Wireless media content transmission technology has become an integral part of the mobile device ecosystem. Users often come across the term Android Cast (or Google Cast), but do not always understand the deep differences between this function and regular screen mirroring. Essentially, this is a protocol that allows you to turn your smartphone into a remote control for your TV, rather than just a video source.
When you start broadcasting through this protocol, the load of video decoding falls on the receiving device. This means that your phone's battery is consumed much more slowly, and the picture quality remains stable, even if you minimize the application or lock the gadget screen. Chromecast and compatible TVs with Android TV autonomously download content from the Internet at the sender's command.
In this article we will analyze in detail the architectural features of the technology, activation methods hidden functions and methods for eliminating common connection errors. You will learn to distinguish between screen mirroring and intelligent media sending modes, which is critical for a comfortable home theater.
Architecture and principle of operation of Cast technology
The fundamental difference Google Cast from traditional Miracast or AirPlay is the distribution of computing resources. In classic mirroring mode, the smartphone encodes the video stream in real time and transmits it to the TV, which requires high processor performance and a stable communication channel. In the case of Kast, the phone acts only as a controller, sending only control commands.
When you press the broadcast button in an application, for example, in YouTube or Netflix, the smartphone transmits the URL of the video stream and playback instructions to the TV. Next receiver (TV or set-top box) independently establishes a connection to the content server. This explains why the video continues to play even if you leave the room with the phone.
The technology relies on a local Wi-Fi network, but does not create its own access point, as some direct connection protocols do. All devices must be on the same subnet. To ensure low management latency, the mDNS (Multicast DNS) protocol is used, which allows devices to automatically discover each other without manually setting IP addresses.
Technical details of the protocol
The protocol uses port 8008 for unencrypted traffic and 8443 for a secure connection. Device discovery occurs through multicast packets on the local network.
It is important to understand that not all content can be transmitted in this way. If your app doesn't have built-in support for Google's SDK, you won't be able to use Smart Push. In such cases, the system switches to screen mirroring mode, which is less efficient and requires the smartphone display to be constantly turned on.
Differences between Cast and screen mirroring
Users often confuse these two concepts, considering them synonymous, but from a technical point of view, these are different processes with different usage scenarios. Screen Mirroring creates an exact copy of what is happening on your phone's display, pixel by pixel. This is useful for demonstrating interfaces, games or applications without built-in broadcast support. Screen Mirroring works selectively. It transmits only a specific media file or stream, optimizing it for the capabilities of the TV. If your phone has Full HD resolution and your TV supports 4K, when using Kasta, the TV can request a 4K version of the video from the server, whereas with mirroring you will be limited to the resolution of the phone's screen.
Android Cast works selectively. It transmits only a specific media file or stream, optimizing it for the capabilities of the TV. If your phone has Full HD resolution and your TV supports 4K, when using Casta, the TV may request a 4K version of the video from the server, whereas with mirroring you will be limited to the phone's screen resolution.
The difference in power consumption is also colossal. When mirroring, the smartphone screen must be constantly lit and the video processor must be running at full capacity to encode the image. When using the Cast protocol, you can continue to use your phone to communicate in instant messengers or read news while the video is played on the big screen.
Use mirroring only for interfaces and games; for video and music, always choose native Cast to save battery and better quality.
In addition, when mirroring, delays (latency) often occur, which makes it impossible to comfortably play dynamic shooters or use the phone as a touchpad. The media transfer protocol does not have this drawback, since buffering occurs directly on the receiving device.
Methods of activating and setting up broadcasting
To get started, you need to make sure that both devices are connected to the same Wi-Fi network. This is the most common requirement, violation of which leads to the fact that the phone simply “does not see” the TV. Check your router settings: sometimes the guest network isolates devices from each other, blocking detection.
The easiest way to start broadcasting is to use the button inside applications. In players YouTube, Vimeo, Spotify or streaming services, look for a rectangle icon with waves in the corner. Clicking on it will bring up a list of available devices. Select your TV from the list and playback will start automatically.
If the application does not support native sharing, you can use the system mirroring feature. In modern Android shells, this item is often called Broadcast, Smart View or Wireless projector. It is located in the notification shade or in the menu Settings → Connected devices → Broadcast.
☑️ Check before connecting
For advanced users, it is possible to configure custom receivers through the app Google Home. Here you can rename devices, group them for multi-room audio, and configure stream quality settings. There is also a guest mode feature available here, which allows you to connect without access to the Wi-Fi network password.
⚠️ Attention: If you are using a dual-band router (2.4 GHz and 5 GHz), make sure that the phone and TV are connected to the same frequency. Some older implementations of the protocol cannot “see” devices at different frequencies, even if they are on the same logical network.
