1 files changed, 75 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/video_coding/frame_dependencies_calculator.cc b/third_party/libwebrtc/modules/video_coding/frame_dependencies_calculator.cc
new file mode 100644
index 0000000000..7ca59f779a
--- /dev/null
+++ b/third_party/libwebrtc/modules/video_coding/frame_dependencies_calculator.cc
@@ -0,0 +1,75 @@
+/*
+ *  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/frame_dependencies_calculator.h"
+
+#include <stdint.h>
+
+#include <iterator>
+#include <set>
+
+#include "absl/algorithm/container.h"
+#include "absl/container/inlined_vector.h"
+#include "api/array_view.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/logging.h"
+
+namespace webrtc {
+
+absl::InlinedVector<int64_t, 5> FrameDependenciesCalculator::FromBuffersUsage(
+    int64_t frame_id,
+    rtc::ArrayView<const CodecBufferUsage> buffers_usage) {
+  absl::InlinedVector<int64_t, 5> dependencies;
+  RTC_DCHECK_GT(buffers_usage.size(), 0);
+  for (const CodecBufferUsage& buffer_usage : buffers_usage) {
+    RTC_CHECK_GE(buffer_usage.id, 0);
+    if (buffers_.size() <= static_cast<size_t>(buffer_usage.id)) {
+      buffers_.resize(buffer_usage.id + 1);
+    }
+  }
+  std::set<int64_t> direct_depenendencies;
+  std::set<int64_t> indirect_depenendencies;
+
+  for (const CodecBufferUsage& buffer_usage : buffers_usage) {
+    if (!buffer_usage.referenced) {
+      continue;
+    }
+    const BufferUsage& buffer = buffers_[buffer_usage.id];
+    if (buffer.frame_id == absl::nullopt) {
+      RTC_LOG(LS_ERROR) << "Odd configuration: frame " << frame_id
+                        << " references buffer #" << buffer_usage.id
+                        << " that was never updated.";
+      continue;
+    }
+    direct_depenendencies.insert(*buffer.frame_id);
+    indirect_depenendencies.insert(buffer.dependencies.begin(),
+                                   buffer.dependencies.end());
+  }
+  // Reduce references: if frame #3 depends on frame #2 and #1, and frame #2
+  // depends on frame #1, then frame #3 needs to depend just on frame #2.
+  // Though this set diff removes only 1 level of indirection, it seems
+  // enough for all currently used structures.
+  absl::c_set_difference(direct_depenendencies, indirect_depenendencies,
+                         std::back_inserter(dependencies));
+
+  // Update buffers.
+  for (const CodecBufferUsage& buffer_usage : buffers_usage) {
+    if (!buffer_usage.updated) {
+      continue;
+    }
+    BufferUsage& buffer = buffers_[buffer_usage.id];
+    buffer.frame_id = frame_id;
+    buffer.dependencies.assign(direct_depenendencies.begin(),
+                               direct_depenendencies.end());
+  }
+
+  return dependencies;
+}
+
+}  // namespace webrtc