libavformat/webmdashenc.c

   1 /*
   2  * WebM DASH Manifest XML muxer
   3  * Copyright (c) 2014 Vignesh Venkatasubramanian
   4  *
   5  * This file is part of FFmpeg.
   6  *
   7  * FFmpeg is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * FFmpeg is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with FFmpeg; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 /*
  23  * WebM DASH Specification:
  24  * https://sites.google.com/a/webmproject.org/wiki/adaptive-streaming/webm-dash-specification
  25  * ISO DASH Specification:
  26  * http://standards.iso.org/ittf/PubliclyAvailableStandards/c065274_ISO_IEC_23009-1_2014.zip
  27  */
  28
  29 #include <float.h>
  30 #include <stdint.h>
  31 #include <string.h>
  32 #include <time.h>
  33
  34 #include "avformat.h"
  35 #include "matroska.h"
  36 #include "mux.h"
  37
  38 #include "libavutil/avstring.h"
  39 #include "libavutil/dict.h"
  40 #include "libavutil/mem.h"
  41 #include "libavutil/opt.h"
  42 #include "libavutil/time_internal.h"
  43
  44 #include "libavcodec/codec_desc.h"
  45
  46 typedef struct AdaptationSet {
  47     char id[10];
  48     int *streams;
  49     int nb_streams;
  50 } AdaptationSet;
  51
  52 typedef struct WebMDashMuxContext {
  53     const AVClass  *class;
  54     char *adaptation_sets;
  55     AdaptationSet *as;
  56     int nb_as;
  57     int representation_id;
  58     int is_live;
  59     int chunk_start_index;
  60     int chunk_duration;
  61     char *utc_timing_url;
  62     double time_shift_buffer_depth;
  63     int minimum_update_period;
  64 } WebMDashMuxContext;
  65
  66 static const char *get_codec_name(int codec_id)
  67 {
  68     return avcodec_descriptor_get(codec_id)->name;
  69 }
  70
  71 static double get_duration(AVFormatContext *s)
  72 {
  73     int i = 0;
  74     double max = 0.0;
  75     for (i = 0; i < s->nb_streams; i++) {
  76         AVDictionaryEntry *duration = av_dict_get(s->streams[i]->metadata,
  77                                                   DURATION, NULL, 0);
  78         if (!duration || atof(duration->value) < 0) continue;
  79         if (atof(duration->value) > max) max = atof(duration->value);
  80     }
  81     return max / 1000;
  82 }
  83
  84 static int write_header(AVFormatContext *s)
  85 {
  86     WebMDashMuxContext *w = s->priv_data;
  87     AVIOContext *pb = s->pb;
  88     double min_buffer_time = 1.0;
  89     avio_printf(pb, "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n");
  90     avio_printf(pb, "<MPD\n");
  91     avio_printf(pb, "  xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n");
  92     avio_printf(pb, "  xmlns=\"urn:mpeg:DASH:schema:MPD:2011\"\n");
  93     avio_printf(pb, "  xsi:schemaLocation=\"urn:mpeg:DASH:schema:MPD:2011\"\n");
  94     avio_printf(pb, "  type=\"%s\"\n", w->is_live ? "dynamic" : "static");
  95     if (!w->is_live) {
  96         avio_printf(pb, "  mediaPresentationDuration=\"PT%gS\"\n",
  97                     get_duration(s));
  98     }
  99     avio_printf(pb, "  minBufferTime=\"PT%gS\"\n", min_buffer_time);
 100     avio_printf(pb, "  profiles=\"%s\"%s",
 101                 w->is_live ? "urn:mpeg:dash:profile:isoff-live:2011" : "urn:mpeg:dash:profile:webm-on-demand:2012",
 102                 w->is_live ? "\n" : ">\n");
 103     if (w->is_live) {
 104         time_t local_time = time(NULL);
 105         struct tm gmt_buffer;
 106         struct tm *gmt = gmtime_r(&local_time, &gmt_buffer);
 107         char gmt_iso[21];
 108         if (!strftime(gmt_iso, 21, "%Y-%m-%dT%H:%M:%SZ", gmt)) {
 109             return AVERROR_UNKNOWN;
 110         }
 111         if (s->flags & AVFMT_FLAG_BITEXACT) {
 112             av_strlcpy(gmt_iso, "", 1);
 113         }
 114         avio_printf(pb, "  availabilityStartTime=\"%s\"\n", gmt_iso);
 115         avio_printf(pb, "  timeShiftBufferDepth=\"PT%gS\"\n", w->time_shift_buffer_depth);
