FFmpeg  4.3
webm_chunk.c
Go to the documentation of this file.
1 /*
2  * Copyright (c) 2015, Vignesh Venkatasubramanian
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 /**
22  * @file WebM Chunk Muxer
23  * The chunk muxer enables writing WebM Live chunks where there is a header
24  * chunk, followed by data chunks where each Cluster is written out as a Chunk.
25  */
26 
27 #include "avformat.h"
28 #include "avio.h"
29 #include "avio_internal.h"
30 #include "internal.h"
31 
32 #include "libavutil/log.h"
33 #include "libavutil/opt.h"
34 #include "libavutil/mathematics.h"
35 
36 #define MAX_FILENAME_SIZE 1024
37 
38 typedef struct WebMChunkContext {
39  const AVClass *class;
43  char *http_method;
44  uint64_t duration_written;
45  int64_t prev_pts;
49 
51 {
52  WebMChunkContext *wc = s->priv_data;
53  ff_const59 AVOutputFormat *oformat;
54  AVFormatContext *oc;
55  AVStream *st, *ost = s->streams[0];
56  AVDictionary *dict = NULL;
57  int ret;
58 
59  // DASH Streams can only have one track per file.
60  if (s->nb_streams != 1)
61  return AVERROR(EINVAL);
62 
63  if (!wc->header_filename) {
64  av_log(s, AV_LOG_ERROR, "No header filename provided\n");
65  return AVERROR(EINVAL);
66  }
67 
69 
70  oformat = av_guess_format("webm", s->url, "video/webm");
71  if (!oformat)
73 
74  ret = avformat_alloc_output_context2(&wc->avf, oformat, NULL, NULL);
75  if (ret < 0)
76  return ret;
77  oc = wc->avf;
78 
80  wc->header_filename = NULL;
81 
83  oc->max_delay = s->max_delay;
87 
88  oc->flush_packets = 0;
89 
90  if ((ret = av_dict_copy(&oc->metadata, s->metadata, 0)) < 0)
91  return ret;
92 
93  if (!(st = avformat_new_stream(oc, NULL)))
94  return AVERROR(ENOMEM);
95 
96  if ((ret = avcodec_parameters_copy(st->codecpar, ost->codecpar)) < 0 ||
97  (ret = av_dict_copy(&st->metadata, ost->metadata, 0)) < 0)
98  return ret;
99 
101  st->disposition = ost->disposition;
103  ost->time_base.den);
104 
105  if (wc->http_method)
106  if ((ret = av_dict_set(&dict, "method", wc->http_method, 0)) < 0)
107  return ret;
108  ret = s->io_open(s, &oc->pb, oc->url, AVIO_FLAG_WRITE, &dict);
109  av_dict_free(&dict);
110  if (ret < 0)
111  return ret;
112  oc->pb->seekable = 0;
113 
114  if ((ret = av_dict_set_int(&dict, "dash", 1, 0)) < 0 ||
115  (ret = av_dict_set_int(&dict, "cluster_time_limit",
116  wc->chunk_duration, 0)) < 0 ||
117  (ret = av_dict_set_int(&dict, "live", 1, 0)) < 0)
118  goto fail;
119 
120  ret = avformat_init_output(oc, &dict);
121 fail:
122  av_dict_free(&dict);
123  if (ret < 0)
124  return ret;
125 
126  // Copy the timing info back to the original stream
127  // so that the timestamps of the packets are directly usable
129  st->time_base.den);
130 
131  // This ensures that the timestamps will already be properly shifted
132  // when the packets arrive here, so we don't need to shift again.
136  oc->avoid_negative_ts = 0;
137 
138  return 0;
139 }
140 
142 {
143  WebMChunkContext *wc = s->priv_data;
144  if (!filename) {
145  return AVERROR(EINVAL);
146  }
147  if (av_get_frame_filename(filename, MAX_FILENAME_SIZE,
148  s->url, wc->chunk_index - 1) < 0) {
149  av_log(s, AV_LOG_ERROR, "Invalid chunk filename template '%s'\n", s->url);
150  return AVERROR(EINVAL);
151  }
152  return 0;
153 }
154 
156 {
157  WebMChunkContext *wc = s->priv_data;
158  AVFormatContext *oc = wc->avf;
159  int ret;
160 
161  ret = avformat_write_header(oc, NULL);
162  ff_format_io_close(s, &oc->pb);
163  wc->header_written = 1;
164  if (ret < 0)
165  return ret;
166  return 0;
167 }
168 
170 {
171  WebMChunkContext *wc = s->priv_data;
172  AVFormatContext *oc = wc->avf;
173  int ret;
174 
175  ret = avio_open_dyn_buf(&oc->pb);
176  if (ret < 0)
177  return ret;
178  wc->chunk_index++;
179  return 0;
180 }
181 
182 static int chunk_end(AVFormatContext *s, int flush)
183 {
184  WebMChunkContext *wc = s->priv_data;
185  AVFormatContext *oc = wc->avf;
186  int ret;
187  int buffer_size;
188  uint8_t *buffer;
189  AVIOContext *pb;
190  char filename[MAX_FILENAME_SIZE];
192 
193  if (!oc->pb)
194  return 0;
195 
196  if (flush)
197  // Flush the cluster in WebM muxer.
