/*
  * Dynamic Adaptive Streaming over HTTP demux
  * Copyright (c) 2017 samsamsam@o2.pl based on HLS demux
  * Copyright (c) 2017 Steven Liu
  *
  * 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 <libxml/parser.h>
 #include "libavutil/intreadwrite.h"
 #include "libavutil/opt.h"
 #include "libavutil/time.h"
 #include "libavutil/parseutils.h"
 #include "internal.h"
 #include "avio_internal.h"
 #include "dash.h"
 
 #define INITIAL_BUFFER_SIZE 32768
 
 struct fragment {
     int64_t url_offset;
     int64_t size;
     char *url;
 };
 
 /*
  * reference to : ISO_IEC_23009-1-DASH-2012
  * Section: 5.3.9.6.2
  * Table: Table 17 — Semantics of SegmentTimeline element
  * */
 struct timeline {
     /* starttime: Element or Attribute Name
      * specifies the MPD start time, in @timescale units,
      * the first Segment in the series starts relative to the beginning of the Period.
      * The value of this attribute must be equal to or greater than the sum of the previous S
      * element earliest presentation time and the sum of the contiguous Segment durations.
      * If the value of the attribute is greater than what is expressed by the previous S element,
      * it expresses discontinuities in the timeline.
      * If not present then the value shall be assumed to be zero for the first S element
      * and for the subsequent S elements, the value shall be assumed to be the sum of
      * the previous S element's earliest presentation time and contiguous duration
      * (i.e. previous S@starttime + @duration * (@repeat + 1)).
      * */
     int64_t starttime;
     /* repeat: Element or Attribute Name
      * specifies the repeat count of the number of following contiguous Segments with
      * the same duration expressed by the value of @duration. This value is zero-based
      * (e.g. a value of three means four Segments in the contiguous series).
      * */
     int64_t repeat;
     /* duration: Element or Attribute Name
      * specifies the Segment duration, in units of the value of the @timescale.
      * */
     int64_t duration;
 };
 
 /*
  * Each playlist has its own demuxer. If it is currently active,
  * it has an opened AVIOContext too, and potentially an AVPacket
  * containing the next packet from this stream.
  */
 struct representation {
     char *url_template;
     AVIOContext pb;
     AVIOContext *input;
     AVFormatContext *parent;
     AVFormatContext *ctx;
     AVPacket pkt;
     int rep_idx;
     int rep_count;
     int stream_index;
 
     enum AVMediaType type;
 
     int n_fragments;
     struct fragment **fragments; /* VOD list of fragment for profile */
 
     int n_timelines;
     struct timeline **timelines;
 
     int64_t first_seq_no;
     int64_t last_seq_no;
     int64_t start_number; /* used in case when we have dynamic list of segment to know which segments are new one*/
 
     int64_t fragment_duration;
     int64_t fragment_timescale;
 
     int64_t presentation_timeoffset;
 
     int64_t cur_seq_no;
     int64_t cur_seg_offset;
     int64_t cur_seg_size;
     struct fragment *cur_seg;
 
     /* Currently active Media Initialization Section */
     struct fragment *init_section;
     uint8_t *init_sec_buf;
     uint32_t init_sec_buf_size;
     uint32_t init_sec_data_len;
     uint32_t init_sec_buf_read_offset;
     int64_t cur_timestamp;
     int is_restart_needed;
 };
 
 typedef struct DASHContext {
     const AVClass *class;
     char *base_url;
     struct representation *cur_video;
     struct representation *cur_audio;
 
     /* MediaPresentationDescription Attribute */
     uint64_t media_presentation_duration;
     uint64_t suggested_presentation_delay;
     uint64_t availability_start_time;
     uint64_t publish_time;
     uint64_t minimum_update_period;
     uint64_t time_shift_buffer_depth;
     uint64_t min_buffer_time;
 
     /* Period Attribute */
     uint64_t period_duration;
     uint64_t period_start;
 
     int is_live;
     AVIOInterruptCB *interrupt_callback;
     char *user_agent;                    ///< holds HTTP user agent set as an AVOption to the HTTP protocol context
     char *cookies;                       ///< holds HTTP cookie values set in either the initial response or as an AVOption to the HTTP protocol context
     char *headers;                       ///< holds HTTP headers set as an AVOption to the HTTP protocol context
     char *allowed_extensions;
     AVDictionary *avio_opts;
 } DASHContext;
 
 static uint64_t get_current_time_in_sec(void)
 {
     return  av_gettime() / 1000000;
 }
 
 static uint64_t get_utc_date_time_insec(AVFormatContext *s, const char *datetime)
 {
     struct tm timeinfo;
     int year = 0;
     int month = 0;
     int day = 0;
     int hour = 0;
     int minute = 0;
     int ret = 0;
     float second = 0.0;
 
     /* ISO-8601 date parser */
     if (!datetime)
         return 0;
 
     ret = sscanf(datetime, "%d-%d-%dT%d:%d:%fZ", &year, &month, &day, &hour, &minute, &second);
     /* year, month, day, hour, minute, second  6 arguments */
     if (ret != 6) {
         av_log(s, AV_LOG_WARNING, "get_utc_date_time_insec get a wrong time format\n");
     }
     timeinfo.tm_year = year - 1900;
     timeinfo.tm_mon  = month - 1;
     timeinfo.tm_mday = day;
     timeinfo.tm_hour = hour;
     timeinfo.tm_min  = minute;
     timeinfo.tm_sec  = (int)second;
 
     return av_timegm(&timeinfo);
 }
 
 static uint32_t get_duration_insec(AVFormatContext *s, const char *duration)
 {
     /* ISO-8601 duration parser */
     uint32_t days = 0;
     uint32_t hours = 0;
     uint32_t mins = 0;
     uint32_t secs = 0;
     int size = 0;
     float value = 0;
     char type = '\0';
     const char *ptr = duration;
 
     while (*ptr) {
         if (*ptr == 'P' || *ptr == 'T') {
             ptr++;
             continue;
         }
 
         if (sscanf(ptr, "%f%c%n", &value, &type, &size) != 2) {
             av_log(s, AV_LOG_WARNING, "get_duration_insec get a wrong time format\n");
             return 0; /* parser error */
         }
         switch (type) {
             case 'D':
                 days = (uint32_t)value;
                 break;
             case 'H':
                 hours = (uint32_t)value;
                 break;
             case 'M':
                 mins = (uint32_t)value;
                 break;
             case 'S':
                 secs = (uint32_t)value;
                 break;
             default:
                 // handle invalid type
                 break;
         }
         ptr += size;
     }
     return  ((days * 24 + hours) * 60 + mins) * 60 + secs;
 }
 
 static int64_t get_segment_start_time_based_on_timeline(struct representation *pls, int64_t cur_seq_no)
 {
     int64_t start_time = 0;
     int64_t i = 0;
     int64_t j = 0;
     int64_t num = 0;
 
     if (pls->n_timelines) {
         for (i = 0; i < pls->n_timelines; i++) {
             if (pls->timelines[i]->starttime > 0) {
                 start_time = pls->timelines[i]->starttime;
             }
             if (num == cur_seq_no)
                 goto finish;
 
             start_time += pls->timelines[i]->duration;
             for (j = 0; j < pls->timelines[i]->repeat; j++) {
                 num++;
                 if (num == cur_seq_no)
                     goto finish;
                 start_time += pls->timelines[i]->duration;
             }
             num++;
         }
     }
 finish:
     return start_time;
 }
 
 static int64_t calc_next_seg_no_from_timelines(struct representation *pls, int64_t cur_time)
 {
     int64_t i = 0;
     int64_t j = 0;
     int64_t num = 0;
     int64_t start_time = 0;
 
     for (i = 0; i < pls->n_timelines; i++) {
         if (pls->timelines[i]->starttime > 0) {
             start_time = pls->timelines[i]->starttime;
         }
         if (start_time > cur_time)
             goto finish;
 
         start_time += pls->timelines[i]->duration;
         for (j = 0; j < pls->timelines[i]->repeat; j++) {
             num++;
             if (start_time > cur_time)
                 goto finish;
             start_time += pls->timelines[i]->duration;
         }
         num++;
     }
 
     return -1;
 
 finish:
     return num;
 }
 
 static void free_fragment(struct fragment **seg)
 {
     if (!(*seg)) {
         return;
     }
     av_freep(&(*seg)->url);
     av_freep(seg);
 }
 
 static void free_fragment_list(struct representation *pls)
 {
     int i;
 
