1396689 - Playback video lags while audio works fine

Status: UNCONFIRMED

(Core :: Audio/Video: Playback, defect, P3)

Description

[Amin Shah Gilani]

Attachment: Screen Shot 2017-09-05 at 6.06.30 AM.png

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:57.0) Gecko/20100101 Firefox/57.0
Build ID: 20170904100131

Steps to reproduce:

1. Open youtube.com
2. Open a bunch of videos at the same time
3. Open a few other tabs
4. Watch the videos


Additionally:
+ Closing all other tabs and playing just a single video sometimes doesn't work
+ If I pause and wait long enough, playback resumes normally
+ I opened Youtube's "stats for nerds" and when the video was stuck, almost all frames were being dropped (509/530)
+ When the video stopped being stuck, the frame drop rate completely vanished

System:
Running this on MacOS Sierra on Firefox Nightly 57

Debug from Youtube:

{
  "ns": "yt",
  "el": "detailpage",
  "cpn": "eGPKvdgFNXvZGQoj",
  "docid": "xfG15i_uQvc",
  "ver": 2,
  "referrer": "https://www.youtube.com/watch?v=JbVs0Bvaqa0",
  "cmt": "28.085",
  "plid": "AAVYZsw8I9Lsv0hy",
  "ei": "6_etWefqLZPqowO2oY7QBQ",
  "fmt": "137",
  "fs": "0",
  "rt": "255.067",
  "of": "utUuQmA0qeiQ4uAOMG7UIg",
  "euri": "",
  "lact": 2,
  "cl": "167319338",
  "mos": 0,
  "state": "4",
  "vm": "CAEQARgE",
  "volume": 100,
  "c": "WEB",
  "cver": "2.20170830",
  "cplayer": "UNIPLAYER",
  "cbr": "Firefox",
  "cbrver": "57.0",
  "cos": "Macintosh",
  "cosver": "10.12",
  "hl": "en_US",
  "cr": "PK",
  "len": "352.321",
  "fexp": "23700092,23700611,23701004,23701895,9406009,9422596,9431754,9441388,9449243,9453650,9456188,9459678,9460072,9461314,9463154,9463830,9467502,9471239,9475650,9476327,9478523,9479708,9480475,9481687,9483010,9488038,9489280,9489592,9489607,9489706,9489822",
  "feature": "watch-vrec",
  "afmt": "251",
  "vct": "28.085",
  "vd": "352.321",
  "vpl": "0.000-28.085,",
  "vbu": "0.000-68.335,",
  "vpa": true,
  "vsk": false,
  "ven": false,
  "vpr": 1,
  "vrs": 4,
  "vns": 2,
  "vec": null,
  "vvol": 1,
  "creationTime": 255670.14,
  "totalVideoFrames": 844,
  "droppedVideoFrames": 9,
  "corruptedVideoFrames": 0,
  "lct": "28.085",
  "lsk": false,
  "lmf": false,
  "lbw": "2212403.243",
  "lhd": "0.211",
  "lst": "570.020",
  "laa": "itag=251,seg=6,range=945140-1097669,time=60.0-70.0,off=0,len=152530,end=1",
  "lva": "itag=137,seg=12,range=14928930-16172540,time=63.0-68.3,off=0,len=1243611,end=1",
  "lar": "itag=251,seg=9,range=1416483-1572180,time=90.0-100.0,off=0,len=155698,end=1",
  "lvr": "itag=137,seg=14,range=17324194-18269692,time=73.7-77.0,off=0,len=945499",
  "lvh": "r1---sn-jtcxg-aixe",
  "lab": "0.000-70.001,",
  "lvb": "0.000-68.335,",
  "ismb": 9980000,
  "relative_loudness": "-1.589",
  "optimal_format": "1080p",
  "user_qual": "auto",
  "debug_videoId": "xfG15i_uQvc",
  "0sz": false,
  "op": "1",
  "yof": false,
  "dis": "",
  "gpu": "Intel_Iris_Pro_OpenGL_Engine",
  "cgr": true,
  "debug_playbackQuality": "hd1080",
  "debug_date": "Tue Sep 05 2017 06:08:01 GMT+0500 (PKT)"
}


Actual results:

5. Video would start dropping frames, while the audio works perfectly


Expected results:

6. Videos should have played smoothly

Comment 1

[Amin Shah Gilani]

Okay, more things happened:

1. After filing this issue, I closed a few videos and began playback
2. There are no new frames being dropped according to the youtube stats
3. Video is still very choppy. Not unwatchable, but far choppier than on Chrome
4. I decided to record this behavior
5. While making the recording the behavior became extremely bad again and I started dropping frames agaon

Note:
+ The video did not capture audio but it was working perfectly
+ I move the mouse around to show that it's just the video getting stuck and not firefox
+ The extreme lag started during screen recording so the load wasn't on firefox at that point, but on the CPU
+ Chrome performs remarkably though, without video lag, even during extreme tasks

You can view the video here: https://youtu.be/cl72jlTx8X4

Comment 2

[Anthony Jones (:ajones, :kentuckyfriedtakahe, :k17e)]

Does full screen work better than windowed?

Comment 3

[Jed]

I seem to be having the same or similar issues on Firefox 58, YouTube video playback stuttering or just generally not working at all whilst the audio plays just fine. I've tested in Microsoft Edge and Google Chrome and it plays perfectly in them.

Comment 4

[Blake Wu [:bwu][:blakewu]]

(In reply to Jed from comment #3)
> I seem to be having the same or similar issues on Firefox 58, YouTube video
> playback stuttering or just generally not working at all whilst the audio
> plays just fine. I've tested in Microsoft Edge and Google Chrome and it
> plays perfectly in them.
Thanks for this information. 
Can you provide us the following information? That would be helpful for us to debug. 

1. Go to your URL bar, enter about:support, and paste its result here. 
2. Right click on the video, select the "stats for nerds", paste the result here.

Comment 5

[Jed]

Pastebin of about:support - https://pastebin.mozilla.org/9071838

Screenshot of Stats for Nerds: https://i.imgur.com/MSGzLm9.png

Also full-screening the video had no effect.

Comment 6

[Blake Wu [:bwu][:blakewu]]

(In reply to Jed from comment #5)
> Pastebin of about:support - https://pastebin.mozilla.org/9071838
> 
> Screenshot of Stats for Nerds: https://i.imgur.com/MSGzLm9.png
> 
> Also full-screening the video had no effect.
Thanks for your prompt feedback!

Comment 7

[Amin Shah Gilani]

Hello Guys

I'm sorry for disappearing. I seemed to have missed these emails before. Is there any other information you need from me? This is the only issue keeping me from switching to Firefox, and man do I want to :D

Comment 8

[Paul Eades]

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Comment 9

[jhone]

Poor internet connection or network congestion can cause video buffering and lag. Make sure you have a stable and high-speed internet connection https://realgrouplinks.com/tag/Funny-Groups/. You can test your internet speed using online tools or apps.