Since smartphones and tablets hardly produce the capabilities of a conventional PC, many users rightly want to connect it to an external display, whether it’s a TV or a standard monitor. You can do this for different purposes: to surf comfortably, if the full computer does not exist, to show presentations, and even watch movies directly from your smartphone or even from online services. However, until now there is no single standard for removing video and audio signals to TV, so we decided to find out how it can be done and what it will do.
One of the first possible standards for connecting smartphones to large screens is the High Definition Multimedia Interface (HDMI High-Definition Multimedia Interface) or HDMI. However, when in 2002 HDMI had just appeared, there was no talk of a handheld device: this standard is primarily intended for stationary TV and media players.
Later, when smartphones and tablets become mass products, standard HDMI connectors are reduced, leading to the emergence of two new types of connectors: mini HDMI and micro-HDMI. They are fully compatible with standard connectors, and you can connect devices with miniature connectors to external displays using a dedicated HDMI-mini-HDMI and HDMI-micro-HDMI cable, or a standard HDMI-HDMI cable with the correct adapter.
The development of HDMI standards involves several technology companies, among them – Philips, Hitachi, and Sony. It is interesting that each manufacturer pays a consortium for each device with HDMI support of 4 cents or 15 cents unless the standard logo is specified. In 2002, the first version of HDMI supported Full HD video transfer at 60 Hz, eight channel audio with 192 kHz (24 bits) frequency and provides a maximum bandwidth of 4.9 Gbps. Since then, HDMI’s capabilities have continued to evolve with the introduction of new specifications: the quality of streaming video and transmitted audio has increased, 3D support has emerged, and content protection has been introduced.
The latest HDMI specification, HDMI 2.0, which should soon be very popular, supports Ultra HD (3840x 2160 pixels) resolution video transmissions at 60 fps, or Full HD (1920×1080 pixels) in 3D, in a new party ratio – 21: 9. The new version of this standard also lets you transfer high quality 24 channel audio with sampling frequency up to 1536 kHz. The total bandwidth of cable HDMI 2.0 to 18 Gb / s.
Among the widespread HDMI advantages and unnecessary external power when connecting devices, as well as a free micro-USB port that you can connect peripherals. The main disadvantage of HDMI about smartphones, perhaps, can be called the need for separate connectors on the device body, which complicates the development of gadgets and increases their thickness. This deficiency is corrected in the MHL standard, which is HDMI based, and was initially developed with a focus on mobile devices.
The Mobile High-Definition Link development consortium includes Toshiba and Sony, who participate in the HDMI design, joining Samsung and Nokia.
MHL incorporates HDMI and micro-USB interface functionality: for HDMI, you can transfer high-definition video and audio, and use the micro-USB standard – charge the device. The MHL 3.0 specification, adopted in late summer 2013, allows you to transfer videos in Ultra HD resolution at 30 Hz, 7.1-channel sound with Dolby TrueHD and DTS-HD support, and charge up to 10 watts. The first device that supports MHL 3.0 is a Sony Xperia Z2 smartphone and tablet Sony Xperia Tablet Z2, presented at the MWC 2014 in Barcelona.
All MHL cables are usually divided into three types. The first and most common is a small adapter that has an HDMI input to connect the HDMI cable from the TV, micro-USB input for external power (without this, the output from the image will not work) and the micro-USB output to connect to the corresponding smartphone connector. This method is universal, but troublesome because it requires presence, in addition to the adapter itself, from two more cables.
This weakness is intended to eliminate new types of MHL cables that can directly connect HDMI TV output and MHL output from the smartphone. The smartphone battery is charged directly through the HDMI cable, and the device does not require external power, but this option is not supported by all TV models.
The third type of MHL cable is Samsung’s exclusive development, both can be found in the form of a separate adapter, and in other accessory structures, for example, docking stations. The main difference from standard MHL connectors is the use of additional contacts – 11 pins on a standard 5-pin micro-USB connector. This solution enables Samsung to extend the standard MHL functionality (for example, it is possible to connect peripherals) but makes a 5-pin connector with an incompatible 11-pin device without a special adapter, and vice versa, an 11-pin cable with all other smartphones.