 116         avio_printf(pb, "  minimumUpdatePeriod=\"PT%dS\"", w->minimum_update_period);
 117         avio_printf(pb, ">\n");
 118         if (w->utc_timing_url) {
 119             avio_printf(pb, "<UTCTiming\n");
 120             avio_printf(pb, "  schemeIdUri=\"urn:mpeg:dash:utc:http-iso:2014\"\n");
 121             avio_printf(pb, "  value=\"%s\"/>\n", w->utc_timing_url);
 122         }
 123     }
 124     return 0;
 125 }
 126
 127 static void write_footer(AVFormatContext *s)
 128 {
 129     avio_printf(s->pb, "</MPD>\n");
 130 }
 131
 132 static int subsegment_alignment(AVFormatContext *s, const AdaptationSet *as)
 133 {
 134     int i;
 135     AVDictionaryEntry *gold = av_dict_get(s->streams[as->streams[0]]->metadata,
 136                                           CUE_TIMESTAMPS, NULL, 0);
 137     if (!gold) return 0;
 138     for (i = 1; i < as->nb_streams; i++) {
 139         AVDictionaryEntry *ts = av_dict_get(s->streams[as->streams[i]]->metadata,
 140                                             CUE_TIMESTAMPS, NULL, 0);
 141         if (!ts || !av_strstart(ts->value, gold->value, NULL)) return 0;
 142     }
 143     return 1;
 144 }
 145
 146 static int bitstream_switching(AVFormatContext *s, const AdaptationSet *as)
 147 {
 148     int i;
 149     const AVStream *gold_st = s->streams[as->streams[0]];
 150     AVDictionaryEntry *gold_track_num = av_dict_get(gold_st->metadata,
 151                                                     TRACK_NUMBER, NULL, 0);
 152     AVCodecParameters *gold_par = gold_st->codecpar;
 153     if (!gold_track_num) return 0;
 154     for (i = 1; i < as->nb_streams; i++) {
 155         const AVStream *st = s->streams[as->streams[i]];
 156         AVDictionaryEntry *track_num = av_dict_get(st->metadata,
 157                                                    TRACK_NUMBER, NULL, 0);
 158         AVCodecParameters *par = st->codecpar;
 159         if (!track_num ||
 160             !av_strstart(track_num->value, gold_track_num->value, NULL) ||
 161             gold_par->codec_id != par->codec_id ||
 162             gold_par->extradata_size != par->extradata_size ||
 163             (par->extradata_size > 0 &&
 164              memcmp(gold_par->extradata, par->extradata, par->extradata_size))) {
 165             return 0;
 166         }
 167     }
 168     return 1;
 169 }
 170
 171 /*
 172  * Writes a Representation within an Adaptation Set. Returns 0 on success and
 173  * < 0 on failure.
 174  */
 175 static int write_representation(AVFormatContext *s, AVStream *st, char *id,
 176                                 int output_width, int output_height,
 177                                 int output_sample_rate)
 178 {
 179     WebMDashMuxContext *w = s->priv_data;
 180     AVIOContext *pb = s->pb;
 181     const AVCodecParameters *par = st->codecpar;
 182     AVDictionaryEntry *bandwidth = av_dict_get(st->metadata, BANDWIDTH, NULL, 0);
 183     const char *bandwidth_str;
 184     avio_printf(pb, "<Representation id=\"%s\"", id);
 185     if (bandwidth) {
 186         bandwidth_str = bandwidth->value;
 187     } else if (w->is_live) {
 188         // if bandwidth for live was not provided, use a default
 189         bandwidth_str = (par->codec_type == AVMEDIA_TYPE_AUDIO) ? "128000" : "1000000";
 190     } else {
 191         return AVERROR(EINVAL);
 192     }
 193     avio_printf(pb, " bandwidth=\"%s\"", bandwidth_str);
 194     if (par->codec_type == AVMEDIA_TYPE_VIDEO && output_width)
 195         avio_printf(pb, " width=\"%d\"", par->width);
 196     if (par->codec_type == AVMEDIA_TYPE_VIDEO && output_height)
 197         avio_printf(pb, " height=\"%d\"", par->height);
 198     if (par->codec_type == AVMEDIA_TYPE_AUDIO && output_sample_rate)
 199         avio_printf(pb, " audioSamplingRate=\"%d\"", par->sample_rate);
 200     if (w->is_live) {
 201         // For live streams, Codec and Mime Type always go in the Representation tag.
