FFmpeg
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:703
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:1833
#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:1517
int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer)
Return the written size and a pointer to the buffer.
Definition: aviobuf.c:1428
AVOption.
Definition: opt.h:248
static void flush(AVCodecContext *avctx)
int flush_packets
Flush the I/O context after each packet.
Definition: avformat.h:1666
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:4871
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:942
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:1704
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:1383
int strict_std_compliance
Allow non-standard and experimental extension.
Definition: avformat.h:1547
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:1239
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
uint8_t
AVOptions.
void ff_format_io_close(AVFormatContext *s, AVIOContext **pb)
Definition: utils.c:5618
#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:4453
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1307
int flags
Flags modifying the (de)muxer behaviour.
Definition: avformat.h:1370
void avio_write(AVIOContext *s, const unsigned char *buf, int size)
Definition: aviobuf.c:225
#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:278
#define AV_PKT_FLAG_KEY
The packet contains a keyframe.
Definition: packet.h:401
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:1380
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
AVDictionary * metadata
Metadata that applies to the whole file.
Definition: avformat.h:1479
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:153
char * url
input or output URL.
Definition: avformat.h:1335
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:369
unsigned int nb_streams
Number of elements in AVFormatContext.streams.
Definition: avformat.h:1295
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:1582
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:5788
AVDictionary * metadata
Definition: avformat.h:944
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:4720
void ffio_free_dyn_buf(AVIOContext **s)
Free a dynamic buffer.
Definition: aviobuf.c:1458
Stream structure.
Definition: avformat.h:880
static const AVClass webm_chunk_class
Definition: webm_chunk.c:291
AVIOContext * pb
I/O context.
Definition: avformat.h:1281
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:4382
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:933
int pts_wrap_bits
number of bits in pts (used for wrapping control)
Definition: avformat.h:1062
int den
Denominator.
Definition: rational.h:60
#define av_free(p)
void * priv_data
Format private data.
Definition: avformat.h:1267
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:1045
int stream_index
Definition: packet.h:365
AVRational time_base
This is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented...
Definition: avformat.h:909
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
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:2077
This structure stores compressed data.
Definition: packet.h:340
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:356
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
GLuint buffer
Definition: opengl_enc.c:101
#define AVFMT_NEEDNUMBER
Needs &#39;d&#39; in filename.
Definition: avformat.h:459