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Issue 3020433002: Finish migrating media metrics to TBMv2 (Closed)
Patch Set: Created 3 years, 3 months ago
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1 <!DOCTYPE html> 1 <!DOCTYPE html>
2 <!-- 2 <!--
3 Copyright 2017 The Chromium Authors. All rights reserved. 3 Copyright 2017 The Chromium Authors. All rights reserved.
4 Use of this source code is governed by a BSD-style license that can be 4 Use of this source code is governed by a BSD-style license that can be
5 found in the LICENSE file. 5 found in the LICENSE file.
6 --> 6 -->
7 7
8 <!-- 8 <!--
9 media_metrics uses Chrome trace events to calculate metrics about video 9 media_metrics uses Chrome trace events to calculate metrics about video
10 and audio playback. It is meant to be used for pages with a <video> or 10 and audio playback. It is meant to be used for pages with a <video> or
11 <audio> element. It is used by videostack-eng@google.com team for 11 <audio> element. It is used by videostack-eng@google.com team for
12 regression testing. 12 regression testing.
13 13
14 This metric currently supports the following measurement: 14 This metric currently supports the following measurement:
15 * time_to_video_play calculates how long after a video is requested to 15 * time_to_video_play calculates how long after a video is requested to
16 start playing before the video actually starts. If time_to_video_play 16 start playing before the video actually starts. If time_to_video_play
17 regresses, then users will click to play videos and then have 17 regresses, then users will click to play videos and then have
18 to wait longer before the videos start actually playing. 18 to wait longer before the videos start actually playing.
19 * time_to_audio_play is similar to time_to_video_play, but measures the 19 * time_to_audio_play is similar to time_to_video_play, but measures the
20 time delay before audio starts playing. 20 time delay before audio starts playing.
21 21 * buffering_time calculates the difference between the actual play time of
22 More measurements are expected to be added in the near future, such as: 22 media vs its expected play time. Ideally the two should be the same.
23 * buffering_time 23 If actual play time is significantly longer than expected play time,
24 * seek_time 24 it indicates that there were stalls during the play for buffering or
25 * dropped_frame_count 25 some other reasons.
26 * dropped_frame_count reports the number of video frames that were dropped.
27 Ideally this should be 0. If a large number of frames are dropped, the
28 video play will not be smooth.
29 * seek_time calculates how long after a user requests a seek operation
30 before the seek completes and the media starts playing at the new
31 location.
26 32
27 Please inform crouleau@chromium.org and johnchen@chromium.org about 33 Please inform crouleau@chromium.org and johnchen@chromium.org about
28 changes to this file. 34 changes to this file.
29 --> 35 -->
30 36
31 <link rel="import" href="/tracing/metrics/metric_registry.html"> 37 <link rel="import" href="/tracing/metrics/metric_registry.html">
32 <link rel="import" href="/tracing/model/helpers/chrome_model_helper.html"> 38 <link rel="import" href="/tracing/model/helpers/chrome_model_helper.html">
33 <link rel="import" href="/tracing/value/histogram.html"> 39 <link rel="import" href="/tracing/value/histogram.html">
34 40
35 <script> 41 <script>
36 'use strict'; 42 'use strict';
37 43
38 tr.exportTo('tr.metrics', function() { 44 tr.exportTo('tr.metrics', function() {
39 function mediaMetric(histograms, model) { 45 function mediaMetric(histograms, model) {
40 let playStart; 46 let playStart;
41 let timeToAudioPlay; 47 let timeToAudioPlay;
42 let timeToVideoPlay; 48 let timeToVideoPlay;
49 let playEnd;
50 let duration;
51 let framesDropped = 0;
52 const seekStartTimes = new Map();
53 const seekTimes = new Map();
43 54
44 const chromeHelper = model.getOrCreateHelper( 55 const chromeHelper = model.getOrCreateHelper(
45 tr.model.helpers.ChromeModelHelper); 56 tr.model.helpers.ChromeModelHelper);
46 if (chromeHelper === undefined) return; 57 if (chromeHelper === undefined) return;
47 58
48 for (const rendererHelper of Object.values(chromeHelper.rendererHelpers)) { 59 for (const rendererHelper of Object.values(chromeHelper.rendererHelpers)) {
49 // Find the threads we're interested in, and if a needed thread 60 // Find the threads we're interested in, and if a needed thread
50 // is missing, no need to look further in this process. 61 // is missing, no need to look further in this process.
