git.sesse.net Git - ffmpeg/blob - libavformat/dashenc.c

   1 /*
   2  * MPEG-DASH ISO BMFF segmenter
   3  * Copyright (c) 2014 Martin Storsjo
   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 #include "config.h"
  23 #if HAVE_UNISTD_H
  24 #include <unistd.h>
  25 #endif
  26
  27 #include "libavutil/avstring.h"
  28 #include "libavutil/intreadwrite.h"
  29 #include "libavutil/mathematics.h"
  30 #include "libavutil/opt.h"
  31 #include "libavutil/time_internal.h"
  32
  33 #include "avc.h"
  34 #include "avformat.h"
  35 #include "avio_internal.h"
  36 #include "internal.h"
  37 #include "isom.h"
  38 #include "os_support.h"
  39 #include "url.h"
  40
  41 typedef struct Segment {
  42     char file[1024];
  43     int64_t start_pos;
  44     int range_length, index_length;
  45     int64_t time;
  46     int duration;
  47     int n;
  48 } Segment;
  49
  50 typedef struct OutputStream {
  51     AVFormatContext *ctx;
  52     int ctx_inited;
  53     uint8_t iobuf[32768];
  54     URLContext *out;
  55     int packets_written;
  56     char initfile[1024];
  57     int64_t init_start_pos;
  58     int init_range_length;
  59     int nb_segments, segments_size, segment_index;
  60     Segment **segments;
  61     int64_t first_dts, start_dts, end_dts;
  62     char bandwidth_str[64];
  63
  64     char codec_str[100];
  65 } OutputStream;
  66
  67 typedef struct DASHContext {
  68     const AVClass *class;  /* Class for private options. */
  69     int window_size;
  70     int extra_window_size;
  71     int min_seg_duration;
  72     int remove_at_exit;
  73     int use_template;
  74     int use_timeline;
  75     int single_file;
  76     OutputStream *streams;
  77     int has_video, has_audio;
  78     int nb_segments;
  79     int last_duration;
  80     int total_duration;
  81     char availability_start_time[100];
  82     char dirname[1024];
  83 } DASHContext;
  84
  85 static int dash_write(void *opaque, uint8_t *buf, int buf_size)
  86 {
  87     OutputStream *os = opaque;
  88     if (os->out)
  89         ffurl_write(os->out, buf, buf_size);
  90     return buf_size;
  91 }
  92
  93 // RFC 6381
  94 static void set_codec_str(AVFormatContext *s, AVCodecContext *codec,
  95                           char *str, int size)
  96 {
  97     const AVCodecTag *tags[2] = { NULL, NULL };
  98     uint32_t tag;
  99     if (codec->codec_type == AVMEDIA_TYPE_VIDEO)
 100         tags[0] = ff_codec_movvideo_tags;
 101     else if (codec->codec_type == AVMEDIA_TYPE_AUDIO)
 102         tags[0] = ff_codec_movaudio_tags;
 103     else
 104         return;
 105
 106     tag = av_codec_get_tag(tags, codec->codec_id);
 107     if (!tag)
 108         return;
 109     if (size < 5)
 110         return;
 111
 112     AV_WL32(str, tag);
 113     str[4] = '\0';
 114     if (!strcmp(str, "mp4a") || !strcmp(str, "mp4v")) {
 115         uint32_t oti;
 116         tags[0] = ff_mp4_obj_type;
 117         oti = av_codec_get_tag(tags, codec->codec_id);
 118         if (oti)
 119             av_strlcatf(str, size, ".%02x", oti);
 120         else
 121             return;
 122
 123         if (tag == MKTAG('m', 'p', '4', 'a')) {
 124             if (codec->extradata_size >= 2) {
 125                 int aot = codec->extradata[0] >> 3;
 126                 if (aot == 31)
 127                     aot = ((AV_RB16(codec->extradata) >> 5) & 0x3f) + 32;
 128                 av_strlcatf(str, size, ".%d", aot);
 129             }
 130         } else if (tag == MKTAG('m', 'p', '4', 'v')) {
 131             // Unimplemented, should output ProfileLevelIndication as a decimal number
 132             av_log(s, AV_LOG_WARNING, "Incomplete RFC 6381 codec string for mp4v\n");
 133         }
 134     } else if (!strcmp(str, "avc1")) {
 135         uint8_t *tmpbuf = NULL;
 136         uint8_t *extradata = codec->extradata;
 137         int extradata_size = codec->extradata_size;
 138         if (!extradata_size)
 139             return;
 140         if (extradata[0] != 1) {
 141             AVIOContext *pb;
 142             if (avio_open_dyn_buf(&pb) < 0)
 143                 return;