The main advantage of the combined MHL combination compared to the “classic” HDMI – no need to use two mobile devices on a mobile device, as well as the ability to simultaneously charge the smartphone. The disadvantage is the inability to simultaneously use a USB host and MHL, which makes it impossible to connect to a gadget, for example, an external drive to watch a movie. Samsung does not have devices and accessories that are aware of USB host functionality through MHL, but this standard does not conform to other MHL devices.
The closest competing standard to MHL is the development of an Analogix company called SlimPort, which, in turn, is based on DisplayPort technology, developed by the VESA association.
The SlimPort feature is very close to the MHL specifications: 4K video and eight audio channels supported. In principle, SlimPort is also almost indistinguishable from MHL: the micro-USB connector is used as input on the smartphone, and a special adapter, similar to that used with MHL, is required to connect a monitor or TV with DisplayPort or HDMI support.
There is also a SlimPort adapter with micro-USB to VGA, but rather exotic, though it can be useful for someone.
Although there are some similarities, there is still a difference between the standards. First, SlimPort does not require external power for smartphones. Secondly, by using SlimPort, it was initially aware of the possibility of USB-host operation – the corresponding device can be connected directly to the SlimPort-HDMI adapter. Well, and thirdly, SlimPort, as well as DisplayPort, unlike HDMI, are free of any patent payments.
It is important to note that SlimPort is not compatible with MHL (although using the same micro-USB connector) and is less common. Currently, this standard is used on the latest Nexus 4 devices, including Nexus 4, Nexus 5 and Nexus 7 (2013), as well as some Chromebooks.
All previously described standards mean one or another way of physical connection of a smartphone to a TV, but now many manufacturers are trying to get rid of cables between devices. One of the most common ways that this can happen is Miracast Wi-Fi Direct, developed by the Wi-Fi Alliance, which has emerged relatively recently in 2012.
Miracast does not require the presence of additional transmitters on mobile devices, except the built-in Wi-Fi module, and interaction with the TV can be realized either via built-in Wi-Fi or through an external dongle connected to an HDMI connector. Standard Miracast has high speed, supports video transmission in resolution up to 1920×1200 pixels (no possibility to transmit current 4K images) and 5.1 Dolby AC3 channel sound.
Of course, the Miracast characteristic feels weaker than MHL or SlimPort. But this can not be called a significant weakness: at the moment some people may need to issue a better picture to the TV than is allowed by this standard. The main obstacle to using Miracast can be a mismatch of its implementation in various models of smartphones, TVs, and dongles. Given the current standard of Miracast does not exist for two years, can be expected in the near future will pursue cable competitors in terms of performance and become universal.
Wireless Display Technology or, in short, WiDi, developed by Intel, is proposed as an alternative to Miracast and because the WiDi 3.5 version is compatible. Characteristics of transmitted video and audio streams are also very close to Miracast: the maximum video resolution is 1080p and 5.1-channel surround sound.
Wi-Fi is more commonly found in modern notebooks with Intel processors, but in the smartphone and tablet market has not gained wide distribution, especially since gadgets like x86 on the shelf are not too many.
AirPlay is an exclusive technology developed by Apple only for its own devices that can function as content transmitters. You can receive and play content either through the Apple TV set box or through one of many compatible devices (including a media player, music center, and many other gadgets) that Apple claims. No additional configuration from requested users – enough that both devices are on the same local network.
Initially, the AirPlay protocol allows only transferring video and audio files from the appropriate app on your iPhone or iPod, but with the introduction of AirPlay Mirroring technology, which first appeared on iPad 2 and iPhone 4S, it became possible to display on widescreen images with live screens from smartphones or tablet. This, for example, lets you play on the big screen, display presentations, work with documents and perform many previous actions that were not available before.
This list of technologies is independent of the Mirrorlink and CarPlay protocols. They, though they function to connect smartphones with external displays, are not designed for use with TVs at home or at work, but for communication with the onboard automobile system.
Mirrorlink is a public standard that smartphone manufacturers can use on any platform. The connection to the car is done with the help of a USB cable, and on the computer screen on board, so it can be displayed only as an image of the smartphone display, and optimized for use in car applications.
