How Chromecast Works

Although the original Chromecast looked a lot like a bulbous flash drive, the third-generation model is disc-shaped with a cord permanently attached that you plug into your TV. It’s 6.4 inches long (162 millimeters) from end to end with the cord included, but the device itself is 2 inches (51.8 millimeters) in diameter and half an inch (13.8 millimeters) thick. In addition to its HDMI connector, it has a micro USB port for power. It comes in two colors — chalk and charcoal.

The Chromecast with Google TV has a similar form factor, although the device itself is ovular. It is 6.4 inches (162 millimeters) long, 2.4 inches (61 millimeters) wide and 0.5 inches (12.5 millimeters) thick. It comes in three colors: snow, sunrise and sky. The remote control for each is color coordinated and offers voice control in addition to physical buttons. Like its brother, the Chromecast with Google TV has an HDMI connector to plug into the TV, but the power cable uses a USB-C connection rather than micro USB.

Specifications for the two are similar, but the Chromecast with Google TV needs additional storage for any apps the user wants to add. Although it has 8GB flash storage, the operating system itself takes around 3GB, cutting usable storage nearly in half.

The third-generation Chromecast offers 1080p resolution with a 60 frames-per-second refresh rate. The Chromecast with Google TV can handle 4k HDR video with a refresh rate of 60 frames per second. It also has functionality the basic Chromecast doesn’t. Its voice remote lets you use Google Assistant, you can play games on Google’s Stadia service and you can control smart-home devices with it as well.

Chromecast is supported by the following operating systems, although some of its features may work with slightly older OSes in a few cases:

A demo of the Chromecast being controlled from a Google Nexus 7 tablet.

© JUSTIN SULLIVAN/GETTY IMAGES

Chromecast gets content to your TV screen from a remote device in part by using something called the DIAL (Discovery And Launch) protocol. DIAL was developed jointly by Netflix and YouTube, which is owned by Google. DIAL is free for others to use and is used in devices and apps by many manufacturers and content providers.

One of Chromecast’s components, the DIAL Service Discovery protocol, uses Simple Service Discovery Protocol (SSDP) version 1.1, which is defined by UPnP (Universal Plug and Play), to allow a DIAL client device to locate a DIAL server device running on the same network. The other component, the DIAL REST (representational state transfer) Service, is then accessed to query, launch or stop applications using HTTP (hypertext transfer protocol) requests from the client device to the server device. In the case of Chromecast, your phone, tablet or computer is the client and the Chromecast itself is the server.

Google created Google Cast screen-sharing technology to work on top of DIAL, adding a lot more functionality than DIAL could offer alone. It developed the Google Cast SDK (software development kit) to enable developers to add related functionality to third-party apps that can be used to launch media from the client device to the Chromecast. There are Google Cast APIs (application programming interfaces) for each compatible operating system. All this allows for functionality such as pausing and volume control, as well as additional features that app developers are free to implement.

The basic Chromecast runs a pared-down version of the Chrome browser. The applications on the device are web applications that receive the aforementioned HTTP requests and react accordingly. Once an app is launched, it runs on the Chromecast, but a communication channel will be open that allows the client device to act as a sort of remote control. This dynamic allows you to turn off your mobile device without stopping whatever is streaming from the Chromecast to your TV.

To set up Chromecast, you have to use the Google Home app on mobile devices, or Google’s Chrome web browser on a computer. Once the Chromecast is set up, you use third-party apps like Netflix, YouTube or the Chrome browser to do the actual launching and controlling of your content.

There are currently other apps that work in conjunction with set-top boxes like gaming systems to enable you to use a smartphone or tablet as a remote control. But in those cases, you have to launch the app on the set-top box and the app on the mobile device and run them simultaneously. Chromecast (via DIAL) eliminates a step by allowing launch and control of an app from a single device for playback on the TV through the Chromecast. It may herald the future simplification of our living room remote control situation.

