rem: return (a.port == b.port) && (a.id == b.id);
add: return (   a.field_rate == b.field_rate && a.interlace == b.interlace && a.first_active == b.first_active && a.last_active == b.last_active && a.orientation == b.orientation && a.pixel_width_aspect == b.pixel_width_aspect && a.pixel_height_aspect == b.pixel_height_aspect && a.display == b.display);
context: bool operator==(const media_source & a, const media_source & b){	return (a.port == b.port) && (a.id == b.id);}