How Google Cast works

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Alejandra Rangel
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How Google Cast works

G, as I mentioned earlier, is the protocol designed and developed by Google to allow the transmission of audio / video content from one device to another, completely wirelessly. To better understand the particularity of this approach and the reason why it has achieved such high success, however, it is good to take a step back in time.

The practice of transmitting the screen of one device to another, called in technical jargon mirroring, existed well before the introduction of Google Cast: the keys and devices compatible with the transmission protocol Miracast, for example, they just "mirror" on the second screen the entire stream coming from the display of the main device (smartphone, tablet or computer), the one that, in fact, runs the app or program you want to view on the second display.

In practice, the mirroring technique through Miracast (but not only) allows you to view on the second screen everything that is reproduced on the screen of the main device, regardless of the type of content, exactly as if it were a mirror; as a direct consequence, when the main device stops sending content (because the app or program in question is closed, because the screen is turned off, because the device goes into standby or for other similar reasons), mirroring is stopped and the second screen no longer transmits anything. Put simply, the secondary display is not just the full copy of the main device display, but it completely depends on it.

This approach, on the other hand, changes profoundly in the protocol G: in this case, the main device (the one containing the app or program to be transmitted) has the task of start transmission of the content, which however is reworked inside the receiver device and reproduced in total autonomy. In practice, the main device becomes a kind of remote control through which to choose what to play, but the actual playback takes place inside the Google Cast receiver, which performs the task in a totally independent way from what happens on the main device.

I'll explain better with an example: imagine you want to cast a movie from the Netflix app for smartphones to a TV equipped with Chromecast (which, as I will explain later, is the device that decreed the spread of Google Cast). What you have to do is turn on the TV (and therefore the Chromecast), start Netflix from the smartphone, select the movie to choose and press the button to send the transmission to the Chromecast (and, therefore, to the TV): once this is done, you can enjoy the movies on the TV screen and do anything else with the smartphone, even turn it off if you want, since the Chromecast will have received the order relating to the content to be played and will do it in complete autonomy. Brilliant, isn't it?

Over time, however, features of mirroring "Pure", ie mirror reproduction of the screen: they can be obtained both on Android, natively (via the system functionality Transmit the screen), both on computer, through the use of the Google Chrome browser. But I'll tell you about this later.

How to use Google Cast

Having clarified the difference between classic "mirroring" and the reproduction of content through the protocol in question, the time has come to move on to the practical aspect of the thing and to understand, in practice, how to use Google Cast.

Exactly as explained above, this technology is mainly based on two categories of devices: those that activate content playback through apps, programs or functions compatible with the protocol (i remote controls I was talking about before), and those who receive the order to play the contents through Google Cast, then taking care of completing the task through the screen to which they are connected. For everything to go well, it is essential that remote control app or program and playback device are both connected to the same network Wi-Fi (or, in some cases, Ethernet).

The apps and programs capable of transmitting content via Google Cast are truly numerous: they range from the well-known apps dedicated to streaming content via the Internet (such as YouTube e Netflix, for example), up to the most well-known on-demand portals relating to television content, via the Google Chrome browser. Leaving aside for a moment this aspect, which I will analyze in one of the following bars of this guide, I would say at this point to focus attention on devices compatible with playback via Google Cast, that is, those capable of receiving "order" and transform it into a concrete action.


The first and certainly best known device compatible with Google Cast is the chromecast: in fact, it is a small one HDMI key designed by Google, able to prepare the TV to play content sent by compatible apps and programs. The Chromecast can be purchased on the official Google store, or in any electronics store, and is currently available in two models: the chromecast "Base", which costs 39€ and allows you to play video with resolution 1080p (Full HD); il Chromecast with Google TV it is instead a real TV box (even if it maintains the key format of the case model) that has a remote control, Google TV operating system with app support and can reach 4K resolution with HDR and Dolby Vision support, at the cost of 69,99€ (the latter took the place of Chromecast Ultra, which featured the same features as Chromecast, but with 4K support and Ethernet port). Both have support for 5GHz Wi-Fi networks.

Note: you may find a third type of Chromecast on the market, the Chromecast Audio, which allows you to receive audio content and transmit it to any device after connecting via a 3.5mm jack. The Chromecast Audio, however, is no longer produced or distributed by Google (although still fully supported).

