1418999 - Youtube videos may freeze when tab has no focus with WebRender

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, defect, P1)

Description

[Lorenzo Ferrillo]

I'm on ArchLinux 64bit, kernel linux-covolunablu-gaming, and Firefox 59 Nightly
I have  webrender active with the following options from about:config:
turn on gfx.webrender.enabled
turn on gfx.webrender.blob-images
turn on layers.acceleration.force-enabled

Reproduction:
Open a tab with youtube playing  a video.
Open other tabs and navigate.
After a while (it may take also some minutes to trigger this issue, and I was not able to find a specific timing) switch back to the youtube tab.
(In some cases I was only able to repro this when letting youtube change video off-focus).

I'm using this playlist  if it can interest: https://www.youtube.com/watch?v=YNvdphVMEJU&index=166&list=PL_jlNRrayn_e_8mXk_evSxp2ogPnUi2Eg

Expected behaviour:
Video still play normally, when switching to youtube tab.

Actual behaviour:
The video is frozen, but the audio is still playing well.
If the autoplay is active and youtube change video when without focus, when switching back to the youtube tab show the same blocked frame over.
If the video change when I have focus on the youtube tab, it return to normality.

Comment 1

[Milan Sreckovic [:milan] (needinfo for best results)]

Can we reproduce this on other platforms?

Comment 2

[Lorenzo Ferrillo]

I asked to a friend that use nightly too and doesn't seem to happen on windows

Comment 3

[Vincent Liu[:vliu]]

The issue I saw on my today's mac build is:

1. Played the recommended link below and make sure video/audio worked normally.

   https://www.youtube.com/watch?v=YNvdphVMEJU&index=166&list=PL_jlNRrayn_e_8mXk_evSxp2ogPnUi2Eg

2. Switched to other tab to surf internet.
3. When audio started playing next song, switched back to youtube tab to observe.

The video got frozen, but the audio is still playing well. Switched to full screen could make the frozen video back to normal. If I set gfx.webrender.enabled to false, the issue disappeared.

Comment 4

[Vincent Liu[:vliu]]

After talked to Sotaro on irc, I would take this bug to work into it.

Comment 5

[Vincent Liu[:vliu]]

(In reply to Vincent Liu[:vliu] from comment #3)
> The issue I saw on my today's mac build is:
> 
> 1. Played the recommended link below and make sure video/audio worked
> normally.
> 
>   
> https://www.youtube.com/
> watch?v=YNvdphVMEJU&index=166&list=PL_jlNRrayn_e_8mXk_evSxp2ogPnUi2Eg
> 
> 2. Switched to other tab to surf internet.
> 3. When audio started playing next song, switched back to youtube tab to
> observe.
> 
> The video got frozen, but the audio is still playing well. Switched to full
> screen could make the frozen video back to normal. If I set
> gfx.webrender.enabled to false, the issue disappeared.

The above issue happens between two video files played in youtube. When the first song started to play, [1] was called to create AsyncImage WR Command associating with a ImageContainer to add a pipeline. In MediaDecoder thread, [2] was called to update video data.
The thing is, 

a. About 5~8 seconds after the first song started, there was another AsyncImage WR Command was created building another pipeline with the same ImageContainer. I am not sure what it is purpose for. Guess there was another video/image other than the youtube file we cared.
b. When the second song started to play under no focus, I didn't see [1] was called to build up pipeline for the second song. In MediaDecoder thread, [2] was keep running with a new ImageContainer instead of the first song used.

From above, It might have issue in Framebuilder phase. I will keep investigating from the current info I found.

[1]: https://searchfox.org/mozilla-central/rev/f42618c99dcb522fb674221acfbc68c2d92e7936/gfx/layers/wr/WebRenderUserData.cpp#176
[2]: https://searchfox.org/mozilla-central/rev/f42618c99dcb522fb674221acfbc68c2d92e7936/gfx/layers/ImageContainer.cpp#326

Comment 6

[Vincent Liu[:vliu]]

(In reply to Vincent Liu[:vliu] from comment #5)

> From above, It might have issue in Framebuilder phase. I will keep
> investigating from the current info I found.
> 

It should be CommandBuilder phase in EndTransaction.

Comment 7

[Jerry Shih[:jerry] (UTC+8) (inactive)]

Attachment: update mPipelineId for different image container.

MozReview-Commit-ID: CNZIkPVDtdc

Comment 8

[Jerry Shih[:jerry] (UTC+8) (inactive)]

Comment on attachment 8940968 [details] [diff] [review]
update mPipelineId for different image container.

Review of attachment 8940968 [details] [diff] [review]:
-----------------------------------------------------------------

::: gfx/layers/wr/WebRenderUserData.cpp
@@ +185,5 @@
>                                                        bool aIsBackfaceVisible)
>  {
>    MOZ_ASSERT(aContainer->IsAsync());
> +
> +  if (!mPipelineId || mContainer != aContainer) {

When we move to next video(we change to the next image container), we might still try to use the original pipeline. Then, the original pipeline is still associated to the old image container.

Comment 9

[Vincent Liu[:vliu]]

Attachment: 0001-Bug-1418999-Update-PipelineId-to-associate-the-lates.patch

Hi Sotaro,

I think Jerry pointed out the root cause based on Comment 5. Thanks for his great help. I would change a little bit for the patch to make it clear. Could you please have a review for the patch? Really thanks.

Comment 10

[Sotaro Ikeda [:sotaro]]

Comment on attachment 8941305 [details] [diff] [review]
0001-Bug-1418999-Update-PipelineId-to-associate-the-lates.patch

Looks good!

Comment 11

[Vincent Liu[:vliu]]

try result: https://treeherder.mozilla.org/#/jobs?repo=try&revision=792185a4e16e4f9c2f327e8a45c3367ea9db0249

Comment 12

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/a4e1e729857b
Update PipelineId to associate the latest ImageContainer. r=sotaro

Comment 13

[Andrei Ciure[:aciure]]

https://hg.mozilla.org/mozilla-central/rev/a4e1e729857b