     for (i = 0; i < pls->n_fragments; i++) {
         free_fragment(&pls->fragments[i]);
     }
     av_freep(&pls->fragments);
     pls->n_fragments = 0;
 }
 
 static void free_timelines_list(struct representation *pls)
 {
     int i;
 
     for (i = 0; i < pls->n_timelines; i++) {
         av_freep(&pls->timelines[i]);
     }
     av_freep(&pls->timelines);
     pls->n_timelines = 0;
 }
 
 static void free_representation(struct representation *pls)
 {
     free_fragment_list(pls);
     free_timelines_list(pls);
     free_fragment(&pls->cur_seg);
     free_fragment(&pls->init_section);
     av_freep(&pls->init_sec_buf);
     av_freep(&pls->pb.buffer);
     if (pls->input)
         ff_format_io_close(pls->parent, &pls->input);
     if (pls->ctx) {
         pls->ctx->pb = NULL;
         avformat_close_input(&pls->ctx);
     }
 
     av_freep(&pls->url_template);
     av_freep(pls);
 }
 
 static void set_httpheader_options(DASHContext *c, AVDictionary *opts)
 {
     // broker prior HTTP options that should be consistent across requests
     av_dict_set(&opts, "user-agent", c->user_agent, 0);
     av_dict_set(&opts, "cookies", c->cookies, 0);
     av_dict_set(&opts, "headers", c->headers, 0);
     if (c->is_live) {
         av_dict_set(&opts, "seekable", "0", 0);
     }
 }
 static void update_options(char **dest, const char *name, void *src)
 {
     av_freep(dest);
     av_opt_get(src, name, AV_OPT_SEARCH_CHILDREN, (uint8_t**)dest);
     if (*dest)
         av_freep(dest);
 }
 
 static int open_url(AVFormatContext *s, AVIOContext **pb, const char *url,
                     AVDictionary *opts, AVDictionary *opts2, int *is_http)
 {
     DASHContext *c = s->priv_data;
     AVDictionary *tmp = NULL;
     const char *proto_name = NULL;
     int ret;
 
     av_dict_copy(&tmp, opts, 0);
     av_dict_copy(&tmp, opts2, 0);
 
     if (av_strstart(url, "crypto", NULL)) {
         if (url[6] == '+' || url[6] == ':')
             proto_name = avio_find_protocol_name(url + 7);
     }
 
     if (!proto_name)
         proto_name = avio_find_protocol_name(url);
 
     if (!proto_name)
         return AVERROR_INVALIDDATA;
 
     // only http(s) & file are allowed
     if (av_strstart(proto_name, "file", NULL)) {
         if (strcmp(c->allowed_extensions, "ALL") && !av_match_ext(url, c->allowed_extensions)) {
             av_log(s, AV_LOG_ERROR,
                 "Filename extension of \'%s\' is not a common multimedia extension, blocked for security reasons.\n"
                 "If you wish to override this adjust allowed_extensions, you can set it to \'ALL\' to allow all\n",
                 url);
             return AVERROR_INVALIDDATA;
         }
     } else if (av_strstart(proto_name, "http", NULL)) {
         ;
     } else
         return AVERROR_INVALIDDATA;
 
     if (!strncmp(proto_name, url, strlen(proto_name)) && url[strlen(proto_name)] == ':')
         ;
     else if (av_strstart(url, "crypto", NULL) && !strncmp(proto_name, url + 7, strlen(proto_name)) && url[7 + strlen(proto_name)] == ':')
         ;
     else if (strcmp(proto_name, "file") || !strncmp(url, "file,", 5))
         return AVERROR_INVALIDDATA;
 
     ret = s->io_open(s, pb, url, AVIO_FLAG_READ, &tmp);
     if (ret >= 0) {
         // update cookies on http response with setcookies.
         char *new_cookies = NULL;
 
         if (!(s->flags & AVFMT_FLAG_CUSTOM_IO))
             av_opt_get(*pb, "cookies", AV_OPT_SEARCH_CHILDREN, (uint8_t**)&new_cookies);
 
         if (new_cookies) {
             av_free(c->cookies);
             c->cookies = new_cookies;
         }
 
         av_dict_set(&opts, "cookies", c->cookies, 0);
     }
 
     av_dict_free(&tmp);
 
     if (is_http)
         *is_http = av_strstart(proto_name, "http", NULL);
 
     return ret;
 }
 
 static char *get_content_url(xmlNodePtr *baseurl_nodes,
                              int n_baseurl_nodes,
                              char *rep_id_val,
                              char *rep_bandwidth_val,
                              char *val)
 {
     int i;
     char *text;
     char *url = NULL;
     char tmp_str[MAX_URL_SIZE];
     char tmp_str_2[MAX_URL_SIZE];
 
     memset(tmp_str, 0, sizeof(tmp_str));
 
     for (i = 0; i < n_baseurl_nodes; ++i) {
         if (baseurl_nodes[i] &&
             baseurl_nodes[i]->children &&
             baseurl_nodes[i]->children->type == XML_TEXT_NODE) {
             text = xmlNodeGetContent(baseurl_nodes[i]->children);
             if (text) {
                 memset(tmp_str, 0, sizeof(tmp_str));
                 memset(tmp_str_2, 0, sizeof(tmp_str_2));
                 ff_make_absolute_url(tmp_str_2, MAX_URL_SIZE, tmp_str, text);
                 av_strlcpy(tmp_str, tmp_str_2, sizeof(tmp_str));

                 xmlFree(text);

             }
         }
     }
 
     if (val)
         av_strlcat(tmp_str, (const char*)val, sizeof(tmp_str));
 
     if (rep_id_val) {
         url = av_strireplace(tmp_str, "$RepresentationID$", (const char*)rep_id_val);
         if (!url) {
             return NULL;
         }
         av_strlcpy(tmp_str, url, sizeof(tmp_str));
         av_free(url);
     }
     if (rep_bandwidth_val && tmp_str[0] != '\0') {
         url = av_strireplace(tmp_str, "$Bandwidth$", (const char*)rep_bandwidth_val);
         if (!url) {
             return NULL;
         }
     }
     return url;
 }
 
 static char *get_val_from_nodes_tab(xmlNodePtr *nodes, const int n_nodes, const char *attrname)
 {
     int i;
     char *val;
 
     for (i = 0; i < n_nodes; ++i) {
         if (nodes[i]) {
             val = xmlGetProp(nodes[i], attrname);
             if (val)
                 return val;
         }
     }
 
     return NULL;
 }
 
 static xmlNodePtr find_child_node_by_name(xmlNodePtr rootnode, const char *nodename)
 {
     xmlNodePtr node = rootnode;
     if (!node) {
         return NULL;
     }
 
     node = xmlFirstElementChild(node);
     while (node) {
         if (!av_strcasecmp(node->name, nodename)) {
             return node;
         }
         node = xmlNextElementSibling(node);
     }
     return NULL;
 }
 
 static enum AVMediaType get_content_type(xmlNodePtr node)
 {
     enum AVMediaType type = AVMEDIA_TYPE_UNKNOWN;
     int i = 0;
     const char *attr;
     char *val = NULL;
 
     if (node) {
         for (i = 0; i < 2; i++) {
             attr = i ? "mimeType" : "contentType";
             val = xmlGetProp(node, attr);
             if (val) {
                 if (av_stristr((const char *)val, "video")) {
                     type = AVMEDIA_TYPE_VIDEO;
                 } else if (av_stristr((const char *)val, "audio")) {
                     type = AVMEDIA_TYPE_AUDIO;
                 }

                 xmlFree(val);

             }
         }
     }
     return type;
 }
 
 static int parse_manifest_segmenturlnode(AVFormatContext *s, struct representation *rep,
                                          xmlNodePtr fragmenturl_node,
                                          xmlNodePtr *baseurl_nodes,
                                          char *rep_id_val,
                                          char *rep_bandwidth_val)
 {
     char *initialization_val = NULL;
     char *media_val = NULL;
 
     if (!av_strcasecmp(fragmenturl_node->name, (const char *)"Initialization")) {
         initialization_val = xmlGetProp(fragmenturl_node, "sourceURL");
         if (initialization_val) {
             rep->init_section = av_mallocz(sizeof(struct fragment));
             if (!rep->init_section) {

                 xmlFree(initialization_val);

                 return AVERROR(ENOMEM);
             }
             rep->init_section->url = get_content_url(baseurl_nodes, 4,
                                                      rep_id_val,
                                                      rep_bandwidth_val,
                                                      initialization_val);
             if (!rep->init_section->url) {
                 av_free(rep->init_section);

                 xmlFree(initialization_val);

                 return AVERROR(ENOMEM);
             }
             rep->init_section->size = -1;

             xmlFree(initialization_val);

