From ffad7a1c08dbb7de3114ac7e149ce440871ab33a Mon Sep 17 00:00:00 2001
From: Miguel Borges de Freitas <92enen@gmail.com>
Date: Mon, 3 Apr 2023 21:57:33 +0100
Subject: [subtitles] Fix mkv subtitles without duration

---
 .../DVDCodecs/Overlay/DVDOverlayCodecText.cpp      | 27 +++++++++++++++++++++-
 .../DVDCodecs/Overlay/DVDOverlayCodecText.h        |  2 ++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/xbmc/cores/VideoPlayer/DVDCodecs/Overlay/DVDOverlayCodecText.cpp b/xbmc/cores/VideoPlayer/DVDCodecs/Overlay/DVDOverlayCodecText.cpp
index db9379c2a7..0c4d81719f 100644
--- a/xbmc/cores/VideoPlayer/DVDCodecs/Overlay/DVDOverlayCodecText.cpp
+++ b/xbmc/cores/VideoPlayer/DVDCodecs/Overlay/DVDOverlayCodecText.cpp
@@ -18,6 +18,15 @@
 
 #include <memory>
 
+namespace
+{
+// Subtitle packets reaching the decoder may not have the stop PTS value,
+// the stop value can be taken from the start PTS of the next subtitle.
+// Otherwise we fallback to a default of 20 secs duration. This is only
+// applied if the subtitle packets have 0 duration (stop > start).
+constexpr double DEFAULT_DURATION = 20.0 * static_cast<double>(DVD_TIME_BASE);
+} // namespace
+
 CDVDOverlayCodecText::CDVDOverlayCodecText() : CDVDOverlayCodec("Text Subtitle Decoder")
 {
   m_pOverlay = nullptr;
@@ -83,7 +92,23 @@ OverlayMessage CDVDOverlayCodecText::Decode(DemuxPacket* pPacket)
   {
     TagConv.ConvertLine(text);
     TagConv.CloseTag(text);
-    AddSubtitle(text, PTSStartTime, PTSStopTime);
+
+    // similar to CC text, if the subtitle duration is invalid (stop > start)
+    // we might want to assume the stop time will be set by the next received
+    // packet
+    if (PTSStopTime < PTSStartTime)
+    {
+      if (m_changePrevStopTime)
+      {
+        ChangeSubtitleStopTime(m_prevSubId, PTSStartTime);
+        m_changePrevStopTime = false;
+      }
+
+      PTSStopTime = PTSStartTime + DEFAULT_DURATION;
+      m_changePrevStopTime = true;
+    }
+
+    m_prevSubId = AddSubtitle(text, PTSStartTime, PTSStopTime);
   }
   else
     CLog::Log(LOGERROR, "{} - Failed to initialize tag converter", __FUNCTION__);
diff --git a/xbmc/cores/VideoPlayer/DVDCodecs/Overlay/DVDOverlayCodecText.h b/xbmc/cores/VideoPlayer/DVDCodecs/Overlay/DVDOverlayCodecText.h
index 98db5cbc3c..5a5c3bfec6 100644
--- a/xbmc/cores/VideoPlayer/DVDCodecs/Overlay/DVDOverlayCodecText.h
+++ b/xbmc/cores/VideoPlayer/DVDCodecs/Overlay/DVDOverlayCodecText.h
@@ -37,5 +37,7 @@ private:
   void Dispose() override;
   CDVDOverlay* m_pOverlay;
   CDVDStreamInfo m_hints;
+  int m_prevSubId{-1};
+  bool m_changePrevStopTime{false};
   AVCodecID m_codecId{AV_CODEC_ID_NONE};
 };
-- 
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