We should add telemetry to report the proportion of frames that are dropped during playback of video. Then we can observe this fluctuating over time to figure out if we're improving performance. I suggest that we do this in the same place that we report the MSE telemetry. We already have the playback quality statistics returned by HTMLVideoElement::GetVideoPlaybackQuality(), it's just a matter of determining whether our media element is playing a video, and if so getting a video element pointer and calling its GetVideoPlaybackQuality function and reporting the results. You can convert from an HTMLMediaElement to an HTMLVideoElement by calling HTMLVideoElement::FromContentOrNull(this) from inside an HTMLMediaElement function I believe, for example (but not from inside HTMLMediaElement): http://mxr.mozilla.org/mozilla-central/source/layout/base/nsLayoutUtils.cpp#7192
Comment on attachment 8718198 [details] [diff] [review] bug-1238433-fix.patch Review of attachment 8718198 [details] [diff] [review]: ----------------------------------------------------------------- I think this is a good start. We'll want more precise telemetry which reports frame drops for different resolutions and formats and values of hardware accelerated video decoding. But this is a good aggregate to start. ::: toolkit/components/telemetry/Histograms.json @@ +10167,5 @@ > + "alert_emails": ["firstname.lastname@example.org", "email@example.com"], > + "expires_in_version": "55", > + "kind": "linear", > + "high": "100", > + "n_buckets": 20, I think you need "n_buckets": "101", as we want higher precision than just 5% increments, and in order to record both values 0 and 100% you need to include the range [0,1...100], i.e. 101 values.
Attachment #8718198 - Flags: review?(cpearce) → review+
Amended with cpearce's comments
Comment on attachment 8718512 [details] [diff] [review] bug-1238433-fix.patch Seems pretty straightforward. You'll probably want correlates in another iteration (video size/frame rate in particular), but good to start with the simple thing.
Attachment #8718512 - Flags: feedback?(benjamin) → feedback+
backed out for bustage like https://treeherder.mozilla.org/logviewer.html#?job_id=21908898&repo=mozilla-inbound
Whoops, didn't upload the version in the last try push.
Will follow up with more detailed telemetry in bug 1249706
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