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Issue 3020433002: Finish migrating media metrics to TBMv2 (Closed)
Patch Set: Update based on feedback from crouleau@ Created 3 years, 2 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()) { 62 if (playStart === undefined) continue;
61 if (event.title === 'WebMediaPlayerImpl::DoLoad') { 63
62 // TODO(johnchen@chromium.org): Support multiple audio/video 64 const timeToVideoPlay = compositorThread === undefined ? undefined :
63 // elements per page. Currently, we only support a single 65 getTimeToVideoPlay(compositorThread, playStart);
64 // audio or video element, so we can store the start time in 66 const timeToAudioPlay = audioThread === undefined ? undefined :
65 // a simple variable, and exit the loop. 67 getTimeToAudioPlay(audioThread, playStart);
66 if (playStart !== undefined) { 68
67 throw new Error( 69 if (timeToVideoPlay === undefined && timeToAudioPlay === undefined) {
68 'Loading multiple audio/video elements not yet supported'); 70 continue;
69 } 71 }
70 playStart = event.start; 72
71 break; 73 const droppedFrameCount = timeToVideoPlay === undefined ? undefined :
74 getDroppedFrameCount(compositorThread);
75 const seekTimes = timeToVideoPlay === undefined ? new Map() :
76 getSeekTimes(mainThread);
77 const bufferingTime = seekTimes.size !== 0 ? undefined :
78 getBufferingTime(mainThread, playStart, timeToVideoPlay,
79 timeToAudioPlay);
80
81 if (timeToVideoPlay !== undefined) {
82 histograms.createHistogram('time_to_video_play',
83 tr.b.Unit.byName.timeDurationInMs_smallerIsBetter,
84 timeToVideoPlay);
85 }
86 if (timeToAudioPlay !== undefined) {
87 histograms.createHistogram('time_to_audio_play',
88 tr.b.Unit.byName.timeDurationInMs_smallerIsBetter,
89 timeToAudioPlay);
90 }
91 if (droppedFrameCount !== undefined) {
92 histograms.createHistogram('dropped_frame_count',
93 tr.b.Unit.byName.count_smallerIsBetter, droppedFrameCount);
94 }
95 if (seekTimes.size !== 0) {
CalebRouleau 2017/09/26 01:26:35 You can drop this "if"
johnchen 2017/09/26 02:22:13 Done.
96 for (const [key, value] of seekTimes.entries()) {
97 histograms.createHistogram('seek_time_' + key,
98 tr.b.Unit.byName.timeDurationInMs_smallerIsBetter, value);
72 } 99 }
73 } 100 }
74 if (playStart === undefined) continue; 101 if (bufferingTime !== undefined) {
75 102 histograms.createHistogram('buffering_time',
76 // Look for video render event. 103 tr.b.Unit.byName.timeDurationInMs_smallerIsBetter, bufferingTime);
77 if (compositorThread !== undefined) {
78 for (const event of compositorThread.getDescendantEvents()) {
79 if (event.title === 'VideoRendererImpl::Render') {
80 timeToVideoPlay = event.start - playStart;
81 break;
82 }
83 }
84 } 104 }
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 } 105 }
107 } 106 }
108 107
108 function getPlayStart(mainThread) {
109 let playStart;
110 for (const event of mainThread.sliceGroup.getDescendantEvents()) {
111 if (event.title === 'WebMediaPlayerImpl::DoLoad') {
112 // TODO(johnchen@chromium.org): Support multiple audio/video
113 // elements per page. Currently, we only support a single
114 // audio or video element, so we can store the start time in
115 // a simple variable.
116 if (playStart !== undefined) {
117 throw new Error(
118 'Loading multiple audio/video elements not yet supported');
119 }
120 playStart = event.start;
121 }
122 }
123 return playStart;
124 }
125
126 function getTimeToVideoPlay(compositorThread, playStart) {
127 for (const event of compositorThread.sliceGroup.getDescendantEvents()) {
128 if (event.title === 'VideoRendererImpl::Render') {
129 return event.start - playStart;
130 }
131 }
132 return undefined;
133 }
134
135 function getTimeToAudioPlay(audioThread, playStart) {
136 for (const event of audioThread.sliceGroup.getDescendantEvents()) {
137 if (event.title === 'AudioRendererImpl::Render') {
138 return event.start - playStart;
139 }
140 }
141 return undefined;
142 }
143
144 function getSeekTimes(mainThread) {
145 // We support multiple seeks per page, as long as they seek to different
146 // target time. Thus the following two variables are maps instead of simple
147 // variables. The key of the maps is event.args.target, which is a numerical
148 // value indicating the target location of the seek, in unit of seconds.
149 // For example, with a seek to 5 seconds mark, event.args.target === 5.
150 const seekStartTimes = new Map();
151 const seekTimes = new Map();
152 for (const event of mainThread.sliceGroup.getDescendantEvents()) {
153 if (event.title === 'WebMediaPlayerImpl::DoSeek') {
154 seekStartTimes.set(event.args.target, event.start);
155 } else if (event.title === 'WebMediaPlayerImpl::OnPipelineSeeked') {
156 const startTime = seekStartTimes.get(event.args.target);
157 if (startTime !== undefined) {
158 seekTimes.set(event.args.target, event.start - startTime);
159 seekStartTimes.delete(event.args.target);
160 }
161 }
162 }
163 return seekTimes;
164 }
165
166 function getBufferingTime(mainThread, playStart, timeToVideoPlay,
167 timeToAudioPlay) {
168 let playEnd;
169 let duration;
170 for (const event of mainThread.sliceGroup.getDescendantEvents()) {
171 if (event.title === 'WebMediaPlayerImpl::OnEnded') {
172 // TODO(johnchen@chromium.org): Support multiple audio/video
173 // elements per page. Currently, we only support a single
174 // audio or video element, so we can store the end time in
175 // a simple variable.
176 if (playEnd !== undefined) {
177 throw new Error(
178 'Multiple media ended events not yet supported');
179 }
180 playEnd = event.start;
181 duration = 1000 * event.args.duration; // seconds to milliseconds
182 }
183 }
184 if (playEnd === undefined) return undefined;
185 let bufferingTime = playEnd - playStart - duration;
186 if (timeToVideoPlay !== undefined) {
187 bufferingTime -= timeToVideoPlay;
188 } else {
189 bufferingTime -= timeToAudioPlay;
190 }
191 return bufferingTime;
192 }
193
194 function getDroppedFrameCount(compositorThread) {
195 let droppedFrameCount = 0;
196 for (const event of compositorThread.sliceGroup.getDescendantEvents()) {
197 if (event.title === 'VideoFramesDropped') {
198 droppedFrameCount += event.args.count;
199 }
200 }
201 return droppedFrameCount;
202 }
203
109 tr.metrics.MetricRegistry.register(mediaMetric); 204 tr.metrics.MetricRegistry.register(mediaMetric);
110 205
111 return { 206 return {
112 mediaMetric, 207 mediaMetric,
113 }; 208 };
114 }); 209 });
115 </script> 210 </script>
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