The Chromecast with Google TV uses the Android TV operating system, rather than a modified Chrome browser. It can run many Android apps from the Google Play Store, including popular streaming media apps. Although you can cast media from your phone or computer to the device, the Chromecast with Google TV can run apps all by itself. Google TV is an interface running on top of the Android TV system that adds Google Assistant, Google Knowledge Graph and machine-learning capability.

At launch, not much besides Netflix and YouTube worked on Chromecast, but many other services have become integrated with the device since then, including video, music, news, media storage and sharing apps, productivity tools and games. Many of them require paid subscriptions to third-party providers.

Neither the Chromecast nor the Chromecast with Google TV require a special app for casting. Instead, developers use Google’s Software Development Kit (SDK) to build compatibility into the apps themselves. Casting requires WiFi, and Google cautions that if you have more than one network in your home, you must be sure that both the device and the Chromecast are on the same WiFi network.

That’s also true if you’re streaming from the Chrome browser to your TV.

The setup instructions for Chromecast are simple — and they’re printed on the inside cover of the box. You might need a little more help than that if you have network issues or an unsupported OS, though. MIKE MOZART/FLICKR (CC BY 2.0)

If you have the requisite WiFi network, a compatible device that is connected to that network, and the desire to use any of the services that can stream through Chromecast, the next step is getting one and going through a few simple steps. You will need to know your WiFi password for setup.

It may also require some configuration of your WiFi router under certain circumstances, and it’s possible for your router to be incompatible with the Chromecast. Google’s support site has a Chromecast router compatibility page with a long list of compatible routers, which also includes the firmware version, possible workarounds for certain issues and contact information for the router manufacturers.

The next step is to plug the USB power cable into the Chromecast and its adapter into a power source, and plug the HDMI connector into an available port on your television set. Turn the TV on and switch its input source to the Chromecast to see its output. You’ll see information about the Chromecast on your screen that you can use to complete the setup using the free Google Home app on your smartphone. Setting up the Chromecast with Google TV follows the same basic procedure, although it doesn’t require the Google Home app.

For third-generation Chromecast owners, the Home app should guide you the rest of the way. For Chromecast with Google TV owners, the Home app should display a QR code that you can scan with your phone to continue.

Once it’s connected to WiFi, the Chromecast will probably do an auto-update to grab the latest software, which may take a few minutes. Whenever updated software is available, the device downloads and installs it automatically, whether you’re performing setup or not.

After all this, provided there are no connection issues, your mobile device or computer should be ready to stream to your TV via Chromecast. The next step is opening an app and casting away.

To use Chromecast on your mobile device, make sure you’re connected to WiFi and open a supported application, such as Netflix, YouTube, Hulu or Pandora. Apps made with the Chromecast SDK have an icon that, when you tap it, opens the cast menu. You may see the icon as soon as you enter the app, or it may appear once you select a video, song or other media to cast. When you click the icon, it prompts you to select a Chromecast (if you have more than one — and you might also see other devices in the menu including Google speakers) and, after a moment, your chosen media should appear on the TV.

To stream a particular tab from your browser, move your mouse to the top-right corner of your Chrome window and click the three-dot drop-down menu button. From there, choose the “Cast” menu option. If you have more than one Google device, you can choose the Chromecast you’d like to use from there.

You may not be able to cast from just any tab in Chrome, it’s limited to certain video sites at this time. But Chrome can do more. Using the same Cast menu, you can also cast media files from your computer or your entire computer screen.

Video cast from a Chrome tab has a maximum resolution of 720p, whereas video streamed on a supported site can reach 1080p. Chromecast-friendly video sites may also deliver 5.1 surround sound. Chromecast-enabled sites play directly on the Chromecast, using fewer of your computer’s resources. You can even close the lid on your computer while the video continues to play.

You generally control streaming from your mobile device using a volume bar, a scrub bar (the scroll bar that lets you move forward and backward through a song or video), and stop, pause and play icons on the screen. There may be other controls available, depending upon the app. The volume in this case is Chromecast’s internal volume, so you may have to use the TV’s remote to really get the volume to your preferred setting. If you have an Android device, you can also control your streaming from the lock screen or notification bar.