         }
     } else if (!av_strcasecmp(fragmenturl_node->name, (const char *)"SegmentURL")) {
         media_val = xmlGetProp(fragmenturl_node, "media");
         if (media_val) {
             struct fragment *seg = av_mallocz(sizeof(struct fragment));
             if (!seg) {

                 xmlFree(media_val);

                 return AVERROR(ENOMEM);
             }
             seg->url = get_content_url(baseurl_nodes, 4,
                                        rep_id_val,
                                        rep_bandwidth_val,
                                        media_val);
             if (!seg->url) {
                 av_free(seg);

                 xmlFree(media_val);

                 return AVERROR(ENOMEM);
             }
             seg->size = -1;
             dynarray_add(&rep->fragments, &rep->n_fragments, seg);

             xmlFree(media_val);

         }
     }
 
     return 0;
 }
 
 static int parse_manifest_segmenttimeline(AVFormatContext *s, struct representation *rep,
                                           xmlNodePtr fragment_timeline_node)
 {
     xmlAttrPtr attr = NULL;
     char *val  = NULL;
 
     if (!av_strcasecmp(fragment_timeline_node->name, (const char *)"S")) {
         struct timeline *tml = av_mallocz(sizeof(struct timeline));
         if (!tml) {
             return AVERROR(ENOMEM);
         }
         attr = fragment_timeline_node->properties;
         while (attr) {
             val = xmlGetProp(fragment_timeline_node, attr->name);
 
             if (!val) {
                 av_log(s, AV_LOG_WARNING, "parse_manifest_segmenttimeline attr->name = %s val is NULL\n", attr->name);
                 continue;
             }
 
             if (!av_strcasecmp(attr->name, (const char *)"t")) {
                 tml->starttime = (int64_t)strtoll(val, NULL, 10);
             } else if (!av_strcasecmp(attr->name, (const char *)"r")) {
                 tml->repeat =(int64_t) strtoll(val, NULL, 10);
             } else if (!av_strcasecmp(attr->name, (const char *)"d")) {
                 tml->duration = (int64_t)strtoll(val, NULL, 10);
             }
             attr = attr->next;

             xmlFree(val);

         }
         dynarray_add(&rep->timelines, &rep->n_timelines, tml);
     }
 
     return 0;
 }
 
 static int parse_manifest_representation(AVFormatContext *s, const char *url,
                                          xmlNodePtr node,
                                          xmlNodePtr adaptionset_node,
                                          xmlNodePtr mpd_baseurl_node,
                                          xmlNodePtr period_baseurl_node,
                                          xmlNodePtr fragment_template_node,
                                          xmlNodePtr content_component_node,
                                          xmlNodePtr adaptionset_baseurl_node)
 {
     int32_t ret = 0;
     int32_t audio_rep_idx = 0;
     int32_t video_rep_idx = 0;
     DASHContext *c = s->priv_data;
     struct representation *rep = NULL;
     struct fragment *seg = NULL;
     xmlNodePtr representation_segmenttemplate_node = NULL;
     xmlNodePtr representation_baseurl_node = NULL;
     xmlNodePtr representation_segmentlist_node = NULL;
     xmlNodePtr fragment_timeline_node = NULL;
     xmlNodePtr fragment_templates_tab[2];
     char *duration_val = NULL;
     char *presentation_timeoffset_val = NULL;
     char *startnumber_val = NULL;
     char *timescale_val = NULL;
     char *initialization_val = NULL;
     char *media_val = NULL;
     xmlNodePtr baseurl_nodes[4];
     xmlNodePtr representation_node = node;
     char *rep_id_val = xmlGetProp(representation_node, "id");
     char *rep_bandwidth_val = xmlGetProp(representation_node, "bandwidth");
     enum AVMediaType type = AVMEDIA_TYPE_UNKNOWN;
 
     // try get information from representation
     if (type == AVMEDIA_TYPE_UNKNOWN)
         type = get_content_type(representation_node);
     // try get information from contentComponen
     if (type == AVMEDIA_TYPE_UNKNOWN)
         type = get_content_type(content_component_node);
     // try get information from adaption set
     if (type == AVMEDIA_TYPE_UNKNOWN)
         type = get_content_type(adaptionset_node);
     if (type == AVMEDIA_TYPE_UNKNOWN) {
         av_log(s, AV_LOG_VERBOSE, "Parsing '%s' - skipp not supported representation type\n", url);
     } else if ((type == AVMEDIA_TYPE_VIDEO && !c->cur_video) || (type == AVMEDIA_TYPE_AUDIO && !c->cur_audio)) {
         // convert selected representation to our internal struct
         rep = av_mallocz(sizeof(struct representation));
         if (!rep) {
             ret = AVERROR(ENOMEM);
             goto end;
         }
         representation_segmenttemplate_node = find_child_node_by_name(representation_node, "SegmentTemplate");
         representation_baseurl_node = find_child_node_by_name(representation_node, "BaseURL");
         representation_segmentlist_node = find_child_node_by_name(representation_node, "SegmentList");
 
         baseurl_nodes[0] = mpd_baseurl_node;
         baseurl_nodes[1] = period_baseurl_node;
         baseurl_nodes[2] = adaptionset_baseurl_node;
         baseurl_nodes[3] = representation_baseurl_node;
 
         if (representation_segmenttemplate_node || fragment_template_node) {
             fragment_timeline_node = NULL;
             fragment_templates_tab[0] = representation_segmenttemplate_node;
             fragment_templates_tab[1] = fragment_template_node;
 
             presentation_timeoffset_val = get_val_from_nodes_tab(fragment_templates_tab, 2, "presentationTimeOffset");
             duration_val = get_val_from_nodes_tab(fragment_templates_tab, 2, "duration");
             startnumber_val = get_val_from_nodes_tab(fragment_templates_tab, 2, "startNumber");
             timescale_val = get_val_from_nodes_tab(fragment_templates_tab, 2, "timescale");
             initialization_val = get_val_from_nodes_tab(fragment_templates_tab, 2, "initialization");
             media_val = get_val_from_nodes_tab(fragment_templates_tab, 2, "media");
 
             if (initialization_val) {
                 rep->init_section = av_mallocz(sizeof(struct fragment));
                 if (!rep->init_section) {
                     av_free(rep);
                     ret = AVERROR(ENOMEM);
                     goto end;
                 }
                 rep->init_section->url = get_content_url(baseurl_nodes, 4, rep_id_val, rep_bandwidth_val, initialization_val);
                 if (!rep->init_section->url) {
                     av_free(rep->init_section);
                     av_free(rep);
                     ret = AVERROR(ENOMEM);
                     goto end;
                 }
                 rep->init_section->size = -1;

                 xmlFree(initialization_val);

             }
 
             if (media_val) {
                 rep->url_template = get_content_url(baseurl_nodes, 4, rep_id_val, rep_bandwidth_val, media_val);

                 xmlFree(media_val);

             }
 
             if (presentation_timeoffset_val) {
                 rep->presentation_timeoffset = (int64_t) strtoll(presentation_timeoffset_val, NULL, 10);

                 xmlFree(presentation_timeoffset_val);

             }
             if (duration_val) {
                 rep->fragment_duration = (int64_t) strtoll(duration_val, NULL, 10);

                 xmlFree(duration_val);

             }
             if (timescale_val) {
                 rep->fragment_timescale = (int64_t) strtoll(timescale_val, NULL, 10);

                 xmlFree(timescale_val);

             }
             if (startnumber_val) {
                 rep->first_seq_no = (int64_t) strtoll(startnumber_val, NULL, 10);

                 xmlFree(startnumber_val);

