/*
  * MPEG-DASH ISO BMFF segmenter
  * Copyright (c) 2014 Martin Storsjo
  *

  * This file is part of FFmpeg.

  *

  * FFmpeg is free software; you can redistribute it and/or

  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *

  * FFmpeg is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public

  * License along with FFmpeg; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 #include "config.h"
 #if HAVE_UNISTD_H
 #include <unistd.h>
 #endif
 

 #include "libavutil/avassert.h"

 #include "libavutil/avutil.h"

 #include "libavutil/avstring.h"
 #include "libavutil/intreadwrite.h"
 #include "libavutil/mathematics.h"
 #include "libavutil/opt.h"

 #include "libavutil/rational.h"

 #include "libavutil/time_internal.h"
 
 #include "avc.h"
 #include "avformat.h"
 #include "avio_internal.h"
 #include "internal.h"
 #include "isom.h"
 #include "os_support.h"
 #include "url.h"

 #include "dash.h"

 typedef struct Segment {
     char file[1024];
     int64_t start_pos;
     int range_length, index_length;
     int64_t time;
     int duration;
     int n;
 } Segment;
 

 typedef struct AdaptationSet {
     char id[10];
     enum AVMediaType media_type;

     AVDictionary *metadata;

     AVRational min_frame_rate, max_frame_rate;
     int ambiguous_frame_rate;

 } AdaptationSet;
 

 typedef struct OutputStream {
     AVFormatContext *ctx;

     int ctx_inited, as_idx;

     AVIOContext *out;

     char format_name[8];

     int packets_written;
     char initfile[1024];

     int64_t init_start_pos, pos;

     int init_range_length;
     int nb_segments, segments_size, segment_index;
     Segment **segments;

     int64_t first_pts, start_pts, max_pts;

     int64_t last_dts;

     int bit_rate;

     char bandwidth_str[64];

 
     char codec_str[100];
 } OutputStream;
 
 typedef struct DASHContext {
     const AVClass *class;  /* Class for private options. */

     char *adaptation_sets;
     AdaptationSet *as;
     int nb_as;

     int window_size;
     int extra_window_size;
     int min_seg_duration;
     int remove_at_exit;
     int use_template;
     int use_timeline;
     int single_file;
     OutputStream *streams;

     int has_video;

     int64_t last_duration;
     int64_t total_duration;

     char availability_start_time[100];
     char dirname[1024];

     const char *single_file_name;
     const char *init_seg_name;
     const char *media_seg_name;

     const char *utc_timing_url;

     const char *user_agent;

 } DASHContext;
 

 static struct codec_string {
     int id;
     const char *str;
 } codecs[] = {
     { AV_CODEC_ID_VP8, "vp8" },
     { AV_CODEC_ID_VP9, "vp9" },
     { AV_CODEC_ID_VORBIS, "vorbis" },
     { AV_CODEC_ID_OPUS, "opus" },
     { 0, NULL }
 };
 

 static void set_codec_str(AVFormatContext *s, AVCodecParameters *par,

                           char *str, int size)
 {
     const AVCodecTag *tags[2] = { NULL, NULL };
     uint32_t tag;

     int i;
 
     // common Webm codecs are not part of RFC 6381
     for (i = 0; codecs[i].id; i++)
         if (codecs[i].id == par->codec_id) {
             av_strlcpy(str, codecs[i].str, size);
             return;
         }
 
     // for codecs part of RFC 6381

     if (par->codec_type == AVMEDIA_TYPE_VIDEO)

         tags[0] = ff_codec_movvideo_tags;

     else if (par->codec_type == AVMEDIA_TYPE_AUDIO)

         tags[0] = ff_codec_movaudio_tags;
     else
         return;
 

     tag = av_codec_get_tag(tags, par->codec_id);

     if (!tag)
         return;
     if (size < 5)
         return;
 
     AV_WL32(str, tag);
     str[4] = '\0';
     if (!strcmp(str, "mp4a") || !strcmp(str, "mp4v")) {
         uint32_t oti;
         tags[0] = ff_mp4_obj_type;

         oti = av_codec_get_tag(tags, par->codec_id);

         if (oti)

             av_strlcatf(str, size, ".%02"PRIx32, oti);

         else
             return;
 
         if (tag == MKTAG('m', 'p', '4', 'a')) {

             if (par->extradata_size >= 2) {
                 int aot = par->extradata[0] >> 3;

                 if (aot == 31)

                     aot = ((AV_RB16(par->extradata) >> 5) & 0x3f) + 32;

                 av_strlcatf(str, size, ".%d", aot);
             }
         } else if (tag == MKTAG('m', 'p', '4', 'v')) {
             // Unimplemented, should output ProfileLevelIndication as a decimal number
             av_log(s, AV_LOG_WARNING, "Incomplete RFC 6381 codec string for mp4v\n");
         }
     } else if (!strcmp(str, "avc1")) {
         uint8_t *tmpbuf = NULL;

         uint8_t *extradata = par->extradata;
         int extradata_size = par->extradata_size;

         if (!extradata_size)
             return;
         if (extradata[0] != 1) {
             AVIOContext *pb;
             if (avio_open_dyn_buf(&pb) < 0)
                 return;
             if (ff_isom_write_avcc(pb, extradata, extradata_size) < 0) {

                 ffio_free_dyn_buf(&pb);

                 return;
             }
             extradata_size = avio_close_dyn_buf(pb, &extradata);
             tmpbuf = extradata;
         }
 
         if (extradata_size >= 4)
             av_strlcatf(str, size, ".%02x%02x%02x",
                         extradata[1], extradata[2], extradata[3]);
         av_free(tmpbuf);
     }
 }
 

 static int flush_dynbuf(OutputStream *os, int *range_length)
 {
     uint8_t *buffer;
 
     if (!os->ctx->pb) {
         return AVERROR(EINVAL);
     }
 
     // flush
     av_write_frame(os->ctx, NULL);
     avio_flush(os->ctx->pb);
 
     // write out to file
     *range_length = avio_close_dyn_buf(os->ctx->pb, &buffer);
     os->ctx->pb = NULL;
     avio_write(os->out, buffer, *range_length);
     av_free(buffer);
 