You can leave the control screen and browse within the app, go to other apps, let your computer or mobile device go to sleep and even shut it off, and your chosen entertainment should keep playing on the TV via the Chromecast.

While you’re streaming a video via Chromecast, if you select another video from within the same app, that video will likely play to your TV screen instead. But you can go to another application and play a different video on your mobile device or computer while the original video continues to stream on your TV screen, unless you choose a cast icon in that app (if available), in which case the video in the new app will take over your TV. If you have wandered off and want to take control of a streaming video to once again, you go back to the app, and there should be a “Now Playing” bar or similar that takes you back to the control screen for that video.

The Chromecast with Google TV comes with a remote of its own, which will also control limited features on your TV, such as volume and power on/off. You may also be able to use your TV remote using the HDMI Consumer Electronics Control (HDMI-CEC) protocol. The Chromecast only allows a small set of functions possible with HDMI-CEC connections, however.

Multiple devices can be used to launch content to the Chromecast, provided they can all connect to your WiFi network and have the appropriate apps installed. They can include your phone, your tablet, your computer or the devices of other household members or friends who are over. That means you can end up fighting for control of the TV, or you can purposefully do a bit of organized social streaming of videos or music.

Roku allows users to connect to the internet with their television by plugging the stick into the HDMI port and adding it to your internet network. BAGOGAMES/FLICKR (CC BY 2.0)

There are many other methods of streaming content to your television, including game systems, DVRs and Blu-ray players. If you have one of those and don’t mind the inconvenience of regular remote controls (or you’re willing to buy a universal remote), you may not need an additional device. But if you’re interested in a stand-alone streaming device, Chromecast is one of many devices you can choose from.

Roku is one of Chromecast’s larger competitors. There are four different models ranging from $30 to $100 as of mid-2021. The lower-end Roku Express and Express+ stream at a maximum of 1080p, whereas the others can stream at 4k. All include WiFi, but the two most expensive, the Roku Ultra LT and Roku Ultra also includes Ethernet for more reliable connections. Roku supports many of the same streaming channels as the Chromecast, although Roku now has its own channel as well. They all come with remotes and don’t require that you have a tablet or smartphone for control, but you can download an app to use your mobile device as a remote if you want. Roku also uses the DIAL protocol in its devices.

The Apple TV 4k starts at $179 and is more like the Roku and Chromecast with Google TV devices. It’s able to run many iPhone and iPad apps. You can cast media to the Apple TV as well. At the time of writing, Apple still sells its Apple TV HD for $149. Both of Apple’s products run the tvOS operating system — the primary difference between the two being screen resolution. It also supports streaming to other devices, though not to Chromecasts.

Miracast isn’t a device but a software standard that connects the casting device and receiving device through peer-to-peer WiFi. Because it works peer-to-peer, Miracast doesn’t need an internet connection. Created by the Wifi Alliance, Miracast technology can be found in devices from many manufacturers.

The Chromecast has been very successful since it went on the market in July 2013. Initially, it sold out very quickly, and the availability of a limited Netflix promotion (three free months of service) ran out within a few hours of launch — the device wound up on backorder for up to three months for some purchasers. By the end of 2013, Chromecast was readily available from retailers.

Reviewers praised the device for being one of the cheapest streaming options, for ease of setup, for working quite well via its supported apps and for its unobtrusive form factor that allows it to hide behind your TV in most cases. It does require a power cable, however, which can make it a slightly awkward addition to your home entertainment system, perhaps especially as these devices have become smaller and sleeker and eventually disappear into the smart TV.

The strength of your WiFi network can also affect Chromecast’s streaming picture quality. Some users experience a lag of a few seconds between casting media and when it actually plays. And if you don’t have a compatible client device running a supported OS and a compatible router, you’re out of luck entirely.

Because any compatible device on the same network can control any Chromecast on that network, multiple devices can interfere with each other. The last one that tries to play a video or music or cast a tab to your Chromecast will win out. This might not be much of a problem on a home network, unless someone unintentionally casts something they wouldn’t want their family or visiting friends to see (or if you live with a jerk).

Chromecast FAQ