 144             if (ff_isom_write_avcc(pb, extradata, extradata_size) < 0) {
 145                 avio_close_dyn_buf(pb, &tmpbuf);
 146                 av_free(tmpbuf);
 147                 return;
 148             }
 149             extradata_size = avio_close_dyn_buf(pb, &extradata);
 150             tmpbuf = extradata;
 151         }
 152
 153         if (extradata_size >= 4)
 154             av_strlcatf(str, size, ".%02x%02x%02x",
 155                         extradata[1], extradata[2], extradata[3]);
 156         av_free(tmpbuf);
 157     }
 158 }
 159
 160 static void dash_free(AVFormatContext *s)
 161 {
 162     DASHContext *c = s->priv_data;
 163     int i, j;
 164     if (!c->streams)
 165         return;
 166     for (i = 0; i < s->nb_streams; i++) {
 167         OutputStream *os = &c->streams[i];
 168         if (os->ctx && os->ctx_inited)
 169             av_write_trailer(os->ctx);
 170         if (os->ctx && os->ctx->pb)
 171             av_free(os->ctx->pb);
 172         ffurl_close(os->out);
 173         os->out =  NULL;
 174         if (os->ctx)
 175             avformat_free_context(os->ctx);
 176         for (j = 0; j < os->nb_segments; j++)
 177             av_free(os->segments[j]);
 178         av_free(os->segments);
 179     }
 180     av_freep(&c->streams);
 181 }
 182
 183 static void output_segment_list(OutputStream *os, AVIOContext *out, DASHContext *c)
 184 {
 185     int i, start_index = 0, start_number = 1;
 186     if (c->window_size) {
 187         start_index  = FFMAX(os->nb_segments   - c->window_size, 0);
 188         start_number = FFMAX(os->segment_index - c->window_size, 1);
 189     }
 190
 191     if (c->use_template) {
 192         int timescale = c->use_timeline ? os->ctx->streams[0]->time_base.den : AV_TIME_BASE;
 193         avio_printf(out, "\t\t\t\t<SegmentTemplate timescale=\"%d\" ", timescale);
 194         if (!c->use_timeline)
 195             avio_printf(out, "duration=\"%d\" ", c->last_duration);
 196         avio_printf(out, "initialization=\"init-stream$RepresentationID$.m4s\" media=\"chunk-stream$RepresentationID$-$Number%%05d$.m4s\" startNumber=\"%d\">\n", c->use_timeline ? start_number : 1);
 197         if (c->use_timeline) {
 198             avio_printf(out, "\t\t\t\t\t<SegmentTimeline>\n");
 199             for (i = start_index; i < os->nb_segments; ) {
 200                 Segment *seg = os->segments[i];
 201                 int repeat = 0;
 202                 avio_printf(out, "\t\t\t\t\t\t<S ");
 203                 if (i == start_index)
 204                     avio_printf(out, "t=\"%"PRId64"\" ", seg->time);
 205                 avio_printf(out, "d=\"%d\" ", seg->duration);
 206                 while (i + repeat + 1 < os->nb_segments && os->segments[i + repeat + 1]->duration == seg->duration)
 207                     repeat++;
 208                 if (repeat > 0)
 209                     avio_printf(out, "r=\"%d\" ", repeat);
 210                 avio_printf(out, "/>\n");
 211                 i += 1 + repeat;
 212             }
 213             avio_printf(out, "\t\t\t\t\t</SegmentTimeline>\n");
 214         }
 215         avio_printf(out, "\t\t\t\t</SegmentTemplate>\n");
 216     } else if (c->single_file) {
 217         avio_printf(out, "\t\t\t\t<BaseURL>%s</BaseURL>\n", os->initfile);
 218         avio_printf(out, "\t\t\t\t<SegmentList timescale=\"%d\" duration=\"%d\" startNumber=\"%d\">\n", AV_TIME_BASE, c->last_duration, start_number);
 219         avio_printf(out, "\t\t\t\t\t<Initialization range=\"%"PRId64"-%"PRId64"\" />\n", os->init_start_pos, os->init_start_pos + os->init_range_length - 1);
 220         for (i = start_index; i < os->nb_segments; i++) {
 221             Segment *seg = os->segments[i];
 222             avio_printf(out, "\t\t\t\t\t<SegmentURL mediaRange=\"%"PRId64"-%"PRId64"\" ", seg->start_pos, seg->start_pos + seg->range_length - 1);
 223             if (seg->index_length)
 224                 avio_printf(out, "indexRange=\"%"PRId64"-%"PRId64"\" ", seg->start_pos, seg->start_pos + seg->index_length - 1);
 225             avio_printf(out, "/>\n");
 226         }