Once you have the Chromecast, you must first connect it to the TV via HDMI and power it via the USB cable supplied (by connecting it to one of the available ports on the TV) or through the power grid (required for the Chromecast Ultra). Then, after turning on and setting the TV to the right source, you can configure the dongle using the app Google Home, available for Android and iOS: in practice, what you need to do is activate the Wi-Fi connection of the terminal you are about to use, start the app and follow the instructions provided on the screen to connect the Chromecast to the Internet, assign it a name and a location. For more details on this device and on the activation and configuration operations, I refer you to reading my specific guide on the subject.

Compatible Smart TVs

All TVs equipped with the operating system Android TV they are natively compatible with the Google Cast protocol: this means, in practice, that it is possible to send content to playback through this technology without carrying out any additional configuration. So, just start the app of your interest, press the broadcast button, select the Android TV in question from the list of nearby devices and that's it!

If you intend to do so and buy a TV that responds to this feature, I suggest you take a look at my guide to choosing a new Smart TV, in which I have given you some very valid tips for choosing the device. best suited to your case.

Note: the same goes for the TV box NVIDIA Shield, also equipped with the Android variant dedicated to televisions. The device is natively compatible with Google Cast and does not require additional configuration for receiving and playing content.

Vedi offers your Amazon

As for Smart TVs not equipped with the Google operating system, the discussion changes slightly: in this case, it is possible to play content via Google Cast through the app YouTube: once the latter has been installed both on the TV and on the "remote control" device (be it a smartphone or tablet), simply press the transmission button from the "mobile" app and choose the TV in the list of devices. surrounding reproduction.

How to cast content via Google Cast

Is everything clear so far? Perfect! Now is the time to get to work and understand how to transmit content through the Google Cast protocol. The first thing you need to do, therefore, is to turn on the device on which you intend to carry out the transmission (for example a TV with Chromecast, an Android TV, or the NVIDIA Shield box).

Later, if you intend to play content starting from smartphone or tablet Android iOS, start the app of your interest (eg. Netflix), select the content to play and then click on broadcast / cast button located in the player screen; this button, in most cases, looks like one screen with waves at the bottom left. Finally, identify the device you intend to use for transmission (e.g. the chromecast) from the proposed list and the game is done: a few moments later, the latter should start playing the content you have chosen, in a totally independent way from the smartphone or tablet from which you acted.

The apps compatible with the transmission of content through Google Cast are really numerous: in the next section of this guide I will show you the ones that, in my humble opinion, are the most important.

Note: where the cast button is not immediately visible (e.g. su Spotify), identifies the section relating to available devices and select the one of your interest from the proposed list.

There is also the option to cast the entire screen to the Chromecast or the receiving device of your choice: to do it from Android, touch the icon Settings located on the Android Home screen, access the sections Connected devices Connection preferences and, finally, touch on the item Broadcast on. Finally, select the device of your interest from the proposed list. If you have Android 7 or earlier, you can access this feature by going to Settings> Display> Cast.

On the iPhone and iPad, however, you need to use a third-party app, such as Replica, which uses the screen recording function to project the iOS / iPadOS screen on the TV via Chromecast. To use the application (free with advertising banners), start it, consent to the use of Bluetooth, select yours chromecast e premi sui pulsnti I will start e Start transmission.

Again, one of the programs that offers full compatibility with broadcasting via Google Cast is Chrome, the Google home browser dedicated to the major desktop platforms: it allows you to send the currently active tab,entire desktop or a file audio/video chosen from the computer memory.

Doing it is really simple: after starting the browser, click on the button (⋮) located at the top right, select the item Broadcast ... from the proposed menu and press the button References to choose what to transmit (card active, desktop o fillet); to conclude and immediately start the transmission, select the device of your interest (eg chromecast) from the proposed list. In this way, the contents of the file, the desktop of the computer or the active card will be immediately reproduced on the device of your choice using the technique of mirroring puro, which I told you about in the opening bars of this guide.

In the latter case, in particular, there are compatible Internet sites (eg. Netflix o YouTube, for example) that allow you to use Google Cast in "remote control" mode, sending the order to play the active content and not the entire browser tab.

Google Cast compatible apps and programs

Now that you have perfectly understood the functioning of the Google Cast protocol and the devices through which to use it, you can't wait to take full advantage of it and would like to have an overview of the most important apps (as well as the most important programs) with which to do it?

Then this is the section of the guide that's right for you! In fact, below I will show you a series of software through which you can "send" content on displays with compatibility with the Google Cast protocol: remember that, as I explained to you a little while ago and except in exceptional cases, you can start the transmission of content by searching L'cast icon (Quella a forma di screen with waves) within the app / program of your interest, select the device on which to start playback (be it a Chromecast, an Android TV, the NVIDIA Shield TV box or, in the case of YouTube, any Smart TV with its app installed) and… enjoy the show!

