *ofmt_ctx = NULL;
50  AVPacket *pkt = NULL;
51  const char *in_filename, *out_filename;
52  int ret, i;
53  int stream_index = 0;
54  int *stream_mapping = NULL;
55  int stream_mapping_size = 0;
56 
57  if (argc < 3) {
58  printf("usage: %s input output\n"
59  "API example program to remux a media file with libavformat and libavcodec.\n"
60  "The output format is guessed according to the file extension.\n"
61  "\n", argv[0]);
62  return 1;
63  }
64 
65  in_filename = argv[1];
66  out_filename = argv[2];
67 
68  pkt = av_packet_alloc();
69  if (!pkt) {
70  fprintf(stderr, "Could not allocate AVPacket\n");
71  return 1;
72  }
73 
74  if ((ret = avformat_open_input(&ifmt_ctx, in_filename, 0, 0)) < 0) {
75  fprintf(stderr, "Could not open input file '%s'", in_filename);
76  goto end;
77  }
78 
79  if ((ret = avformat_find_stream_info(ifmt_ctx, 0)) < 0) {
80  fprintf(stderr, "Failed to retrieve input stream information");
81  goto end;
82  }
83 
84  av_dump_format(ifmt_ctx, 0, in_filename, 0);
85 
86  avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, out_filename);
87  if (!ofmt_ctx) {
88  fprintf(stderr, "Could not create output context\n");
89  ret = AVERROR_UNKNOWN;
90  goto end;
91  }
92 
93  stream_mapping_size = ifmt_ctx->nb_streams;
94  stream_mapping = av_calloc(stream_mapping_size, sizeof(*stream_mapping));
95  if (!stream_mapping) {
96  ret = AVERROR(ENOMEM);
97  goto end;
98  }
99 
100  ofmt = ofmt_ctx->oformat;
101 
102  for (i = 0; i < ifmt_ctx->nb_streams; i++) {
103  AVStream *out_stream;
104  AVStream *in_stream = ifmt_ctx->streams[i];
105  AVCodecParameters *in_codecpar = in_stream->codecpar;
106 
107  if (in_codecpar->codec_type != AVMEDIA_TYPE_AUDIO &&
108  in_codecpar->codec_type != AVMEDIA_TYPE_VIDEO &&
109  in_codecpar->codec_type != AVMEDIA_TYPE_SUBTITLE) {
110  stream_mapping[i] = -1;
111  continue;
112  }
113 
114  stream_mapping[i] = stream_index++;
115 
116  out_stream = avformat_new_stream(ofmt_ctx, NULL);
117  if (!out_stream) {
118  fprintf(stderr, "Failed allocating output stream\n");
119  ret = AVERROR_UNKNOWN;
120  goto end;
121  }
122 
123  ret = avcodec_parameters_copy(out_stream->codecpar, in_codecpar);
124  if (ret < 0) {
125  fprintf(stderr, "Failed to copy codec parameters\n");
126  goto end;
127  }
128  out_stream->codecpar->codec_tag = 0;
129  }
130  av_dump_format(ofmt_ctx, 0, out_filename, 1);
131 
132  if (!(ofmt->flags & AVFMT_NOFILE)) {
133  ret = avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_WRITE);
134  if (ret < 0) {
135  fprintf(stderr, "Could not open output file '%s'", out_filename);
136  goto end;
137  }
138  }
139 
140  ret = avformat_write_header(ofmt_ctx, NULL);
141  if (ret < 0) {
142  fprintf(stderr, "Error occurred when opening output file\n");
143  goto end;
144  }
145 
146  while (1) {
147  AVStream *in_stream, *out_stream;
148 
149  ret = av_read_frame(ifmt_ctx, pkt);
150  if (ret < 0)
151  break;
152 
153  in_stream = ifmt_ctx->streams[pkt->stream_index];
154  if (pkt->stream_index >= stream_mapping_size ||
155  stream_mapping[pkt->stream_index] < 0) {
157  continue;
158  }
159 
160  pkt->stream_index = stream_mapping[pkt->stream_index];
161  out_stream = ofmt_ctx->streams[pkt->stream_index];
162  log_packet(ifmt_ctx, pkt, "in");
163 
164  /* copy packet */
165  av_packet_rescale_ts(pkt, in_stream->time_base, out_stream->time_base);
166  pkt->pos = -1;
167  log_packet(ofmt_ctx, pkt, "out");
168 
170  /* pkt is now blank (av_interleaved_write_frame() takes ownership of
171  * its contents and resets pkt), so that no unreferencing is necessary.
172  * This would be different if one used av_write_frame(). */
173  if (ret < 0) {
174  fprintf(stderr, "Error muxing packet\n");
175  break;
176  }
177  }
178 
180 end:
182 
184 
185  /* close output */
186  if (ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE))
189 
190  av_freep(&stream_mapping);
191 
192  if (ret < 0 && ret != AVERROR_EOF) {
193  fprintf(stderr, "Error occurred: %s\n", av_err2str(ret));
194  return 1;
195  }
196 
197  return 0;
198 }
Main libavformat public API header.