51 const mainThread = rendererHelper.mainThread; 62 const mainThread = rendererHelper.mainThread;
52 if (mainThread === undefined) continue; 63 if (mainThread === undefined) continue;
53 64
54 const compositorThread = rendererHelper.compositorThread; 65 const compositorThread = rendererHelper.compositorThread;
55 const audioThread = 66 const audioThread =
56 rendererHelper.process.findAtMostOneThreadNamed('AudioOutputDevice'); 67 rendererHelper.process.findAtMostOneThreadNamed('AudioOutputDevice');
57 if (compositorThread === undefined && audioThread === undefined) continue; 68 if (compositorThread === undefined && audioThread === undefined) continue;
58 69
59 // Look for the media player DoLoad event on main thread. 70 processMainThread(mainThread);
60 for (const event of mainThread.getDescendantEvents()) { 71 if (playStart === undefined) continue;
72
73 processCompositorThread(compositorThread);
74 processAudioThread(audioThread);
75
76 if (timeToVideoPlay !== undefined) break;
77 if (timeToAudioPlay !== undefined) break;
78 }
79
80 calculateMetrics();
81
82 // Look for events on main thread.
83 function processMainThread(thread) {
CalebRouleau 2017/09/20 22:53:20 Even though the concept of what you're doing here
84 for (const event of thread.getDescendantEvents()) {
61 if (event.title === 'WebMediaPlayerImpl::DoLoad') { 85 if (event.title === 'WebMediaPlayerImpl::DoLoad') {
62 // TODO(johnchen@chromium.org): Support multiple audio/video 86 // TODO(johnchen@chromium.org): Support multiple audio/video
63 // elements per page. Currently, we only support a single 87 // elements per page. Currently, we only support a single
64 // audio or video element, so we can store the start time in 88 // audio or video element, so we can store the start time in
65 // a simple variable, and exit the loop. 89 // a simple variable.
66 if (playStart !== undefined) { 90 if (playStart !== undefined) {
67 throw new Error( 91 throw new Error(
68 'Loading multiple audio/video elements not yet supported'); 92 'Loading multiple audio/video elements not yet supported');
69 } 93 }
70 playStart = event.start; 94 playStart = event.start;
95 } else if (event.title === 'WebMediaPlayerImpl::DoSeek') {
96 seekStartTimes.set(event.args.target, event.start);
97 } else if (event.title === 'WebMediaPlayerImpl::OnPipelineSeeked') {
98 const startTime = seekStartTimes.get(event.args.target);
99 if (startTime !== undefined) {
100 seekTimes.set(event.args.target, event.start - startTime);
101 seekStartTimes.delete(event.args.target);
102 }
103 } else if (event.title === 'WebMediaPlayerImpl::OnEnded') {
104 if (playEnd === undefined) {
105 playEnd = event.start;
106 duration = 1000 * event.args.duration; // seconds to milliseconds
107 }
CalebRouleau 2017/09/20 22:53:20 We throw an error for multiple playStart events. W
108 }
109 }
110 }
111
112 // Look for events on compositor thread.
113 function processCompositorThread(thread) {
114 if (thread === undefined) {
115 return;
116 }
117 for (const event of thread.getDescendantEvents()) {
118 if (event.title === 'VideoRendererImpl::Render') {
119 if (timeToVideoPlay === undefined) {
120 timeToVideoPlay = event.start - playStart;
121 }
122 } else if (event.title === 'FramesDropped') {
123 framesDropped += event.args.count;
124 }
125 }
126 }
127
128 // Look for audio render event on audio thread.