Similarly, CarPlay works, except that this technology, like AirPlay, is very exclusive, and is only available for Apple mobile devices running iOS. When you connect an iPhone or other compatible devices to the car, a number of customized apps are available, including phones, maps, messages, and music. Manage programs in several ways, depending on whether their car manufacturers provide them – by using the onboard computer’s touchscreen, using the buttons on the steering wheel and dashboard, or using Siri sound.
It is great to be able to beam video directly from a tablet to your TV. The good thing about Android is that there are several ways to do this. Miracast is a wireless standard that creates an ad hoc network between two devices, usually your tablet and a set-top box that supports Micracast.
An increasing number of TVs supports Micracast without the need for extra hardware. Miracast uses H.264 for video transmission, which means efficient compression and good full-HD picture quality. Even better, Miracast supports DRM (Digital Rights Management), which means that services such as iPlayer and YouTube can be streamed to a TV. But not all services work. Android devices with Android 4.2 have Miracast support.
An alternative is Google’s Chromecast.This cheap dongle can be plugged into an unused HDMI port on your TV, and it connects to your wireless network. Chromecast support is becoming more ubiquitous, allowing content from services such as iPlayer, Netflix, etc. to play with the Chromecast while the dongle is doing all the work instead of your tablet, and that’s good news for your battery life.
Since July 2014, it is also possible to use Chromecast to flip the display on your Android device, allowing you to press Play on your tablet and play (DRM-free) video on your TV. The same applies to everything that the screen can display, including apps, games, and photos.
Apple users again have a simpler but more expensive solution. The iPad and iPhone do not support any open streaming standard, so you will have to purchase an Apple TV (about 95 euros). This supports AirPlay mirroring, exclusively from iOS devices, and just like Chromecast, it offers various streaming services including Netflix.
Which devices support Chromecast mirroring?
Mirroring on Chromecast is new, and the list of devices that support it is currently limited. Do you have one of the following devices? Then you are lucky.
- Nexus 4
Nexus 7 (2013)
Samsung Galaxy S4
Samsung Galaxy S5
Samsung Galaxy Note 3
Samsung Galaxy Note 10 (2014)
HTC One M7
LG G Pro2
The market presence of large numbers of cars with Mirrorlink and Carplay support is predicted to be in the second half of 2014, and more automotive companies will be introducing support for this protocol in the future.
Within this material framework, we can not consider any way to display images from the smartphone screen to an external TV or monitor. For example, there are various apps that let you duplicate a handheld device’s screen on a monitor connected to a PC. Nevertheless, we try to tell you about the most common and universal way, the knowledge that will be useful if you need to display it on a large screen presentation or just watch movies directly from your smartphone. We hope that the article has helped to understand the intertwining of different standards and they are sometimes compatible specifications: Each method has a number of pros and cons, therefore it is advisable to choose the one that you are most comfortable and easy to access.
Make sure it works
Streaming video from your smartphone or tablet to your TV will depend on the setup you have chosen. If you use a physical connection, such as HDMI, MHL or SlimPort, the content on the display of your tablet will appear on your TV as soon as everything is connected.
This is simple, but there are a number of drawbacks. Your tablet only sends a signal when the screen is on. This means that your battery is draining quickly, so chances are you will have to plug in the charger to ensure that it will not stop during the show.
If your tablet has a video that you have provided yourself, in the form of DRM-free files, you can use fine mirroring, and the same applies to commercial services such as Netflix, ITV Player, and iPlayer. But it is not all rosy. Content providers know that consumers will pay extra for the convenience of streaming TV series throughout the house.
If you go wireless, Miracast is currently the best option for display mirroring, as it simply transmits content on the screen of your Android device wirelessly. So when you open a photo on the screen of your tablet, it appears on your TV – just like with a physical connection such as HDMI. The same applies to many apps: BBC’s iPlayer, YouTube, and Vimeo all work via Miracast.
The disadvantage of Miracast is the same as with a cable connection: the screen of your tablet must be on all the time to make it work. That, combined with higher requirements for your device’s wireless radio (especially if you are streaming from the internet at the same time), can ensure that you have a much shorter battery life.