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gaia/shared/js/media/video_stats.js

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+'use strict';
+/* global dump, MediaUtils */
+/* exported VideoStats */
+
+//
+// VideoStats records video playback statistics and
+// dumps them to the native console
+//
+var VideoStats = (function() {
+  var startQuality;
+
+  var startTime;
+
+  var endQuality;
+
+  var endTime;
+
+  var video;
+
+  // Start recording stats
+  function start(v) {
+    video = v;
+    if (!video.getVideoPlaybackQuality) {
+      // This API is needed to record stats.
+      // It is enabled in gecko by setting
+      // the media.mediasource.enabled pref to true.
+      return;
+    }
+
+    startQuality = video.getVideoPlaybackQuality();
+    startTime = video.currentTime;
+    endQuality = null;
+    endTime = null;
+  }
+
+  // Stop recording stats
+  function stop() {
+    if (!video) {
+      dump('Warning: no stats have been recorded. ' +
+        'Make sure start() has been called');
+      return;
+    }
+
+    if (!video.getVideoPlaybackQuality) {
+      // This API is needed to record stats.
+      // It is enabled in gecko by setting
+      // the media.mediasource.enabled pref to true.
+      return;
+    }
+
+    endQuality = video.getVideoPlaybackQuality();
+    endTime = video.currentTime;
+  }
+
+  // Dump stats to the native console
+  function print() {
+    if (!video) {
+      dump('Warning: no stats have been recorded. ' +
+        'Make sure start() has been called');
+      return;
+    }
+
+    if (!video.getVideoPlaybackQuality) {
+      // This API is needed to record stats.
+      // It is enabled in gecko by setting
+      // the media.mediasource.enabled pref to true.
+      return;
+    }
+
+    if (!startQuality || !endQuality) {
+      dump('Warning: no stats have been recorded. ' +
+        'Make sure start() and stop() have been called');
+      return;
+    }
+
+    // Playback segment duration in seconds
+    var segmentDuration =
+      (endQuality.creationTime - startQuality.creationTime) / 1000;
+    var startRendered =
+      startQuality.totalVideoFrames - startQuality.droppedVideoFrames;
+    var endRendered =
+      endQuality.totalVideoFrames - endQuality.droppedVideoFrames;
+    var segmentRendered = endRendered - startRendered;
+    var fps = segmentRendered / segmentDuration;
+
+    dump('Video statistics start');
+    dump('Dimensions: ' + video.videoWidth + 'x' + video.videoHeight);
+    dump('Complete duration: ' + MediaUtils.formatDuration(video.duration));
+    dump('Start time: ' + MediaUtils.formatDuration(startTime));
+    dump('End time: ' + MediaUtils.formatDuration(endTime));
+    dump('Total frames: ' + endQuality.totalVideoFrames);
+    dump('Decoded frames: ' +
+      (endQuality.totalVideoFrames - endQuality.corruptedVideoFrames));
+    dump('Corrupted frames: ' + endQuality.corruptedVideoFrames);
+    dump('Rendered frames: ' +
+      (endQuality.totalVideoFrames - endQuality.droppedVideoFrames));
+    dump('Dropped frames: ' + endQuality.droppedVideoFrames);
+    dump('Average rendered FPS: ' + fps.toFixed(2));
+    dump('Video statistics end');
+  }
+
+  return {
+    start: start,
+    stop: stop,
+    dump: print
+  };
+})();