             }
 
             fragment_timeline_node = find_child_node_by_name(representation_segmenttemplate_node, "SegmentTimeline");
 
             if (!fragment_timeline_node)
                 fragment_timeline_node = find_child_node_by_name(fragment_template_node, "SegmentTimeline");
             if (fragment_timeline_node) {
                 fragment_timeline_node = xmlFirstElementChild(fragment_timeline_node);
                 while (fragment_timeline_node) {
                     ret = parse_manifest_segmenttimeline(s, rep, fragment_timeline_node);
                     if (ret < 0) {
                         return ret;
                     }
                     fragment_timeline_node = xmlNextElementSibling(fragment_timeline_node);
                 }
             }
         } else if (representation_baseurl_node && !representation_segmentlist_node) {
             seg = av_mallocz(sizeof(struct fragment));
             if (!seg) {
                 ret = AVERROR(ENOMEM);
                 goto end;
             }
             seg->url = get_content_url(baseurl_nodes, 4, rep_id_val, rep_bandwidth_val, NULL);
             if (!seg->url) {
                 av_free(seg);
                 ret = AVERROR(ENOMEM);
                 goto end;
             }
             seg->size = -1;
             dynarray_add(&rep->fragments, &rep->n_fragments, seg);
         } else if (representation_segmentlist_node) {
             // TODO: https://www.brendanlong.com/the-structure-of-an-mpeg-dash-mpd.html
             // http://www-itec.uni-klu.ac.at/dash/ddash/mpdGenerator.php?fragmentlength=15&type=full
             xmlNodePtr fragmenturl_node = NULL;
             duration_val = xmlGetProp(representation_segmentlist_node, "duration");
             timescale_val = xmlGetProp(representation_segmentlist_node, "timescale");
             if (duration_val) {
                 rep->fragment_duration = (int64_t) strtoll(duration_val, NULL, 10);

                 xmlFree(duration_val);

             }
             if (timescale_val) {
                 rep->fragment_timescale = (int64_t) strtoll(timescale_val, NULL, 10);

                 xmlFree(timescale_val);

             }
             fragmenturl_node = xmlFirstElementChild(representation_segmentlist_node);
             while (fragmenturl_node) {
                 ret = parse_manifest_segmenturlnode(s, rep, fragmenturl_node,
                                                     baseurl_nodes,
                                                     rep_id_val,
                                                     rep_bandwidth_val);
                 if (ret < 0) {
                     return ret;
                 }
                 fragmenturl_node = xmlNextElementSibling(fragmenturl_node);
             }
 
             fragment_timeline_node = find_child_node_by_name(representation_segmenttemplate_node, "SegmentTimeline");
 
             if (!fragment_timeline_node)
                 fragment_timeline_node = find_child_node_by_name(fragment_template_node, "SegmentTimeline");
             if (fragment_timeline_node) {
                 fragment_timeline_node = xmlFirstElementChild(fragment_timeline_node);
                 while (fragment_timeline_node) {
                     ret = parse_manifest_segmenttimeline(s, rep, fragment_timeline_node);
                     if (ret < 0) {
                         return ret;
                     }
                     fragment_timeline_node = xmlNextElementSibling(fragment_timeline_node);
                 }
             }
         } else {
             free_representation(rep);
             rep = NULL;
             av_log(s, AV_LOG_ERROR, "Unknown format of Representation node id[%s] \n", (const char *)rep_id_val);
         }
 
         if (rep) {
             if (rep->fragment_duration > 0 && !rep->fragment_timescale)
                 rep->fragment_timescale = 1;
             if (type == AVMEDIA_TYPE_VIDEO) {
                 rep->rep_idx = video_rep_idx;
                 c->cur_video = rep;
             } else {
                 rep->rep_idx = audio_rep_idx;
                 c->cur_audio = rep;
             }
         }
     }
 
     video_rep_idx += type == AVMEDIA_TYPE_VIDEO;
     audio_rep_idx += type == AVMEDIA_TYPE_AUDIO;
 
 end:
     if (rep_id_val)

         xmlFree(rep_id_val);

     if (rep_bandwidth_val)

         xmlFree(rep_bandwidth_val);

 
     return ret;
 }
 
 static int parse_manifest_adaptationset(AVFormatContext *s, const char *url,
                                         xmlNodePtr adaptionset_node,
                                         xmlNodePtr mpd_baseurl_node,
                                         xmlNodePtr period_baseurl_node)
 {
     int ret = 0;
     xmlNodePtr fragment_template_node = NULL;
     xmlNodePtr content_component_node = NULL;
     xmlNodePtr adaptionset_baseurl_node = NULL;
     xmlNodePtr node = NULL;
 
     node = xmlFirstElementChild(adaptionset_node);
     while (node) {
         if (!av_strcasecmp(node->name, (const char *)"SegmentTemplate")) {
             fragment_template_node = node;
         } else if (!av_strcasecmp(node->name, (const char *)"ContentComponent")) {
             content_component_node = node;
         } else if (!av_strcasecmp(node->name, (const char *)"BaseURL")) {
             adaptionset_baseurl_node = node;
         } else if (!av_strcasecmp(node->name, (const char *)"Representation")) {
             ret = parse_manifest_representation(s, url, node,
                                                 adaptionset_node,
                                                 mpd_baseurl_node,
                                                 period_baseurl_node,
                                                 fragment_template_node,
                                                 content_component_node,
                                                 adaptionset_baseurl_node);
             if (ret < 0) {
                 return ret;
             }
         }
         node = xmlNextElementSibling(node);
     }
     return 0;
 }
 
 static int parse_manifest(AVFormatContext *s, const char *url, AVIOContext *in)
 {
     DASHContext *c = s->priv_data;
     int ret = 0;
     int close_in = 0;
     uint8_t *new_url = NULL;
     int64_t filesize = 0;
     char *buffer = NULL;
     AVDictionary *opts = NULL;
     xmlDoc *doc = NULL;
     xmlNodePtr root_element = NULL;
     xmlNodePtr node = NULL;
     xmlNodePtr period_node = NULL;
     xmlNodePtr mpd_baseurl_node = NULL;
     xmlNodePtr period_baseurl_node = NULL;
     xmlNodePtr adaptionset_node = NULL;
     xmlAttrPtr attr = NULL;
     char *val  = NULL;
     uint32_t perdiod_duration_sec = 0;
     uint32_t perdiod_start_sec = 0;
     int32_t audio_rep_idx = 0;
     int32_t video_rep_idx = 0;
 
     if (!in) {
         close_in = 1;
 
         set_httpheader_options(c, opts);
         ret = avio_open2(&in, url, AVIO_FLAG_READ, c->interrupt_callback, &opts);
         av_dict_free(&opts);
         if (ret < 0)
             return ret;
     }
 
     if (av_opt_get(in, "location", AV_OPT_SEARCH_CHILDREN, &new_url) >= 0) {
         c->base_url = av_strdup(new_url);
     } else {
         c->base_url = av_strdup(url);
     }
 
     filesize = avio_size(in);
     if (filesize <= 0) {
         filesize = 8 * 1024;
     }
 
     buffer = av_mallocz(filesize);
     if (!buffer) {
         av_free(c->base_url);
         return AVERROR(ENOMEM);
     }
 
     filesize = avio_read(in, buffer, filesize);
     if (filesize <= 0) {
         av_log(s, AV_LOG_ERROR, "Unable to read to offset '%s'\n", url);
         ret = AVERROR_INVALIDDATA;
     } else {
         LIBXML_TEST_VERSION
 
         doc = xmlReadMemory(buffer, filesize, c->base_url, NULL, 0);
         root_element = xmlDocGetRootElement(doc);
         node = root_element;
 
         if (!node) {
             ret = AVERROR_INVALIDDATA;
             av_log(s, AV_LOG_ERROR, "Unable to parse '%s' - missing root node\n", url);
             goto cleanup;
         }
 
         if (node->type != XML_ELEMENT_NODE ||
             av_strcasecmp(node->name, (const char *)"MPD")) {
             ret = AVERROR_INVALIDDATA;
             av_log(s, AV_LOG_ERROR, "Unable to parse '%s' - wrong root node name[%s] type[%d]\n", url, node->name, (int)node->type);
             goto cleanup;
         }
 
         val = xmlGetProp(node, "type");
         if (!val) {
             av_log(s, AV_LOG_ERROR, "Unable to parse '%s' - missing type attrib\n", url);
             ret = AVERROR_INVALIDDATA;
             goto cleanup;
         }
         if (!av_strcasecmp(val, (const char *)"dynamic"))
             c->is_live = 1;

         xmlFree(val);

 
         attr = node->properties;
         while (attr) {
             val = xmlGetProp(node, attr->name);
 
             if (!av_strcasecmp(attr->name, (const char *)"availabilityStartTime")) {
                 c->availability_start_time = get_utc_date_time_insec(s, (const char *)val);
             } else if (!av_strcasecmp(attr->name, (const char *)"publishTime")) {
                 c->publish_time = get_utc_date_time_insec(s, (const char *)val);
             } else if (!av_strcasecmp(attr->name, (const char *)"minimumUpdatePeriod")) {
                 c->minimum_update_period = get_duration_insec(s, (const char *)val);
             } else if (!av_strcasecmp(attr->name, (const char *)"timeShiftBufferDepth")) {
                 c->time_shift_buffer_depth = get_duration_insec(s, (const char *)val);
             } else if (!av_strcasecmp(attr->name, (const char *)"minBufferTime")) {
                 c->min_buffer_time = get_duration_insec(s, (const char *)val);
             } else if (!av_strcasecmp(attr->name, (const char *)"suggestedPresentationDelay")) {
                 c->suggested_presentation_delay = get_duration_insec(s, (const char *)val);
             } else if (!av_strcasecmp(attr->name, (const char *)"mediaPresentationDuration")) {
                 c->media_presentation_duration = get_duration_insec(s, (const char *)val);
             }
             attr = attr->next;

             xmlFree(val);

