1646959 - Webm video is black (no picture)

Status: RESOLVED WORKSFORME

(Core :: Graphics, defect)

Description

[[:estemal]]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Firefox/68.0

Steps to reproduce:

Play this video https://gitlab.gnome.org/GNOME/gtk/uploads/acf519cdd3a35191704bcc7a87e3a11a/Screencast_28.05.2020_01_25_18.webm or play it on the page https://gitlab.gnome.org/GNOME/gtk/-/issues/2794

Actual results:

Black area where video should play. If I play it on the page, it is white instead.

Expected results:

Video picture visible.

Comment 1

[[:estemal]]

My mistake, I use Firefox version 77, not 68. Cannot edit bug now.

Comment 2

[BugBot [:suhaib / :marco/ :calixte]]

Bugbug thinks this bug should belong to this component, but please revert this change in case of error.

Comment 3

[:Gijs (he/him)]

Works for me on macOS, with Firefox 78 beta.

Can you reproduce in a clean Firefox profile ( https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles ) ?

Comment 4

[[:estemal]]

I reproduced this on clean profile. The only thing that changed is now that part of window where the video plays was completely tranpsrent - I could see my background image.

BTW, I use linux, sway (wayland).

Comment 5

[Bryce Seager van Dyk [:bryce] (he/him) - Not reading bugmail]

S3 on the assumption this is related to VA-API.

Comment 6

[[:estemal]]

this is related to VA-API.

this is not. I tried disabling widget.wayland-dmabuf-vaapi.enabled - it didn't matter

Comment 7

[Bryce Seager van Dyk [:bryce] (he/him) - Not reading bugmail]

• Could you navigate to about:support and copy that information onto this bug?
• Do you experience issues with any other videos in Fx, or is the problem specific to the video in comment 0?

Comment 8

[[:estemal]]

Attachment: about:support

Comment 9

[[:estemal]]

Do you experience issues with any other videos in Fx, or is the problem specific to the video in comment 0?

The problem is just with the video in comment #0

Comment 10

[Bryce Seager van Dyk [:bryce] (he/him) - Not reading bugmail]

I've poked at the video from comment 0 a bit and don't see anything odd with it. I wondered if this was a bug related to the alpha channel in WebM, but the file doesn't appear to have any alpha channel data. So far I'm unable to reproduce this.

Comment 4 mentions the area being transparent when using a clean profile. Is the area transparent for both the gitlab and the directly linked video?

Can you try using the Firefox Profiler with Firefox Nightly and record a profile of this taking place using the 'Media' preset then share that profile and paste the link here?

Comment 11

[[:estemal]]

Comment 4 mentions the area being transparent when using a clean profile. Is the area transparent for both the gitlab and the directly linked video?

Yes, it's transparent in both cases.

Comment 12

[[:estemal]]

What I found out:

1. The bug is reproduced only with hardware compositing enabled. In the Nightly, which I installed from the mozilla website hardware compositing was disabled and the video played normally. I enabled layers.acceleration.force-enabled in Nightly and reproduced the transparent video.
2. In my OS Firefox is built with layers.acceleration.force-enabled enabled by default, that's why I had hardware compositing enabled even in the clean profile.

Do I still need to record the profile?

Comment 13

[Bryce Seager van Dyk [:bryce] (he/him) - Not reading bugmail]

(In reply to sorrow from comment #12)
<snip>

Do I still need to record the profile?

No, the information you provided is helpful in indicating this is a compositing issue. I'll change the component as the folks familiar with compositing should be better suited to debug further.

Comment 14

[Andrew Osmond [:aosmond] (he/him)]

I installed sway, forced wayland, and OpenGL compositing on for Firefox, to match your about:support configuration. Works for me. Same with WebRender. Maybe darkspirit will have more luck reproducing.

Comment 15

[[:estemal]]

With webrender it works for me too. But with opengl the video is transparent (not as css opacity, but wayland compositor level transparency, I can see what's behind the Fx window). Even with latest sway 1.5-rc1.

Comment 16

[Andrew Osmond [:aosmond] (he/him)]

The only time I have seen similar symptoms is when a surface was incorrectly marked as opaque, and contained transparency. It ended up showing what was underneath like you noted. I wonder if that could be related.