Video conferences are not working with Firefox

[jgeerds]

Describe the bug
It seems to me that it is currently not possible to use Firefox for video conferences like Google Meet or Jitsi. In both services, after joining a conference room, I see no video/audio from the other attendees and nobody can hear/see me.

I'm not sure what exactly the problem is. I don't think it's a permission problem in Firefox or something similar. For example in Google Meet, before joining a room, there is a step where you can see yourself (configure the correct camera/microphone and so on) and that works. That sounds to me that Firefox can access the camera/microphone.

To Reproduce
Steps to reproduce the behavior:

1. nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/6bcb1dec8ea16f20e6404631668cf69e76424eef.tar.gz -p firefox --run "firefox --ProfileManager" (current nixpkgs-unstable)
2. Create a new temporary profile to make sure that no installed plugin causes the trouble
3. Join a Google Meet or Jitsi room.

Expected behavior
I should see see and hear the other attendees (and they should hear/see me).

Additional context
I'm running NixOS 20.03 and using the firefox package from nixpkgs-unstable. I've already tried:

• firefox-wayland from nixpkgs-unstable
• firefox from nixpkgs-unstable
• firefox-esr from nixpkgs-unstable
• Xorg and Wayland
• Clean Firefox profile (e.g. no installed plugins)

Here comes the interesting thing: firefox-bin from nixpkgs-unstable works. Maybe we miss some (optional) dependency or something like that? Unfortunately, I don't see any interesting logs.

Notify maintainers
@edolstra @andir

Metadata

❯ nix-shell -p nix-info --run "nix-info -m"
 - system: `"x86_64-linux"`
 - host os: `Linux 5.4.38, NixOS, 20.03.git.5adf2a6c116 (Markhor)`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.3.4`
 - channels(jgeerds): `""`
 - nixpkgs: `/var/src/nixpkgs` # I'm using krops: https://github.com/krebs/krops

Maintainer information:

- nixpkgs.firefox
- nixpkgs.fiefox-esr

[fabianhjr]

Hi @jgeerds, I am using firefox from nixos-20.03 rather than nixos-unstable. However, as additional context other applications like discord also have this issue. (Noticed it a week and a half or so ago)

[fabianhjr]

Investigating the differences between nixos.firefox and nixos.firefox-bin, in particular:

dependency: firefox -> firefox-bin
-------------------------
ffmpeg: 3.4.7 -> 4.2.2
libva: missing -> 2.7.1

[xaverdh]

Might be that #87708 (or a backport of it) fixes this.

[jgeerds]

@xaverdh I'm pretty sure that this patch will fix it. Thank you! I'm closing the issue.

[jgeerds]

FYI: It's working again on recent nixpkgs-unstable 👍