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Issue 3020433002: Finish migrating media metrics to TBMv2 (Closed)
Patch Set: Refactoring 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;
41 let timeToAudioPlay;
42 let timeToVideoPlay;
43
44 const chromeHelper = model.getOrCreateHelper( 46 const chromeHelper = model.getOrCreateHelper(
45 tr.model.helpers.ChromeModelHelper); 47 tr.model.helpers.ChromeModelHelper);
46 if (chromeHelper === undefined) return; 48 if (chromeHelper === undefined) return;
47 49
48 for (const rendererHelper of Object.values(chromeHelper.rendererHelpers)) { 50 for (const rendererHelper of Object.values(chromeHelper.rendererHelpers)) {
49 // Find the threads we're interested in, and if a needed thread 51 // Find the threads we're interested in, and if a needed thread
50 // is missing, no need to look further in this process. 52 // is missing, no need to look further in this process.
51 const mainThread = rendererHelper.mainThread; 53 const mainThread = rendererHelper.mainThread;
52 if (mainThread === undefined) continue; 54 if (mainThread === undefined) continue;
53 55
54 const compositorThread = rendererHelper.compositorThread; 56 const compositorThread = rendererHelper.compositorThread;
55 const audioThread = 57 const audioThread =
56 rendererHelper.process.findAtMostOneThreadNamed('AudioOutputDevice'); 58 rendererHelper.process.findAtMostOneThreadNamed('AudioOutputDevice');
57 if (compositorThread === undefined && audioThread === undefined) continue; 59 if (compositorThread === undefined && audioThread === undefined) continue;
58 60
59 // Look for the media player DoLoad event on main thread. 61 const playStart = getPlayStart(mainThread);
60 for (const event of mainThread.getDescendantEvents()) {
61 if (event.title === 'WebMediaPlayerImpl::DoLoad') {
62 // TODO(johnchen@chromium.org): Support multiple audio/video
63 // elements per page. Currently, we only support a single
64 // audio or video element, so we can store the start time in
65 // a simple variable, and exit the loop.
66 if (playStart !== undefined) {
67 throw new Error(
68 'Loading multiple audio/video elements not yet supported');
69 }
70 playStart = event.start;
71 break;
72 }
73 }
74 if (playStart === undefined) continue; 62 if (playStart === undefined) continue;
75 63
76 // Look for video render event. 64 const timeToVideoPlay = getTimeToVideoPlay(
77 if (compositorThread !== undefined) { 65 compositorThread, playStart, histograms);
78 for (const event of compositorThread.getDescendantEvents()) { 66 const timeToAudioPlay = getTimeToAudioPlay(
79 if (event.title === 'VideoRendererImpl::Render') { 67 audioThread, playStart, histograms);
80 timeToVideoPlay = event.start - playStart; 68
81 break; 69 if (timeToVideoPlay === undefined && timeToAudioPlay === undefined) {
82 } 70 continue;
83 }
84 } 71 }
85 72
86 // Look for audio render event. 73 const droppedFrameCount = getDroppedFrameCount(compositorThread,
87 if (audioThread !== undefined) { 74 timeToVideoPlay, histograms);
88 for (const event of audioThread.getDescendantEvents()) { 75 const seekTimes = getSeekTimes(mainThread, timeToVideoPlay, histograms);
89 if (event.title === 'AudioRendererImpl::Render') { 76 const bufferingTime = getBufferingTime(mainThread, playStart,
90 timeToAudioPlay = event.start - playStart; 77 timeToVideoPlay, timeToAudioPlay, seekTimes, histograms);
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 } 78 }
107 } 79 }
108 80
81 function getPlayStart(mainThread) {
82 let playStart;
83 for (const event of mainThread.getDescendantEvents()) {
84 if (event.title === 'WebMediaPlayerImpl::DoLoad') {
85 // TODO(johnchen@chromium.org): Support multiple audio/video
86 // elements per page. Currently, we only support a single
87 // audio or video element, so we can store the start time in
88 // a simple variable.