 227         avio_printf(out, "\t\t\t\t</SegmentList>\n");
 228     } else {
 229         avio_printf(out, "\t\t\t\t<SegmentList timescale=\"%d\" duration=\"%d\" startNumber=\"%d\">\n", AV_TIME_BASE, c->last_duration, start_number);
 230         avio_printf(out, "\t\t\t\t\t<Initialization sourceURL=\"%s\" />\n", os->initfile);
 231         for (i = start_index; i < os->nb_segments; i++) {
 232             Segment *seg = os->segments[i];
 233             avio_printf(out, "\t\t\t\t\t<SegmentURL media=\"%s\" />\n", seg->file);
 234         }
 235         avio_printf(out, "\t\t\t\t</SegmentList>\n");
 236     }
 237 }
 238
 239 static char *xmlescape(const char *str) {
 240     int outlen = strlen(str)*3/2 + 6;
 241     char *out = av_realloc(NULL, outlen + 1);
 242     int pos = 0;
 243     if (!out)
 244         return NULL;
 245     for (; *str; str++) {
 246         if (pos + 6 > outlen) {
 247             char *tmp;
 248             outlen = 2 * outlen + 6;
 249             tmp = av_realloc(out, outlen + 1);
 250             if (!tmp) {
 251                 av_free(out);
 252                 return NULL;
 253             }
 254             out = tmp;
 255         }
 256         if (*str == '&') {
 257             memcpy(&out[pos], "&amp;", 5);
 258             pos += 5;
 259         } else if (*str == '<') {
 260             memcpy(&out[pos], "&lt;", 4);
 261             pos += 4;
 262         } else if (*str == '>') {
 263             memcpy(&out[pos], "&gt;", 4);
 264             pos += 4;
 265         } else if (*str == '\'') {
 266             memcpy(&out[pos], "&apos;", 6);
 267             pos += 6;
 268         } else if (*str == '\"') {
 269             memcpy(&out[pos], "&quot;", 6);
 270             pos += 6;
 271         } else {
 272             out[pos++] = *str;
 273         }
 274     }
 275     out[pos] = '\0';
 276     return out;
 277 }
 278
 279 static void write_time(AVIOContext *out, int64_t time)
 280 {
 281     int seconds = time / AV_TIME_BASE;
 282     int fractions = time % AV_TIME_BASE;
 283     int minutes = seconds / 60;
 284     int hours = minutes / 60;
 285     seconds %= 60;
 286     minutes %= 60;
 287     avio_printf(out, "PT");
 288     if (hours)
 289         avio_printf(out, "%dH", hours);
 290     if (hours || minutes)
 291         avio_printf(out, "%dM", minutes);
 292     avio_printf(out, "%d.%dS", seconds, fractions / (AV_TIME_BASE / 10));
 293 }
 294
 295 static int write_manifest(AVFormatContext *s, int final)
 296 {
 297     DASHContext *c = s->priv_data;
 298     AVIOContext *out;
 299     char temp_filename[1024];
 300     int ret, i;
 301     AVDictionaryEntry *title = av_dict_get(s->metadata, "title", NULL, 0);
 302
 303     snprintf(temp_filename, sizeof(temp_filename), "%s.tmp", s->filename);
 304     ret = avio_open2(&out, temp_filename, AVIO_FLAG_WRITE, &s->interrupt_callback, NULL);
 305     if (ret < 0) {
 306         av_log(s, AV_LOG_ERROR, "Unable to open %s for writing\n", temp_filename);
 307         return ret;
 308     }
 309     avio_printf(out, "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n");
 310     avio_printf(out, "<MPD xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n"
 311                 "\txmlns=\"urn:mpeg:dash:schema:mpd:2011\"\n"
 312                 "\txmlns:xlink=\"http://www.w3.org/1999/xlink\"\n"
 313                 "\txsi:schemaLocation=\"urn:mpeg:DASH:schema:MPD:2011 http://standards.iso.org/ittf/PubliclyAvailableStandards/MPEG-DASH_schema_files/DASH-MPD.xsd\"\n"
 314                 "\tprofiles=\"urn:mpeg:dash:profile:isoff-live:2011\"\n"
 315                 "\ttype=\"%s\"\n", final ? "static" : "dynamic");
 316     if (final) {
 317         avio_printf(out, "\tmediaPresentationDuration=\"");
 318         write_time(out, c->total_duration);
 319         avio_printf(out, "\"\n");
 320     } else {
 321         int update_period = c->last_duration / AV_TIME_BASE;
 322         if (c->use_template && !c->use_timeline)
 323             update_period = 500;
 324         avio_printf(out, "\tminimumUpdatePeriod=\"PT%dS\"\n", update_period);
 325         avio_printf(out, "\tsuggestedPresentationDelay=\"PT%dS\"\n", c->last_duration / AV_TIME_BASE);
