1 files changed, 62 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/video_coding/chain_diff_calculator.cc b/third_party/libwebrtc/modules/video_coding/chain_diff_calculator.cc
new file mode 100644
index 0000000000..5f852717b5
--- /dev/null
+++ b/third_party/libwebrtc/modules/video_coding/chain_diff_calculator.cc
@@ -0,0 +1,62 @@
+/*
+ *  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.
+ */
+#include "modules/video_coding/chain_diff_calculator.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <algorithm>
+#include <vector>
+
+#include "absl/container/inlined_vector.h"
+#include "absl/types/optional.h"
+#include "rtc_base/logging.h"
+
+namespace webrtc {
+
+void ChainDiffCalculator::Reset(const std::vector<bool>& chains) {
+  last_frame_in_chain_.resize(chains.size());
+  for (size_t i = 0; i < chains.size(); ++i) {
+    if (chains[i]) {
+      last_frame_in_chain_[i] = absl::nullopt;
+    }
+  }
+}
+
+absl::InlinedVector<int, 4> ChainDiffCalculator::ChainDiffs(
+    int64_t frame_id) const {
+  absl::InlinedVector<int, 4> result;
+  result.reserve(last_frame_in_chain_.size());
+  for (const auto& frame_id_in_chain : last_frame_in_chain_) {
+    result.push_back(frame_id_in_chain ? (frame_id - *frame_id_in_chain) : 0);
+  }
+  return result;
+}
+
+absl::InlinedVector<int, 4> ChainDiffCalculator::From(
+    int64_t frame_id,
+    const std::vector<bool>& chains) {
+  auto result = ChainDiffs(frame_id);
+  if (chains.size() != last_frame_in_chain_.size()) {
+    RTC_LOG(LS_ERROR) << "Insconsistent chain configuration for frame#"
+                      << frame_id << ": expected "
+                      << last_frame_in_chain_.size() << " chains, found "
+                      << chains.size();
+  }
+  size_t num_chains = std::min(last_frame_in_chain_.size(), chains.size());
+  for (size_t i = 0; i < num_chains; ++i) {
+    if (chains[i]) {
+      last_frame_in_chain_[i] = frame_id;
+    }
+  }
+  return result;
+}
+
+}  // namespace webrtc