1 files changed, 306 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/video_coding/timing/timing.cc b/third_party/libwebrtc/modules/video_coding/timing/timing.cc
new file mode 100644
index 0000000000..735f6328d8
--- /dev/null
+++ b/third_party/libwebrtc/modules/video_coding/timing/timing.cc
@@ -0,0 +1,306 @@
+/*
+ *  Copyright (c) 2011 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/timing/timing.h"
+
+#include <algorithm>
+
+#include "api/units/time_delta.h"
+#include "modules/video_coding/timing/decode_time_percentile_filter.h"
+#include "modules/video_coding/timing/timestamp_extrapolator.h"
+#include "rtc_base/experiments/field_trial_parser.h"
+#include "rtc_base/logging.h"
+#include "system_wrappers/include/clock.h"
+
+namespace webrtc {
+namespace {
+
+// Default pacing that is used for the low-latency renderer path.
+constexpr TimeDelta kZeroPlayoutDelayDefaultMinPacing = TimeDelta::Millis(8);
+constexpr TimeDelta kLowLatencyStreamMaxPlayoutDelayThreshold =
+    TimeDelta::Millis(500);
+
+void CheckDelaysValid(TimeDelta min_delay, TimeDelta max_delay) {
+  if (min_delay > max_delay) {
+    RTC_LOG(LS_ERROR)
+        << "Playout delays set incorrectly: min playout delay (" << min_delay
+        << ") > max playout delay (" << max_delay
+        << "). This is undefined behaviour. Application writers should "
+           "ensure that the min delay is always less than or equals max "
+           "delay. If trying to use the playout delay header extensions "
+           "described in "
+           "https://webrtc.googlesource.com/src/+/refs/heads/main/docs/"
+           "native-code/rtp-hdrext/playout-delay/, be careful that a playout "
+           "delay hint or A/V sync settings may have caused this conflict.";
+  }
+}
+
+}  // namespace
+
+VCMTiming::VCMTiming(Clock* clock, const FieldTrialsView& field_trials)
+    : clock_(clock),
+      ts_extrapolator_(
+          std::make_unique<TimestampExtrapolator>(clock_->CurrentTime())),
+      decode_time_filter_(std::make_unique<DecodeTimePercentileFilter>()),
+      render_delay_(kDefaultRenderDelay),
+      min_playout_delay_(TimeDelta::Zero()),
+      max_playout_delay_(TimeDelta::Seconds(10)),
+      jitter_delay_(TimeDelta::Zero()),
+      current_delay_(TimeDelta::Zero()),
+      prev_frame_timestamp_(0),
+      num_decoded_frames_(0),
+      zero_playout_delay_min_pacing_("min_pacing",
+                                     kZeroPlayoutDelayDefaultMinPacing),
+      last_decode_scheduled_(Timestamp::Zero()) {
+  ParseFieldTrial({&zero_playout_delay_min_pacing_},
+                  field_trials.Lookup("WebRTC-ZeroPlayoutDelay"));
+}
+
+void VCMTiming::Reset() {
+  MutexLock lock(&mutex_);
+  ts_extrapolator_->Reset(clock_->CurrentTime());
+  decode_time_filter_ = std::make_unique<DecodeTimePercentileFilter>();
+  render_delay_ = kDefaultRenderDelay;
+  min_playout_delay_ = TimeDelta::Zero();
+  jitter_delay_ = TimeDelta::Zero();
+  current_delay_ = TimeDelta::Zero();
+  prev_frame_timestamp_ = 0;
+}
+
+void VCMTiming::set_render_delay(TimeDelta render_delay) {
+  MutexLock lock(&mutex_);
+  render_delay_ = render_delay;
+}
+
+TimeDelta VCMTiming::min_playout_delay() const {
+  MutexLock lock(&mutex_);
+  return min_playout_delay_;
+}
+
+void VCMTiming::set_min_playout_delay(TimeDelta min_playout_delay) {
+  MutexLock lock(&mutex_);
+  if (min_playout_delay_ != min_playout_delay) {
+    CheckDelaysValid(min_playout_delay, max_playout_delay_);
+    min_playout_delay_ = min_playout_delay;
+  }
+}
+
+void VCMTiming::set_max_playout_delay(TimeDelta max_playout_delay) {
+  MutexLock lock(&mutex_);
+  if (max_playout_delay_ != max_playout_delay) {
+    CheckDelaysValid(min_playout_delay_, max_playout_delay);
+    max_playout_delay_ = max_playout_delay;
+  }
+}
+
+void VCMTiming::SetJitterDelay(TimeDelta jitter_delay) {
+  MutexLock lock(&mutex_);
+  if (jitter_delay != jitter_delay_) {
+    jitter_delay_ = jitter_delay;
+    // When in initial state, set current delay to minimum delay.
