1717868 - Tab captures via media.getusermedia.browser.enabled have low frame rate

Status: UNCONFIRMED

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

Description

[Zach Bloomquist]

Attachment: foo.webm - recording showing 1fps video

With media.getusermedia.browser.enabled set to true to enable capturing per-tab video with getUserMedia/getDisplayMedia, the recorded per-tab videos have a very low frame rate.

To reproduce:

1. Download the attached .zip with project files, and install dependencies using yarn (yarn install)
2. Run yarn start to start the server.
3. Enable media.getusermedia.browser.enabled in about:config and restart FF (maybe unnecessary?)
4. Visit http://localhost:5001/public and confirm the permissions prompt, ensuring that the capture is for "some test" - a per-tab capture. You can observe in the permissions prompt that the preview is only updating at roughly 1 frame per second.
5. Wait for some time. A video is recorded to /tmp/foo.webm of the capture. When you inspect this file, you will see that the recording is at roughly 1 frame per second.

We use the per-tab capturing in https://github.com/cypress-io/cypress to capture video of user web automation tests. Since this is the only way to obtain tab captures in Firefox, we would really like to see this fixed or understand a way to work around it.

Comment 1

[Zach Bloomquist]

Attachment: normal.webm - showing normal fps with non-browser desktop capture

Comment 2

[Zach Bloomquist]

Attachment: record-repl-pub.zip - reproduction recording project

Comment 3

[Jan-Ivar Bruaroey [:jib] (needinfo? me)]

Thanks for reporting! — I'm able to reproduce this with https://jsfiddle.net/jib1/pafxt2bL/ as well.

Unfortunately, since this feature is behind pref atm, it receives low priority. Patches welcome!

It may receive more attention in the (near?) future depending on our roadmap planning.