     // re-open buffer
     return avio_open_dyn_buf(&os->ctx->pb);
 }
 

 static void set_http_options(AVDictionary **options, DASHContext *c)
 {
     if (c->user_agent)
         av_dict_set(options, "user_agent", c->user_agent, 0);
 }
 

 static int flush_init_segment(AVFormatContext *s, OutputStream *os)
 {
     DASHContext *c = s->priv_data;
     int ret, range_length;
 
     ret = flush_dynbuf(os, &range_length);
     if (ret < 0)
         return ret;
 
     os->pos = os->init_range_length = range_length;
     if (!c->single_file)
         ff_format_io_close(s, &os->out);
     return 0;
 }
 

 static void dash_free(AVFormatContext *s)
 {
     DASHContext *c = s->priv_data;
     int i, j;

 
     if (c->as) {

         for (i = 0; i < c->nb_as; i++)
             av_dict_free(&c->as[i].metadata);

         av_freep(&c->as);
         c->nb_as = 0;
     }
 

     if (!c->streams)
         return;
     for (i = 0; i < s->nb_streams; i++) {
         OutputStream *os = &c->streams[i];
         if (os->ctx && os->ctx_inited)
             av_write_trailer(os->ctx);
         if (os->ctx && os->ctx->pb)

             ffio_free_dyn_buf(&os->ctx->pb);

         ff_format_io_close(s, &os->out);

         if (os->ctx)
             avformat_free_context(os->ctx);
         for (j = 0; j < os->nb_segments; j++)
             av_free(os->segments[j]);
         av_free(os->segments);
     }
     av_freep(&c->streams);
 }
 
 static void output_segment_list(OutputStream *os, AVIOContext *out, DASHContext *c)
 {
     int i, start_index = 0, start_number = 1;
     if (c->window_size) {
         start_index  = FFMAX(os->nb_segments   - c->window_size, 0);
         start_number = FFMAX(os->segment_index - c->window_size, 1);
     }
 
     if (c->use_template) {
         int timescale = c->use_timeline ? os->ctx->streams[0]->time_base.den : AV_TIME_BASE;
         avio_printf(out, "\t\t\t\t<SegmentTemplate timescale=\"%d\" ", timescale);
         if (!c->use_timeline)

             avio_printf(out, "duration=\"%"PRId64"\" ", c->last_duration);

         avio_printf(out, "initialization=\"%s\" media=\"%s\" startNumber=\"%d\">\n", c->init_seg_name, c->media_seg_name, c->use_timeline ? start_number : 1);

         if (c->use_timeline) {

             int64_t cur_time = 0;

             avio_printf(out, "\t\t\t\t\t<SegmentTimeline>\n");
             for (i = start_index; i < os->nb_segments; ) {
                 Segment *seg = os->segments[i];
                 int repeat = 0;
                 avio_printf(out, "\t\t\t\t\t\t<S ");

                 if (i == start_index || seg->time != cur_time) {
                     cur_time = seg->time;

                     avio_printf(out, "t=\"%"PRId64"\" ", seg->time);

                 }

                 avio_printf(out, "d=\"%d\" ", seg->duration);

                 while (i + repeat + 1 < os->nb_segments &&
                        os->segments[i + repeat + 1]->duration == seg->duration &&
                        os->segments[i + repeat + 1]->time == os->segments[i + repeat]->time + os->segments[i + repeat]->duration)

                     repeat++;
                 if (repeat > 0)
                     avio_printf(out, "r=\"%d\" ", repeat);
                 avio_printf(out, "/>\n");
                 i += 1 + repeat;

                 cur_time += (1 + repeat) * seg->duration;

             }
             avio_printf(out, "\t\t\t\t\t</SegmentTimeline>\n");
         }
         avio_printf(out, "\t\t\t\t</SegmentTemplate>\n");
     } else if (c->single_file) {
         avio_printf(out, "\t\t\t\t<BaseURL>%s</BaseURL>\n", os->initfile);

         avio_printf(out, "\t\t\t\t<SegmentList timescale=\"%d\" duration=\"%"PRId64"\" startNumber=\"%d\">\n", AV_TIME_BASE, c->last_duration, start_number);

         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);
         for (i = start_index; i < os->nb_segments; i++) {
             Segment *seg = os->segments[i];
             avio_printf(out, "\t\t\t\t\t<SegmentURL mediaRange=\"%"PRId64"-%"PRId64"\" ", seg->start_pos, seg->start_pos + seg->range_length - 1);
             if (seg->index_length)
                 avio_printf(out, "indexRange=\"%"PRId64"-%"PRId64"\" ", seg->start_pos, seg->start_pos + seg->index_length - 1);
             avio_printf(out, "/>\n");
         }
         avio_printf(out, "\t\t\t\t</SegmentList>\n");
     } else {

         avio_printf(out, "\t\t\t\t<SegmentList timescale=\"%d\" duration=\"%"PRId64"\" startNumber=\"%d\">\n", AV_TIME_BASE, c->last_duration, start_number);

         avio_printf(out, "\t\t\t\t\t<Initialization sourceURL=\"%s\" />\n", os->initfile);
         for (i = start_index; i < os->nb_segments; i++) {
             Segment *seg = os->segments[i];
             avio_printf(out, "\t\t\t\t\t<SegmentURL media=\"%s\" />\n", seg->file);
         }
         avio_printf(out, "\t\t\t\t</SegmentList>\n");
     }
 }
 
 static char *xmlescape(const char *str) {
     int outlen = strlen(str)*3/2 + 6;
     char *out = av_realloc(NULL, outlen + 1);
     int pos = 0;
     if (!out)
         return NULL;
     for (; *str; str++) {
         if (pos + 6 > outlen) {
             char *tmp;
             outlen = 2 * outlen + 6;
             tmp = av_realloc(out, outlen + 1);
             if (!tmp) {
                 av_free(out);
                 return NULL;
             }
             out = tmp;
         }
         if (*str == '&') {
             memcpy(&out[pos], "&amp;", 5);
             pos += 5;
         } else if (*str == '<') {
             memcpy(&out[pos], "&lt;", 4);
             pos += 4;
         } else if (*str == '>') {
             memcpy(&out[pos], "&gt;", 4);
             pos += 4;
         } else if (*str == '\'') {
             memcpy(&out[pos], "&apos;", 6);
             pos += 6;
         } else if (*str == '\"') {
             memcpy(&out[pos], "&quot;", 6);
             pos += 6;
         } else {
             out[pos++] = *str;
         }
     }
     out[pos] = '\0';
     return out;
 }
 