+    if (current_delay_.IsZero()) {
+      current_delay_ = jitter_delay_;
+    }
+  }
+}
+
+void VCMTiming::UpdateCurrentDelay(uint32_t frame_timestamp) {
+  MutexLock lock(&mutex_);
+  TimeDelta target_delay = TargetDelayInternal();
+
+  if (current_delay_.IsZero()) {
+    // Not initialized, set current delay to target.
+    current_delay_ = target_delay;
+  } else if (target_delay != current_delay_) {
+    TimeDelta delay_diff = target_delay - current_delay_;
+    // Never change the delay with more than 100 ms every second. If we're
+    // changing the delay in too large steps we will get noticeable freezes. By
+    // limiting the change we can increase the delay in smaller steps, which
+    // will be experienced as the video is played in slow motion. When lowering
+    // the delay the video will be played at a faster pace.
+    TimeDelta max_change = TimeDelta::Zero();
+    if (frame_timestamp < 0x0000ffff && prev_frame_timestamp_ > 0xffff0000) {
+      // wrap
+      max_change =
+          TimeDelta::Millis(kDelayMaxChangeMsPerS *
+                            (frame_timestamp + (static_cast<int64_t>(1) << 32) -
+                             prev_frame_timestamp_) /
+                            90000);
+    } else {
+      max_change =
+          TimeDelta::Millis(kDelayMaxChangeMsPerS *
+                            (frame_timestamp - prev_frame_timestamp_) / 90000);
+    }
+
+    if (max_change <= TimeDelta::Zero()) {
+      // Any changes less than 1 ms are truncated and will be postponed.
+      // Negative change will be due to reordering and should be ignored.
+      return;
+    }
+    delay_diff = std::max(delay_diff, -max_change);
+    delay_diff = std::min(delay_diff, max_change);
+
+    current_delay_ = current_delay_ + delay_diff;
+  }
+  prev_frame_timestamp_ = frame_timestamp;
+}
+
+void VCMTiming::UpdateCurrentDelay(Timestamp render_time,
+                                   Timestamp actual_decode_time) {
+  MutexLock lock(&mutex_);
+  TimeDelta target_delay = TargetDelayInternal();
+  TimeDelta delayed = (actual_decode_time - render_time) +
+                      EstimatedMaxDecodeTime() + render_delay_;
+
+  // Only consider `delayed` as negative by more than a few microseconds.
+  if (delayed.ms() < 0) {
+    return;
+  }
+  if (current_delay_ + delayed <= target_delay) {
+    current_delay_ += delayed;
+  } else {
+    current_delay_ = target_delay;
+  }
+}
+
+void VCMTiming::StopDecodeTimer(TimeDelta decode_time, Timestamp now) {
+  MutexLock lock(&mutex_);
+  decode_time_filter_->AddTiming(decode_time.ms(), now.ms());
+  RTC_DCHECK_GE(decode_time, TimeDelta::Zero());
+  ++num_decoded_frames_;
+}
+
+void VCMTiming::IncomingTimestamp(uint32_t rtp_timestamp, Timestamp now) {
+  MutexLock lock(&mutex_);
+  ts_extrapolator_->Update(now, rtp_timestamp);
+}
+
+Timestamp VCMTiming::RenderTime(uint32_t frame_timestamp, Timestamp now) const {
+  MutexLock lock(&mutex_);
+  return RenderTimeInternal(frame_timestamp, now);
+}
+
+void VCMTiming::SetLastDecodeScheduledTimestamp(
+    Timestamp last_decode_scheduled) {
+  MutexLock lock(&mutex_);
+  last_decode_scheduled_ = last_decode_scheduled;
+}
+
+Timestamp VCMTiming::RenderTimeInternal(uint32_t frame_timestamp,
+                                        Timestamp now) const {
+  if (UseLowLatencyRendering()) {
+    // Render as soon as possible or with low-latency renderer algorithm.
+    return Timestamp::Zero();
+  }
+  // Note that TimestampExtrapolator::ExtrapolateLocalTime is not a const
+  // method; it mutates the object's wraparound state.
+  Timestamp estimated_complete_time =
+      ts_extrapolator_->ExtrapolateLocalTime(frame_timestamp).value_or(now);
+
+  // Make sure the actual delay stays in the range of `min_playout_delay_`
+  // and `max_playout_delay_`.