129 function processAudioThread(thread) {
130 if (thread === undefined) {
131 return;
132 }
133 for (const event of thread.getDescendantEvents()) {
134 if (event.title === 'AudioRendererImpl::Render') {
135 timeToAudioPlay = event.start - playStart;
71 break; 136 break;
72 } 137 }
73 } 138 }
74 if (playStart === undefined) continue; 139 }
75 140
76 // Look for video render event. 141 // Calculate all metrics after event have been collected.
77 if (compositorThread !== undefined) { 142 function calculateMetrics() {
78 for (const event of compositorThread.getDescendantEvents()) { 143 if (timeToVideoPlay !== undefined) {
79 if (event.title === 'VideoRendererImpl::Render') { 144 histograms.createHistogram('time_to_video_play',
80 timeToVideoPlay = event.start - playStart; 145 tr.b.Unit.byName.timeDurationInMs_smallerIsBetter, timeToVideoPlay);
81 break; 146 // dropped_frame_count is meaningful only if we have video.
82 } 147 histograms.createHistogram('dropped_frame_count',
148 tr.b.Unit.byName.count_smallerIsBetter, framesDropped);
149 }
150 if (timeToAudioPlay !== undefined) {
151 histograms.createHistogram('time_to_audio_play',
152 tr.b.Unit.byName.timeDurationInMs_smallerIsBetter, timeToAudioPlay);
153 }
154 if (playStart !== undefined && playEnd !== undefined &&
155 duration !== undefined && seekTimes.size === 0 &&
156 (timeToVideoPlay !== undefined || timeToAudioPlay !== undefined)) {
157 // We can calculate buffering time only if the media is played from
158 // beginning to end. Thus if any seek operations had occurred, we skip
159 // calculating this metric.
160 let bufferingTime = playEnd - playStart - duration;
161 if (timeToVideoPlay !== undefined) {
162 bufferingTime -= timeToVideoPlay;
163 } else {
164 bufferingTime -= timeToAudioPlay;
165 }
166 histograms.createHistogram('buffering_time',
167 tr.b.Unit.byName.timeDurationInMs_smallerIsBetter, bufferingTime);
168 }
169 if (seekTimes.size > 0) {
170 for (const [key, value] of seekTimes.entries()) {
171 histograms.createHistogram('seek_time_' + key,
172 tr.b.Unit.byName.timeDurationInMs_smallerIsBetter, value);
83 } 173 }
84 } 174 }
85
86 // Look for audio render event.
87 if (audioThread !== undefined) {
88 for (const event of audioThread.getDescendantEvents()) {
89 if (event.title === 'AudioRendererImpl::Render') {
90 timeToAudioPlay = event.start - playStart;
91 break;
92 }
93 }
94 }
95 if (timeToVideoPlay !== undefined) break;
96 if (timeToAudioPlay !== undefined) break;
97 }
98
99 if (timeToVideoPlay !== undefined) {
100 histograms.createHistogram('time_to_video_play',
101 tr.b.Unit.byName.timeDurationInMs_smallerIsBetter, timeToVideoPlay);
102 }
103 if (timeToAudioPlay !== undefined) {
104 histograms.createHistogram('time_to_audio_play',
105 tr.b.Unit.byName.timeDurationInMs_smallerIsBetter, timeToAudioPlay);
106 } 175 }
107 } 176 }
108 177
109 tr.metrics.MetricRegistry.register(mediaMetric); 178 tr.metrics.MetricRegistry.register(mediaMetric);
110 179
111 return { 180 return {
112 mediaMetric, 181 mediaMetric,
113 }; 182 };
114 }); 183 });
115 </script> 184 </script>
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