         }
 
         mpd_baseurl_node = find_child_node_by_name(node, "BaseURL");
 
         // at now we can handle only one period, with the longest duration
         node = xmlFirstElementChild(node);
         while (node) {
             if (!av_strcasecmp(node->name, (const char *)"Period")) {
                 perdiod_duration_sec = 0;
                 perdiod_start_sec = 0;
                 attr = node->properties;
                 while (attr) {
                     val = xmlGetProp(node, attr->name);
                     if (!av_strcasecmp(attr->name, (const char *)"duration")) {
                         perdiod_duration_sec = get_duration_insec(s, (const char *)val);
                     } else if (!av_strcasecmp(attr->name, (const char *)"start")) {
                         perdiod_start_sec = get_duration_insec(s, (const char *)val);
                     }
                     attr = attr->next;

                     xmlFree(val);

                 }
                 if ((perdiod_duration_sec) >= (c->period_duration)) {
                     period_node = node;
                     c->period_duration = perdiod_duration_sec;
                     c->period_start = perdiod_start_sec;
                     if (c->period_start > 0)
                         c->media_presentation_duration = c->period_duration;
                 }
             }
             node = xmlNextElementSibling(node);
         }
         if (!period_node) {
             av_log(s, AV_LOG_ERROR, "Unable to parse '%s' - missing Period node\n", url);
             ret = AVERROR_INVALIDDATA;
             goto cleanup;
         }
 
         adaptionset_node = xmlFirstElementChild(period_node);
         while (adaptionset_node) {
             if (!av_strcasecmp(adaptionset_node->name, (const char *)"BaseURL")) {
                 period_baseurl_node = adaptionset_node;
             } else if (!av_strcasecmp(adaptionset_node->name, (const char *)"AdaptationSet")) {
                 parse_manifest_adaptationset(s, url, adaptionset_node, mpd_baseurl_node, period_baseurl_node);
             }
             adaptionset_node = xmlNextElementSibling(adaptionset_node);
         }
         if (c->cur_video) {
             c->cur_video->rep_count = video_rep_idx;
             av_log(s, AV_LOG_VERBOSE, "rep_idx[%d]\n", (int)c->cur_video->rep_idx);
             av_log(s, AV_LOG_VERBOSE, "rep_count[%d]\n", (int)video_rep_idx);
         }
         if (c->cur_audio) {
             c->cur_audio->rep_count = audio_rep_idx;
         }
 cleanup:
         /*free the document */
         xmlFreeDoc(doc);
         xmlCleanupParser();
     }
 
     av_free(new_url);
     av_free(buffer);
     if (close_in) {
         avio_close(in);
     }
     return ret;
 }
 
 static int64_t calc_cur_seg_no(AVFormatContext *s, struct representation *pls)
 {
     DASHContext *c = s->priv_data;
     int64_t num = 0;
     int64_t start_time_offset = 0;
 
     if (c->is_live) {
         if (pls->n_fragments) {
             num = pls->first_seq_no;
         } else if (pls->n_timelines) {
             start_time_offset = get_segment_start_time_based_on_timeline(pls, 0xFFFFFFFF) - pls->timelines[pls->first_seq_no]->starttime; // total duration of playlist
             if (start_time_offset < 60 * pls->fragment_timescale)
                 start_time_offset = 0;
             else
                 start_time_offset = start_time_offset - 60 * pls->fragment_timescale;
 
             num = calc_next_seg_no_from_timelines(pls, pls->timelines[pls->first_seq_no]->starttime + start_time_offset);
             if (num == -1)
                 num = pls->first_seq_no;
         } else if (pls->fragment_duration){
             if (pls->presentation_timeoffset) {
                 num = pls->presentation_timeoffset * pls->fragment_timescale / pls->fragment_duration;
             } else if (c->publish_time > 0 && !c->availability_start_time) {
                 num = pls->first_seq_no + (((c->publish_time - c->availability_start_time) - c->suggested_presentation_delay) * pls->fragment_timescale) / pls->fragment_duration;
             } else {
                 num = pls->first_seq_no + (((get_current_time_in_sec() - c->availability_start_time) - c->suggested_presentation_delay) * pls->fragment_timescale) / pls->fragment_duration;
             }
         }
     } else {
         num = pls->first_seq_no;
     }
     return num;
 }
 
 static int64_t calc_min_seg_no(AVFormatContext *s, struct representation *pls)
 {
     DASHContext *c = s->priv_data;
     int64_t num = 0;
 
     if (c->is_live && pls->fragment_duration) {
         num = pls->first_seq_no + (((get_current_time_in_sec() - c->availability_start_time) - c->time_shift_buffer_depth) * pls->fragment_timescale) / pls->fragment_duration;
     } else {
         num = pls->first_seq_no;
     }
     return num;
 }
 
 static int64_t calc_max_seg_no(struct representation *pls)
 {
     DASHContext *c = pls->parent->priv_data;
     int64_t num = 0;
 
     if (pls->n_fragments) {
         num = pls->first_seq_no + pls->n_fragments - 1;
     } else if (pls->n_timelines) {
         int i = 0;
         num = pls->first_seq_no + pls->n_timelines - 1;
         for (i = 0; i < pls->n_timelines; i++) {
             num += pls->timelines[i]->repeat;
         }
     } else if (c->is_live && pls->fragment_duration) {
         num = pls->first_seq_no + (((get_current_time_in_sec() - c->availability_start_time)) * pls->fragment_timescale)  / pls->fragment_duration;
     } else if (pls->fragment_duration) {
         num = pls->first_seq_no + (c->media_presentation_duration * pls->fragment_timescale) / pls->fragment_duration;
     }
 
     return num;
 }
 
 static void move_timelines(struct representation *rep_src, struct representation *rep_dest)
 {
     if (rep_dest && rep_src ) {
         free_timelines_list(rep_dest);
         rep_dest->timelines    = rep_src->timelines;
         rep_dest->n_timelines  = rep_src->n_timelines;
         rep_dest->first_seq_no = rep_src->first_seq_no;
         rep_dest->last_seq_no = calc_max_seg_no(rep_dest);
         rep_src->timelines = NULL;
         rep_src->n_timelines = 0;
         rep_dest->cur_seq_no = rep_src->cur_seq_no;
     }
 }
 
 static void move_segments(struct representation *rep_src, struct representation *rep_dest)
 {
     if (rep_dest && rep_src ) {
         free_fragment_list(rep_dest);
         if (rep_src->start_number > (rep_dest->start_number + rep_dest->n_fragments))
             rep_dest->cur_seq_no = 0;
         else
             rep_dest->cur_seq_no += rep_src->start_number - rep_dest->start_number;
         rep_dest->fragments    = rep_src->fragments;
         rep_dest->n_fragments  = rep_src->n_fragments;
         rep_dest->parent  = rep_src->parent;
         rep_dest->last_seq_no = calc_max_seg_no(rep_dest);
         rep_src->fragments = NULL;
         rep_src->n_fragments = 0;
     }
 }
 
 
 static int refresh_manifest(AVFormatContext *s)
 {
 
     int ret = 0;
     DASHContext *c = s->priv_data;
 