 static void write_time(AVIOContext *out, int64_t time)
 {
     int seconds = time / AV_TIME_BASE;
     int fractions = time % AV_TIME_BASE;
     int minutes = seconds / 60;
     int hours = minutes / 60;
     seconds %= 60;
     minutes %= 60;
     avio_printf(out, "PT");
     if (hours)
         avio_printf(out, "%dH", hours);
     if (hours || minutes)
         avio_printf(out, "%dM", minutes);
     avio_printf(out, "%d.%dS", seconds, fractions / (AV_TIME_BASE / 10));
 }
 

 static void format_date_now(char *buf, int size)
 {
     time_t t = time(NULL);
     struct tm *ptm, tmbuf;
     ptm = gmtime_r(&t, &tmbuf);
     if (ptm) {

         if (!strftime(buf, size, "%Y-%m-%dT%H:%M:%SZ", ptm))

             buf[0] = '\0';
     }
 }
 

 static int write_adaptation_set(AVFormatContext *s, AVIOContext *out, int as_index)
 {
     DASHContext *c = s->priv_data;
     AdaptationSet *as = &c->as[as_index];

     AVDictionaryEntry *lang, *role;

     int i;
 

     avio_printf(out, "\t\t<AdaptationSet id=\"%s\" contentType=\"%s\" segmentAlignment=\"true\" bitstreamSwitching=\"true\"",

                 as->id, as->media_type == AVMEDIA_TYPE_VIDEO ? "video" : "audio");

     if (as->media_type == AVMEDIA_TYPE_VIDEO && as->max_frame_rate.num && !as->ambiguous_frame_rate && av_cmp_q(as->min_frame_rate, as->max_frame_rate) < 0)
         avio_printf(out, " maxFrameRate=\"%d/%d\"", as->max_frame_rate.num, as->max_frame_rate.den);

     lang = av_dict_get(as->metadata, "language", NULL, 0);
     if (lang)
         avio_printf(out, " lang=\"%s\"", lang->value);

     avio_printf(out, ">\n");

     role = av_dict_get(as->metadata, "role", NULL, 0);
     if (role)
         avio_printf(out, "\t\t\t<Role schemeIdUri=\"urn:mpeg:dash:role:2011\" value=\"%s\"/>\n", role->value);

 
     for (i = 0; i < s->nb_streams; i++) {
         OutputStream *os = &c->streams[i];
 
         if (os->as_idx - 1 != as_index)
             continue;
 
         if (as->media_type == AVMEDIA_TYPE_VIDEO) {

             AVStream *st = s->streams[i];

             avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"video/%s\" codecs=\"%s\"%s width=\"%d\" height=\"%d\"",

                 i, os->format_name, os->codec_str, os->bandwidth_str, s->streams[i]->codecpar->width, s->streams[i]->codecpar->height);

             if (st->avg_frame_rate.num)
                 avio_printf(out, " frameRate=\"%d/%d\"", st->avg_frame_rate.num, st->avg_frame_rate.den);
             avio_printf(out, ">\n");

         } else {

             avio_printf(out, "\t\t\t<Representation id=\"%d\" mimeType=\"audio/%s\" codecs=\"%s\"%s audioSamplingRate=\"%d\">\n",
                 i, os->format_name, os->codec_str, os->bandwidth_str, s->streams[i]->codecpar->sample_rate);

             avio_printf(out, "\t\t\t\t<AudioChannelConfiguration schemeIdUri=\"urn:mpeg:dash:23003:3:audio_channel_configuration:2011\" value=\"%d\" />\n",
                 s->streams[i]->codecpar->channels);
         }
         output_segment_list(os, out, c);
         avio_printf(out, "\t\t\t</Representation>\n");
     }
     avio_printf(out, "\t\t</AdaptationSet>\n");
 
     return 0;
 }
 
 static int add_adaptation_set(AVFormatContext *s, AdaptationSet **as, enum AVMediaType type)
 {
     DASHContext *c = s->priv_data;
 
     void *mem = av_realloc(c->as, sizeof(*c->as) * (c->nb_as + 1));
     if (!mem)
         return AVERROR(ENOMEM);
     c->as = mem;
     ++c->nb_as;
 
     *as = &c->as[c->nb_as - 1];
     memset(*as, 0, sizeof(**as));
     (*as)->media_type = type;
 
     return 0;
 }
 

 static int adaptation_set_add_stream(AVFormatContext *s, int as_idx, int i)
 {
     DASHContext *c = s->priv_data;
     AdaptationSet *as = &c->as[as_idx - 1];
     OutputStream *os = &c->streams[i];
 
     if (as->media_type != s->streams[i]->codecpar->codec_type) {
         av_log(s, AV_LOG_ERROR, "Codec type of stream %d doesn't match AdaptationSet's media type\n", i);
         return AVERROR(EINVAL);
     } else if (os->as_idx) {
         av_log(s, AV_LOG_ERROR, "Stream %d is already assigned to an AdaptationSet\n", i);
         return AVERROR(EINVAL);
     }
     os->as_idx = as_idx;
 
     return 0;
 }
 

 static int parse_adaptation_sets(AVFormatContext *s)
 {
     DASHContext *c = s->priv_data;
     const char *p = c->adaptation_sets;
     enum { new_set, parse_id, parsing_streams } state;
     AdaptationSet *as;
     int i, n, ret;
 

     // default: one AdaptationSet for each stream

     if (!p) {

         for (i = 0; i < s->nb_streams; i++) {
             if ((ret = add_adaptation_set(s, &as, s->streams[i]->codecpar->codec_type)) < 0)
                 return ret;
             snprintf(as->id, sizeof(as->id), "%d", i);

             c->streams[i].as_idx = c->nb_as;

