1 files changed, 46 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/video_coding/chain_diff_calculator.h b/third_party/libwebrtc/modules/video_coding/chain_diff_calculator.h
new file mode 100644
index 0000000000..bca7340c6f
--- /dev/null
+++ b/third_party/libwebrtc/modules/video_coding/chain_diff_calculator.h
@@ -0,0 +1,46 @@
+/*
+ *  Copyright (c) 2020 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef MODULES_VIDEO_CODING_CHAIN_DIFF_CALCULATOR_H_
+#define MODULES_VIDEO_CODING_CHAIN_DIFF_CALCULATOR_H_
+
+#include <stdint.h>
+
+#include <vector>
+
+#include "absl/container/inlined_vector.h"
+#include "absl/types/optional.h"
+
+namespace webrtc {
+
+// This class is thread compatible.
+class ChainDiffCalculator {
+ public:
+  ChainDiffCalculator() = default;
+  ChainDiffCalculator(const ChainDiffCalculator&) = default;
+  ChainDiffCalculator& operator=(const ChainDiffCalculator&) = default;
+
+  // Restarts chains, i.e. for position where chains[i] == true next chain_diff
+  // will be 0. Saves chains.size() as number of chains in the stream.
+  void Reset(const std::vector<bool>& chains);
+
+  // Returns chain diffs based on flags if frame is part of the chain.
+  absl::InlinedVector<int, 4> From(int64_t frame_id,
+                                   const std::vector<bool>& chains);
+
+ private:
+  absl::InlinedVector<int, 4> ChainDiffs(int64_t frame_id) const;
+
+  absl::InlinedVector<absl::optional<int64_t>, 4> last_frame_in_chain_;
+};
+
+}  // namespace webrtc
+
+#endif  // MODULES_VIDEO_CODING_CHAIN_DIFF_CALCULATOR_H_