     // save current context
     struct representation *cur_video =  c->cur_video;
     struct representation *cur_audio =  c->cur_audio;
     char *base_url = c->base_url;
 
     c->base_url = NULL;
     c->cur_video = NULL;
     c->cur_audio = NULL;
     ret = parse_manifest(s, s->filename, NULL);
     if (ret)
         goto finish;
 
     if (cur_video && cur_video->timelines || cur_audio && cur_audio->timelines) {
         // calc current time
         int64_t currentVideoTime = 0;
         int64_t currentAudioTime = 0;
         if (cur_video && cur_video->timelines)
             currentVideoTime = get_segment_start_time_based_on_timeline(cur_video, cur_video->cur_seq_no) / cur_video->fragment_timescale;
         if (cur_audio && cur_audio->timelines)
             currentAudioTime = get_segment_start_time_based_on_timeline(cur_audio, cur_audio->cur_seq_no) / cur_audio->fragment_timescale;
         // update segments
         if (cur_video && cur_video->timelines) {
             c->cur_video->cur_seq_no = calc_next_seg_no_from_timelines(c->cur_video, currentVideoTime * cur_video->fragment_timescale - 1);
             if (c->cur_video->cur_seq_no >= 0) {
                 move_timelines(c->cur_video, cur_video);
             }
         }
         if (cur_audio && cur_audio->timelines) {
             c->cur_audio->cur_seq_no = calc_next_seg_no_from_timelines(c->cur_audio, currentAudioTime * cur_audio->fragment_timescale - 1);
             if (c->cur_audio->cur_seq_no >= 0) {
                move_timelines(c->cur_audio, cur_audio);
             }
         }
     }
     if (cur_video && cur_video->fragments) {
         move_segments(c->cur_video, cur_video);
     }
     if (cur_audio && cur_audio->fragments) {
         move_segments(c->cur_audio, cur_audio);
     }
 
 finish:
     // restore context
     if (c->base_url)
         av_free(base_url);
     else
         c->base_url  = base_url;
     if (c->cur_audio)
         free_representation(c->cur_audio);
     if (c->cur_video)
         free_representation(c->cur_video);
     c->cur_audio = cur_audio;
     c->cur_video = cur_video;
     return ret;
 }
 
 static struct fragment *get_current_fragment(struct representation *pls)
 {
     int64_t min_seq_no = 0;
     int64_t max_seq_no = 0;
     struct fragment *seg = NULL;
     struct fragment *seg_ptr = NULL;
     DASHContext *c = pls->parent->priv_data;
 
     while (( !ff_check_interrupt(c->interrupt_callback)&& pls->n_fragments > 0)) {
         if (pls->cur_seq_no < pls->n_fragments) {
             seg_ptr = pls->fragments[pls->cur_seq_no];
             seg = av_mallocz(sizeof(struct fragment));
             if (!seg) {
                 return NULL;
             }
             seg->url = av_strdup(seg_ptr->url);
             if (!seg->url) {
                 av_free(seg);
                 return NULL;
             }
             seg->size = seg_ptr->size;
             seg->url_offset = seg_ptr->url_offset;
             return seg;
         } else if (c->is_live) {
             refresh_manifest(pls->parent);
         } else {
             break;
         }
     }
     if (c->is_live) {
         min_seq_no = calc_min_seg_no(pls->parent, pls);
         max_seq_no = calc_max_seg_no(pls);
 
         if (pls->timelines || pls->fragments) {
             refresh_manifest(pls->parent);
         }
         if (pls->cur_seq_no <= min_seq_no) {
             av_log(pls->parent, AV_LOG_VERBOSE, "old fragment: cur[%"PRId64"] min[%"PRId64"] max[%"PRId64"], playlist %d\n", (int64_t)pls->cur_seq_no, min_seq_no, max_seq_no, (int)pls->rep_idx);
             pls->cur_seq_no = calc_cur_seg_no(pls->parent, pls);
         } else if (pls->cur_seq_no > max_seq_no) {
             av_log(pls->parent, AV_LOG_VERBOSE, "new fragment: min[%"PRId64"] max[%"PRId64"], playlist %d\n", min_seq_no, max_seq_no, (int)pls->rep_idx);
         }
         seg = av_mallocz(sizeof(struct fragment));
         if (!seg) {
             return NULL;
         }
     } else if (pls->cur_seq_no <= pls->last_seq_no) {
         seg = av_mallocz(sizeof(struct fragment));
         if (!seg) {
             return NULL;
         }
     }
     if (seg) {
         char tmpfilename[MAX_URL_SIZE];
 
         ff_dash_fill_tmpl_params(tmpfilename, sizeof(tmpfilename), pls->url_template, 0, pls->cur_seq_no, 0, get_segment_start_time_based_on_timeline(pls, pls->cur_seq_no));
         seg->url = av_strireplace(pls->url_template, pls->url_template, tmpfilename);
         if (!seg->url) {
             av_log(pls->parent, AV_LOG_WARNING, "Unable to resolve template url '%s', try to use origin template\n", pls->url_template);
             seg->url = av_strdup(pls->url_template);
             if (!seg->url) {
                 av_log(pls->parent, AV_LOG_ERROR, "Cannot resolve template url '%s'\n", pls->url_template);
                 return NULL;
             }
         }
 
         seg->size = -1;
     }
 
     return seg;
 }
 
 enum ReadFromURLMode {
     READ_NORMAL,
     READ_COMPLETE,
 };
 
 static int read_from_url(struct representation *pls, struct fragment *seg,
                          uint8_t *buf, int buf_size,
                          enum ReadFromURLMode mode)
 {
     int ret;
 
     /* limit read if the fragment was only a part of a file */
     if (seg->size >= 0)
         buf_size = FFMIN(buf_size, pls->cur_seg_size - pls->cur_seg_offset);
 
     if (mode == READ_COMPLETE) {
         ret = avio_read(pls->input, buf, buf_size);
         if (ret < buf_size) {
             av_log(pls->parent, AV_LOG_WARNING, "Could not read complete fragment.\n");
         }
     } else {
         ret = avio_read(pls->input, buf, buf_size);
     }
     if (ret > 0)
         pls->cur_seg_offset += ret;
 
     return ret;
 }
 
 static int open_input(DASHContext *c, struct representation *pls, struct fragment *seg)
 {
     AVDictionary *opts = NULL;
     char url[MAX_URL_SIZE];
     int ret;
 
     set_httpheader_options(c, opts);
     if (seg->size >= 0) {
         /* try to restrict the HTTP request to the part we want
          * (if this is in fact a HTTP request) */
         av_dict_set_int(&opts, "offset", seg->url_offset, 0);
         av_dict_set_int(&opts, "end_offset", seg->url_offset + seg->size, 0);
     }
 
     ff_make_absolute_url(url, MAX_URL_SIZE, c->base_url, seg->url);
     av_log(pls->parent, AV_LOG_VERBOSE, "DASH request for url '%s', offset %"PRId64", playlist %d\n",
            url, seg->url_offset, pls->rep_idx);
     ret = open_url(pls->parent, &pls->input, url, c->avio_opts, opts, NULL);
     if (ret < 0) {
         goto cleanup;
     }
 
     /* Seek to the requested position. If this was a HTTP request, the offset
      * should already be where want it to, but this allows e.g. local testing
      * without a HTTP server. */
     if (!ret && seg->url_offset) {
         int64_t seekret = avio_seek(pls->input, seg->url_offset, SEEK_SET);
         if (seekret < 0) {
             av_log(pls->parent, AV_LOG_ERROR, "Unable to seek to offset %"PRId64" of DASH fragment '%s'\n", seg->url_offset, seg->url);
             ret = (int) seekret;
             ff_format_io_close(pls->parent, &pls->input);
         }
     }
 
 cleanup:
     av_dict_free(&opts);
     pls->cur_seg_offset = 0;
     pls->cur_seg_size = seg->size;
     return ret;
 }
 
 static int update_init_section(struct representation *pls)
 {
     static const int max_init_section_size = 1024 * 1024;
     DASHContext *c = pls->parent->priv_data;
     int64_t sec_size;
     int64_t urlsize;
     int ret;
 
     if (!pls->init_section || pls->init_sec_buf)
         return 0;
 
     ret = open_input(c, pls, pls->init_section);
     if (ret < 0) {
         av_log(pls->parent, AV_LOG_WARNING,
                "Failed to open an initialization section in playlist %d\n",
                pls->rep_idx);
         return ret;
     }
 
     if (pls->init_section->size >= 0)
         sec_size = pls->init_section->size;
     else if ((urlsize = avio_size(pls->input)) >= 0)
         sec_size = urlsize;
     else
         sec_size = max_init_section_size;
 
     av_log(pls->parent, AV_LOG_DEBUG,
            "Downloading an initialization section of size %"PRId64"\n",
            sec_size);
 
     sec_size = FFMIN(sec_size, max_init_section_size);
 
     av_fast_malloc(&pls->init_sec_buf, &pls->init_sec_buf_size, sec_size);
 
     ret = read_from_url(pls, pls->init_section, pls->init_sec_buf,
                         pls->init_sec_buf_size, READ_COMPLETE);
     ff_format_io_close(pls->parent, &pls->input);
 
     if (ret < 0)
         return ret;
 
     pls->init_sec_data_len = ret;
     pls->init_sec_buf_read_offset = 0;
 
     return 0;
 }
 
 static int64_t seek_data(void *opaque, int64_t offset, int whence)
 {
     struct representation *v = opaque;
     if (v->n_fragments && !v->init_sec_data_len) {
         return avio_seek(v->input, offset, whence);
     }
 
     return AVERROR(ENOSYS);
 }
 
 static int read_data(void *opaque, uint8_t *buf, int buf_size)
 {
     int ret = 0;
     struct representation *v = opaque;
     DASHContext *c = v->parent->priv_data;
 
 restart:
     if (!v->input) {
         free_fragment(&v->cur_seg);
         v->cur_seg = get_current_fragment(v);
         if (!v->cur_seg) {
             ret = AVERROR_EOF;
             goto end;
         }
 
