From 773eb62dd0667905a167252b0da0e45ae54e19d1 Mon Sep 17 00:00:00 2001
From: CastagnaIT <gottardo.stefano.83@gmail.com>
Date: Mon, 25 Nov 2024 17:08:21 +0100
Subject: [PATCH] [HLSTree] Add support to read subtitle codec

---
 src/parser/HLSTree.cpp | 38 +++++++++++++++++++++++++++++++++++---
 src/parser/HLSTree.h   |  9 +++++++++
 2 files changed, 44 insertions(+), 3 deletions(-)

diff --git a/src/parser/HLSTree.cpp b/src/parser/HLSTree.cpp
index 808fc2060..12fe178fd 100644
--- a/src/parser/HLSTree.cpp
+++ b/src/parser/HLSTree.cpp
@@ -137,6 +137,18 @@ std::string GetVideoCodec(std::string_view codecs)
   }
   return "";
 }
+
+// \brief Get the first subtitle codec string from CODECS attribute list
+std::string GetSubtitleCodec(std::string_view codecs)
+{
+  const std::vector<std::string> list = STRING::SplitToVec(codecs, ',');
+  for (const std::string& codecStr : list)
+  {
+    if (CODEC::IsSubtitleFourCC(codecStr))
+      return codecStr;
+  }
+  return "";
+}
 } // unnamed namespace
 
 adaptive::CHLSTree::CHLSTree() : AdaptiveTree()
@@ -1645,9 +1657,17 @@ bool adaptive::CHLSTree::ParseMultivariantPlaylist(const std::string& data)
 
     if (!ParseRenditon(r, newAdpSet, newRepr))
       continue;
-    // Use WebVTT as default subtitle codec
-    newRepr->AddCodecs(CODEC::FOURCC_WVTT);
-    newAdpSet->AddCodecs(CODEC::FOURCC_WVTT);
+
+    // Find the codec string from a variant that references it
+    const Variant* varFound = FindVariantBySubtitleGroupId(r.m_groupId, pl.m_variants);
+    std::string codecStr;
+    if (varFound)
+      codecStr = GetSubtitleCodec(varFound->m_codecs);
+    if (codecStr.empty())
+      codecStr = CODEC::FOURCC_WVTT; // WebVTT as default subtitle codec
+
+    newRepr->AddCodecs(codecStr);
+    newAdpSet->AddCodecs(codecStr);
 
     newAdpSet->AddRepresentation(newRepr);
     period->AddAdaptationSet(newAdpSet);
@@ -1872,6 +1892,18 @@ const adaptive::CHLSTree::Variant* adaptive::CHLSTree::FindVariantByAudioGroupId
   return nullptr;
 }
 
+const adaptive::CHLSTree::Variant* adaptive::CHLSTree::FindVariantBySubtitleGroupId(
+    std::string groupId, std::vector<Variant>& variants) const
+{
+  auto itVar =
+      std::find_if(variants.cbegin(), variants.cend(),
+                   [&groupId](const Variant& item) { return item.m_groupIdSubtitles == groupId; });
+  if (itVar != variants.cend())
+    return &(*itVar);
+
+  return nullptr;
+}
+
 const adaptive::CHLSTree::Rendition* adaptive::CHLSTree::FindRenditionByGroupId(
     std::string groupId, std::vector<adaptive::CHLSTree::Rendition>& renditions) const
 {
diff --git a/src/parser/HLSTree.h b/src/parser/HLSTree.h
index 71754ddeb..c7f6911e0 100644
--- a/src/parser/HLSTree.h
+++ b/src/parser/HLSTree.h
@@ -209,6 +209,15 @@ class ATTR_DLL_LOCAL CHLSTree : public AdaptiveTree
   const Variant* FindVariantByAudioGroupId(std::string groupId,
                                            std::vector<Variant>& variants) const;
 
+  /*!
+   * \brief Find the first variant with the specified audio group id.
+   * \param groupId The group id
+   * \param variants The variants where search for
+   * \return The variant if found, otherwise nullptr
+   */
+  const adaptive::CHLSTree::Variant* FindVariantBySubtitleGroupId(
+      std::string groupId, std::vector<Variant>& variants) const;
+
   /*!
    * \brief Find the first rendition with the specified group id.
    * \param groupId The group id