198  av_write_frame(oc, NULL);
199  buffer_size = avio_close_dyn_buf(oc->pb, &buffer);
200  oc->pb = NULL;
201  ret = get_chunk_filename(s, filename);
202  if (ret < 0)
203  goto fail;
204  if (wc->http_method)
205  if ((ret = av_dict_set(&options, "method", wc->http_method, 0)) < 0)
206  goto fail;
207  ret = s->io_open(s, &pb, filename, AVIO_FLAG_WRITE, &options);
208  av_dict_free(&options);
209  if (ret < 0)
210  goto fail;
211  avio_write(pb, buffer, buffer_size);
212  ff_format_io_close(s, &pb);
213 fail:
214  av_free(buffer);
215  return (ret < 0) ? ret : 0;
216 }
217 
219 {
220  WebMChunkContext *wc = s->priv_data;
221  AVFormatContext *oc = wc->avf;
222  AVStream *st = s->streams[pkt->stream_index];
223  int ret;
224 
225  if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
226  if (wc->prev_pts != AV_NOPTS_VALUE)
227  wc->duration_written += av_rescale_q(pkt->pts - wc->prev_pts,
228  st->time_base,
229  (AVRational) {1, 1000});
230  wc->prev_pts = pkt->pts;
231  }
232 
233  // For video, a new chunk is started only on key frames. For audio, a new
234  // chunk is started based on chunk_duration. Also, a new chunk is started
235  // unconditionally if there is no currently open chunk.
236  if (!oc->pb || (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&
237  (pkt->flags & AV_PKT_FLAG_KEY)) ||
239  wc->duration_written >= wc->chunk_duration)) {
240  wc->duration_written = 0;
241  if ((ret = chunk_end(s, 1)) < 0 || (ret = chunk_start(s)) < 0) {
242  return ret;
243  }
244  }
245 
246  // We only have one stream, so use the non-interleaving av_write_frame.
247  return av_write_frame(oc, pkt);
248 }
249 
251 {
252  WebMChunkContext *wc = s->priv_data;
253  AVFormatContext *oc = wc->avf;
254  int ret;
255 
256  if (!oc->pb) {
257  ret = chunk_start(s);
258  if (ret < 0)
259  return ret;
260  }
261  ret = av_write_trailer(oc);
262  if (ret < 0)
263  return ret;
264  return chunk_end(s, 0);
265 }
266 
268 {
269  WebMChunkContext *wc = s->priv_data;
270 
271  if (!wc->avf)
272  return;
273 
274  if (wc->header_written)
275  ffio_free_dyn_buf(&wc->avf->pb);
276  else
277  ff_format_io_close(s, &wc->avf->pb);
279  wc->avf = NULL;
280 }
281 
282 #define OFFSET(x) offsetof(WebMChunkContext, x)
283 static const AVOption options[] = {
284  { "chunk_start_index", "start index of the chunk", OFFSET(chunk_index), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
285  { "header", "filename of the header where the initialization data will be written", OFFSET(header_filename), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, AV_OPT_FLAG_ENCODING_PARAM },
286  { "audio_chunk_duration", "duration of each chunk in milliseconds", OFFSET(chunk_duration), AV_OPT_TYPE_INT, {.i64 = 5000}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
287  { "method", "set the HTTP method", OFFSET(http_method), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, AV_OPT_FLAG_ENCODING_PARAM },
288  { NULL },
289 };
290 
291 static const AVClass webm_chunk_class = {
292  .class_name = "WebM Chunk Muxer",
293  .item_name = av_default_item_name,
294  .option = options,
295  .version = LIBAVUTIL_VERSION_INT,
296 };
297 
299  .name = "webm_chunk",
300  .long_name = NULL_IF_CONFIG_SMALL("WebM Chunk Muxer"),
301  .mime_type = "video/webm",
302  .extensions = "chk",
305  .priv_data_size = sizeof(WebMChunkContext),
310  .deinit = webm_chunk_deinit,
311  .priv_class = &webm_chunk_class,
312 };
static void write_packet(OutputFile *of, AVPacket *pkt, OutputStream *ost, int unqueue)
Definition: ffmpeg.c:701
int(* io_open)(struct AVFormatContext *s, AVIOContext **pb, const char *url, int flags, AVDictionary **options)
A callback for opening new IO streams.
