Basic Video support

[essboyer]

Basic Video Support

This PR provides a working POC (proof-of-concept) demonstrating native video playback capabilities inside Linux Show Player. In the final phase it will provide a basic implementation of video support which should be good enough for many shows (and which should ultimately address issue #3).

In the POC Phase (Phase I) LSP uses the WaylandSink for full-sized video playback on the main display. The video can be set to play in fullscreen. In Phase II a choice of video sinks may be presented to suit the environment.

Code changes are entirely within the gst_backend plugin.

This is my first contribution to the project (and my first time contributing to a python project) and I hope it will spark some interest in further development in LSP as a capable rival to the likes of QLab.

What's working

• add a video cue (right-click context menu)
• add a video cue (drag & drop)
• video playback on main display only
• fullscreen playback on main display
• seek/pause/etc
• audio playback
• audio pipeline (db meters, etc)
• video duration

TODO

• video playback on external monitor/projector
• more robust video sink selection
• hide mouse during playback
• fade video opacity
• adjust other video parameters (brightness, contrast, etc)
• image transform (keystone)
• video playback in a window (audition)
• video thumbnail