Compatible devices and ecosystem
The Google Cast ecosystem is extremely wide and is not limited to Android-based smartphones. The protocol is supported by iOS devices via the Google Home app, laptops with a browser Chrome and even some smart speakers. This makes the technology a universal standard for a smart home.
The main signal recipients are TVs with a built-in platform Android TV or Google TV. The function is also supported by many models from Samsung (Tizen), LG (WebOS) and Sonythat have a built-in Chromecast built-in module. Separately, there are external set-top boxes, such as Chromecast with Google TV, which add this function to any old TV with an HDMI port.
Below is a table of compatibility of various types of devices and supported operating modes:
| Device type | Cast support | Mirroring support | Additional required. Software |
|---|---|---|---|
| Android TV / Google TV | Native | Native | No |
| Samsung (Tizen) | Built-in | Smart View | No |
| LG (WebOS) | Built-in | Screen Share | No |
| Old TV + PC | Via Chrome browser | Via Chrome browser | Chrome browser |
| iOS device | through the app | through the app | Google Home |
It is worth noting that some budget TV manufacturers claim Cast support, but implement it unstable. In such cases, purchasing a separate set-top box Chromecast or Xiaomi Mi Stick often solves problems with freezes and lack of codecs.
If your TV does not support Cast natively, but has a USB port, you can try to power the external Chromecast adapter directly from the TV, getting rid of unnecessary wires to socket.
Troubleshooting and optimizing the connection
The most common problem is desynchronization of audio and video or periodic slowdowns in the picture. Most often, the reason lies in an overloaded Wi-Fi channel or a weak signal. Try to place the router closer to the viewing area or use a repeater to strengthen the signal.
If the device does not appear in the list of available ones, try clearing the application cache Google Play Services and Google Home on a smartphone. Sometimes simply switching the airplane mode on the phone to restart the network interfaces helps. Make sure that AP Isolation is not enabled on the router.
For diagnostics, you can use the developer mode on the TV (if it is Android TV). Enable USB debugging and use the logs to view connection errors. Often the problem is solved by updating the TV firmware, as manufacturers regularly release patches for network modules.
⚠️ Attention: When using a VPN on a smartphone, the Cast function stops working locally, since traffic is redirected through a remote server. Be sure to disable the VPN before starting the broadcast.
In cases where video is broadcast but there is no sound, check the audio output settings in the source application itself. Sometimes the system by default tries to output audio to the phone, even if the video is on the TV. Switch the audio output in the Bluetooth or multimedia settings of the device.
Secret command to reboot
On the Chromecast TV remote, hold the power button for 10 seconds to force the system to reboot without disconnecting from the power supply.
Advanced features and use cases
The technology allows you to implement scenarios that go beyond simply watching a video. For example, the feature Backdrop turns your TV into a digital photo frame, showing photos from your Google Photos account when the device is in standby mode. This creates a cozy atmosphere without the need to buy additional hardware.
Gamers can use the low latency mode for streaming game services such as Stadia (when it was active) or cloud platforms. However, this method is not suitable for local games from phone to TV due to input lags. Here it is better to use special gamepads that connect directly to a TV or set-top box.
Music enthusiasts will appreciate the possibility of creating a multi-room system. By combining several speakers or TVs into one group via the app Google Home, you can synchronously play music throughout the apartment. The delay between rooms is compensated by synchronization algorithms, making the desync unnoticeable to the ear.
It is also possible to broadcast a browser tab Chrome from a computer. This is useful for showing presentations or browsing websites that are not optimized for TVs. You can broadcast just a tab or the entire desktop, turning your TV into a second monitor.
⚠️ Attention: Application interfaces and settings menus may differ depending on the version of Android and the shell manufacturer. If you do not find the described function, check the current location of the items in the official help of your device.
Use grouping devices in Google Home to create a full-fledged multi-room audio system without purchasing expensive specialized solutions.
Frequently asked questions (FAQ)
Why the TV does not see the phone, although they are in same network?
Most often the problem is in the router settings. Check to see if AP Isolation is enabled, which prevents devices on the same network from communicating. Also try restarting both devices and the router.
Is it possible to use Android Cast without the Internet?
Yes, you don’t need the Internet to locally stream files or screen mirroring, a local Wi-Fi network is enough. However, to stream content from online services (YouTube, Netflix), access to the global network is required for the receiving device.
Does broadcasting affect the speed of mobile data?
When using native Cast (when the TV itself downloads video), phone traffic is not consumed at all. Screen mirroring can waste bandwidth if you're watching an online video because your phone acts as a repeater.
How to improve picture quality when broadcasting?
Make sure your router supports 802.11ac (5 GHz) and both devices are connected to this frequency. Also check if there are any background downloads running on your phone that could clog the communication channel.
Does this feature work on iPhone?
Yes, iOS owners can use the Cast feature by installing the Google Home app or using supporting apps (YouTube, Spotify), where the cast icon works identically to Android devices.