Definition: avformat.h:1933
#define NULL
Definition: coverity.c:32
Bytestream IO Context.
Definition: avio.h:161
Buffered I/O operations.
AVIOInterruptCB interrupt_callback
Custom interrupt callbacks for the I/O layer.
Definition: avformat.h:1629
int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer)
Return the written size and a pointer to the buffer.
Definition: aviobuf.c:1401
AVOption.
Definition: opt.h:246
static void flush(AVCodecContext *avctx)
int flush_packets
Flush the I/O context after each packet.
Definition: avformat.h:1766
int av_write_frame(AVFormatContext *s, AVPacket *pkt)
Write a packet to an output media file.
Definition: mux.c:1190
static int chunk_start(AVFormatContext *s)
Definition: webm_chunk.c:169
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
void avpriv_set_pts_info(AVStream *s, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: utils.c:4938
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
AVFormatContext * avf
Definition: webm_chunk.c:46
AVRational sample_aspect_ratio
sample aspect ratio (0 if unknown)
Definition: avformat.h:938
int num
Numerator.
Definition: rational.h:59
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:235
AVFormatInternal * internal
An opaque field for libavformat internal usage.
Definition: avformat.h:1804
uint64_t duration_written
Definition: webm_chunk.c:44
#define AVIO_FLAG_WRITE
write-only
Definition: avio.h:675
int av_dict_copy(AVDictionary **dst, const AVDictionary *src, int flags)
Copy entries from one AVDictionary struct into another.
Definition: dict.c:217
int avoid_negative_ts_use_pts
Definition: internal.h:119
static AVPacket pkt
int avio_open_dyn_buf(AVIOContext **s)
Open a write only memory stream.
Definition: aviobuf.c:1356
int strict_std_compliance
Allow non-standard and experimental extension.
Definition: avformat.h:1659
char * http_method
Definition: webm_chunk.c:43
#define AVFMT_TS_NONSTRICT
Format does not require strictly increasing timestamps, but they must still be monotonic.
Definition: avformat.h:472
Format I/O context.
Definition: avformat.h:1351
const char * class_name
The name of the class; usually it is the same name as the context structure type to which the AVClass...
Definition: log.h:72
static char buffer[20]
Definition: seek.c:32
uint8_t
AVOptions.
void ff_format_io_close(AVFormatContext *s, AVIOContext **pb)
Definition: utils.c:5685
#define MAX_FILENAME_SIZE
Definition: webm_chunk.c:36
char * header_filename
Definition: webm_chunk.c:40
static void webm_chunk_deinit(AVFormatContext *s)
Definition: webm_chunk.c:267
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4519
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1419
int flags
Flags modifying the (de)muxer behaviour.
Definition: avformat.h:1482
void avio_write(AVIOContext *s, const unsigned char *buf, int size)
Definition: aviobuf.c:213
#define av_log(a,...)
#define AV_OPT_FLAG_ENCODING_PARAM
a generic parameter which can be set by the user for muxing or encoding
Definition: opt.h:276
#define AV_PKT_FLAG_KEY
The packet contains a keyframe.
Definition: packet.h:388
int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq)
Rescale a 64-bit integer by 2 rational numbers.
Definition: mathematics.c:142
#define ff_const59
The ff_const59 define is not part of the public API and will be removed without further warning...
Definition: avformat.h:544
#define AVFMT_FLAG_FLUSH_PACKETS
Flush the AVIOContext every packet.
Definition: avformat.h:1492
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
AVDictionary * metadata
Metadata that applies to the whole file.
Definition: avformat.h:1591
#define AVERROR(e)
Definition: error.h:43
static const AVOption options[]
Definition: webm_chunk.c:283
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
char * url
input or output URL.
Definition: avformat.h:1447
void av_dict_free(AVDictionary **pm)
Free all the memory allocated for an AVDictionary struct and all keys and values. ...