89 if (playStart !== undefined) {
90 throw new Error(
91 'Loading multiple audio/video elements not yet supported');
92 }
93 playStart = event.start;
94 }
95 }
96 return playStart;
97 }
98
99 function getTimeToVideoPlay(compositorThread, playStart, histograms) {
100 if (compositorThread !== undefined) {
101 for (const event of compositorThread.getDescendantEvents()) {
102 if (event.title === 'VideoRendererImpl::Render') {
103 const timeToVideoPlay = event.start - playStart;
104 histograms.createHistogram('time_to_video_play',
105 tr.b.Unit.byName.timeDurationInMs_smallerIsBetter,
106 timeToVideoPlay);
107 return timeToVideoPlay;
108 }
109 }
110 }
111 return undefined;
112 }
113
114 function getTimeToAudioPlay(audioThread, playStart, histograms) {
115 if (audioThread !== undefined) {
116 for (const event of audioThread.getDescendantEvents()) {
benjhayden 2017/09/21 05:57:30 Can you iterate over only one of the thread's even
johnchen 2017/09/22 16:25:39 Done. Now getting events from sliceGroup.
117 if (event.title === 'AudioRendererImpl::Render') {
118 const timeToAudioPlay = event.start - playStart;
119 histograms.createHistogram('time_to_audio_play',
120 tr.b.Unit.byName.timeDurationInMs_smallerIsBetter,
121 timeToAudioPlay);
122 return timeToAudioPlay;
123 }
124 }
125 }
126 return undefined;
127 }
128
129 function getSeekTimes(mainThread, timeToVideoPlay, histograms) {
130 if (timeToVideoPlay === undefined) return new Map();
131
132 const seekStartTimes = new Map();
133 const seekTimes = new Map();
134 for (const event of mainThread.getDescendantEvents()) {
135 if (event.title === 'WebMediaPlayerImpl::DoSeek') {
136 seekStartTimes.set(event.args.target, event.start);
benjhayden 2017/09/21 05:57:30 We're a bit leery of copying strings from the trac
johnchen 2017/09/22 16:25:39 Target are numerical values, not strings. It equal
137 } else if (event.title === 'WebMediaPlayerImpl::OnPipelineSeeked') {
138 const startTime = seekStartTimes.get(event.args.target);
139 if (startTime !== undefined) {
140 seekTimes.set(event.args.target, event.start - startTime);
141 seekStartTimes.delete(event.args.target);
142 }
143 }
144 }
145 for (const [key, value] of seekTimes.entries()) {
146 histograms.createHistogram('seek_time_' + key,
147 tr.b.Unit.byName.timeDurationInMs_smallerIsBetter, value);
148 }
149 return seekTimes;
150 }
151
152 function getBufferingTime(mainThread, playStart, timeToVideoPlay,
153 timeToAudioPlay, seekTimes, histograms) {
154 // We can calculate buffering time only if the media is played from
155 // beginning to end. Thus if any seek operations had occurred, we skip
156 // calculating this metric.
157 if (seekTimes.size !== 0) return undefined;
158
159 let playEnd;
160 let duration;
161 for (const event of mainThread.getDescendantEvents()) {
162 if (event.title === 'WebMediaPlayerImpl::OnEnded') {
163 // TODO(johnchen@chromium.org): Support multiple audio/video
164 // elements per page. Currently, we only support a single
165 // audio or video element, so we can store the end time in
166 // a simple variable.
167 if (playEnd !== undefined) {
168 throw new Error(
169 'Multiple media ended events not yet supported');
170 }
171 playEnd = event.start;
172 duration = 1000 * event.args.duration; // seconds to milliseconds
173 }
174 }
175 let bufferingTime = playEnd - playStart - duration;
176 if (timeToVideoPlay !== undefined) {
177 bufferingTime -= timeToVideoPlay;
178 } else {
179 bufferingTime -= timeToAudioPlay;
180 }
181 histograms.createHistogram('buffering_time',
182 tr.b.Unit.byName.timeDurationInMs_smallerIsBetter, bufferingTime);
183 return bufferingTime;
184 }
185
186 function getDroppedFrameCount(compositorThread, timeToVideoPlay,
187 histograms) {
188 if (timeToVideoPlay === undefined) return undefined;
benjhayden 2017/09/21 05:57:30 If this function only needs timeToVideoPlay in ord
johnchen 2017/09/22 16:25:39 Done
189
190 let droppedFrameCount = 0;
191 for (const event of compositorThread.getDescendantEvents()) {
192 if (event.title === 'VideoFramesDropped') {
193 droppedFrameCount += event.args.count;
194 }
195 }
196 histograms.createHistogram('dropped_frame_count',
197 tr.b.Unit.byName.count_smallerIsBetter, droppedFrameCount);
198 return droppedFrameCount;
199 }
200
109 tr.metrics.MetricRegistry.register(mediaMetric); 201 tr.metrics.MetricRegistry.register(mediaMetric);
110 202
111 return { 203 return {
112 mediaMetric, 204 mediaMetric,
113 }; 205 };
114 }); 206 });
115 </script> 207 </script>
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