         }
         goto end;
     }
 
     // syntax id=0,streams=0,1,2 id=1,streams=3,4 and so on
     state = new_set;
     while (*p) {
         if (*p == ' ') {
             p++;
             continue;
         } else if (state == new_set && av_strstart(p, "id=", &p)) {
 
             if ((ret = add_adaptation_set(s, &as, AVMEDIA_TYPE_UNKNOWN)) < 0)
                 return ret;
 
             n = strcspn(p, ",");
             snprintf(as->id, sizeof(as->id), "%.*s", n, p);
 
             p += n;
             if (*p)
                 p++;
             state = parse_id;
         } else if (state == parse_id && av_strstart(p, "streams=", &p)) {
             state = parsing_streams;
         } else if (state == parsing_streams) {
             AdaptationSet *as = &c->as[c->nb_as - 1];
             char idx_str[8], *end_str;
 
             n = strcspn(p, " ,");
             snprintf(idx_str, sizeof(idx_str), "%.*s", n, p);
             p += n;
 

             // if value is "a" or "v", map all streams of that type
             if (as->media_type == AVMEDIA_TYPE_UNKNOWN && (idx_str[0] == 'v' || idx_str[0] == 'a')) {
                 enum AVMediaType type = (idx_str[0] == 'v') ? AVMEDIA_TYPE_VIDEO : AVMEDIA_TYPE_AUDIO;
                 av_log(s, AV_LOG_DEBUG, "Map all streams of type %s\n", idx_str);
 
                 for (i = 0; i < s->nb_streams; i++) {
                     if (s->streams[i]->codecpar->codec_type != type)
                         continue;
 
                     as->media_type = s->streams[i]->codecpar->codec_type;
 
                     if ((ret = adaptation_set_add_stream(s, c->nb_as, i)) < 0)
                         return ret;
                 }
             } else { // select single stream
                 i = strtol(idx_str, &end_str, 10);
                 if (idx_str == end_str || i < 0 || i >= s->nb_streams) {
                     av_log(s, AV_LOG_ERROR, "Selected stream \"%s\" not found!\n", idx_str);
                     return AVERROR(EINVAL);
                 }
                 av_log(s, AV_LOG_DEBUG, "Map stream %d\n", i);
 
                 if (as->media_type == AVMEDIA_TYPE_UNKNOWN) {
                     as->media_type = s->streams[i]->codecpar->codec_type;
                 }

                 if ((ret = adaptation_set_add_stream(s, c->nb_as, i)) < 0)
                     return ret;

             }
 
             if (*p == ' ')
                 state = new_set;
             if (*p)
                 p++;
         } else {
             return AVERROR(EINVAL);
         }
     }
 
 end:
     // check for unassigned streams
     for (i = 0; i < s->nb_streams; i++) {
         OutputStream *os = &c->streams[i];
         if (!os->as_idx) {
             av_log(s, AV_LOG_ERROR, "Stream %d is not mapped to an AdaptationSet\n", i);
             return AVERROR(EINVAL);
         }
     }
     return 0;
 }
 

 static int write_manifest(AVFormatContext *s, int final)
 {
     DASHContext *c = s->priv_data;
     AVIOContext *out;
     char temp_filename[1024];

     int ret, i;

     const char *proto = avio_find_protocol_name(s->filename);
     int use_rename = proto && !strcmp(proto, "file");
     static unsigned int warned_non_file = 0;

     AVDictionaryEntry *title = av_dict_get(s->metadata, "title", NULL, 0);

     AVDictionary *opts = NULL;

     if (!use_rename && !warned_non_file++)
         av_log(s, AV_LOG_ERROR, "Cannot use rename on non file protocol, this may lead to races and temporary partial files\n");
 
     snprintf(temp_filename, sizeof(temp_filename), use_rename ? "%s.tmp" : "%s", s->filename);

     set_http_options(&opts, c);
     ret = s->io_open(s, &out, temp_filename, AVIO_FLAG_WRITE, &opts);

     if (ret < 0) {

         av_log(s, AV_LOG_ERROR, "Unable to open %s for writing\n", temp_filename);

         return ret;
     }

     av_dict_free(&opts);

     avio_printf(out, "<?xml version=\"1.0\" encoding=\"utf-8\"?>\n");
     avio_printf(out, "<MPD xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n"
                 "\txmlns=\"urn:mpeg:dash:schema:mpd:2011\"\n"
                 "\txmlns:xlink=\"http://www.w3.org/1999/xlink\"\n"
                 "\txsi:schemaLocation=\"urn:mpeg:DASH:schema:MPD:2011 http://standards.iso.org/ittf/PubliclyAvailableStandards/MPEG-DASH_schema_files/DASH-MPD.xsd\"\n"
                 "\tprofiles=\"urn:mpeg:dash:profile:isoff-live:2011\"\n"
                 "\ttype=\"%s\"\n", final ? "static" : "dynamic");
     if (final) {
         avio_printf(out, "\tmediaPresentationDuration=\"");
         write_time(out, c->total_duration);
         avio_printf(out, "\"\n");
     } else {

         int64_t update_period = c->last_duration / AV_TIME_BASE;

         char now_str[100];

         if (c->use_template && !c->use_timeline)
             update_period = 500;

         avio_printf(out, "\tminimumUpdatePeriod=\"PT%"PRId64"S\"\n", update_period);

         avio_printf(out, "\tsuggestedPresentationDelay=\"PT%"PRId64"S\"\n", c->last_duration / AV_TIME_BASE);

         if (!c->availability_start_time[0] && s->nb_streams > 0 && c->streams[0].nb_segments > 0) {

             format_date_now(c->availability_start_time, sizeof(c->availability_start_time));

