1670334 - Black border around window captured with Screen Capture API

Status: NEW

(Core :: WebRTC: Audio/Video, defect, P3)

Description

[xxluke]

Attachment: Screenshot of non-maximized window in Firefox Nightly

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:81.0) Gecko/20100101 Firefox/81.0

Steps to reproduce:

Use the Screen Capture API and choose to capture a window.

Demo website: https://mdn.mozillademos.org/en-US/docs/Web/API/Screen_Capture_API/Using_Screen_Capture$samples/Simple_screen_capture?revision=1626398

I'm on Windows 10 1909, have two 1920x1080px monitors and tested it on Firefox 81 and Nightly.

Actual results:

Maximized, not full-screen windows, have a black border on the top (8px), left (8px) and bottom (4px) in the resulting video stream.
Not-maximized windows have a 7px wide black border on the left, right and bottom.

+------------+-------------------------------+-------------+------------+-----------------------------------------------------+
| Browser | Window type | Actual size | Video size | Comment |
+------------+-------------------------------+-------------+------------+-----------------------------------------------------+
| Firefox 81 | Monitor or Full Screen window | 1920x1080 | 1920x1080 | Correct |
+------------+-------------------------------+-------------+------------+-----------------------------------------------------+
| Firefox 81 | Maximized | 1920x1040 | 1928x1052 | Black border on top (8px), left (8px), bottom (4px) |
+------------+-------------------------------+-------------+------------+-----------------------------------------------------+
| Firefox 81 | Non-maximized | 1000x700 | 1014x707 | 7px black border on left, right, bottom |
+------------+-------------------------------+-------------+------------+-----------------------------------------------------+

Expected results:

No black borders; Video has same size as the window.

Comment 1

[Marcela (Please NI request to Brindusa Tot)]

I was able to reproduce it on latest Nightly version 83.0a1, Beta version 82.ob9, and Firefox Release. I'll change flags accordingly.

Comment 2

[Marcela (Please NI request to Brindusa Tot)]

The suggested severity is S3

Comment 3

[Timothy Nikkel (:tnikkel)]

I think this falls under webrtc.