 326         if (!c->availability_start_time[0] && s->nb_streams > 0 && c->streams[0].nb_segments > 0) {
 327             time_t t = time(NULL);
 328             struct tm *ptm, tmbuf;
 329             ptm = gmtime_r(&t, &tmbuf);
 330             if (ptm) {
 331                 if (!strftime(c->availability_start_time, sizeof(c->availability_start_time),
 332                               "%Y-%m-%dT%H:%M:%S", ptm))
 333                     c->availability_start_time[0] = '\0';
 334             }
 335         }
 336         if (c->availability_start_time[0])
 337             avio_printf(out, "\tavailabilityStartTime=\"%s\"\n", c->availability_start_time);
 338         if (c->window_size && c->use_template) {
 339             avio_printf(out, "\ttimeShiftBufferDepth=\"");
 340             write_time(out, c->last_duration * c->window_size);
 341             avio_printf(out, "\"\n");
 342         }
 343     }
 344     avio_printf(out, "\tminBufferTime=\"");
 345     write_time(out, c->last_duration);
 346     avio_printf(out, "\">\n");
 347     avio_printf(out, "\t<ProgramInformation>\n");
 348     if (title) {
 349         char *escaped = xmlescape(title->value);
 350         avio_printf(out, "\t\t<Title>%s</Title>\n", escaped);
 351         av_free(escaped);
 352     }
 353     avio_printf(out, "\t</ProgramInformation>\n");
 354     if (c->window_size && s->nb_streams > 0 && c->streams[0].nb_segments > 0 && !c->use_template) {
 355         OutputStream *os = &c->streams[0];
 356         int start_index = FFMAX(os->nb_segments - c->window_size, 0);
 357         int64_t start_time = av_rescale_q(os->segments[start_index]->time, s->streams[0]->time_base, AV_TIME_BASE_Q);
 358         avio_printf(out, "\t<Period start=\"");
 359         write_time(out, start_time);
 360         avio_printf(out, "\">\n");
 361     } else {
 362         avio_printf(out, "\t<Period start=\"PT0.0S\">\n");
 363     }
 364
 365     if (c->has_video) {
 366         avio_printf(out, "\t\t<AdaptationSet id=\"video\" segmentAlignment=\"true\" bitstreamSwitching=\"true\">\n");
 367         for (i = 0; i < s->nb_streams; i++) {
 368             AVStream *st = s->streams[i];
 369             OutputStream *os = &c->streams[i];
 370             if (s->streams[i]->codec->codec_type != AVMEDIA_TYPE_VIDEO)
 371                 continue;
 372             avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"video/mp4\" codecs=\"%s\"%s width=\"%d\" height=\"%d\">\n", i, os->codec_str, os->bandwidth_str, st->codec->width, st->codec->height);
 373             output_segment_list(&c->streams[i], out, c);
 374             avio_printf(out, "\t\t\t</Representation>\n");
 375         }
 376         avio_printf(out, "\t\t</AdaptationSet>\n");
 377     }
 378     if (c->has_audio) {
 379         avio_printf(out, "\t\t<AdaptationSet id=\"audio\" segmentAlignment=\"true\" bitstreamSwitching=\"true\">\n");
 380         for (i = 0; i < s->nb_streams; i++) {
 381             AVStream *st = s->streams[i];
 382             OutputStream *os = &c->streams[i];
 383             if (s->streams[i]->codec->codec_type != AVMEDIA_TYPE_AUDIO)
 384                 continue;
 385             avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"audio/mp4\" codecs=\"%s\"%s audioSamplingRate=\"%d\">\n", i, os->codec_str, os->bandwidth_str, st->codec->sample_rate);
 386             avio_printf(out, "\t\t\t\t<AudioChannelConfiguration schemeIdUri=\"urn:mpeg:dash:23003:3:audio_channel_configuration:2011\" value=\"%d\" />\n", st->codec->channels);
 387             output_segment_list(&c->streams[i], out, c);
 388             avio_printf(out, "\t\t\t</Representation>\n");
 389         }
 390         avio_printf(out, "\t\t</AdaptationSet>\n");
 391     }
 392     avio_printf(out, "\t</Period>\n");
 393     avio_printf(out, "</MPD>\n");
 394     avio_flush(out);
 395     avio_close(out);
 396     return ff_rename(temp_filename, s->filename, s);
 397 }
 398
 399 static int dash_write_header(AVFormatContext *s)
 400 {
 401     DASHContext *c = s->priv_data;
 402     int ret = 0, i;