#define AVFMT_NOFILE
Demuxer will use avio_open, no opened file should be provided by the caller.
Definition: avformat.h:470
int avformat_alloc_output_context2(AVFormatContext **ctx, const AVOutputFormat *oformat, const char *format_name, const char *filename)
Allocate an AVFormatContext for an output format.
int avio_open(AVIOContext **s, const char *url, int flags)
Create and initialize a AVIOContext for accessing the resource indicated by url.
#define AVIO_FLAG_WRITE
write-only
Definition: avio.h:629
int avio_closep(AVIOContext **s)
Close the resource accessed by the AVIOContext *s, free it and set the pointer pointing to it to NULL...
int avcodec_parameters_copy(AVCodecParameters *dst, const AVCodecParameters *src)
Copy the contents of src to dst.
static AVPacket * pkt
static AVFormatContext * fmt_ctx
void av_packet_free(AVPacket **pkt)
Free the packet, if the packet is reference counted, it will be unreferenced first.
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
AVPacket * av_packet_alloc(void)
Allocate an AVPacket and set its fields to default values.
void av_packet_rescale_ts(AVPacket *pkt, AVRational tb_src, AVRational tb_dst)
Convert valid timing fields (timestamps / durations) in a packet from one timebase to another.
void avformat_free_context(AVFormatContext *s)
Free an AVFormatContext and all its streams.
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
int av_read_frame(AVFormatContext *s, AVPacket *pkt)
Return the next frame of a stream.
int avformat_open_input(AVFormatContext **ps, const char *url, const AVInputFormat *fmt, AVDictionary **options)
Open an input stream and read the header.
int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
Read packets of a media file to get stream information.
void avformat_close_input(AVFormatContext **s)
Close an opened input AVFormatContext.
av_warn_unused_result int avformat_write_header(AVFormatContext *s, AVDictionary **options)
Allocate the stream private data and write the stream header to an output media file.
int av_interleaved_write_frame(AVFormatContext *s, AVPacket *pkt)
Write a packet to an output media file ensuring correct interleaving.
int av_write_trailer(AVFormatContext *s)
Write the stream trailer to an output media file and free the file private data.
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,...
#define AVERROR_UNKNOWN
Unknown error, typically from an external library.
Definition: error.h:73
#define AVERROR_EOF
End of file.
Definition: error.h:57
#define av_err2str(errnum)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition: error.h:121
#define AVERROR(e)
Definition: error.h:45
void av_freep(void *ptr)
Free a memory block which has been allocated with a function of av_malloc() or av_realloc() family,...
void * av_calloc(size_t nmemb, size_t size) av_malloc_attrib
Allocate a memory block for an array with av_mallocz().
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
@ AVMEDIA_TYPE_SUBTITLE
Definition: avutil.h:204
@ AVMEDIA_TYPE_VIDEO
Definition: avutil.h:201
int main(int argc, char **argv)
Definition: remuxing.c:46
static void log_packet(const AVFormatContext *fmt_ctx, const AVPacket *pkt, const char *tag)
Definition: remuxing.c:34
This struct describes the properties of an encoded stream.
Definition: codec_par.h:53
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:57
uint32_t codec_tag
Additional information about the codec (corresponds to the AVI FOURCC).
Definition: codec_par.h:65
Format I/O context.
Definition: avformat.h:1213
unsigned int nb_streams
Number of elements in AVFormatContext.streams.
Definition: avformat.h:1269
AVIOContext * pb
I/O context.
Definition: avformat.h:1255
const struct AVOutputFormat * oformat
The output container format.
Definition: avformat.h:1232
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1281
int flags
can use flags: AVFMT_NOFILE, AVFMT_NEEDNUMBER, AVFMT_GLOBALHEADER, AVFMT_NOTIMESTAMPS,...
Definition: avformat.h:529
This structure stores compressed data.
Definition: packet.h:351
int stream_index
Definition: packet.h:376
int64_t duration
Duration of this packet in AVStream->time_base units, 0 if unknown.
Definition: packet.h:392
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:367
int64_t dts
Decompression timestamp in AVStream->time_base units; the time at which the packet is decompressed.
Definition: packet.h:373
int64_t pos
byte position in stream, -1 if unknown
Definition: packet.h:394
Rational number (pair of numerator and denominator).
Definition: rational.h:58
Stream structure.
Definition: avformat.h:948
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1108
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented.
Definition: avformat.h:978
timestamp utils, mostly useful for debugging/logging purposes
#define av_ts2str(ts)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition: timestamp.h:54
#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 AVFormatContext * ifmt_ctx
Definition: transcoding.c:39
static AVFormatContext * ofmt_ctx
Definition: transcoding.c:40