         }
         if (c->availability_start_time[0])
             avio_printf(out, "\tavailabilityStartTime=\"%s\"\n", c->availability_start_time);

         format_date_now(now_str, sizeof(now_str));
         if (now_str[0])
             avio_printf(out, "\tpublishTime=\"%s\"\n", now_str);

         if (c->window_size && c->use_template) {
             avio_printf(out, "\ttimeShiftBufferDepth=\"");
             write_time(out, c->last_duration * c->window_size);
             avio_printf(out, "\"\n");
         }
     }
     avio_printf(out, "\tminBufferTime=\"");

     write_time(out, c->last_duration * 2);

     avio_printf(out, "\">\n");
     avio_printf(out, "\t<ProgramInformation>\n");
     if (title) {
         char *escaped = xmlescape(title->value);
         avio_printf(out, "\t\t<Title>%s</Title>\n", escaped);
         av_free(escaped);
     }
     avio_printf(out, "\t</ProgramInformation>\n");

     if (c->window_size && s->nb_streams > 0 && c->streams[0].nb_segments > 0 && !c->use_template) {
         OutputStream *os = &c->streams[0];
         int start_index = FFMAX(os->nb_segments - c->window_size, 0);
         int64_t start_time = av_rescale_q(os->segments[start_index]->time, s->streams[0]->time_base, AV_TIME_BASE_Q);

         avio_printf(out, "\t<Period id=\"0\" start=\"");

         write_time(out, start_time);
         avio_printf(out, "\">\n");
     } else {

         avio_printf(out, "\t<Period id=\"0\" start=\"PT0.0S\">\n");

     }
 

     for (i = 0; i < c->nb_as; i++) {
         if ((ret = write_adaptation_set(s, out, i)) < 0)
             return ret;

     }
     avio_printf(out, "\t</Period>\n");

 
     if (c->utc_timing_url)
         avio_printf(out, "\t<UTCTiming schemeIdUri=\"urn:mpeg:dash:utc:http-xsdate:2014\" value=\"%s\"/>\n", c->utc_timing_url);
 

     avio_printf(out, "</MPD>\n");
     avio_flush(out);

     ff_format_io_close(s, &out);

 
     if (use_rename)
         return avpriv_io_move(temp_filename, s->filename);
 
     return 0;

 }
 

 static int dict_copy_entry(AVDictionary **dst, const AVDictionary *src, const char *key)
 {
     AVDictionaryEntry *entry = av_dict_get(src, key, NULL, 0);
     if (entry)
         av_dict_set(dst, key, entry->value, AV_DICT_DONT_OVERWRITE);
     return 0;
 }
 

 static int dash_init(AVFormatContext *s)

 {
     DASHContext *c = s->priv_data;
     int ret = 0, i;
     char *ptr;
     char basename[1024];
 

     if (c->single_file_name)
         c->single_file = 1;

     if (c->single_file)
         c->use_template = 0;
 
     av_strlcpy(c->dirname, s->filename, sizeof(c->dirname));
     ptr = strrchr(c->dirname, '/');
     if (ptr) {
         av_strlcpy(basename, &ptr[1], sizeof(basename));
         ptr[1] = '\0';
     } else {
         c->dirname[0] = '\0';
         av_strlcpy(basename, s->filename, sizeof(basename));
     }
 
     ptr = strrchr(basename, '.');
     if (ptr)
         *ptr = '\0';
 
     c->streams = av_mallocz(sizeof(*c->streams) * s->nb_streams);

     if (!c->streams)
         return AVERROR(ENOMEM);

     if ((ret = parse_adaptation_sets(s)) < 0)

         return ret;

     for (i = 0; i < s->nb_streams; i++) {
         OutputStream *os = &c->streams[i];

         AdaptationSet *as = &c->as[os->as_idx - 1];

         AVFormatContext *ctx;
         AVStream *st;
         AVDictionary *opts = NULL;
         char filename[1024];
 

         os->bit_rate = s->streams[i]->codecpar->bit_rate;
         if (os->bit_rate) {
             snprintf(os->bandwidth_str, sizeof(os->bandwidth_str),
                      " bandwidth=\"%d\"", os->bit_rate);
         } else {
             int level = s->strict_std_compliance >= FF_COMPLIANCE_STRICT ?
                         AV_LOG_ERROR : AV_LOG_WARNING;
             av_log(s, level, "No bit rate set for stream %d\n", i);
             if (s->strict_std_compliance >= FF_COMPLIANCE_STRICT)
                 return AVERROR(EINVAL);
         }
 

         // copy AdaptationSet language and role from stream metadata
         dict_copy_entry(&as->metadata, s->streams[i]->metadata, "language");
         dict_copy_entry(&as->metadata, s->streams[i]->metadata, "role");
 

         ctx = avformat_alloc_context();

         if (!ctx)
             return AVERROR(ENOMEM);

 
         // choose muxer based on codec: webm for VP8/9 and opus, mp4 otherwise
         // note: os->format_name is also used as part of the mimetype of the
         //       representation, e.g. video/<format_name>
         if (s->streams[i]->codecpar->codec_id == AV_CODEC_ID_VP8 ||
             s->streams[i]->codecpar->codec_id == AV_CODEC_ID_VP9 ||
             s->streams[i]->codecpar->codec_id == AV_CODEC_ID_OPUS ||
             s->streams[i]->codecpar->codec_id == AV_CODEC_ID_VORBIS) {
             snprintf(os->format_name, sizeof(os->format_name), "webm");
         } else {
             snprintf(os->format_name, sizeof(os->format_name), "mp4");
         }
         ctx->oformat = av_guess_format(os->format_name, NULL, NULL);

         if (!ctx->oformat)
             return AVERROR_MUXER_NOT_FOUND;

         os->ctx = ctx;
         ctx->interrupt_callback = s->interrupt_callback;

         ctx->opaque             = s->opaque;
         ctx->io_close           = s->io_close;
         ctx->io_open            = s->io_open;

         if (!(st = avformat_new_stream(ctx, NULL)))
             return AVERROR(ENOMEM);

         avcodec_parameters_copy(st->codecpar, s->streams[i]->codecpar);

         st->sample_aspect_ratio = s->streams[i]->sample_aspect_ratio;
         st->time_base = s->streams[i]->time_base;

         st->avg_frame_rate = s->streams[i]->avg_frame_rate;

         ctx->avoid_negative_ts = s->avoid_negative_ts;

         ctx->flags = s->flags;

         if ((ret = avio_open_dyn_buf(&ctx->pb)) < 0)

             return ret;

         if (c->single_file) {
             if (c->single_file_name)

                 ff_dash_fill_tmpl_params(os->initfile, sizeof(os->initfile), c->single_file_name, i, 0, os->bit_rate, 0);

             else
                 snprintf(os->initfile, sizeof(os->initfile), "%s-stream%d.m4s", basename, i);
         } else {

             ff_dash_fill_tmpl_params(os->initfile, sizeof(os->initfile), c->init_seg_name, i, 0, os->bit_rate, 0);