 403     AVOutputFormat *oformat;
 404     char *ptr;
 405     char basename[1024];
 406
 407     if (c->single_file)
 408         c->use_template = 0;
 409
 410     av_strlcpy(c->dirname, s->filename, sizeof(c->dirname));
 411     ptr = strrchr(c->dirname, '/');
 412     if (ptr) {
 413         av_strlcpy(basename, &ptr[1], sizeof(basename));
 414         ptr[1] = '\0';
 415     } else {
 416         c->dirname[0] = '\0';
 417         av_strlcpy(basename, s->filename, sizeof(basename));
 418     }
 419
 420     ptr = strrchr(basename, '.');
 421     if (ptr)
 422         *ptr = '\0';
 423
 424     oformat = av_guess_format("mp4", NULL, NULL);
 425     if (!oformat) {
 426         ret = AVERROR_MUXER_NOT_FOUND;
 427         goto fail;
 428     }
 429
 430     c->streams = av_mallocz(sizeof(*c->streams) * s->nb_streams);
 431     if (!c->streams) {
 432         ret = AVERROR(ENOMEM);
 433         goto fail;
 434     }
 435
 436     for (i = 0; i < s->nb_streams; i++) {
 437         OutputStream *os = &c->streams[i];
 438         AVFormatContext *ctx;
 439         AVStream *st;
 440         AVDictionary *opts = NULL;
 441         char filename[1024];
 442
 443         int bit_rate = s->streams[i]->codec->bit_rate ?
 444                        s->streams[i]->codec->bit_rate :
 445                        s->streams[i]->codec->rc_max_rate;
 446         if (bit_rate) {
 447             snprintf(os->bandwidth_str, sizeof(os->bandwidth_str),
 448                      " bandwidth=\"%d\"", bit_rate);
 449         } else {
 450             int level = s->strict_std_compliance >= FF_COMPLIANCE_STRICT ?
 451                         AV_LOG_ERROR : AV_LOG_WARNING;
 452             av_log(s, level, "No bit rate set for stream %d\n", i);
 453             if (s->strict_std_compliance >= FF_COMPLIANCE_STRICT) {
 454                 ret = AVERROR(EINVAL);
 455                 goto fail;
 456             }
 457         }
 458
 459         ctx = avformat_alloc_context();
 460         if (!ctx) {
 461             ret = AVERROR(ENOMEM);
 462             goto fail;
 463         }
 464         os->ctx = ctx;
 465         ctx->oformat = oformat;
 466         ctx->interrupt_callback = s->interrupt_callback;
 467
 468         if (!(st = avformat_new_stream(ctx, NULL))) {
 469             ret = AVERROR(ENOMEM);
 470             goto fail;
 471         }
 472         avcodec_copy_context(st->codec, s->streams[i]->codec);
 473         st->sample_aspect_ratio = s->streams[i]->sample_aspect_ratio;
 474         st->time_base = s->streams[i]->time_base;
 475         ctx->avoid_negative_ts = s->avoid_negative_ts;
 476
 477         ctx->pb = avio_alloc_context(os->iobuf, sizeof(os->iobuf), AVIO_FLAG_WRITE, os, NULL, dash_write, NULL);
 478         if (!ctx->pb) {
 479             ret = AVERROR(ENOMEM);
 480             goto fail;
 481         }
 482
 483         if (c->single_file)
 484             snprintf(os->initfile, sizeof(os->initfile), "%s-stream%d.m4s", basename, i);
 485         else
 486             snprintf(os->initfile, sizeof(os->initfile), "init-stream%d.m4s", i);
 487         snprintf(filename, sizeof(filename), "%s%s", c->dirname, os->initfile);
 488         ret = ffurl_open(&os->out, filename, AVIO_FLAG_WRITE, &s->interrupt_callback, NULL);
 489         if (ret < 0)
 490             goto fail;
 491         os->init_start_pos = 0;
 492
 493         av_dict_set(&opts, "movflags", "frag_custom+dash", 0);
 494         if ((ret = avformat_write_header(ctx, &opts)) < 0) {
 495              goto fail;
 496         }
 497         os->ctx_inited = 1;
 498         avio_flush(ctx->pb);
 499         av_dict_free(&opts);
 500
 501         if (c->single_file) {
 502             os->init_range_length = avio_tell(ctx->pb);
 503         } else {
 504             ffurl_close(os->out);
 505             os->out = NULL;
 506         }
 507
 508         s->streams[i]->time_base = st->time_base;
 509         // If the muxer wants to shift timestamps, request to have them shifted
 510         // already before being handed to this muxer, so we don't have mismatches
 511         // between the MPD and the actual segments.
