Put branding over tv signal
In VLC you have an overlay feature among the out-of-the-box effects (Tools->Effects and Filters->Video Effects->Overlay). The overlay can be a logo, de-logo eraser, or text. You can run VLC centrally and restream the TV channel, or you can run it in a Linux settop box and control it centrally via its internal built-in web server, via telnet, or via the Lua interface. You can also make more complex overlays such as PIP (picture in picture) but that requires some mastering of the VLC command syntax.