 202         avio_printf(pb, " codecs=\"%s\"", get_codec_name(par->codec_id));
 203         avio_printf(pb, " mimeType=\"%s/webm\"",
 204                     par->codec_type == AVMEDIA_TYPE_VIDEO ? "video" : "audio");
 205         // For live streams, subsegments always start with key frames. So this
 206         // is always 1.
 207         avio_printf(pb, " startsWithSAP=\"1\"");
 208         avio_printf(pb, ">");
 209     } else {
 210         AVDictionaryEntry *irange = av_dict_get(st->metadata, INITIALIZATION_RANGE, NULL, 0);
 211         AVDictionaryEntry *cues_start = av_dict_get(st->metadata, CUES_START, NULL, 0);
 212         AVDictionaryEntry *cues_end = av_dict_get(st->metadata, CUES_END, NULL, 0);
 213         AVDictionaryEntry *filename = av_dict_get(st->metadata, FILENAME, NULL, 0);
 214         if (!irange || !cues_start || !cues_end || !filename)
 215             return AVERROR(EINVAL);
 216
 217         avio_printf(pb, ">\n");
 218         avio_printf(pb, "<BaseURL>%s</BaseURL>\n", filename->value);
 219         avio_printf(pb, "<SegmentBase\n");
 220         avio_printf(pb, "  indexRange=\"%s-%s\">\n", cues_start->value, cues_end->value);
 221         avio_printf(pb, "<Initialization\n");
 222         avio_printf(pb, "  range=\"0-%s\" />\n", irange->value);
 223         avio_printf(pb, "</SegmentBase>\n");
 224     }
 225     avio_printf(pb, "</Representation>\n");
 226     return 0;
 227 }
 228
 229 /*
 230  * Checks if width of all streams are the same. Returns 1 if true, 0 otherwise.
 231  */
 232 static int check_matching_width(AVFormatContext *s, const AdaptationSet *as)
 233 {
 234     int first_width, i;
 235     if (as->nb_streams < 2) return 1;
 236     first_width = s->streams[as->streams[0]]->codecpar->width;
 237     for (i = 1; i < as->nb_streams; i++)
 238         if (first_width != s->streams[as->streams[i]]->codecpar->width)
 239           return 0;
 240     return 1;
 241 }
 242
 243 /*
 244  * Checks if height of all streams are the same. Returns 1 if true, 0 otherwise.
 245  */
 246 static int check_matching_height(AVFormatContext *s, const AdaptationSet *as)
 247 {
 248     int first_height, i;
 249     if (as->nb_streams < 2) return 1;
 250     first_height = s->streams[as->streams[0]]->codecpar->height;
 251     for (i = 1; i < as->nb_streams; i++)
 252         if (first_height != s->streams[as->streams[i]]->codecpar->height)
 253           return 0;
 254     return 1;
 255 }
 256
 257 /*
 258  * Checks if sample rate of all streams are the same. Returns 1 if true, 0 otherwise.
 259  */
 260 static int check_matching_sample_rate(AVFormatContext *s, const AdaptationSet *as)
 261 {
 262     int first_sample_rate, i;
 263     if (as->nb_streams < 2) return 1;
 264     first_sample_rate = s->streams[as->streams[0]]->codecpar->sample_rate;
 265     for (i = 1; i < as->nb_streams; i++)
 266         if (first_sample_rate != s->streams[as->streams[i]]->codecpar->sample_rate)
 267           return 0;
 268     return 1;
 269 }
 270
 271 static void free_adaptation_sets(AVFormatContext *s)
 272 {
 273     WebMDashMuxContext *w = s->priv_data;
 274     int i;
 275     for (i = 0; i < w->nb_as; i++) {
 276         av_freep(&w->as[i].streams);
 277     }
 278     av_freep(&w->as);
 279     w->nb_as = 0;
 280 }
 281
 282 /*
 283  * Parses a live header filename and returns the position of the '_' and '.'
 284  * delimiting <file_description> and <representation_id>.
 285  *
 286  * Name of the header file should conform to the following pattern:
 287  * <file_description>_<representation_id>.hdr where <file_description> can be
 288  * anything. The chunks should be named according to the following pattern:
 289  * <file_description>_<representation_id>_<chunk_number>.chk
 290  */
 291 static int split_filename(char *filename, char **underscore_pos,
 292                           char **period_pos)
 293 {
 294     *underscore_pos = strrchr(filename, '_');
 295     if (!*underscore_pos)
 296         return AVERROR(EINVAL);
 297     *period_pos = strchr(*underscore_pos, '.');
 298     if (!*period_pos)
 299         return AVERROR(EINVAL);
 300     return 0;
 301 }
 302
 303 /*
 304  * Writes an Adaptation Set. Returns 0 on success and < 0 on failure.