 512         s->avoid_negative_ts = ctx->avoid_negative_ts;
 513         if (st->codec->codec_type == AVMEDIA_TYPE_VIDEO)
 514             c->has_video = 1;
 515         else if (st->codec->codec_type == AVMEDIA_TYPE_AUDIO)
 516             c->has_audio = 1;
 517
 518         set_codec_str(s, os->ctx->streams[0]->codec, os->codec_str, sizeof(os->codec_str));
 519         os->first_dts = AV_NOPTS_VALUE;
 520         os->segment_index = 1;
 521     }
 522
 523     if (!c->has_video && c->min_seg_duration <= 0) {
 524         av_log(s, AV_LOG_WARNING, "no video stream and no min seg duration set\n");
 525         ret = AVERROR(EINVAL);
 526     }
 527     ret = write_manifest(s, 0);
 528
 529 fail:
 530     if (ret)
 531         dash_free(s);
 532     return ret;
 533 }
 534
 535 static int add_segment(OutputStream *os, const char *file,
 536                        int64_t time, int duration,
 537                        int64_t start_pos, int64_t range_length,
 538                        int64_t index_length)
 539 {
 540     int err;
 541     Segment *seg;
 542     if (os->nb_segments >= os->segments_size) {
 543         os->segments_size = (os->segments_size + 1) * 2;
 544         if ((err = av_reallocp(&os->segments, sizeof(*os->segments) *
 545                                os->segments_size)) < 0) {
 546             os->segments_size = 0;
 547             os->nb_segments = 0;
 548             return err;
 549         }
 550     }
 551     seg = av_mallocz(sizeof(*seg));
 552     if (!seg)
 553         return AVERROR(ENOMEM);
 554     av_strlcpy(seg->file, file, sizeof(seg->file));
 555     seg->time = time;
 556     seg->duration = duration;
 557     seg->start_pos = start_pos;
 558     seg->range_length = range_length;
 559     seg->index_length = index_length;
 560     os->segments[os->nb_segments++] = seg;
 561     os->segment_index++;
 562     return 0;
 563 }
 564
 565 static void write_styp(AVIOContext *pb)
 566 {
 567     avio_wb32(pb, 24);
 568     ffio_wfourcc(pb, "styp");
 569     ffio_wfourcc(pb, "msdh");
 570     avio_wb32(pb, 0); /* minor */
 571     ffio_wfourcc(pb, "msdh");
 572     ffio_wfourcc(pb, "msix");
 573 }
 574
 575 static void find_index_range(AVFormatContext *s, const char *dirname,
 576                              const char *filename, int64_t pos,
 577                              int *index_length)
 578 {
 579     char full_path[1024];
 580     uint8_t buf[8];
 581     URLContext *fd;
 582     int ret;
 583
 584     snprintf(full_path, sizeof(full_path), "%s%s", dirname, filename);
 585     ret = ffurl_open(&fd, full_path, AVIO_FLAG_READ, &s->interrupt_callback, NULL);
 586     if (ret < 0)
 587         return;
 588     if (ffurl_seek(fd, pos, SEEK_SET) != pos) {
 589         ffurl_close(fd);
 590         return;
 591     }
 592     ret = ffurl_read(fd, buf, 8);
 593     ffurl_close(fd);
 594     if (ret < 8)
 595         return;
 596     if (AV_RL32(&buf[4]) != MKTAG('s', 'i', 'd', 'x'))
 597         return;
 598     *index_length = AV_RB32(&buf[0]);
 599 }
 600
 601 static int dash_flush(AVFormatContext *s, int final)
 602 {
 603     DASHContext *c = s->priv_data;
