1710815 - VAAPI: Video playback jumps with black bar when started

Status: RESOLVED INCOMPLETE

(Core :: Graphics: WebRender, defect)

Description

[klk745]

Attachment: Peek 2021-05-12 12-15.mp4

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:88.0) Gecko/20100101 Firefox/88.0

Steps to reproduce:

I'm using FF 88.0.1+linuxmint1+ulyssa.

1. Open https://twitter.com/catsdotexe/status/1392172811469328390
2. Play the video

The bug might be related to the fact that I have set MOZ_X11_EGL=1 in /etc/environment.

Actual results:

Before starting the video a black bar is displayed at the bottom and the video itself seems to be squeezed by that amount.
When hitting the play button, the black bar goes away and the video pops to it's original size.
This repeats, which is especially annoying when you have short clips on auto-repeat.

I included a short MP4 screencap of the bug.

Expected results:

Smooth playback without a black bar that pops up/disappears.

Comment 1

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

The Bugbug bot thinks this bug should belong to the 'Core::Audio/Video: Playback' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.

Comment 2

[klk745]

This seems to affect any embedded MP4 playback - my above screencap file above shows the same behavior.

Some additional information:
WebGL Renderer: X.Org -- AMD RENOIR (DRM 3.38.0, 5.8.0-53-generic, LLVM 11.0.0)
WebGL Driver Version: 4.6 (Compatibility Profile) Mesa 20.2.6
HW_COMPOSITING available by default
OPENGL_COMPOSITING available by default
Blockiert; Fehlercode BLOCKLIST_FEATURE_FAILURE_SOFTWARE_GL
WEBRENDER available by default
force_enabled by user: Force enabled by pref
WEBRENDER_QUALIFIED available by default
WEBRENDER_COMPOSITOR disabled by default: Disabled by default
WEBRENDER_PARTIAL available by default
WEBRENDER_OPTIMIZED_SHADERS available by default
WEBRENDER_ANGLE available by default unavailable by env: OS not supported
WEBRENDER_DCOMP_PRESENT available by default
disabled by user: User disabled via pref
unavailable by env: Requires Windows 10 or later
unavailable by runtime: Requires ANGLE
WEBRENDER_SOFTWARE available by default
OMTP disabled by default: Disabled by default broken by runtime: OMTP is not supported when using cairo
WEBGPU disabled by default: Disabled by default blocked by runtime: WebGPU can only be enabled in nightly
X11_EGL available by default
force_enabled by user: Force enabled by envvar
blocklisted by env: Blocklisted by gfxInfo
DMABUF available by default

Comment 3

[Sotaro Ikeda [:sotaro]]

(In reply to klk745 from comment #2)

X11_EGL available by default
force_enabled by user: Force enabled by envvar
blocklisted by env: Blocklisted by gfxInfo
DMABUF available by default

I wonder if the problem might be related to DMABUF.

Comment 4

[klk745]

(In reply to Sotaro Ikeda [:sotaro] from comment #3)

I wonder if the problem might be related to DMABUF.

I set media.ffmpeg.dmabuf-textures.disabled to true and restarted FF -> problem persists.
I then reverted this to false and set widget.dmabuf-webgl.enabled to false -> no difference after FF restart.

Comment 5

[Robert Mader [:rmader]]

klk745: do you have media.ffmpeg.vaapi.enabled enabled?

Comment 6

[klk745]

@rmader Yes, and setting it to false fixes the problem.

Comment 7

[Darkspirit]

Is this bug still present?

Comment 8

[Martin Stránský [:stransky] (ni? me)]

No info, closing.

Comment 9

[klk745]

It seems to be fixed.
Bug doesn't occur anymore for me in FF 96.0.3 with media.ffmpeg.vaapi.enabled = true and MOZ_X11_EGL=1 in /etc/environment.