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