 604     int i, ret = 0;
 605
 606     for (i = 0; i < s->nb_streams; i++) {
 607         OutputStream *os = &c->streams[i];
 608         char filename[1024] = "", full_path[1024], temp_path[1024];
 609         int64_t start_pos = avio_tell(os->ctx->pb);
 610         int range_length, index_length = 0;
 611
 612         if (!os->packets_written)
 613             continue;
 614
 615         if (!c->single_file) {
 616             snprintf(filename, sizeof(filename), "chunk-stream%d-%05d.m4s", i, os->segment_index);
 617             snprintf(full_path, sizeof(full_path), "%s%s", c->dirname, filename);
 618             snprintf(temp_path, sizeof(temp_path), "%s.tmp", full_path);
 619             ret = ffurl_open(&os->out, temp_path, AVIO_FLAG_WRITE, &s->interrupt_callback, NULL);
 620             if (ret < 0)
 621                 break;
 622             write_styp(os->ctx->pb);
 623         }
 624         av_write_frame(os->ctx, NULL);
 625         avio_flush(os->ctx->pb);
 626         os->packets_written = 0;
 627
 628         range_length = avio_tell(os->ctx->pb) - start_pos;
 629         if (c->single_file) {
 630             find_index_range(s, c->dirname, os->initfile, start_pos, &index_length);
 631         } else {
 632             ffurl_close(os->out);
 633             os->out = NULL;
 634             ret = ff_rename(temp_path, full_path, s);
 635             if (ret < 0)
 636                 break;
 637         }
 638         add_segment(os, filename, os->start_dts, os->end_dts - os->start_dts, start_pos, range_length, index_length);
 639     }
 640
 641     if (c->window_size || (final && c->remove_at_exit)) {
 642         for (i = 0; i < s->nb_streams; i++) {
 643             OutputStream *os = &c->streams[i];
 644             int j;
 645             int remove = os->nb_segments - c->window_size - c->extra_window_size;
 646             if (final && c->remove_at_exit)
 647                 remove = os->nb_segments;
 648             if (remove > 0) {
 649                 for (j = 0; j < remove; j++) {
 650                     char filename[1024];
 651                     snprintf(filename, sizeof(filename), "%s%s", c->dirname, os->segments[j]->file);
 652                     unlink(filename);
 653                     av_free(os->segments[j]);
 654                 }
 655                 os->nb_segments -= remove;
 656                 memmove(os->segments, os->segments + remove, os->nb_segments * sizeof(*os->segments));
 657             }
 658         }
 659     }
 660
 661     if (ret >= 0)
 662         ret = write_manifest(s, final);
 663     return ret;
 664 }
 665
 666 static int dash_write_packet(AVFormatContext *s, AVPacket *pkt)
 667 {
 668     DASHContext *c = s->priv_data;
 669     AVStream *st = s->streams[pkt->stream_index];
 670     OutputStream *os = &c->streams[pkt->stream_index];
 671     int64_t seg_end_duration = (c->nb_segments + 1) * (int64_t) c->min_seg_duration;
 672     int ret;
 673
 674     // If forcing the stream to start at 0, the mp4 muxer will set the start
 675     // timestamps to 0. Do the same here, to avoid mismatches in duration/timestamps.
