From e25b285ca77c05b4c503038d624454b04fc51e6a Mon Sep 17 00:00:00 2001
From: Moonchild <moonchild@palemoon.org>
Date: Sun, 29 Dec 2024 13:31:47 +0100
Subject: [PATCH] Issue #2673 - Part 2: Add ADTS format sniffer.

---
 dom/media/ADTSDemuxer.cpp | 22 ++++++++++++++++++++++
 dom/media/ADTSDemuxer.h   |  3 +++
 2 files changed, 25 insertions(+)

diff --git a/dom/media/ADTSDemuxer.cpp b/dom/media/ADTSDemuxer.cpp
index 5d32e29cc7..cb4fe61541 100644
--- a/dom/media/ADTSDemuxer.cpp
+++ b/dom/media/ADTSDemuxer.cpp
@@ -840,4 +840,26 @@ ADTSTrackDemuxer::AverageFrameLength() const
   return 0.0;
 }
 
+/* static */ bool
+ADTSDemuxer::ADTSSniffer(const uint8_t* aData, const uint32_t aLength)
+{
+  if (aLength < 7) {
+    return false;
+  }
+  auto parser = MakeUnique<adts::FrameParser>();
+
+  if (!parser->Parse(0, aData, aData + aLength)) {
+    return false;
+  }
+  const adts::Frame& currentFrame = parser->CurrentFrame();
+  // Check for sync marker after the found frame, since it's
+  // possible to find sync marker in AAC data. If sync marker
+  // exists after the current frame then we've found a frame
+  // header.
+  int64_t nextFrameHeaderOffset = currentFrame.Offset() + currentFrame.Length();
+  return int64_t(aLength) > nextFrameHeaderOffset &&
+         aLength - nextFrameHeaderOffset >= 2 &&
+         adts::FrameHeader::MatchesSync(aData + nextFrameHeaderOffset);
+}
+
 } // namespace mozilla
diff --git a/dom/media/ADTSDemuxer.h b/dom/media/ADTSDemuxer.h
index e1daa29e67..fcd3b1f272 100644
--- a/dom/media/ADTSDemuxer.h
+++ b/dom/media/ADTSDemuxer.h
@@ -32,6 +32,9 @@ public:
     TrackInfo::TrackType aType, uint32_t aTrackNumber) override;
   bool IsSeekable() const override;
 
+  // Return true if a valid ADTS frame header could be found.
+  static bool ADTSSniffer(const uint8_t* aData, const uint32_t aLength);
+
 private:
   bool InitInternal();