From f5cb2c5cba651707114d3e51931aadb98c6396ca Mon Sep 17 00:00:00 2001
From: Martchus <martchus@gmx.net>
Date: Fri, 9 Apr 2021 22:15:44 +0200
Subject: [PATCH] Preserve media type of MP4 tracks if media type is unknown

---
 mp4/mp4track.cpp | 10 ++++++----
 mp4/mp4track.h   |  1 +
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/mp4/mp4track.cpp b/mp4/mp4track.cpp
index b65ef34..3317d03 100644
--- a/mp4/mp4track.cpp
+++ b/mp4/mp4track.cpp
@@ -140,6 +140,7 @@ Mp4Track::Mp4Track(Mp4Atom &trakAtom)
     , m_stscAtom(nullptr)
     , m_stcoAtom(nullptr)
     , m_stszAtom(nullptr)
+    , m_rawMediaType(0)
     , m_framesPerSample(1)
     , m_chunkOffsetSize(4)
     , m_chunkCount(0)
@@ -1340,8 +1341,10 @@ void Mp4Track::makeMedia(Diagnostics &diag)
         outputStream().write("meta", 4);
         break;
     default:
-        diag.emplace_back(DiagLevel::Critical, "Media type is invalid; The media type video is assumed.", "making hdlr atom");
-        outputStream().write("vide", 4);
+        if (m_mediaType != MediaType::Unknown) {
+            diag.emplace_back(DiagLevel::Critical, "Media type is invalid; keeping media type as-is.", "making hdlr atom");
+        }
+        writer().writeUInt32BE(m_rawMediaType);
         break;
     }
     for (int i = 0; i < 3; ++i)
@@ -1600,7 +1603,7 @@ void Mp4Track::internalParseHeader(Diagnostics &diag, AbortableProgressFeedback
     // -> seek to begin skipping size, name, version, flags and reserved bytes
     m_istream->seekg(static_cast<streamoff>(m_hdlrAtom->dataOffset() + 8));
     // -> track type
-    switch (reader.readUInt32BE()) {
+    switch (m_rawMediaType = reader.readUInt32BE()) {
     case 0x76696465:
         m_mediaType = MediaType::Video;
         break;
@@ -1619,7 +1622,6 @@ void Mp4Track::internalParseHeader(Diagnostics &diag, AbortableProgressFeedback
     default:
         m_mediaType = MediaType::Unknown;
     }
-    // FIXME: save raw media type in next major release so unknown ones can still be written correctly in Mp4Track::makeMedia()
     // -> name
     m_istream->seekg(12, ios_base::cur); // skip reserved bytes
     if (static_cast<std::uint64_t>(tmp = static_cast<std::uint8_t>(m_istream->peek())) == m_hdlrAtom->dataSize() - 12 - 4 - 8 - 1) {
diff --git a/mp4/mp4track.h b/mp4/mp4track.h
index 99af20e..3cf4e7d 100644
--- a/mp4/mp4track.h
+++ b/mp4/mp4track.h
@@ -182,6 +182,7 @@ private:
     Mp4Atom *m_stscAtom;
     Mp4Atom *m_stcoAtom;
     Mp4Atom *m_stszAtom;
+    std::uint32_t m_rawMediaType;
     std::uint16_t m_framesPerSample;
     std::vector<std::uint32_t> m_sampleSizes;
     unsigned int m_chunkOffsetSize;