NEW YORK (AP) - More choice - and confusion - is coming to the next generation of TVs. At least three new software systems were announced Monday for Internet-connected television sets, which let viewers watch Internet video and interact with friends online on the big screen. The new smart TV operating systems will compete with software already available from Google and individual TV manufacturers. The slew of options is in contrast to the smartphone market, where just two operating systems - Apple's iOS and Google's Android - dominate. But more consumer choice will also mean more difficulties for services such as Hulu and Netflix to write apps. As a result, app selection on any given TV will be limited. To fully enjoy the range of Internet video on the TV, many consumers will still have to buy a separate device such as Apple TV and Roku - and then figure out how to install it. Those devices cost about $100, though Google sells a $35 Chromecast device with fewer features. TV manufacturers have been pushing smart TVs to give consumers a reason to upgrade their sets more frequently. The Internet capability also keeps the TV central to households, even as people spend more time watching Internet video. But so far, apps on smart TVs aren't as extensive as what's found on phones and stand-alone streaming devices, in part because no one operating system has enough users to make it a priority for app makers. "I keep hoping we will see convergence," said Colin Dixon, chief analyst at nScreen Media, a research firm in Sunnyvale, Calif. Unfortunately we keep seeing the number of operating systems . increasing, not decreasing. Chet Kanojia, whose Aereo online television service has been trying to expand onto more devices, said the tendency for TV set manufacturers to differentiate their systems with unique features turns app development into "a royal pain." That's because Aereo's engineers have to write new apps for each one. The announcements at the International CES gadget show in Las Vegas include: Mozilla, the nonprofit organization behind the Firefox Web browser, said it is putting its Firefox OS software on smart TVs, starting with Panasonic's. The code powering Web browsers had been adapted last year to run smartphones targeted at emerging markets. Now, Firefox will be tweaked further with Panasonic's help to work on bigger screens and incorporate TV-specific features such as electronic program guides. Panasonic expects to start selling TVs with Firefox OS later in the year. Other TV manufacturers will be able to use the same software without charge. LG Corp. announced plans to power 70 percent of its smart TVs this year with the webOS mobile system it bought from Hewlett-Packard Co. last March. Although LG hasn't disclosed specifics, the use of webOS paves the way for owners of LG sets to control home appliances from the TV. For starters, LG said the new software will make its TVs easier to set up and use. The streaming video device maker Roku Inc. said it is partnering with two large Chinese TV makers, TCL Corp. and Hisense International Co. Ltd., to incorporate its software so Roku apps can run on TVs without a separate device. Several TV makers already have their own smart TV software. Opera Software is also trying to adapt its Opera Web browser to work on TV sets, similar to what Mozilla is doing with Firefox. Opera said some of its software is already on sets made by Sony, Samsung and Toshiba. There also has been long-standing speculation that Apple is working on its own smart TV system, but the company hasn't said anything about it and there's no indication such a system is imminent. If Apple does make it, it would likely be limited to TVs under its own brand and would negate the need for a stand-alone Apple TV device. In 2010, Google Inc. attempted to unify smart TV software by creating its Google TV system. Sony Corp. was among the companies that made TVs using Google TV. But Dixon said adoption of Google TV has been slow, in part because TV manufacturers didn't want to turn their sets into conduits for Google's services, as Android phones have become. Although there are many versions of Android on phones, there's enough in common that app developers don't have to start from scratch each time. Google is trying to promote a similar approach on Internet-connected cars. On Monday, Google and car makers Audi, General Motors, Honda and Hyundai announced an alliance to bring Android to cars. Chipmaker Nvidia is also part of that. Andreas Gal, Mozilla's vice president for mobile engineering, acknowledges that fragmentation on TVs is a big problem, but he said Firefox is trying to address that through the use of Web-based standards, known as HTML5. Opera is doing that, too. With such an approach, an app that works with Firefox OS or Opera TV will need only minimal changes to work on other systems that use the same standards, similar to how the same websites can work on competing browsers. And because many services already have websites that support HTML5 on the desktop, Gal said, those also should work on smart TVs through a browser. Merwan Mereby, an executive with Panasonic Corp.'s interactive content business in North America, said that after years of developing its own proprietary technologies, Panasonic decided to embrace Firefox OS so that publishers and Web developers can bring content to the big screens more easily. Still, there are challenges. Dixon said people tend to keep their TVs for several years. With a phone, upgrades are frequent enough that many users will have speedy enough processors to run the latest features. With TVs, he said, it's likely that older sets won't run all the latest apps, regardless of the system used. AP Technology Writers Youkyung Lee in Seoul, South Korea, and Ryan Nakashima in Las Vegas contributed to this story.