MiracastIf you have a BQ device, among its options, you may have seen “Wireless screen”. As of Android 4.2, Google has introduced a new protocol that allows the diffusion of multimedia content from an Android device to other compatible ones over a Wi-Fi connection. This is known as Miracast.

Miracast wireless screen

Miracast is a protocol created by the Wi-Fi Alliance. Via Wi-Fi Direct connections in the 2.4 and 5 GHz bands, it allows video and audio content from an Android device to be displayed on another, and even share the terminal’s screen. It’s true that the connection between the transmitter and receiver isn’t always as good as one would expect, however, there are progressively more manufacturers, of televisions for example, that are incorporating Miracast compatibility into their products. Miracast supports WPA2-PSK encryption as well as DRM (digital rights management), indicating a focus on security from the very start.

Miracast uses peer-to-peer connections to send information directly from the transmitter to the receiver. All that’s required is for both to be connected to the same wireless network, an external connection to Internet is unnecessary. As for the quality of the transmitted information, Miracast can send 1080p high definition video and 5.1 surround sound. It’s important to mention that the Miracast specifications don’t say anything about a maximum latency that must be complied with. This means there’s no rule about the time that elapses between seeing an image on the transmitting device, and the moment it appears on the receiving one. This “uncontrolled” latency is not a problem as long as it remains constant (that is, as long as it’s not continually changing, causing what’s know as jitter or jittering), and as long as we don’t use Miracast for playing video games on the TV.

Explained in a little more detail: If you are watching a film that’s being played from your BQ tablet, and it constantly takes 2 seconds for a frame that appears on the tablet to show up on the TV, then this wouldn’t pose a problem. You would only notice this lag with the very first frame, from here on each frame will fluidly follow the next (the first frame takes 2 seconds to appear on the TV, the second frame takes another 2 seconds, appearing right after the first, maintaining in this way the temporal continuity on the television). However, if the latency is not constant (sometimes 2 seconds, other times 1…), then some frames will arrive ahead of time, because the previous one still hasn’t arrived, and others will arrive later. This would make film watching somewhat unpleasant. Obviously, whether variable or constant, the latency makes it difficult to play games on the television. As an example, when you must jump to avoid an enemy, if you do this looking at the TV, then you would have done it two seconds after you should have (this is because the jump should have been done while looking at the tablet which is executing the game in real time).

Previously I mentioned that the transmitting and receiving devices must both be Miracast compatible. If your television is not, you might want to consider purchasing an HDMI Miracast dongle. These small adapters are cheap (you can find them starting at around €20), and apart from Miracast, they often support AirPlay and DLNA.

ezCast Miracast adaptor

ezCast Miracast adaptor

DLNA connections

Speaking of DLNA, what do these letters stand for? Well DLNA, or Digital Living Network Alliance, is another protocol initially established by Sony in 2003, used to connect devices (wirelessly or by Ethernet) in the most user-friendly way possible. Most commonly, it is used to access and play multimedia content from one networked computer to another. So if your television supports DLNA and has a Wi-Fi connection, you can connect to your PC and turn it into a DLNA server. In this way, the content of the PC can be reproduced on your television, without the need of cables. DLNA also uses DRM protection, meaning that some content might not be able to be played.

In the aforementioned case, the PC would be considered a Digital Media Server, and the television screen a Digital Media Renderer. Another role is that of Digital Media Controller, which controls communication between the server and renderer; this device may be a smartphone, a tablet, etc. In any case, the television could even perform the three roles simultaneously given there is no conflict between one role and another.

So what differences are there between DLNA and Miracast? Well, lots. To start with, one system might not be compatible with the other. You could have a television with a Wi-Fi adapter (either integrated or external), that does not allow you to use Miracast, but does allow DLNA. In this case, your computer (with Windows, for example), can share your multimedia library folders, permitting other devices to access them. Your television will “find” this content on the network when your PC is turned on, and be able to access and play it. You can customize these settings in the “Media streaming options” in Windows.

Another fundamental difference is that DLNA is not intended for duplicating the screen of a mobile device to a television, that is, it does not allow screen mirroring, but focuses on reproducing multimedia content. So if you want to broadcast a video from your mobile device to a television that does not support Miracast, but does support DLNA, the best thing to do is install an application that allows your tablet or smartphone to act as a DLNA server so that it can be “found” by the television. There are many available; undoubtedly, one of the better known ones is DLNA Server, which allows you to create your own servers and set them up as you like: change their names, the port used, configure them to automatically launch with the device or when you connect to a certain Wi-Fi network, add the folders you wish to share, etc. Keep in mind that with an application like this, you won’t be able to reproduce web content (like YouTube) on the television from an Android device, but only those files that are physically on your device.

DLNA Server application for Android

DLNA Server application for Android

Now you know a little more about the different technologies for displaying the content of your smartphone or tablet on a television that has a Wi-Fi connection: depending on the said connection, you can use the Miracast wireless screen to duplicate the mobile device’s screen on the television, or use DLNA to wirelessly reproduce the multimedia files on the television.

Sources

Miracast

DLNA

Carlos Ávila is an information systems administrator with 10 years of experience in the field. Passionate about science and technology, he maintains his own blog which he uses to share his knowledge about the subject. He also collaborates with BQ, writing articles related to smartphones, tablets, networks and technology.