text: ﻿/*
   * Copyright (c) 2016 The ZLMediaKit project authors. All Rights Reserved.
   *
   * This file is part of ZLMediaKit(https://github.com/xia-chu/ZLMediaKit).
   *
   * Use of this source code is governed by MIT license that can be found in the
   * LICENSE file in the root of the source tree. All contributing project authors
   * may be found in the AUTHORS file in the root of the source tree.
   */
  
  #include "HlsMaker.h"
  
  using namespace std;
  
  namespace mediakit {
  
  HlsMaker::HlsMaker(float seg_duration, uint32_t seg_number) {
      //最小允许设置为0，0个切片代表点播
      _seg_number = seg_number;
      _seg_duration = seg_duration;
  }
  
  HlsMaker::~HlsMaker() {
  }
  
  
  void HlsMaker::makeIndexFile(bool eof) {
      char file_content[1024];
      int maxSegmentDuration = 0;
  
      for (auto &tp : _seg_dur_list) {
          int dur = std::get<0>(tp);
          if (dur > maxSegmentDuration) {
              maxSegmentDuration = dur;
          }
      }
  
      auto sequence = _seg_number ? (_file_index > _seg_number ? _file_index - _seg_number : 0LL) : 0LL;
  
      string m3u8;
       if (_seg_number == 0) {
          // 录像点播支持时移
          snprintf(file_content, sizeof(file_content),
                   "#EXTM3U\n"
                   "#EXT-X-PLAYLIST-TYPE:EVENT\n"
                   "#EXT-X-VERSION:4\n"
                   "#EXT-X-TARGETDURATION:%u\n"
                   "#EXT-X-MEDIA-SEQUENCE:%llu\n",
                   (maxSegmentDuration + 999) / 1000,
                   sequence);
      } else {
          snprintf(file_content, sizeof(file_content),
                   "#EXTM3U\n"
                   "#EXT-X-VERSION:3\n"
                   "#EXT-X-ALLOW-CACHE:NO\n"
                   "#EXT-X-TARGETDURATION:%u\n"
                   "#EXT-X-MEDIA-SEQUENCE:%llu\n",
                   (maxSegmentDuration + 999) / 1000,
                   sequence);
      }
      
      m3u8.assign(file_content);
  
      for (auto &tp : _seg_dur_list) {
          snprintf(file_content, sizeof(file_content), "#EXTINF:%.3f,\n%s\n", std::get<0>(tp) / 1000.0, std::get<1>(tp).data());
          m3u8.append(file_content);
      }
  
      if (eof) {
          snprintf(file_content, sizeof(file_content), "#EXT-X-ENDLIST\n");
          m3u8.append(file_content);
      }
      onWriteHls(m3u8);
  }
  
  
  void HlsMaker::inputData(void *data, size_t len, uint32_t timestamp, bool is_idr_fast_packet) {
      if (data && len) {
          if (timestamp < _last_timestamp) {
              //时间戳回退了，切片时长重新计时
              WarnL << "stamp reduce: " << _last_timestamp << " -> " << timestamp;
              _last_seg_timestamp = _last_timestamp = timestamp;
          }
          if (is_idr_fast_packet) {
              //尝试切片ts
              addNewSegment(timestamp);
          }
          if (!_last_file_name.empty()) {
              //存在切片才写入ts数据
              onWriteSegment((char *) data, len);
              _last_timestamp = timestamp;
          }
      } else {
          //resetTracks时触发此逻辑
          flushLastSegment(false);
      }
  }
  
  void HlsMaker::delOldSegment() {
      if (_seg_number == 0) {
          //如果设置为保留0个切片，则认为是保存为点播
          return;
      }
      //在hls m3u8索引文件中,我们保存的切片个数跟_seg_number相关设置一致
      if (_file_index > _seg_number) {
          _seg_dur_list.pop_front();
      }
  
      GET_CONFIG(uint32_t, segRetain, Hls::kSegmentRetain);
      //但是实际保存的切片个数比m3u8所述多若干个,这样做的目的是防止播放器在切片删除前能下载完毕
      if (_file_index > _seg_number + segRetain) {
          onDelSegment(_file_index - _seg_number - segRetain - 1);
      }
  }
  
  void HlsMaker::addNewSegment(uint32_t stamp) {
      if (!_last_file_name.empty() && stamp - _last_seg_timestamp < _seg_duration * 1000) {
          //存在上个切片，并且未到分片时间
          return;
      }
  
      //关闭并保存上一个切片，如果_seg_number==0,那么是点播。
      flushLastSegment(false);
      //新增切片
      _last_file_name = onOpenSegment(_file_index++);
      //记录本次切片的起始时间戳
      _last_seg_timestamp = _last_timestamp ? _last_timestamp : stamp;
  }
  
  void HlsMaker::flushLastSegment(bool eof){
      if (_last_file_name.empty()) {
          //不存在上个切片
          return;
      }
      //文件创建到最后一次数据写入的时间即为切片长度
      auto seg_dur = _last_timestamp - _last_seg_timestamp;
      if (seg_dur <= 0) {
          seg_dur = 100;
      }
      _seg_dur_list.push_back(std::make_tuple(seg_dur, std::move(_last_file_name)));
      delOldSegment();
      //先flush ts切片，否则可能存在ts文件未写入完毕就被访问的情况
      onFlushLastSegment(seg_dur);
      //然后写m3u8文件
      makeIndexFile(eof);
  }
  
  bool HlsMaker::isLive() {
      return _seg_number != 0;
  }
  
  void HlsMaker::clear() {
      _file_index = 0;
      _last_timestamp = 0;
      _last_seg_timestamp = 0;
      _seg_dur_list.clear();
      _last_file_name.clear();
  }
  
  }//namespace mediakit
  