         }

         snprintf(filename, sizeof(filename), "%s%s", c->dirname, os->initfile);

         set_http_options(&opts, c);
         ret = s->io_open(s, &os->out, filename, AVIO_FLAG_WRITE, &opts);

         if (ret < 0)

             return ret;

         av_dict_free(&opts);

         os->init_start_pos = 0;
 

         if (!strcmp(os->format_name, "mp4")) {
             av_dict_set(&opts, "movflags", "frag_custom+dash+delay_moov", 0);
         } else {

             av_dict_set_int(&opts, "cluster_time_limit", c->min_seg_duration / 1000, 0);
             av_dict_set_int(&opts, "cluster_size_limit", 5 * 1024 * 1024, 0); // set a large cluster size limit

             av_dict_set_int(&opts, "dash", 1, 0);
             av_dict_set_int(&opts, "dash_track_number", i + 1, 0);
             av_dict_set_int(&opts, "live", 1, 0);

         }

         if ((ret = avformat_init_output(ctx, &opts)) < 0)

             return ret;

         os->ctx_inited = 1;
         avio_flush(ctx->pb);
         av_dict_free(&opts);
 

         av_log(s, AV_LOG_VERBOSE, "Representation %d init segment will be written to: %s\n", i, filename);

         // Flush init segment
         // except for mp4, since delay_moov is set and the init segment
         // is then flushed after the first packets
         if (strcmp(os->format_name, "mp4")) {
             flush_init_segment(s, os);
         }
 

         s->streams[i]->time_base = st->time_base;
         // If the muxer wants to shift timestamps, request to have them shifted
         // already before being handed to this muxer, so we don't have mismatches
         // between the MPD and the actual segments.
         s->avoid_negative_ts = ctx->avoid_negative_ts;

         if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {

             AVRational avg_frame_rate = s->streams[i]->avg_frame_rate;
             if (avg_frame_rate.num > 0) {

                 if (av_cmp_q(avg_frame_rate, as->min_frame_rate) < 0)
                     as->min_frame_rate = avg_frame_rate;
                 if (av_cmp_q(as->max_frame_rate, avg_frame_rate) < 0)
                     as->max_frame_rate = avg_frame_rate;

             } else {

                 as->ambiguous_frame_rate = 1;

             }

             c->has_video = 1;

         }

         set_codec_str(s, st->codecpar, os->codec_str, sizeof(os->codec_str));

         os->first_pts = AV_NOPTS_VALUE;
         os->max_pts = AV_NOPTS_VALUE;

         os->last_dts = AV_NOPTS_VALUE;

         os->segment_index = 1;
     }
 
     if (!c->has_video && c->min_seg_duration <= 0) {
         av_log(s, AV_LOG_WARNING, "no video stream and no min seg duration set\n");

         return AVERROR(EINVAL);

     }

     return 0;
 }
 
 static int dash_write_header(AVFormatContext *s)
 {
     DASHContext *c = s->priv_data;
     int i, ret;
     for (i = 0; i < s->nb_streams; i++) {
         OutputStream *os = &c->streams[i];
         if ((ret = avformat_write_header(os->ctx, NULL)) < 0) {
             dash_free(s);
             return ret;
         }
     }

     ret = write_manifest(s, 0);

     if (!ret)
         av_log(s, AV_LOG_VERBOSE, "Manifest written to: %s\n", s->filename);

     return ret;
 }
 
 static int add_segment(OutputStream *os, const char *file,
                        int64_t time, int duration,
                        int64_t start_pos, int64_t range_length,
                        int64_t index_length)
 {
     int err;
     Segment *seg;
     if (os->nb_segments >= os->segments_size) {
         os->segments_size = (os->segments_size + 1) * 2;
         if ((err = av_reallocp(&os->segments, sizeof(*os->segments) *
                                os->segments_size)) < 0) {
             os->segments_size = 0;
             os->nb_segments = 0;
             return err;
         }
     }
     seg = av_mallocz(sizeof(*seg));
     if (!seg)
         return AVERROR(ENOMEM);
     av_strlcpy(seg->file, file, sizeof(seg->file));
     seg->time = time;
     seg->duration = duration;

     if (seg->time < 0) { // If pts<0, it is expected to be cut away with an edit list
         seg->duration += seg->time;
         seg->time = 0;
     }

     seg->start_pos = start_pos;
     seg->range_length = range_length;
     seg->index_length = index_length;
     os->segments[os->nb_segments++] = seg;
     os->segment_index++;
     return 0;
 }
 
 static void write_styp(AVIOContext *pb)
 {
     avio_wb32(pb, 24);
     ffio_wfourcc(pb, "styp");
     ffio_wfourcc(pb, "msdh");
     avio_wb32(pb, 0); /* minor */
     ffio_wfourcc(pb, "msdh");
     ffio_wfourcc(pb, "msix");
 }
 

 static void find_index_range(AVFormatContext *s, const char *full_path,
                              int64_t pos, int *index_length)

 {
     uint8_t buf[8];

     AVIOContext *pb;

     int ret;
 

     ret = s->io_open(s, &pb, full_path, AVIO_FLAG_READ, NULL);

     if (ret < 0)
         return;

     if (avio_seek(pb, pos, SEEK_SET) != pos) {
         ff_format_io_close(s, &pb);

         return;
     }

     ret = avio_read(pb, buf, 8);
     ff_format_io_close(s, &pb);

     if (ret < 8)
         return;
     if (AV_RL32(&buf[4]) != MKTAG('s', 'i', 'd', 'x'))
         return;
     *index_length = AV_RB32(&buf[0]);
 }
 

 static int update_stream_extradata(AVFormatContext *s, OutputStream *os,

                                    AVCodecParameters *par)

