What does "drops lots of frames" mean? Is it visual perception, chrome://media-internals counters or what? How exactly to reproduce?

it repro all the time. on my tested device, Mac dropped most frame (about 20 frames after switch to background 10s then switch back to foreground)
The playback quality is still good enough, no obvious glittering.

20 frames is 1/3 a second on a 60fps clip, so not bad for recovery time actually I think.

Is this with disable background video enabled?

It NOT repro when disable background video optimization. it dropped much more frames on vp9 (around 6% of total decoded frames) and around 20 frames on mp4 video. But I have to say the general video playback smoothness is not obviously affected. There is no glittering or stutter observed. I agree this bug is not blocking bug.

Yining, could you please clarify how do you check the number of dropped frames? I'm fairly new to working with the video QA so literally have no clue.

Are you looking at chrome://media-internals for the player? Are you using chrome logs or any other tools?

Dale, dropping frames while recovering the decoder is probably expected, right? So unless it visually affects the user experience, it's ok.

Sounds like we should watch the number of dropped frames during our experiments to note regressions (is there a histogram already?).

Yeah I'd expect some number of dropped frames here. Audio has been playing but video has been stopped, so some number will be dropped even after video playback resumes (since it'll start slightly behind wherever audio ends up at).

Anton, on Android, the only way to check dropped frame is using DevToolBar, on desktop device, it is easy to right click YouTube video, Stats for nerds

I agree c#9. 

-dahlke@ because I believe johnpallett@ is PM'ing this feature.

The dropped frames seem to be expected. Though, yiningc@, would you mind clarifying what do you mean by 6% of total decoded frames are dropped?

answer mlamouri@ question in c#11, when play vp9 60fps video, when switch back and forward in between background and foreground tabs, the dropped frame is about 6% of total decoded frame. see attached screenshot.
But as said before, the playback is not stutter or glitter though there are some dropped frame. 

Deleted: Screen Shot 2017-01-23 at 1.31.14 PM.png 81.6 KB

	Screen Shot 2017-01-23 at 1.31.14 PM.png 81.6 KB View Download

optimize video in background is enabled on M62. This bug still repro but the dropped frames reduced a lot on VP9 60fps video. Still has a high dropped frame when switch background video to foreground, roughly the dropped frame is 
20frame/second * seconds video stay in background  

Dale, can you justify this dropped rate is acceptable?

I believe it is but I'll let Dale confirm.

Since we have a 10s timeout now this is much better and avoid long chains of dropped frames; any remaining ones are expected.