Nixpkgs: tdesktop: Needs libwebrtc for video calls (or crashes)

[mkg20001]

Describe the bug
Application crashes when other side enables camera in video call

To Reproduce
Steps to reproduce the behavior:

1. Open telegram-desktop
2. Make a video-call

Expected behavior
It works

Screenshots

Additional context
It hangs instead with the app being frozen and some ffmpeg errors

Notify maintainers

@primeos @abbradar

Metadata

• system: "x86_64-linux"
• host os: Linux 5.4.67, NixOS, 21.03pre-git (Okapi)
• multi-user?: yes
• sandbox: yes
• version: nix-env (Nix) 2.3.7
• channels(root): "nixos-21.03pre244416.daaa0e33505, nixpkgs, solaros"
• channels(maciej): "nixpkgs-21.03pre243895.72b9660dc18, solaros"
• nixpkgs: /home/maciej/.nix-defexpr/channels/nixpkgs

Maintainer information:

# a list of nixpkgs attributes affected by the problem
attribute:
 - tdesktop
# a list of nixos modules affected by the problem
module:

[primeos]

That's unfortunately to be expected. It shouldn't crash (I assume upstream didn't test that code path) but due to our lack of libwebrtc we don't support video calls.

If someone is interested in that feature we'd need to figure out how to package Telegram-Desktop's version of libwebrtc for Nixpkgs but it will likely be a huge PITA (beware!). Upstream doesn't make packaging easy (libwebrtc is a mess similar to Chromium) and our build sandboxing will likely cause most of the pain. I can try to help if someone is interested.

Arch already successfully packaged libwebrtc and we may reuse their work (which should help a lot to get started):

• https://github.com/archlinux/svntogit-community/commits/packages/libwebrtc/trunk
• https://github.com/archlinux/svntogit-community/commit/824fc94f41a9a05ff73f53bcf00c212136179cdf#diff-8d0411b338c83cd8cd8ad9d9db127101

[mkg20001]

Normal calls seem affected aswell

[mkg20001]

I'm currently cooking up something in https://github.com/NixOS/nixpkgs/pull/100062

[oxalica]

In building-cmake.md of tdesktop, libwebrtc is built from tg_owt which seems to be another fork of libwebrtc.

Why do Arch patch cmake files to replace it? Would it be easier for us to use tg_owt?

EDIT: Oops, I want to post this under #100062 but opened a wrong tab. :( Well, same author. @mkg20001

[mkg20001]

https://github.com/NixOS/nixpkgs/pull/100450

This PR seems to work. I think we should merge this and worry about non-forked libwebrtc later