2034130 - Video frames dropped on HLS mkv HEVC video after Alt + Tab away for some time

Status: UNCONFIRMED

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

Description

[[:anutrix]]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:150.0) Gecko/20100101 Firefox/150.0

Steps to reproduce:

1. Open Firefox 150 on Windows 11.
2. Play a mkv HEVC Main 10 video via HLS.
3. Let video play for 30 seconds or more. Notice no frame drop. Then Alt+Tab to other maximized windows.
4. Wait for 30 seconds. Alt+Tab back to video window(it's taskbar tab in my case).

Some more video details:

Stream type - HLS
Player dimensions - 2560x1003
Video resolution - 1920x1080
Video codec - HEVC (direct)
Audio codec - AAC
Container - mkv
Size - 278.3 MiB
Bitrate - 2.0 Mbps
Video codec - HEVC Main 10
Video bitrate - 1.7 Mbps
Video range type  - SDR
Audio codec - EAC3
Audio bitrate - 224 kbps
Audio channels - 2
Audio sample rate - 48000 Hz

Actual results:

AFTER Alt + Tabbing back, lag is seen due to dropped frames almost continuously. No way to fix except page refresh.
Issue is NOT seen if never Alt + Tab.
Issue is NOT seen on Edge browser with same steps.

Expected results:

No lag or dropped frames simply due to Alt + Tab.
It does not look like bandwidth or performance issue since the issue is not seen on MS Edge and also not seen if video is never Alt-Tabed out.

Comment 1

[[:anutrix]]

I meant there's no server performance issue in the description not browser performance.
There's no transcoding in done in both Firefox and MS Edge cases.

Comment 2

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

The Bugbug bot thinks this bug should belong to the 'Core::Widget: Win32' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 3

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

The Bugbug bot thinks this bug should belong to the 'Core::Widget: Win32' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 4

[Karl Tomlinson (:karlt)]

Would you be able to capture and upload a profile with media logging, please?
See bug 1935757 comment 2 for instructions on that.

Do you have a URL to a publicly available site that reproduces the problem?

Comment 5

[[:anutrix]]

(In reply to Karl Tomlinson (:karlt) from comment #4)

Do you have a URL to a publicly available site that reproduces the problem?

I couldn't find one with same conditions: mkv, HLS, HEVC Main 10.

Would you be able to capture and upload a profile with media logging, please?
See bug 1935757 comment 2 for instructions on that.

Ok.
https://share.firefox.dev/3OwNs5D
Issue is seen in last 45-60 seconds at least.

Comment 6

[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 7

[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.