NEW YORK -- I was happy watching television shows and movies on my computer -- until I realized what I was missing.

Streaming video devices such as Roku, Apple (AAPL) TV and Google's (GOOG) Chromecast project video from Netflix (NFLX), YouTube and other services onto the big-screen TV. Suddenly, the computer seems inadequate. Internet television will never be the same.

Internet-connected TVs, TiVo digital video recorders and various game consoles also come with apps for video services. But frequent users of these services will likely want a device that focuses on doing that one thing well.

People must still subscribe individually to Netflix, Hulu Plus, Amazon Instant Video, Major League Baseball and other services, though that can often be done right from the TV screen. Some services require a subscription with certain cable or satellite TV providers. With HBO Go, for instance, Comcast and DirecTV subscribers can use Apple TVs but not Rokus, while it's the other way around with Charter.

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-- Roku 3 ($100):

Roku started as a project within Netflix, which was looking for a cheap way for subscribers to get Internet movies and TV shows onto regular TVs. Roku was spun out into a separate company, and the device now works all major video services except Apple's iTunes.

It also plays games such as "Angry Birds," offers language lessons, supports music services such as Pandora and Spotify and lets you browse photos on Smugmug, Flickr and other services. All told, there are more than 1,000 apps available from Roku's store, many of them free.

Apps often replicate the experience on the services' websites. With Hulu, for instance, you can browse video by genre or play items in your queue. With Netflix, you get profiles for up to five individuals, with separate recommendations and watch lists.

With each service designing its own app, it feels as though I have 1,000 devices in one. Each app has its own on-screen keyboard when searching for video. The remote's up button gets me options such as closed captioning on Hulu, but it exits the video on Amazon and Netflix.

Roku's remote control has an unconventional headphone jack. Plug a pair in, and sound on the TV will automatically turn off. That's great if others in your household are trying to read or sleep.

Like Apple TV and Chromecast, the Roku 3 requires a high-definition TV with an HDMI port. Roku has cheaper models that work on older TVs, but they have slower processors and require Wi-Fi. The Roku 3 and Apple TV let you plug in an Internet cable if your wireless connection is fussy.

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-- Apple TV ($99):

Think of Apple TV as a Roku with fewer apps -- only 27, plus Apple's own services. Apple is constantly adding new ones, and those get installed automatically. Apple wants to keep the device clean and focus on the services people use most. It offers Netflix, Hulu, PBS, HBO, ESPN, YouTube and more -- though Amazon's service is missing.

However, Apple TV is alone in supporting Apple's services. You can buy or rent iTunes content right from the device, or you can play music and video stored on iCloud or your computer, iPhone or iPad. Instead of Pandora or Spotify, you get Apple's streaming music service, iTunes Radio.

Where Apple TV excels is in consistency. The keyboard is the same whether you're on HBO Go, Hulu Plus or Netflix, and the menu layout is similar from app to app. You can subscribe to many of the services right from the device and have that billed to your iTunes account. No need to search for your credit card each time, as Roku requires.

Apple TV works fine as a stand-alone device, but much of its power comes from working with other Apple products. Place an iPhone or an iPad with iOS 7 near the Apple TV to bypass the initial setup and transfer account information wirelessly.

With AirPlay, your iPhone, iPad or Mac can launch content not available through the included apps. That's the way I watched "Margin Call" on Amazon. Charter subscribers can watch HBO that way, too. Unfortunately, DVDs are blocked because of rights issues. You'll have to figure out a way to hook up your computer to the TV directly, or buy a DVD player. On Windows computers, AirPlay is limited to iTunes content and photos.

In many cases, you can keep using your phone or tablet while the video plays on the TV. With the latest Mac system, Mavericks, you also can turn the Apple TV into an extension of your desktop, though your Mac and Internet connection both need to be strong.

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-- Chromecast ($35):

Google's device is a third the price of the others, but it's also quite dumb by design. It is the size of a USB flash drive and plugs into an HDMI port. Turn on the TV -- and nothing happens.

It's more of a conduit between the TV and your mobile device.

Start by downloading Google's Chromecast app on your Apple or Android device. Then download one or more of the 17 apps supported. The list is short, but growing. As with Apple TV, Amazon's service isn't supported. Neither is Apple's iTunes. But it's alone among the three devices to support music and video through Google Play.

The Chromecast is the best option when individuals in a household have separate accounts for Hulu and other services. Each person controls the device from his or her phone; with Apple TV and Roku, it's annoying to sign in and out each time.

Once you have content running on your phone or tablet, you tap a button to fling it to the TV. You can then use your device for other things. You can forward, rewind or pause video from the phone, but you're stuck with that video once the phone loses its connection with the Chromecast, which happened often. The Wi-Fi connection needs to be strong, and Chromecast offers no wired alternative, as the others do.

From a personal computer, you can mirror a Chrome browser tab on the big screen. Again, the connection often cuts out.

With all three devices, I have occasional problems with audio and video not syncing properly, making it seem as though I'm watching a badly dubbed foreign film. It happened most often on the Chromecast and the least on Apple TV.

But I sometimes had hiccups when using AirPlay. Playing content through a native app is the smoothest option, and Roku has the most choices for that. For me, Apple TV is the best choice if you use iTunes and have other Apple gadgets.

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Online:

Roku: http://www.roku.com

Apple TV: http://www.apple.com/appletv

Chromecast: http://chromecast.com