+  TimeDelta actual_delay =
+      current_delay_.Clamped(min_playout_delay_, max_playout_delay_);
+  return estimated_complete_time + actual_delay;
+}
+
+TimeDelta VCMTiming::EstimatedMaxDecodeTime() const {
+  const int decode_time_ms = decode_time_filter_->RequiredDecodeTimeMs();
+  RTC_DCHECK_GE(decode_time_ms, 0);
+  return TimeDelta::Millis(decode_time_ms);
+}
+
+TimeDelta VCMTiming::MaxWaitingTime(Timestamp render_time,
+                                    Timestamp now,
+                                    bool too_many_frames_queued) const {
+  MutexLock lock(&mutex_);
+
+  if (render_time.IsZero() && zero_playout_delay_min_pacing_->us() > 0 &&
+      min_playout_delay_.IsZero() && max_playout_delay_ > TimeDelta::Zero()) {
+    // `render_time` == 0 indicates that the frame should be decoded and
+    // rendered as soon as possible. However, the decoder can be choked if too
+    // many frames are sent at once. Therefore, limit the interframe delay to
+    // |zero_playout_delay_min_pacing_| unless too many frames are queued in
+    // which case the frames are sent to the decoder at once.
+    if (too_many_frames_queued) {
+      return TimeDelta::Zero();
+    }
+    Timestamp earliest_next_decode_start_time =
+        last_decode_scheduled_ + zero_playout_delay_min_pacing_;
+    TimeDelta max_wait_time = now >= earliest_next_decode_start_time
+                                  ? TimeDelta::Zero()
+                                  : earliest_next_decode_start_time - now;
+    return max_wait_time;
+  }
+  return render_time - now - EstimatedMaxDecodeTime() - render_delay_;
+}
+
+TimeDelta VCMTiming::TargetVideoDelay() const {
+  MutexLock lock(&mutex_);
+  return TargetDelayInternal();
+}
+
+TimeDelta VCMTiming::TargetDelayInternal() const {
+  return std::max(min_playout_delay_,
+                  jitter_delay_ + EstimatedMaxDecodeTime() + render_delay_);
+}
+
+// TODO(crbug.com/webrtc/15197): Centralize delay arithmetic.
+TimeDelta VCMTiming::StatsTargetDelayInternal() const {
+  TimeDelta stats_target_delay =
+      TargetDelayInternal() - (EstimatedMaxDecodeTime() + render_delay_);
+  return std::max(TimeDelta::Zero(), stats_target_delay);
+}
+
+VideoFrame::RenderParameters VCMTiming::RenderParameters() const {
+  MutexLock lock(&mutex_);
+  return {.use_low_latency_rendering = UseLowLatencyRendering(),
+          .max_composition_delay_in_frames = max_composition_delay_in_frames_};
+}
+
+bool VCMTiming::UseLowLatencyRendering() const {
+  // min_playout_delay_==0,
+  // max_playout_delay_<=kLowLatencyStreamMaxPlayoutDelayThreshold indicates
+  // that the low-latency path should be used, which means that frames should be
+  // decoded and rendered as soon as possible.
+  return min_playout_delay_.IsZero() &&
+         max_playout_delay_ <= kLowLatencyStreamMaxPlayoutDelayThreshold;
+}
+
+VCMTiming::VideoDelayTimings VCMTiming::GetTimings() const {
+  MutexLock lock(&mutex_);
+  return VideoDelayTimings{
+      .num_decoded_frames = num_decoded_frames_,
+      .minimum_delay = jitter_delay_,
+      .estimated_max_decode_time = EstimatedMaxDecodeTime(),
+      .render_delay = render_delay_,
+      .min_playout_delay = min_playout_delay_,
+      .max_playout_delay = max_playout_delay_,
+      .target_delay = StatsTargetDelayInternal(),
+      .current_delay = current_delay_};
+}
+
+void VCMTiming::SetTimingFrameInfo(const TimingFrameInfo& info) {
+  MutexLock lock(&mutex_);
+  timing_frame_info_.emplace(info);
+}
+
+absl::optional<TimingFrameInfo> VCMTiming::GetTimingFrameInfo() {
+  MutexLock lock(&mutex_);
+  return timing_frame_info_;
+}
+
+void VCMTiming::SetMaxCompositionDelayInFrames(
+    absl::optional<int> max_composition_delay_in_frames) {
+  MutexLock lock(&mutex_);
+  max_composition_delay_in_frames_ = max_composition_delay_in_frames;
+}
+
+}  // namespace webrtc