 676     if (os->first_dts == AV_NOPTS_VALUE &&
 677         s->avoid_negative_ts == AVFMT_AVOID_NEG_TS_MAKE_ZERO) {
 678         pkt->pts -= pkt->dts;
 679         pkt->dts  = 0;
 680     }
 681
 682     if (os->first_dts == AV_NOPTS_VALUE)
 683         os->first_dts = pkt->dts;
 684
 685     if ((!c->has_video || st->codec->codec_type == AVMEDIA_TYPE_VIDEO) &&
 686         pkt->flags & AV_PKT_FLAG_KEY && os->packets_written &&
 687         av_compare_ts(pkt->dts - os->first_dts, st->time_base,
 688                       seg_end_duration, AV_TIME_BASE_Q) >= 0) {
 689         int64_t prev_duration = c->last_duration;
 690
 691         c->last_duration = av_rescale_q(pkt->dts - os->start_dts,
 692                                         st->time_base,
 693                                         AV_TIME_BASE_Q);
 694         c->total_duration = av_rescale_q(pkt->dts - os->first_dts,
 695                                          st->time_base,
 696                                          AV_TIME_BASE_Q);
 697
 698         if ((!c->use_timeline || !c->use_template) && prev_duration) {
 699             if (c->last_duration < prev_duration*9/10 ||
 700                 c->last_duration > prev_duration*11/10) {
 701                 av_log(s, AV_LOG_WARNING,
 702                        "Segment durations differ too much, enable use_timeline "
 703                        "and use_template, or keep a stricter keyframe interval\n");
 704             }
 705         }
 706
 707         if ((ret = dash_flush(s, 0)) < 0)
 708             return ret;
 709         c->nb_segments++;
 710     }
 711
 712     if (!os->packets_written)
 713         os->start_dts = pkt->dts;
 714     os->end_dts = pkt->dts + pkt->duration;
 715     os->packets_written++;
 716     return ff_write_chained(os->ctx, 0, pkt, s, 0);
 717 }
 718
 719 static int dash_write_trailer(AVFormatContext *s)
 720 {
 721     DASHContext *c = s->priv_data;
 722
 723     if (s->nb_streams > 0) {
 724         OutputStream *os = &c->streams[0];
 725         // If no segments have been written so far, try to do a crude
 726         // guess of the segment duration
 727         if (!c->last_duration)
 728             c->last_duration = av_rescale_q(os->end_dts - os->start_dts,
 729                                             s->streams[0]->time_base,
 730                                             AV_TIME_BASE_Q);
 731         c->total_duration = av_rescale_q(os->end_dts - os->first_dts,
 732                                          s->streams[0]->time_base,
 733                                          AV_TIME_BASE_Q);
 734     }
 735     dash_flush(s, 1);
 736
 737     if (c->remove_at_exit) {
 738         char filename[1024];
 739         int i;
 740         for (i = 0; i < s->nb_streams; i++) {
 741             OutputStream *os = &c->streams[i];
 742             snprintf(filename, sizeof(filename), "%s%s", c->dirname, os->initfile);
 743             unlink(filename);
 744         }
 745         unlink(s->filename);
 746     }
 747
 748     dash_free(s);
 749     return 0;
 750 }
 751
 752 #define OFFSET(x) offsetof(DASHContext, x)
 753 #define E AV_OPT_FLAG_ENCODING_PARAM
 754 static const AVOption options[] = {
 755     { "window_size", "number of segments kept in the manifest", OFFSET(window_size), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, E },
 756     { "extra_window_size", "number of segments kept outside of the manifest before removing from disk", OFFSET(extra_window_size), AV_OPT_TYPE_INT, { .i64 = 5 }, 0, INT_MAX, E },
 757     { "min_seg_duration", "minimum segment duration (in microseconds)", OFFSET(min_seg_duration), AV_OPT_TYPE_INT64, { .i64 = 5000000 }, 0, INT_MAX, E },
 758     { "remove_at_exit", "remove all segments when finished", OFFSET(remove_at_exit), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, E },
 759     { "use_template", "Use SegmentTemplate instead of SegmentList", OFFSET(use_template), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, E },
 760     { "use_timeline", "Use SegmentTimeline in SegmentTemplate", OFFSET(use_timeline), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, E },
 761     { "single_file", "Store all segments in one file, accessed using byte ranges", OFFSET(single_file), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, E },
 762     { NULL },
 763 };
 764
 765 static const AVClass dash_class = {
 766     .class_name = "dash muxer",
 767     .item_name  = av_default_item_name,
 768     .option     = options,
 769     .version    = LIBAVUTIL_VERSION_INT,
 770 };
 771
 772 AVOutputFormat ff_dash_muxer = {
 773     .name           = "dash",
 774     .long_name      = NULL_IF_CONFIG_SMALL("DASH Muxer"),
 775     .priv_data_size = sizeof(DASHContext),
 776     .audio_codec    = AV_CODEC_ID_AAC,
 777     .video_codec    = AV_CODEC_ID_H264,
 778     .flags          = AVFMT_GLOBALHEADER | AVFMT_NOFILE | AVFMT_TS_NEGATIVE,
 779     .write_header   = dash_write_header,
 780     .write_packet   = dash_write_packet,
 781     .write_trailer  = dash_write_trailer,
 782     .codec_tag      = (const AVCodecTag* const []){ ff_mp4_obj_type, 0 },
 783     .priv_class     = &dash_class,
 784 };