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-rw-r--r--third_party/libwebrtc/common_video/framerate_controller.cc88
1 files changed, 88 insertions, 0 deletions
diff --git a/third_party/libwebrtc/common_video/framerate_controller.cc b/third_party/libwebrtc/common_video/framerate_controller.cc
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+++ b/third_party/libwebrtc/common_video/framerate_controller.cc
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+/*
+ * Copyright 2021 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 "common_video/framerate_controller.h"
+
+#include <limits>
+
+#include "rtc_base/time_utils.h"
+
+namespace webrtc {
+namespace {
+constexpr double kMinFramerate = 0.5;
+} // namespace
+
+FramerateController::FramerateController()
+ : FramerateController(std::numeric_limits<double>::max()) {}
+
+FramerateController::FramerateController(double max_framerate)
+ : max_framerate_(max_framerate) {}
+
+FramerateController::~FramerateController() {}
+
+void FramerateController::SetMaxFramerate(double max_framerate) {
+ max_framerate_ = max_framerate;
+}
+
+double FramerateController::GetMaxFramerate() const {
+ return max_framerate_;
+}
+
+bool FramerateController::ShouldDropFrame(int64_t in_timestamp_ns) {
+ if (max_framerate_ < kMinFramerate)
+ return true;
+
+ // If `max_framerate_` is not set (i.e. maxdouble), `frame_interval_ns` is
+ // rounded to 0.
+ int64_t frame_interval_ns = rtc::kNumNanosecsPerSec / max_framerate_;
+ if (frame_interval_ns <= 0) {
+ // Frame rate throttling not enabled.
+ return false;
+ }
+
+ if (next_frame_timestamp_ns_) {
+ // Time until next frame should be outputted.
+ const int64_t time_until_next_frame_ns =
+ (*next_frame_timestamp_ns_ - in_timestamp_ns);
+ // Continue if timestamp is within expected range.
+ if (std::abs(time_until_next_frame_ns) < 2 * frame_interval_ns) {
+ // Drop if a frame shouldn't be outputted yet.
+ if (time_until_next_frame_ns > 0)
+ return true;
+ // Time to output new frame.
+ *next_frame_timestamp_ns_ += frame_interval_ns;
+ return false;
+ }
+ }
+
+ // First timestamp received or timestamp is way outside expected range, so
+ // reset. Set first timestamp target to just half the interval to prefer
+ // keeping frames in case of jitter.
+ next_frame_timestamp_ns_ = in_timestamp_ns + frame_interval_ns / 2;
+ return false;
+}
+
+void FramerateController::Reset() {
+ max_framerate_ = std::numeric_limits<double>::max();
+ next_frame_timestamp_ns_ = absl::nullopt;
+}
+
+void FramerateController::KeepFrame(int64_t in_timestamp_ns) {
+ if (ShouldDropFrame(in_timestamp_ns)) {
+ if (max_framerate_ < kMinFramerate)
+ return;
+
+ int64_t frame_interval_ns = rtc::kNumNanosecsPerSec / max_framerate_;
+ if (next_frame_timestamp_ns_)
+ *next_frame_timestamp_ns_ += frame_interval_ns;
+ }
+}
+
+} // namespace webrtc