Cristian Baica [:cbaica], Release Desktop QA Reporter
	Description • 6 years ago

[Affected versions]:
- Fx 61.0 RC
- Fx 62.0a1
- Fx 60.0.2 ESR

[Affected platforms]:
- Windows 10 x64
- Windows 7 x64
- macOS 10.13

[Steps to reproduce]:
1. Launch Firefox.
2. Go to https://www.bbc.com/news/video_and_audio/headlines
3. Once the video starts playing click its thumbnail from the headline section again.
4. Repeat step 3 until a video add is received 5 or 6 times.
(Optional: Other video thumbnails could be clicked, but make sure the video add is received)

[Expected result]:
- Only the video add should play every time it is received.

[Actual result]:
- Both videos are playing (the add video and the article video) at the same time.

[Regression range]:
- I will investigate the regression range as soon as possible.

[Additional notes]:
- The bug doesn't have a 100% repro rate.
- I could not reproduce this using chrome.
- I was not able to reproduce the issue on Ubuntu 14.04 LTS
- After the video add finishes playing over the video article, the play/pause button of the video article becomes unresponsive (the video only pauses when clicking on the seekbar)

	Cristian Baica [:cbaica], Release Desktop QA Reporter
	Comment 1 • 6 years ago

Using mozregression I have managed to trace the bug back to:
https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=7e496e6bac00d2acbf3dcd5615c13d4ac489724e&tochange=a599289ac64ba1d52a1552e33150342746e3e61b

Please note that the bug is easier to reproduce on the latest versions of Firefox.

	Andreas Pehrson [:pehrsons]
	Comment 2 • 6 years ago

(In reply to Cristian Baica [:cbaica], Release Desktop QA from comment #1)
> Using mozregression I have managed to trace the bug back to:
> https://hg.mozilla.org/mozilla-central/
> pushloghtml?fromchange=7e496e6bac00d2acbf3dcd5615c13d4ac489724e&tochange=a599
> 289ac64ba1d52a1552e33150342746e3e61b
> 
> Please note that the bug is easier to reproduce on the latest versions of
> Firefox.

I'll have to question the accuracy here I'm afraid. The only commit I see that is related to media is [1] which is for WebAudio. However, the bbc page doesn't use any WebAudio AudioContexts according to devtools. Oh, and it was also backed out in the same push.

I also find it hard from the video to tell what the issue is. Perhaps because I can't tell when the clicks happen?

I think we need to debug this far enough to determine whether it's Firefox or the application that is at fault. I don't see evidence suggesting it's the former yet. Then we can dig in further.


[1] https://hg.mozilla.org/mozilla-central/rev/cd615bff6069

	Cristian Baica [:cbaica], Release Desktop QA Reporter
	Comment 3 • 6 years ago

(In reply to Andreas Pehrson [:pehrsons] from comment #2)

> I also find it hard from the video to tell what the issue is. Perhaps
> because I can't tell when the clicks happen?

It is pretty difficult to record the mouse click operations on windows. Best I can do right now is to tell you that every time a BBC video loads means 1 mouse-click on a video.

In order to 'see' the issue, you'd have to also use headphones. Visually nothing appears to be wrong (the add plays perfectly normal), but both audio tracks are playing at the same time, along with the video. If the ad is paused, the article video keeps playing in the background.

Indeed, the regression may not be very accurate because of the difficulty to reproduce the bug on older versions of Fx.

	Bryce Seager van Dyk [:bryce] (he/him) - Not reading bugmail
	Comment 4 • 6 years ago

My 2 cents: I was only able to reproduce the issue on Firefox when I triaged this. Hard to be sure, given that it's intermittent, but across 20+ runs of switching between the first 2 videos on the BBC page I hit at least a couple of repros in FF, but none in other browsers (Windows 10).

	Andreas Pehrson [:pehrsons]
	Comment 5 • 6 years ago

Should repro with some logs over what API calls are made, then at least we have something to inspect.

(In reply to Cristian Baica [:cbaica], Release Desktop QA from comment #3)
> In order to 'see' the issue, you'd have to also use headphones. Visually
> nothing appears to be wrong (the add plays perfectly normal), but both audio
> tracks are playing at the same time, along with the video. If the ad is
> paused, the article video keeps playing in the background.

Yes, thanks. Headphones helped :-)

	Andreas Pehrson [:pehrsons]
	Comment 6 • 6 years ago

nsMediaElement:5 logs of failure case

I have filtered the interesting bits (load, play, pause) out of this log, from the last load of the main video element before the ad (the one that played in parallel), to after the end of the ad.

