1898567 - Video and audio synced perfectly initially, but become VERY slightly desynced for the rest of the video unless paused again

Status: UNCONFIRMED

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

Description

[Chobits1717]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:126.0) Gecko/20100101 Firefox/126.0

Steps to reproduce:

Play a video (Youtube works best, though any video sharing site seems to work), most noticeable in videos with dialogue/moving character mouths. Video stays normally synced for 5-10 seconds, then some micro delay happens (but doesn't accumulate), which continues until the video is paused again. Unpausing produces the same 5-10 seconds of normality before the slight desync.

Happens on two ASUS laptops:
One on an Intel Iris XE iGPU, one running through an AMD iGPU
Both on Windows 11
Both on the current version of Firefox.

Actual results:

It doesn't accumulate into something super noticeable, but it is jarring nonetheless.

Expected results:

Audio should stay synced the whole time without issue

Comment 1

[Jim Mathies [:jimm]]

Could you help us out by trying to capture a Firefox performance profile when this happens? Visit https://profiler.firefox.com/ for more information and to enable the profiling toolbar button. When capturing, please select the Media profile in the button drop down, upload the resulting profile and post the url here.

Comment 2

[Chobits1717]

https://share.firefox.dev/3R6q7FO

Comment 3

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

The severity field is not set for this bug.
:jimm, could you have a look please?

For more information, please visit BugBot documentation.

Comment 4

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

The severity field is not set for this bug.
:jimm, could you have a look please?

For more information, please visit BugBot documentation.

Comment 5

[Chobits1717]

Any updates on this?

Comment 6

[Alastor Wu [:alwu]]

Would you mind to capture a profile on the latest Nightly (follow this instruction)? We've added more markers which might help us understand this issue better. Thanks!