 305  */
 306 static int write_adaptation_set(AVFormatContext *s, int as_index)
 307 {
 308     WebMDashMuxContext *w = s->priv_data;
 309     AdaptationSet *as = &w->as[as_index];
 310     const AVStream *st = s->streams[as->streams[0]];
 311     AVCodecParameters *par = st->codecpar;
 312     AVDictionaryEntry *lang;
 313     AVIOContext *pb = s->pb;
 314     int i;
 315     static const char boolean[2][6] = { "false", "true" };
 316     int subsegmentStartsWithSAP = 1;
 317
 318     // Width, Height and Sample Rate will go in the AdaptationSet tag if they
 319     // are the same for all contained Representations. otherwise, they will go
 320     // on their respective Representation tag. For live streams, they always go
 321     // in the Representation tag.
 322     int width_in_as = 1, height_in_as = 1, sample_rate_in_as = 1;
 323     if (par->codec_type == AVMEDIA_TYPE_VIDEO) {
 324       width_in_as  = !w->is_live && check_matching_width (s, as);
 325       height_in_as = !w->is_live && check_matching_height(s, as);
 326     } else {
 327       sample_rate_in_as = !w->is_live && check_matching_sample_rate(s, as);
 328     }
 329
 330     avio_printf(pb, "<AdaptationSet id=\"%s\"", as->id);
 331     avio_printf(pb, " mimeType=\"%s/webm\"",
 332                 par->codec_type == AVMEDIA_TYPE_VIDEO ? "video" : "audio");
 333     avio_printf(pb, " codecs=\"%s\"", get_codec_name(par->codec_id));
 334
 335     lang = av_dict_get(st->metadata, "language", NULL, 0);
 336     if (lang)
 337         avio_printf(pb, " lang=\"%s\"", lang->value);
 338
 339     if (par->codec_type == AVMEDIA_TYPE_VIDEO && width_in_as)
 340         avio_printf(pb, " width=\"%d\"", par->width);
 341     if (par->codec_type == AVMEDIA_TYPE_VIDEO && height_in_as)
 342         avio_printf(pb, " height=\"%d\"", par->height);
 343     if (par->codec_type == AVMEDIA_TYPE_AUDIO && sample_rate_in_as)
 344         avio_printf(pb, " audioSamplingRate=\"%d\"", par->sample_rate);
 345
 346     avio_printf(pb, " bitstreamSwitching=\"%s\"",
 347                 boolean[bitstream_switching(s, as)]);
 348     avio_printf(pb, " subsegmentAlignment=\"%s\"",
 349                 boolean[w->is_live || subsegment_alignment(s, as)]);
 350
 351     for (i = 0; i < as->nb_streams; i++) {
 352         AVDictionaryEntry *kf = av_dict_get(s->streams[as->streams[i]]->metadata,
 353                                             CLUSTER_KEYFRAME, NULL, 0);
 354         if (!w->is_live && (!kf || !strncmp(kf->value, "0", 1))) subsegmentStartsWithSAP = 0;
 355     }
 356     avio_printf(pb, " subsegmentStartsWithSAP=\"%d\"", subsegmentStartsWithSAP);
 357     avio_printf(pb, ">\n");
 358
 359     if (w->is_live) {
 360         AVDictionaryEntry *filename =
 361             av_dict_get(st->metadata, FILENAME, NULL, 0);
 362         char *underscore_pos, *period_pos;
 363         int ret;
 364         if (!filename)
 365             return AVERROR(EINVAL);
 366         ret = split_filename(filename->value, &underscore_pos, &period_pos);
 367         if (ret) return ret;
 368         *underscore_pos = '\0';
 369         avio_printf(pb, "<ContentComponent id=\"1\" type=\"%s\"/>\n",
 370                     par->codec_type == AVMEDIA_TYPE_VIDEO ? "video" : "audio");
 371         avio_printf(pb, "<SegmentTemplate");
 372         avio_printf(pb, " timescale=\"1000\"");
 373         avio_printf(pb, " duration=\"%d\"", w->chunk_duration);
 374         avio_printf(pb, " media=\"%s_$RepresentationID$_$Number$.chk\"",
 375                     filename->value);
 376         avio_printf(pb, " startNumber=\"%d\"", w->chunk_start_index);
 377         avio_printf(pb, " initialization=\"%s_$RepresentationID$.hdr\"",
 378                     filename->value);
 379         avio_printf(pb, "/>\n");
 380         *underscore_pos = '_';
