From 05a65d4961e99486ec58c210b6f157f9298c8d0f Mon Sep 17 00:00:00 2001
From: baiyfcu <baiyfcu@gmail.com>
Date: Wed, 17 Jun 2020 15:51:02 +0800
Subject: [PATCH] merge stamp

---
 src/Common/Stamp.cpp | 54 ++++++++++++++++++++++++++++++++++++--------
 src/Common/Stamp.h   | 23 +++++++++++++------
 2 files changed, 60 insertions(+), 17 deletions(-)

diff --git a/src/Common/Stamp.cpp b/src/Common/Stamp.cpp
index 0bbaf958..e5fd631c 100644
--- a/src/Common/Stamp.cpp
+++ b/src/Common/Stamp.cpp
@@ -42,7 +42,48 @@ void Stamp::setPlayBack(bool playback) {
     _playback = playback;
 }
 
+void Stamp::syncTo(Stamp &other){
+    _sync_master = &other;
+    _sync_finished = false;
+}
+
 void Stamp::revise(int64_t dts, int64_t pts, int64_t &dts_out, int64_t &pts_out,bool modifyStamp) {
+    revise_l(dts,pts,dts_out,pts_out,modifyStamp);
+    if(_sync_finished || modifyStamp || _playback){
+        //自动生成时间戳或回放或同步完毕
+        if(dts_out < 0) { dts_out = 0; }
+        if(pts_out < 0) { pts_out = 0; }
+        return;
+    }
+
+    if(_sync_master && _sync_master->_last_dts){
+        //音视频dts当前时间差
+        int64_t dts_diff = _last_dts - _sync_master->_last_dts;
+        if(ABS(dts_diff) < 5000){
+            //如果绝对时间戳小于5秒，那么说明他们的起始时间戳是一致的，那么强制同步
+            _last_relativeStamp = _relativeStamp;
+            _relativeStamp = _sync_master->_relativeStamp + dts_diff;
+        }
+        //下次不用再强制同步
+        _sync_master = nullptr;
+    }
+
+    if (dts_out < 0 || dts_out < _last_relativeStamp) {
+        //相对时间戳小于0，或者小于上次的时间戳，
+        //那么说明是同步时间戳导致的,在这个过渡期内，我们一直返回上次的结果(目的是为了防止时间戳回退)
+        pts_out = _last_relativeStamp + (pts_out - dts_out);
+        dts_out = _last_relativeStamp;
+    } else if(!_sync_master){
+        //音视频同步过渡期完毕
+        _sync_finished = true;
+    }
+
+    if(pts_out < 0){
+        pts_out = dts_out;
+    }
+}
+
+void Stamp::revise_l(int64_t dts, int64_t pts, int64_t &dts_out, int64_t &pts_out,bool modifyStamp) {
     if(!pts){
         //没有播放时间戳,使其赋值为解码时间戳
         pts = dts;
@@ -52,10 +93,8 @@ void Stamp::revise(int64_t dts, int64_t pts, int64_t &dts_out, int64_t &pts_out,
         //这是点播
         dts_out = dts;
         pts_out = pts;
+        _relativeStamp = dts_out;
         _last_dts = dts;
-        if (_dts_base == -1)
-            _dts_base = dts;
-        _relativeStamp = _npt_base + dts - _dts_base;
         return;
     }
 
@@ -65,6 +104,7 @@ void Stamp::revise(int64_t dts, int64_t pts, int64_t &dts_out, int64_t &pts_out,
     if(_last_dts != dts){
         //时间戳发生变更
         if(modifyStamp){
+            //内部自己生产时间戳
             _relativeStamp = _ticker.elapsedTime();
         }else{
             _relativeStamp += deltaStamp(dts);
@@ -80,15 +120,9 @@ void Stamp::revise(int64_t dts, int64_t pts, int64_t &dts_out, int64_t &pts_out,
     }
 
     pts_out = dts_out + pts_dts_diff;
-    if(pts_out < 0){
-        //时间戳不能小于0
-        pts_out = 0;
-    }
 }
 
 void Stamp::setRelativeStamp(int64_t relativeStamp) {
-    _dts_base = _last_dts;
-    _npt_base = relativeStamp;
     _relativeStamp = relativeStamp;
 }
 
@@ -141,7 +175,7 @@ bool DtsGenerator::getDts_l(uint32_t pts, uint32_t &dts){
                 //已经出现多次非B帧的情况，那么我们就能知道P帧间B帧的个数
                 _sorter_max_size = _frames_since_last_max_pts;
                 //我们记录P帧间时间间隔(也就是多个B帧时间戳增量累计)
-                _dts_pts_offset = (pts - _last_max_pts) / 2;
+                _dts_pts_offset = (pts - _last_max_pts);
             }
             //遇到P帧或关键帧，连续B帧计数清零
             _frames_since_last_max_pts = 0;
diff --git a/src/Common/Stamp.h b/src/Common/Stamp.h
index 5d3897bf..cf374277 100644
--- a/src/Common/Stamp.h
+++ b/src/Common/Stamp.h
@@ -32,6 +32,7 @@ public:
 private:
     int64_t _last_stamp = 0;
 };
+
 //该类解决时间戳回环、回退问题
 //计算相对时间戳或者产生平滑时间戳
 class Stamp : public DeltaStamp{
@@ -66,17 +67,27 @@ public:
      * @param playback 是否为回放模式
      */
     void setPlayBack(bool playback = true);
+
+    /**
+     * 音视频同步用，音频应该同步于视频(只修改音频时间戳)
+     * 因为音频时间戳修改后不影响播放速度
+     */
+    void syncTo(Stamp &other);
+
+private:
+    void revise_l(int64_t dts, int64_t pts, int64_t &dts_out, int64_t &pts_out,bool modifyStamp = false);
 private:
     int64_t _relativeStamp = 0;
-    int64_t _last_dts = -1;
+    int64_t _last_relativeStamp = 0;
+    int64_t _last_dts = 0;
     SmoothTicker _ticker;
     bool _playback = false;
-
-    int64_t _dts_base = 0;
-    int64_t _npt_base = 0;
+    Stamp *_sync_master = nullptr;
+    bool _sync_finished = true;
 };
 
-
+//dts生成器，
+//pts排序后就是dts
 class DtsGenerator{
 public:
     DtsGenerator() = default;
@@ -93,8 +104,6 @@ private:
     int _sorter_max_size = 0;
     int _count_sorter_max_size = 0;
     set<uint32_t> _pts_sorter;
-
-
 };
 
 }//namespace mediakit