 {
     uint8_t *extradata;
 

     if (os->ctx->streams[0]->codecpar->extradata_size || !par->extradata_size)

         return 0;
 

     extradata = av_malloc(par->extradata_size);

 
     if (!extradata)
         return AVERROR(ENOMEM);
 

     memcpy(extradata, par->extradata, par->extradata_size);

     os->ctx->streams[0]->codecpar->extradata = extradata;
     os->ctx->streams[0]->codecpar->extradata_size = par->extradata_size;

     set_codec_str(s, par, os->codec_str, sizeof(os->codec_str));

 
     return 0;
 }
 

 static int dash_flush(AVFormatContext *s, int final, int stream)

 {
     DASHContext *c = s->priv_data;
     int i, ret = 0;

 
     const char *proto = avio_find_protocol_name(s->filename);
     int use_rename = proto && !strcmp(proto, "file");
 

     int cur_flush_segment_index = 0;
     if (stream >= 0)
         cur_flush_segment_index = c->streams[stream].segment_index;

 
     for (i = 0; i < s->nb_streams; i++) {
         OutputStream *os = &c->streams[i];

         AVStream *st = s->streams[i];

         char filename[1024] = "", full_path[1024], temp_path[1024];
         int range_length, index_length = 0;
 
         if (!os->packets_written)
             continue;
 

         // Flush the single stream that got a keyframe right now.
         // Flush all audio streams as well, in sync with video keyframes,
         // but not the other video streams.
         if (stream >= 0 && i != stream) {

             if (s->streams[i]->codecpar->codec_type != AVMEDIA_TYPE_AUDIO)

                 continue;
             // Make sure we don't flush audio streams multiple times, when
             // all video streams are flushed one at a time.
             if (c->has_video && os->segment_index > cur_flush_segment_index)
                 continue;
         }
 

         if (!os->init_range_length) {

             flush_init_segment(s, os);

         }
 

         if (!c->single_file) {

             AVDictionary *opts = NULL;

             ff_dash_fill_tmpl_params(filename, sizeof(filename), c->media_seg_name, i, os->segment_index, os->bit_rate, os->start_pts);

             snprintf(full_path, sizeof(full_path), "%s%s", c->dirname, filename);

             snprintf(temp_path, sizeof(temp_path), use_rename ? "%s.tmp" : "%s", full_path);

             set_http_options(&opts, c);
             ret = s->io_open(s, &os->out, temp_path, AVIO_FLAG_WRITE, &opts);

             if (ret < 0)
                 break;

             av_dict_free(&opts);

             if (!strcmp(os->format_name, "mp4"))
                 write_styp(os->ctx->pb);

         } else {
             snprintf(full_path, sizeof(full_path), "%s%s", c->dirname, os->initfile);

         }

         ret = flush_dynbuf(os, &range_length);
         if (ret < 0)
             break;

         os->packets_written = 0;
 
         if (c->single_file) {

             find_index_range(s, full_path, os->pos, &index_length);

         } else {

             ff_format_io_close(s, &os->out);

 
             if (use_rename) {
                 ret = avpriv_io_move(temp_path, full_path);
                 if (ret < 0)
                     break;
             }

         }

 
         if (!os->bit_rate) {
             // calculate average bitrate of first segment

             int64_t bitrate = (int64_t) range_length * 8 * AV_TIME_BASE / av_rescale_q(os->max_pts - os->start_pts,
                                                                                        st->time_base,
                                                                                        AV_TIME_BASE_Q);

             if (bitrate >= 0) {
                 os->bit_rate = bitrate;
                 snprintf(os->bandwidth_str, sizeof(os->bandwidth_str),
                      " bandwidth=\"%d\"", os->bit_rate);
             }
         }

         add_segment(os, filename, os->start_pts, os->max_pts - os->start_pts, os->pos, range_length, index_length);

         av_log(s, AV_LOG_VERBOSE, "Representation %d media segment %d written to: %s\n", i, os->segment_index, full_path);

 
         os->pos += range_length;

     }
 
     if (c->window_size || (final && c->remove_at_exit)) {
         for (i = 0; i < s->nb_streams; i++) {
             OutputStream *os = &c->streams[i];
             int j;
             int remove = os->nb_segments - c->window_size - c->extra_window_size;
             if (final && c->remove_at_exit)
                 remove = os->nb_segments;
             if (remove > 0) {
                 for (j = 0; j < remove; j++) {
                     char filename[1024];
                     snprintf(filename, sizeof(filename), "%s%s", c->dirname, os->segments[j]->file);
                     unlink(filename);
                     av_free(os->segments[j]);
                 }
                 os->nb_segments -= remove;
                 memmove(os->segments, os->segments + remove, os->nb_segments * sizeof(*os->segments));
             }
         }
     }
 
     if (ret >= 0)
         ret = write_manifest(s, final);
     return ret;
 }
 
 static int dash_write_packet(AVFormatContext *s, AVPacket *pkt)
 {
     DASHContext *c = s->priv_data;
     AVStream *st = s->streams[pkt->stream_index];
     OutputStream *os = &c->streams[pkt->stream_index];
     int ret;
 

     ret = update_stream_extradata(s, os, st->codecpar);

     if (ret < 0)
         return ret;
 

     // Fill in a heuristic guess of the packet duration, if none is available.
     // The mp4 muxer will do something similar (for the last packet in a fragment)
     // if nothing is set (setting it for the other packets doesn't hurt).
     // By setting a nonzero duration here, we can be sure that the mp4 muxer won't
     // invoke its heuristic (this doesn't have to be identical to that algorithm),
     // so that we know the exact timestamps of fragments.
     if (!pkt->duration && os->last_dts != AV_NOPTS_VALUE)
         pkt->duration = pkt->dts - os->last_dts;
     os->last_dts = pkt->dts;
 

     // If forcing the stream to start at 0, the mp4 muxer will set the start
     // timestamps to 0. Do the same here, to avoid mismatches in duration/timestamps.

