Fix Bug: Video with Variable Frame Rate plays at incorrect speed.

media/filters/video_renderer_algorithm.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "media/filters/video_renderer_algorithm.h"
 
 #include <algorithm>
 #include <limits>
 
 namespace media {
@@ skipping 466 matching lines @@
       frame_duration_calculator_.AddSample(frame.end_time - frame.start_time);
   }
   frame_queue_.back().start_time = wall_clock_times.back();
 
   if (!frame_duration_calculator_.count())
     return;
 
   // Compute |average_frame_duration_|, a moving average of the last few frames;
   // see kMovingAverageSamples for the exact number.
   average_frame_duration_ = frame_duration_calculator_.Average();
+  const base::TimeDelta deviation = frame_duration_calculator_.Deviation();
 
   // Update the frame end time for the last frame based on the average.
   frame_queue_.back().end_time =
       frame_queue_.back().start_time + average_frame_duration_;
 
   // ITU-R BR.265 recommends a maximum acceptable drift of +/- half of the frame
   // duration; there are other asymmetric, more lenient measures, that we're
   // forgoing in favor of simplicity.
   //
   // We'll always allow at least 16.66ms of drift since literature suggests it's
   // well below the floor of detection and is high enough to ensure stability
   // for 60fps content.
   max_acceptable_drift_ = std::max(average_frame_duration_ / 2,
                                    base::TimeDelta::FromSecondsD(1.0 / 60));
 
   // If we were called via RemoveExpiredFrames() and Render() was never called,
   // we may not have a render interval yet.
   if (render_interval_ == base::TimeDelta())
     return;
 
   const bool cadence_changed = cadence_estimator_.UpdateCadenceEstimate(
-      render_interval_, average_frame_duration_, max_acceptable_drift_);
+      render_interval_, average_frame_duration_, deviation,
+      max_acceptable_drift_);
 
   // No need to update cadence if there's been no change; cadence will be set
   // as frames are added to the queue.
   if (!cadence_changed)
     return;
 
   cadence_frame_counter_ = 0;
   UpdateCadenceForFrames();
 }
 
@@ skipping 162 matching lines @@
   if (frame.start_time > deadline_min)
     return frame.start_time - deadline_min;
 
   // Drift is zero for frames which overlap the deadline interval.
   DCHECK_GE(deadline_min, frame.start_time);
   DCHECK_GE(frame.end_time, deadline_min);
   return base::TimeDelta();
 }
 
 }  // namespace media