 381     }
 382
 383     for (i = 0; i < as->nb_streams; i++) {
 384         char buf[25], *representation_id = buf, *underscore_pos, *period_pos;
 385         AVStream *st = s->streams[as->streams[i]];
 386         int ret;
 387         if (w->is_live) {
 388             AVDictionaryEntry *filename =
 389                 av_dict_get(st->metadata, FILENAME, NULL, 0);
 390             if (!filename)
 391                 return AVERROR(EINVAL);
 392             ret = split_filename(filename->value, &underscore_pos, &period_pos);
 393             if (ret < 0)
 394                 return ret;
 395             representation_id = underscore_pos + 1;
 396             *period_pos       = '\0';
 397         } else {
 398             snprintf(buf, sizeof(buf), "%d", w->representation_id++);
 399         }
 400         ret = write_representation(s, st, representation_id, !width_in_as,
 401                                    !height_in_as, !sample_rate_in_as);
 402         if (ret) return ret;
 403         if (w->is_live)
 404             *period_pos = '.';
 405     }
 406     avio_printf(s->pb, "</AdaptationSet>\n");
 407     return 0;
 408 }
 409
 410 static int parse_adaptation_sets(AVFormatContext *s)
 411 {
 412     WebMDashMuxContext *w = s->priv_data;
 413     char *p = w->adaptation_sets;
 414     char *q;
 415     enum { new_set, parsed_id, parsing_streams } state;
 416     if (!w->adaptation_sets) {
 417         av_log(s, AV_LOG_ERROR, "The 'adaptation_sets' option must be set.\n");
 418         return AVERROR(EINVAL);
 419     }
 420     // syntax id=0,streams=0,1,2 id=1,streams=3,4 and so on
 421     state = new_set;
 422     while (1) {
 423         if (*p == '\0') {
 424             if (state == new_set)
 425                 break;
 426             else
 427                 return AVERROR(EINVAL);
 428         } else if (state == new_set && *p == ' ') {
 429             p++;
 430             continue;
 431         } else if (state == new_set && !strncmp(p, "id=", 3)) {
 432             void *mem = av_realloc(w->as, sizeof(*w->as) * (w->nb_as + 1));
 433             const char *comma;
 434             if (mem == NULL)
 435                 return AVERROR(ENOMEM);
 436             w->as = mem;
 437             ++w->nb_as;
 438             w->as[w->nb_as - 1].nb_streams = 0;
 439             w->as[w->nb_as - 1].streams = NULL;
 440             p += 3; // consume "id="
 441             q = w->as[w->nb_as - 1].id;
 442             comma = strchr(p, ',');
 443             if (!comma || comma - p >= sizeof(w->as[w->nb_as - 1].id)) {
 444                 av_log(s, AV_LOG_ERROR, "'id' in 'adaptation_sets' is malformed.\n");
 445                 return AVERROR(EINVAL);
 446             }
 447             while (*p != ',') *q++ = *p++;
 448             *q = 0;
 449             p++;
 450             state = parsed_id;
 451         } else if (state == parsed_id && !strncmp(p, "streams=", 8)) {
 452             p += 8; // consume "streams="
 453             state = parsing_streams;
 454         } else if (state == parsing_streams) {
 455             struct AdaptationSet *as = &w->as[w->nb_as - 1];
 456             int64_t num;
 457             int ret = av_reallocp_array(&as->streams, ++as->nb_streams,
 458                                         sizeof(*as->streams));
 459             if (ret < 0)
 460                 return ret;
 461             num = strtoll(p, &q, 10);
 462             if (!av_isdigit(*p) || (*q != ' ' && *q != '\0' && *q != ',') ||
 463                 num < 0 || num >= s->nb_streams) {
 464                 av_log(s, AV_LOG_ERROR, "Invalid value for 'streams' in adapation_sets.\n");
 465                 return AVERROR(EINVAL);
 466             }
 467             as->streams[as->nb_streams - 1] = num;
 468             if (*q == '\0') break;