  • Allcast (Android / iOS) - this is an extremely popular app that allows you to stream photos and videos from the memory of Android and iOS devices to the Google Cast device. The free trial version of the app limits the duration of the content to 5 minutes: to eliminate this limitation, you need to purchase Allcast Premium.
  • Android - as mentioned above, the Google operating system is natively compatible with Google Cast; therefore, you can transmit the entire screen of Android smartphones and tablets directly to a device compatible with reception via the aforementioned protocol. To do this, you need to go to Settings> Connected devices> Connection preferences> Cast on Android 8 and later, or in Settings> Display> Cast on previous versions of the Google operating system. Finally, you have to select the transmission device of your interest (Chromecast, Android TV and so on).
  • BubbleUPnP (Android) - this is an app dedicated to streaming video from smartphones, tablets, UPnP servers and DLNA servers (which must be properly configured). BubbleUPnP is basically a free app, however there are additional features (such as on-the-fly decoding of video formats not supported by the receiving device) that can only be unlocked by purchasing a paid license (3,99€).
  • Deezer (Android / iOS) - is one of the most provided music streaming services in the world, boasting a library of over 43 million music contents. For more information, I recommend reading my thematic tutorial.
  • Google Chrome (Windows / macOS / Linux) - the “desktop” version of the Google home browser allows the transmission of tabs, windows or multimedia files. I explained how to do this in the previous section of this guide. The "mobile" version of the browser, on the other hand, does not have transmission functionality.
  • ChromeOS (Chromebook) - is Google's operating system dedicated to a small range of notebooks. Based on the Google Chrome engine, it allows you to transmit content through Google Cast in an almost identical way to the browser it is inspired by.
  • Google Play Movie (Android / iOS / Browser) - a platform that works very similar to the previous one, but this time dedicated to the transmission of video content (movies, shows, TV series and so on). For more information on this service, you can consult my specific guide.
  • Infinity (Android / iOS / Browser) - this is the video on-demand service offered and managed by Mediaset, based on a content gallery full of films, shows and TV series. If you are interested in learning more about the topic, you can take a look at the comprehensive presentation article I dedicated to this service.
  • Localcast (Android / iOS) - similar to BubbleUPnP, this is an app dedicated to content residing on UPnP, DLNA or Samba servers (the classic Windows network share).
  • Netflix (Android / iOS / Browser) - is one of the best known video streaming platforms in the world, boasting a huge library populated by hundreds and hundreds of movies, documentaries and TV series. For information on prices and subscription methods, I suggest you read my dedicated in-depth study.
  • NOW TV (Android / iOS) - is the streaming service designed by Sky for the transmission of the best contents of the platform via the Internet (also in on-demand mode), without subscription restrictions. For further information, I invite you to consult my guide dedicated to the service.
  • Plex  (Android / iOS) - is a very famous multimedia server that allows you to manage your audio / video library and share it with other devices. For more information, you can take a look at my tutorial on how to use Plex on Smart TV, in which I was able to explain to you in detail how it works.
  • Spotify (Android / iOS / Browser) - currently, it is the most famous and used music streaming service in the world. I have provided you with additional information on prices, subscription methods and so on in my dedicated tutorial.
  • TIMVision (Android / iOS / Browser) - is the on-demand streaming platform created by TIM, containing over ten thousand titles including films, TV series, documentaries and, not least, cartoons. To learn more, you can take a look at my presentation article dedicated to the service.
  • TuneIn Radio (Android / iOS) - is an audio streaming service that allows you to listen to radio stations from all over the world.
  • YouTube (Android / iOS / Browser) - Google's video platform that, of course, needs no additional introduction! It is possible to take advantage of the Google Cast protocol also for the “official” variants of the service, such as YouTube Music/Premium (Android/iOS/Browser) e YouTube Kids (Android / iOS).
  • Web video cast (Android / iOS) - this is an app capable of "capturing" the video streams played within a Web page and retransmitting them via the Google Cast protocol.

Note: the browser-based versions of the aforementioned services allow the transmission of contents only through the Google Chrome browser. By doing so, only the audio / video content will be reproduced on the screen and not the entire browser tab.

How do you say? Were you satisfied with the potential of Google Cast but would you still like a more complete overview of how the screen is transmitted? No problem: I have prepared for you a series of specific guides on the subject, in which I have provided you with a complete overview of the most popular and simple technologies dedicated to the transmission of content from one device to another: how to split the screen, how to connect the smartphone to the TV and how to connect the tablet to the TV.

How Google Cast works

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