This involved me pressing pause and play on the player (pausing and playing the ad) three times.

I end up with:
> 2018-06-25 16:53:50.063724 UTC - [931:Main Thread]: D/nsMediaElement 0x12981a000 Load() hasSrcAttrStream=0 hasSrcAttr=0 hasSourceChildren=0 handlingInput=0 hasAutoplayAttr=0 IsAllowedToPlay=1 ownerDoc=0x129dd0000 (https://emp.bbc.com) ownerDocUserActivated=0 muted=0 volume=0.700000
> 2018-06-25 16:53:50.281815 UTC - [931:Main Thread]: D/nsMediaElement 0x12981a000 Trying load from src=blob:https://emp.bbc.com/5e93b539-a544-3042-86da-3d1b38c9429b
> 2018-06-25 16:53:50.315046 UTC - [931:Main Thread]: D/nsMediaElement 0x12981a000 Play() called by JS readyState=0
> 2018-06-25 16:53:50.469054 UTC - [931:Main Thread]: D/nsMediaElement 0x12981a000 Pause() called by JS
> 2018-06-25 16:53:50.549300 UTC - [931:Main Thread]: D/nsMediaElement 0x12981a000 Play() called by JS readyState=4
> 2018-06-25 16:53:51.140221 UTC - [931:Main Thread]: D/nsMediaElement 0x13685b800 Load() hasSrcAttrStream=0 hasSrcAttr=1 hasSourceChildren=0 handlingInput=0 hasAutoplayAttr=0 IsAllowedToPlay=1 ownerDoc=0x12ace6800 (https://imasdk.googleapis.com) ownerDocUserActivated=0 muted=0 volume=1.000000
> 2018-06-25 16:53:51.166386 UTC - [931:Main Thread]: D/nsMediaElement 0x13685b800 Trying load from src=https://adassets.bbc.com/tvc/20180619%20Hisense%20VOD%20Pre-roll%2015s%20V2%20J.mp4
> 2018-06-25 16:53:51.281842 UTC - [931:Main Thread]: D/nsMediaElement 0x13685b800 Play() called by JS readyState=1
> 2018-06-25 16:53:58.019479 UTC - [931:Main Thread]: D/nsMediaElement 0x13685b800 Pause() called by JS
> 2018-06-25 16:53:58.927788 UTC - [931:Main Thread]: D/nsMediaElement 0x13685b800 Play() called by JS readyState=4
> 2018-06-25 16:53:59.576298 UTC - [931:Main Thread]: D/nsMediaElement 0x13685b800 Pause() called by JS
> 2018-06-25 16:54:00.223612 UTC - [931:Main Thread]: D/nsMediaElement 0x13685b800 Play() called by JS readyState=4
> 2018-06-25 16:54:00.800974 UTC - [931:Main Thread]: D/nsMediaElement 0x13685b800 Pause() called by JS
> 2018-06-25 16:54:01.419206 UTC - [931:Main Thread]: D/nsMediaElement 0x13685b800 Play() called by JS readyState=4
> 2018-06-25 16:54:08.571312 UTC - [931:Main Thread]: D/nsMediaElement 0x13685b800 Pause() called by JS
> 2018-06-25 16:54:08.605797 UTC - [931:Main Thread]: D/nsMediaElement 0x13685b800 Load() hasSrcAttrStream=0 hasSrcAttr=1 hasSourceChildren=0 handlingInput=0 hasAutoplayAttr=0 IsAllowedToPlay=1 ownerDoc=0x12ace6800 (https://imasdk.googleapis.com) ownerDocUserActivated=0 muted=0 volume=0.700000
> 2018-06-25 16:54:08.606274 UTC - [931:Main Thread]: D/nsMediaElement 0x13685b800 Trying load from src=
> 2018-06-25 16:54:08.657249 UTC - [931:Main Thread]: D/nsMediaElement 0x12981a000 Play() called by JS readyState=4


Note that 0x12981a000 is the main media element, and 0x13685b800 is the ad media element.

There's no attempt at pausing the main media element before loading and starting the ad media element. There are also no attempts at muting or setting the volume to 0 throughout the log.

	Andreas Pehrson [:pehrsons]
	Comment 7 • 6 years ago

Moving to tech evangelism for outreach to BBC.

	Sergiu Logigan [:sergiu]
	Comment 8 • 6 years ago

Hey, Adam!
Could we contact BBC about this issue?

	Mike Taylor [:miketaylr]
	Comment 9 • 6 years ago

(see Comment #6 for explanation)

	Adam Stevenson [:adamopenweb]
	Comment 10 • 6 years ago

Reaching out via our partner mailing list.