         /* load/update Media Initialization Section, if any */
         ret = update_init_section(v);
         if (ret)
             goto end;
 
         ret = open_input(c, v, v->cur_seg);
         if (ret < 0) {
             if (ff_check_interrupt(c->interrupt_callback)) {
                 goto end;
                 ret = AVERROR_EXIT;
             }
             av_log(v->parent, AV_LOG_WARNING, "Failed to open fragment of playlist %d\n", v->rep_idx);
             v->cur_seq_no++;
             goto restart;
         }
     }
 
     if (v->init_sec_buf_read_offset < v->init_sec_data_len) {
         /* Push init section out first before first actual fragment */
         int copy_size = FFMIN(v->init_sec_data_len - v->init_sec_buf_read_offset, buf_size);
         memcpy(buf, v->init_sec_buf, copy_size);
         v->init_sec_buf_read_offset += copy_size;
         ret = copy_size;
         goto end;
     }
 
     /* check the v->cur_seg, if it is null, get current and double check if the new v->cur_seg*/
     if (!v->cur_seg) {
         v->cur_seg = get_current_fragment(v);
     }
     if (!v->cur_seg) {
         ret = AVERROR_EOF;
         goto end;
     }
     ret = read_from_url(v, v->cur_seg, buf, buf_size, READ_NORMAL);
     if (ret > 0)
         goto end;
 
     if (!v->is_restart_needed)
         v->cur_seq_no++;
     v->is_restart_needed = 1;
 
 end:
     return ret;
 }
 
 static int save_avio_options(AVFormatContext *s)
 {
     DASHContext *c = s->priv_data;
     const char *opts[] = { "headers", "user_agent", "user-agent", "cookies", NULL }, **opt = opts;
     uint8_t *buf = NULL;
     int ret = 0;
 
     while (*opt) {
         if (av_opt_get(s->pb, *opt, AV_OPT_SEARCH_CHILDREN, &buf) >= 0) {
             if (buf[0] != '\0') {
                 ret = av_dict_set(&c->avio_opts, *opt, buf, AV_DICT_DONT_STRDUP_VAL);
                 if (ret < 0)
                     return ret;
             }
         }
         opt++;
     }
 
     return ret;
 }
 
 static int nested_io_open(AVFormatContext *s, AVIOContext **pb, const char *url,
                           int flags, AVDictionary **opts)
 {
     av_log(s, AV_LOG_ERROR,
            "A DASH playlist item '%s' referred to an external file '%s'. "
            "Opening this file was forbidden for security reasons\n",
            s->filename, url);
     return AVERROR(EPERM);
 }
 
 static int reopen_demux_for_component(AVFormatContext *s, struct representation *pls)
 {
     DASHContext *c = s->priv_data;
     AVInputFormat *in_fmt = NULL;
     AVDictionary  *in_fmt_opts = NULL;
     uint8_t *avio_ctx_buffer  = NULL;
     int ret = 0;
 
     if (pls->ctx) {
         /* note: the internal buffer could have changed, and be != avio_ctx_buffer */
         av_freep(&pls->pb.buffer);
         memset(&pls->pb, 0x00, sizeof(AVIOContext));
         pls->ctx->pb = NULL;
         avformat_close_input(&pls->ctx);
         pls->ctx = NULL;
     }
     if (!(pls->ctx = avformat_alloc_context())) {
         ret = AVERROR(ENOMEM);
         goto fail;
     }
 
     avio_ctx_buffer  = av_malloc(INITIAL_BUFFER_SIZE);
     if (!avio_ctx_buffer ) {
         ret = AVERROR(ENOMEM);
         avformat_free_context(pls->ctx);
         pls->ctx = NULL;
         goto fail;
     }
     if (c->is_live) {
         ffio_init_context(&pls->pb, avio_ctx_buffer , INITIAL_BUFFER_SIZE, 0, pls, read_data, NULL, NULL);
     } else {
         ffio_init_context(&pls->pb, avio_ctx_buffer , INITIAL_BUFFER_SIZE, 0, pls, read_data, NULL, seek_data);
     }
     pls->pb.seekable = 0;
 
     if ((ret = ff_copy_whiteblacklists(pls->ctx, s)) < 0)
         goto fail;
 
     pls->ctx->flags = AVFMT_FLAG_CUSTOM_IO;
     pls->ctx->probesize = 1024 * 4;
     pls->ctx->max_analyze_duration = 4 * AV_TIME_BASE;
     ret = av_probe_input_buffer(&pls->pb, &in_fmt, "", NULL, 0, 0);
     if (ret < 0) {
         av_log(s, AV_LOG_ERROR, "Error when loading first fragment, playlist %d\n", (int)pls->rep_idx);
         avformat_free_context(pls->ctx);
         pls->ctx = NULL;
         goto fail;
     }
 
     pls->ctx->pb = &pls->pb;
     pls->ctx->io_open  = nested_io_open;
 
     // provide additional information from mpd if available
     ret = avformat_open_input(&pls->ctx, "", in_fmt, &in_fmt_opts); //pls->init_section->url
     av_dict_free(&in_fmt_opts);
     if (ret < 0)
         goto fail;
     if (pls->n_fragments) {
         ret = avformat_find_stream_info(pls->ctx, NULL);
         if (ret < 0)
             goto fail;
     }
 
 fail:
     return ret;
 }
 
 static int open_demux_for_component(AVFormatContext *s, struct representation *pls)
 {
     int ret = 0;
     int i;
 
     pls->parent = s;
     pls->cur_seq_no  = calc_cur_seg_no(s, pls);
     pls->last_seq_no = calc_max_seg_no(pls);
 
     ret = reopen_demux_for_component(s, pls);
     if (ret < 0) {
         goto fail;
     }
     for (i = 0; i < pls->ctx->nb_streams; i++) {
         AVStream *st = avformat_new_stream(s, NULL);
         AVStream *ist = pls->ctx->streams[i];
         if (!st) {
             ret = AVERROR(ENOMEM);
             goto fail;
         }
         st->id = i;
         avcodec_parameters_copy(st->codecpar, pls->ctx->streams[i]->codecpar);
         avpriv_set_pts_info(st, ist->pts_wrap_bits, ist->time_base.num, ist->time_base.den);
     }
 
     return 0;
 fail:
     return ret;
 }
 
 static int dash_read_header(AVFormatContext *s)
 {
     void *u = (s->flags & AVFMT_FLAG_CUSTOM_IO) ? NULL : s->pb;
     DASHContext *c = s->priv_data;
     int ret = 0;
     int stream_index = 0;
 
     c->interrupt_callback = &s->interrupt_callback;
     // if the URL context is good, read important options we must broker later
     if (u) {
         update_options(&c->user_agent, "user-agent", u);
         update_options(&c->cookies, "cookies", u);
         update_options(&c->headers, "headers", u);
     }
 
     if ((ret = parse_manifest(s, s->filename, s->pb)) < 0)
         goto fail;
 
     if ((ret = save_avio_options(s)) < 0)
         goto fail;
 
     /* If this isn't a live stream, fill the total duration of the
      * stream. */
     if (!c->is_live) {
         s->duration = (int64_t) c->media_presentation_duration * AV_TIME_BASE;
     }
 