 469             if (*q == ' ') state = new_set;
 470             p = ++q;
 471         } else {
 472             return -1;
 473         }
 474     }
 475     return 0;
 476 }
 477
 478 static int webm_dash_manifest_write_header(AVFormatContext *s)
 479 {
 480     int i;
 481     double start = 0.0;
 482     int ret;
 483     WebMDashMuxContext *w = s->priv_data;
 484
 485     for (unsigned i = 0; i < s->nb_streams; i++) {
 486         enum AVCodecID codec_id = s->streams[i]->codecpar->codec_id;
 487         if (codec_id != AV_CODEC_ID_VP8    && codec_id != AV_CODEC_ID_VP9 &&
 488             codec_id != AV_CODEC_ID_AV1    && codec_id != AV_CODEC_ID_VORBIS &&
 489             codec_id != AV_CODEC_ID_OPUS)
 490             return AVERROR(EINVAL);
 491     }
 492
 493     ret = parse_adaptation_sets(s);
 494     if (ret < 0) {
 495         goto fail;
 496     }
 497     ret = write_header(s);
 498     if (ret < 0) {
 499         goto fail;
 500     }
 501     avio_printf(s->pb, "<Period id=\"0\"");
 502     avio_printf(s->pb, " start=\"PT%gS\"", start);
 503     if (!w->is_live) {
 504         avio_printf(s->pb, " duration=\"PT%gS\"", get_duration(s));
 505     }
 506     avio_printf(s->pb, " >\n");
 507
 508     for (i = 0; i < w->nb_as; i++) {
 509         ret = write_adaptation_set(s, i);
 510         if (ret < 0) {
 511             goto fail;
 512         }
 513     }
 514
 515     avio_printf(s->pb, "</Period>\n");
 516     write_footer(s);
 517 fail:
 518     free_adaptation_sets(s);
 519     return ret < 0 ? ret : 0;
 520 }
 521
 522 static int webm_dash_manifest_write_packet(AVFormatContext *s, AVPacket *pkt)
 523 {
 524     return AVERROR_EOF;
 525 }
 526
 527 #define OFFSET(x) offsetof(WebMDashMuxContext, x)
 528 static const AVOption options[] = {
 529     { "adaptation_sets", "Adaptation sets. Syntax: id=0,streams=0,1,2 id=1,streams=3,4 and so on", OFFSET(adaptation_sets), AV_OPT_TYPE_STRING, { 0 }, 0, 0, AV_OPT_FLAG_ENCODING_PARAM },
 530     { "live", "create a live stream manifest", OFFSET(is_live), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, AV_OPT_FLAG_ENCODING_PARAM },
 531     { "chunk_start_index",  "start index of the chunk", OFFSET(chunk_start_index), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
 532     { "chunk_duration_ms", "duration of each chunk (in milliseconds)", OFFSET(chunk_duration), AV_OPT_TYPE_INT, {.i64 = 1000}, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
 533     { "utc_timing_url", "URL of the page that will return the UTC timestamp in ISO format", OFFSET(utc_timing_url), AV_OPT_TYPE_STRING, { 0 }, 0, 0, AV_OPT_FLAG_ENCODING_PARAM },
 534     { "time_shift_buffer_depth", "Smallest time (in seconds) shifting buffer for which any Representation is guaranteed to be available.", OFFSET(time_shift_buffer_depth), AV_OPT_TYPE_DOUBLE, { .dbl = 60.0 }, 1.0, DBL_MAX, AV_OPT_FLAG_ENCODING_PARAM },
 535     { "minimum_update_period", "Minimum Update Period (in seconds) of the manifest.", OFFSET(minimum_update_period), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
 536     { NULL },
 537 };
 538
 539 static const AVClass webm_dash_class = {
 540     .class_name = "WebM DASH Manifest muxer",
 541     .item_name  = av_default_item_name,
 542     .option     = options,
 543     .version    = LIBAVUTIL_VERSION_INT,
 544 };
 545
 546 const FFOutputFormat ff_webm_dash_manifest_muxer = {
 547     .p.name            = "webm_dash_manifest",
 548     .p.long_name       = NULL_IF_CONFIG_SMALL("WebM DASH Manifest"),
 549     .p.mime_type       = "application/xml",
 550     .p.extensions      = "xml",
 551     .priv_data_size    = sizeof(WebMDashMuxContext),
 552     .write_header      = webm_dash_manifest_write_header,
 553     .write_packet      = webm_dash_manifest_write_packet,
 554     .p.priv_class      = &webm_dash_class,
 555 };