From 43a205ff43b7f9b66bc0312760e3ae8c1fad28ef Mon Sep 17 00:00:00 2001
From: Francois Cartegnie <fcvlcdev@free.fr>
Date: Tue, 26 Oct 2021 22:44:22 +0200
Subject: [PATCH] demux: adaptive: rework segmentlist update

---
 .../demux/adaptive/playlist/SegmentList.cpp   | 70 +++++++++++++------
 1 file changed, 48 insertions(+), 22 deletions(-)

diff --git a/modules/demux/adaptive/playlist/SegmentList.cpp b/modules/demux/adaptive/playlist/SegmentList.cpp
index 147d611760..0d183946e7 100644
--- a/modules/demux/adaptive/playlist/SegmentList.cpp
+++ b/modules/demux/adaptive/playlist/SegmentList.cpp
@@ -31,6 +31,8 @@
 #include "SegmentTimeline.h"
 
 #include <limits>
+#include <cassert>
+#include <algorithm>
 
 using namespace adaptive;
 using namespace adaptive::playlist;
@@ -90,41 +92,65 @@ void SegmentList::addSegment(Segment *seg)
 void SegmentList::updateWith(AbstractMultipleSegmentBaseType *updated_,
                              bool b_restamp)
 {
+    stime_t duration = inheritDuration();
+
     AbstractMultipleSegmentBaseType::updateWith(updated_);
 
     SegmentList *updated = dynamic_cast<SegmentList *>(updated_);
     if(!updated || updated->segments.empty())
         return;
 
-    const Segment * lastSegment = (segments.empty()) ? nullptr : segments.back();
-    const Segment * prevSegment = lastSegment;
+    b_restamp = b_relative_mediatimes;
 
-    uint64_t firstnumber = updated->segments.front()->getSequenceNumber();
-
-    std::vector<Segment *>::iterator it;
-    for(it = updated->segments.begin(); it != updated->segments.end(); ++it)
+    if(!b_restamp || segments.empty())
     {
-        Segment *cur = *it;
-        if(!lastSegment || lastSegment->compare(cur) < 0)
-        {
-            if(b_restamp && prevSegment)
-            {
-                stime_t starttime = prevSegment->startTime.Get() + prevSegment->duration.Get();
-                if(starttime != cur->startTime.Get() && !cur->discontinuity)
-                {
-                    cur->startTime.Set(starttime);
-                }
+        if(!segments.empty())
+            pruneBySegmentNumber(std::numeric_limits<uint64_t>::max());
+        assert(segments.empty());
+        for(auto seg : updated->segments)
+            addSegment(seg);
+        updated->segments.clear();
+    }
+    else
+    {
+        const Segment * prevSegment = segments.back();
+        const uint64_t oldest = updated->segments.front()->getSequenceNumber();
 
-                prevSegment = cur;
+        /* filter out known segments from the update */
+        updated->segments.erase(
+            std::remove_if(updated->segments.begin(), updated->segments.end(),
+                [updated, prevSegment](Segment *s){
+                    return s->getSequenceNumber() <= prevSegment->getSequenceNumber();
+                }),
+            updated->segments.end());
+
+        if(updated->segments.empty())
+            return;
+
+        /* merge update with current list */
+        for(auto it = updated->segments.begin(); it != updated->segments.end(); ++it)
+        {
+            Segment *cur = *it;
+            cur->startTime.Set(prevSegment->startTime.Get() + prevSegment->duration.Get());
+            /* not continuous */
+            if(cur->getSequenceNumber() != prevSegment->getSequenceNumber() + 1)
+            {
+                assert(prevSegment->getSequenceNumber() < cur->getSequenceNumber());
+                assert(duration);
+                uint64_t gap = cur->getSequenceNumber() - prevSegment->getSequenceNumber() - 1;
+                cur->startTime.Set(cur->startTime.Get() + duration * gap);
             }
+            prevSegment = cur;
             addSegment(cur);
         }
-        else
-            delete cur;
-    }
-    updated->segments.clear();
+        updated->segments.clear();
 
-    pruneBySegmentNumber(firstnumber);
+        /* prune previous list using update window start */
+        segments.erase(std::remove_if(segments.begin(), segments.end(),
+                            [this, oldest](Segment *s){return s->getSequenceNumber() < oldest;}),
+                       segments.end());
+
+    }
 }
 
 void SegmentList::pruneByPlaybackTime(vlc_tick_t time)