Definition: dict.c:203
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:56
int avformat_alloc_output_context2(AVFormatContext **ctx, ff_const59 AVOutputFormat *oformat, const char *format_name, const char *filename)
Allocate an AVFormatContext for an output format.
Definition: mux.c:135
#define fail()
Definition: checkasm.h:123
int flags
A combination of AV_PKT_FLAG values.
Definition: packet.h:361
unsigned int nb_streams
Number of elements in AVFormatContext.streams.
Definition: avformat.h:1407
int seekable
A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
Definition: avio.h:260
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.
Definition: mux.c:505
static int write_trailer(AVFormatContext *s1)
Definition: v4l2enc.c:98
#define AVFMT_GLOBALHEADER
Format wants global header.
Definition: avformat.h:461
const char * name
Definition: avformat.h:500
#define OFFSET(x)
Definition: webm_chunk.c:282
#define s(width, name)
Definition: cbs_vp9.c:257
int avoid_negative_ts
Avoid negative timestamps during muxing.
Definition: avformat.h:1682
static int webm_chunk_write_packet(AVFormatContext *s, AVPacket *pkt)
Definition: webm_chunk.c:218
void ff_format_set_url(AVFormatContext *s, char *url)
Set AVFormatContext url field to the provided pointer.
Definition: utils.c:5845
AVDictionary * metadata
Definition: avformat.h:940
av_warn_unused_result int avformat_init_output(AVFormatContext *s, AVDictionary **options)
Allocate the stream private data and initialize the codec, but do not write the header.
Definition: mux.c:485
int av_get_frame_filename(char *buf, int buf_size, const char *path, int number)
Definition: utils.c:4787
void ffio_free_dyn_buf(AVIOContext **s)
Free a dynamic buffer.
Definition: aviobuf.c:1431
Stream structure.
Definition: avformat.h:876
static const AVClass webm_chunk_class
Definition: webm_chunk.c:291
AVIOContext * pb
I/O context.
Definition: avformat.h:1393
static int webm_chunk_write_header(AVFormatContext *s)
Definition: webm_chunk.c:155
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
Describe the class of an AVClass context structure.
Definition: log.h:67
ff_const59 AVOutputFormat * av_guess_format(const char *short_name, const char *filename, const char *mime_type)
Return the output format in the list of registered output formats which best matches the provided par...
Definition: format.c:51
Rational number (pair of numerator and denominator).
Definition: rational.h:58
void avformat_free_context(AVFormatContext *s)
Free an AVFormatContext and all its streams.
Definition: utils.c:4448
static AVStream * ost
static int get_chunk_filename(AVFormatContext *s, char filename[MAX_FILENAME_SIZE])
Definition: webm_chunk.c:141
Main libavformat public API header.
AVOutputFormat ff_webm_chunk_muxer
Definition: webm_chunk.c:298
#define AVFMT_NOFILE
Demuxer will use avio_open, no opened file should be provided by the caller.
Definition: avformat.h:458
static int webm_chunk_write_trailer(AVFormatContext *s)
Definition: webm_chunk.c:250
int av_dict_set_int(AVDictionary **pm, const char *key, int64_t value, int flags)
Convenience wrapper for av_dict_set that converts the value to a string and stores it...
Definition: dict.c:147
int disposition
AV_DISPOSITION_* bit field.
Definition: avformat.h:929
int pts_wrap_bits
number of bits in pts (used for wrapping control)
Definition: avformat.h:1068
int den
Denominator.
Definition: rational.h:60
#define av_free(p)
void * priv_data
Format private data.
Definition: avformat.h:1379
static void write_header(FFV1Context *f)
Definition: ffv1enc.c:346
static int chunk_end(AVFormatContext *s, int flush)
Definition: webm_chunk.c:182
int av_write_trailer(AVFormatContext *s)
Write the stream trailer to an output media file and free the file private data.
Definition: mux.c:1251
int64_t prev_pts
Definition: webm_chunk.c:45
#define AVERROR_MUXER_NOT_FOUND
Muxer not found.
Definition: error.h:60
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1023
int stream_index
Definition: packet.h:357
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented...
Definition: avformat.h:905
static int webm_chunk_init(AVFormatContext *s)
Definition: webm_chunk.c:50
int avcodec_parameters_copy(AVCodecParameters *dst, const AVCodecParameters *src)
Copy the contents of src to dst.
Definition: utils.c:2064
This structure stores compressed data.
Definition: packet.h:332
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:348
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
#define AVFMT_NEEDNUMBER
Needs &#39;d&#39; in filename.
Definition: avformat.h:459