libVLC backend support

[ahjolinna]

this really funny request from me as I don't like VLC....well as a main player..

Pros:

• crossplatfom
• can work better than gstreamer or mpv for some
• VLC is Qt based, and the backends API is the best part of the whole thing

Cons:

• you may need to install whole VLC instead of just the backend (like qtav)... some linux distros do have the backend splited from the GUI.
• the codec support is really wide but the quality sucks at times really bad (so I dont know how twitch streams will work, codec wise)

Mixed(feelings):

• it's maybe the most popular cross platform mediaplayer ever

PS. also maybe VLC could just replace qtav? (can't remember for what it was for)...

dev doc

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there is also KDE's Phonon) system that uses gst or vlc