     /* Open the demuxer for curent video and current audio components if available */
     if (!ret && c->cur_video) {
         ret = open_demux_for_component(s, c->cur_video);
         if (!ret) {
             c->cur_video->stream_index = stream_index;
             ++stream_index;
         } else {
             free_representation(c->cur_video);
             c->cur_video = NULL;
         }
     }
 
     if (!ret && c->cur_audio) {
         ret = open_demux_for_component(s, c->cur_audio);
         if (!ret) {
             c->cur_audio->stream_index = stream_index;
             ++stream_index;
         } else {
             free_representation(c->cur_audio);
             c->cur_audio = NULL;
         }
     }
 
     if (!stream_index) {
         ret = AVERROR_INVALIDDATA;
         goto fail;
     }
 
     /* Create a program */
     if (!ret) {
         AVProgram *program;
         program = av_new_program(s, 0);
         if (!program) {
             goto fail;
         }
 
         if (c->cur_video) {
             av_program_add_stream_index(s, 0, c->cur_video->stream_index);
         }
         if (c->cur_audio) {
             av_program_add_stream_index(s, 0, c->cur_audio->stream_index);
         }
     }
 
     return 0;
 fail:
     return ret;
 }
 
 static int dash_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     DASHContext *c = s->priv_data;
     int ret = 0;
     struct representation *cur = NULL;
 
     if (!c->cur_audio && !c->cur_video ) {
         return AVERROR_INVALIDDATA;
     }
     if (c->cur_audio && !c->cur_video) {
         cur = c->cur_audio;
     } else if (!c->cur_audio && c->cur_video) {
         cur = c->cur_video;
     } else if (c->cur_video->cur_timestamp < c->cur_audio->cur_timestamp) {
         cur = c->cur_video;
     } else {
         cur = c->cur_audio;
     }
 
     if (cur->ctx) {
         while (!ff_check_interrupt(c->interrupt_callback) && !ret) {
             ret = av_read_frame(cur->ctx, pkt);
             if (ret >= 0) {
                 /* If we got a packet, return it */
                 cur->cur_timestamp = av_rescale(pkt->pts, (int64_t)cur->ctx->streams[0]->time_base.num * 90000, cur->ctx->streams[0]->time_base.den);
                 pkt->stream_index = cur->stream_index;
                 return 0;
             }
             if (cur->is_restart_needed) {
                 cur->cur_seg_offset = 0;
                 cur->init_sec_buf_read_offset = 0;
                 if (cur->input)
                     ff_format_io_close(cur->parent, &cur->input);
                 ret = reopen_demux_for_component(s, cur);
                 cur->is_restart_needed = 0;
             }
 
         }
     }
     return AVERROR_EOF;
 }
 
 static int dash_close(AVFormatContext *s)
 {
     DASHContext *c = s->priv_data;
     if (c->cur_audio) {
         free_representation(c->cur_audio);
     }
     if (c->cur_video) {
         free_representation(c->cur_video);
     }
 
     av_freep(&c->cookies);
     av_freep(&c->user_agent);
     av_dict_free(&c->avio_opts);
     av_freep(&c->base_url);
     return 0;
 }
 
 static int dash_seek(AVFormatContext *s, struct representation *pls, int64_t seek_pos_msec, int flags)
 {
     int ret = 0;
     int i = 0;
     int j = 0;
     int64_t duration = 0;
 
     av_log(pls->parent, AV_LOG_VERBOSE, "DASH seek pos[%"PRId64"ms], playlist %d\n", seek_pos_msec, pls->rep_idx);
 
     // single fragment mode
     if (pls->n_fragments == 1) {
         pls->cur_timestamp = 0;
         pls->cur_seg_offset = 0;
         ff_read_frame_flush(pls->ctx);
         return av_seek_frame(pls->ctx, -1, seek_pos_msec * 1000, flags);
     }
 
     if (pls->input)
         ff_format_io_close(pls->parent, &pls->input);
 
     // find the nearest fragment
     if (pls->n_timelines > 0 && pls->fragment_timescale > 0) {
         int64_t num = pls->first_seq_no;
         av_log(pls->parent, AV_LOG_VERBOSE, "dash_seek with SegmentTimeline start n_timelines[%d] "
                "last_seq_no[%"PRId64"], playlist %d.\n",
                (int)pls->n_timelines, (int64_t)pls->last_seq_no, (int)pls->rep_idx);
         for (i = 0; i < pls->n_timelines; i++) {
             if (pls->timelines[i]->starttime > 0) {
                 duration = pls->timelines[i]->starttime;
             }
             duration += pls->timelines[i]->duration;
             if (seek_pos_msec < ((duration * 1000) /  pls->fragment_timescale)) {
                 goto set_seq_num;
             }
             for (j = 0; j < pls->timelines[i]->repeat; j++) {
                 duration += pls->timelines[i]->duration;
                 num++;
                 if (seek_pos_msec < ((duration * 1000) /  pls->fragment_timescale)) {
                     goto set_seq_num;
                 }
             }
             num++;
         }
 
 set_seq_num:
         pls->cur_seq_no = num > pls->last_seq_no ? pls->last_seq_no : num;
         av_log(pls->parent, AV_LOG_VERBOSE, "dash_seek with SegmentTimeline end cur_seq_no[%"PRId64"], playlist %d.\n",
                (int64_t)pls->cur_seq_no, (int)pls->rep_idx);
     } else if (pls->fragment_duration > 0) {
         pls->cur_seq_no = pls->first_seq_no + ((seek_pos_msec * pls->fragment_timescale) / pls->fragment_duration) / 1000;
     } else {
         av_log(pls->parent, AV_LOG_ERROR, "dash_seek missing fragment_duration\n");
         pls->cur_seq_no = pls->first_seq_no;
     }
     pls->cur_timestamp = 0;
     pls->cur_seg_offset = 0;
     pls->init_sec_buf_read_offset = 0;
     ret = reopen_demux_for_component(s, pls);
 
     return ret;
 }
 
 static int dash_read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
 {
     int ret = 0;
     DASHContext *c = s->priv_data;
     int64_t seek_pos_msec = av_rescale_rnd(timestamp, 1000,
                                            s->streams[stream_index]->time_base.den,
                                            flags & AVSEEK_FLAG_BACKWARD ?
                                            AV_ROUND_DOWN : AV_ROUND_UP);
     if ((flags & AVSEEK_FLAG_BYTE) || c->is_live)
         return AVERROR(ENOSYS);
     if (c->cur_audio) {
         ret = dash_seek(s, c->cur_audio, seek_pos_msec, flags);
     }
     if (!ret && c->cur_video) {
         ret = dash_seek(s, c->cur_video, seek_pos_msec, flags);
     }
     return ret;
 }
 
 static int dash_probe(AVProbeData *p)
 {
     if (!av_stristr(p->buf, "<MPD"))
         return 0;
 
     if (av_stristr(p->buf, "dash:profile:isoff-on-demand:2011") ||
         av_stristr(p->buf, "dash:profile:isoff-live:2011") ||
         av_stristr(p->buf, "dash:profile:isoff-live:2012") ||
         av_stristr(p->buf, "dash:profile:isoff-main:2011")) {
         return AVPROBE_SCORE_MAX;
     }
     if (av_stristr(p->buf, "dash:profile")) {
         return AVPROBE_SCORE_MAX;
     }
 
     return 0;
 }
 
 #define OFFSET(x) offsetof(DASHContext, x)
 #define FLAGS AV_OPT_FLAG_DECODING_PARAM
 static const AVOption dash_options[] = {
     {"allowed_extensions", "List of file extensions that dash is allowed to access",
         OFFSET(allowed_extensions), AV_OPT_TYPE_STRING,
         {.str = "aac,m4a,m4s,m4v,mov,mp4"},
         INT_MIN, INT_MAX, FLAGS},
     {NULL}
 };
 
 static const AVClass dash_class = {
     .class_name = "dash",
     .item_name  = av_default_item_name,
     .option     = dash_options,
     .version    = LIBAVUTIL_VERSION_INT,
 };
 
 AVInputFormat ff_dash_demuxer = {
     .name           = "dash",
     .long_name      = NULL_IF_CONFIG_SMALL("Dynamic Adaptive Streaming over HTTP"),
     .priv_class     = &dash_class,
     .priv_data_size = sizeof(DASHContext),
     .read_probe     = dash_probe,
     .read_header    = dash_read_header,
     .read_packet    = dash_read_packet,
     .read_close     = dash_close,
     .read_seek      = dash_read_seek,
     .flags          = AVFMT_NO_BYTE_SEEK,
 };