     if (os->first_pts == AV_NOPTS_VALUE &&

         s->avoid_negative_ts == AVFMT_AVOID_NEG_TS_MAKE_ZERO) {
         pkt->pts -= pkt->dts;
         pkt->dts  = 0;
     }
 

     if (os->first_pts == AV_NOPTS_VALUE)
         os->first_pts = pkt->pts;

     if ((!c->has_video || st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) &&

         pkt->flags & AV_PKT_FLAG_KEY && os->packets_written &&

         av_compare_ts(pkt->pts - os->start_pts, st->time_base,
                       c->min_seg_duration, AV_TIME_BASE_Q) >= 0) {

         int64_t prev_duration = c->last_duration;
 

         c->last_duration = av_rescale_q(pkt->pts - os->start_pts,

                                         st->time_base,
                                         AV_TIME_BASE_Q);

         c->total_duration = av_rescale_q(pkt->pts - os->first_pts,

                                          st->time_base,
                                          AV_TIME_BASE_Q);
 
         if ((!c->use_timeline || !c->use_template) && prev_duration) {
             if (c->last_duration < prev_duration*9/10 ||
                 c->last_duration > prev_duration*11/10) {
                 av_log(s, AV_LOG_WARNING,
                        "Segment durations differ too much, enable use_timeline "
                        "and use_template, or keep a stricter keyframe interval\n");
             }
         }
 

         if ((ret = dash_flush(s, 0, pkt->stream_index)) < 0)

             return ret;
     }
 

     if (!os->packets_written) {
         // If we wrote a previous segment, adjust the start time of the segment
         // to the end of the previous one (which is the same as the mp4 muxer
         // does). This avoids gaps in the timeline.

         if (os->max_pts != AV_NOPTS_VALUE)
             os->start_pts = os->max_pts;

         else

             os->start_pts = pkt->pts;

     }

     if (os->max_pts == AV_NOPTS_VALUE)
         os->max_pts = pkt->pts + pkt->duration;
     else
         os->max_pts = FFMAX(os->max_pts, pkt->pts + pkt->duration);

     os->packets_written++;

     return ff_write_chained(os->ctx, 0, pkt, s, 0);

 }
 
 static int dash_write_trailer(AVFormatContext *s)
 {
     DASHContext *c = s->priv_data;
 
     if (s->nb_streams > 0) {
         OutputStream *os = &c->streams[0];
         // If no segments have been written so far, try to do a crude
         // guess of the segment duration
         if (!c->last_duration)

             c->last_duration = av_rescale_q(os->max_pts - os->start_pts,

                                             s->streams[0]->time_base,
                                             AV_TIME_BASE_Q);

         c->total_duration = av_rescale_q(os->max_pts - os->first_pts,

                                          s->streams[0]->time_base,
                                          AV_TIME_BASE_Q);
     }

     dash_flush(s, 1, -1);

 
     if (c->remove_at_exit) {
         char filename[1024];
         int i;
         for (i = 0; i < s->nb_streams; i++) {
             OutputStream *os = &c->streams[i];
             snprintf(filename, sizeof(filename), "%s%s", c->dirname, os->initfile);
             unlink(filename);
         }
         unlink(s->filename);
     }
 
     return 0;
 }
 

 static int dash_check_bitstream(struct AVFormatContext *s, const AVPacket *avpkt)
 {
     DASHContext *c = s->priv_data;
     OutputStream *os = &c->streams[avpkt->stream_index];
     AVFormatContext *oc = os->ctx;
     if (oc->oformat->check_bitstream) {
         int ret;
         AVPacket pkt = *avpkt;
         pkt.stream_index = 0;
         ret = oc->oformat->check_bitstream(oc, &pkt);
         if (ret == 1) {
             AVStream *st = s->streams[avpkt->stream_index];
             AVStream *ost = oc->streams[0];
             st->internal->bsfcs = ost->internal->bsfcs;
             st->internal->nb_bsfcs = ost->internal->nb_bsfcs;
             ost->internal->bsfcs = NULL;
             ost->internal->nb_bsfcs = 0;
         }
         return ret;
     }
     return 1;
 }
 

 #define OFFSET(x) offsetof(DASHContext, x)
 #define E AV_OPT_FLAG_ENCODING_PARAM
 static const AVOption options[] = {

     { "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 },

     { "window_size", "number of segments kept in the manifest", OFFSET(window_size), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, E },
     { "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 },

     { "min_seg_duration", "minimum segment duration (in microseconds)", OFFSET(min_seg_duration), AV_OPT_TYPE_INT, { .i64 = 5000000 }, 0, INT_MAX, E },

     { "remove_at_exit", "remove all segments when finished", OFFSET(remove_at_exit), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, E },
     { "use_template", "Use SegmentTemplate instead of SegmentList", OFFSET(use_template), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, E },
     { "use_timeline", "Use SegmentTimeline in SegmentTemplate", OFFSET(use_timeline), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, E },
     { "single_file", "Store all segments in one file, accessed using byte ranges", OFFSET(single_file), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, E },

     { "single_file_name", "DASH-templated name to be used for baseURL. Implies storing all segments in one file, accessed using byte ranges", OFFSET(single_file_name), AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, E },

     { "init_seg_name", "DASH-templated name to used for the initialization segment", OFFSET(init_seg_name), AV_OPT_TYPE_STRING, {.str = "init-stream$RepresentationID$.m4s"}, 0, 0, E },
     { "media_seg_name", "DASH-templated name to used for the media segments", OFFSET(media_seg_name), AV_OPT_TYPE_STRING, {.str = "chunk-stream$RepresentationID$-$Number%05d$.m4s"}, 0, 0, E },

     { "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, E },

     { "http_user_agent", "override User-Agent field in HTTP header", OFFSET(user_agent), AV_OPT_TYPE_STRING, {.str = NULL}, 0, 0, E},

     { NULL },
 };
 
 static const AVClass dash_class = {
     .class_name = "dash muxer",
     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,
 };
 
 AVOutputFormat ff_dash_muxer = {
     .name           = "dash",
     .long_name      = NULL_IF_CONFIG_SMALL("DASH Muxer"),

     .extensions     = "mpd",

     .priv_data_size = sizeof(DASHContext),
     .audio_codec    = AV_CODEC_ID_AAC,
     .video_codec    = AV_CODEC_ID_H264,
     .flags          = AVFMT_GLOBALHEADER | AVFMT_NOFILE | AVFMT_TS_NEGATIVE,

     .init           = dash_init,

     .write_header   = dash_write_header,
     .write_packet   = dash_write_packet,
     .write_trailer  = dash_write_trailer,

     .deinit         = dash_free,

     .check_bitstream = dash_check_bitstream,

     .priv_class     = &dash_class,
 };