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MHL - What It Is and How It Impacts Home Theater


Photo of an MHL-enabled HDMI Port

Photo of an MHL-enabled HDMI Port

Photo © Robert Silva - Licensed to About.com

Definition: With the advent of HDMI as the default wired audio/video connection protocol for home theater, new ways to take advantage of its capabilities are always being looked at.

At first, HDMI was a way to combine both high-resolution digital video (which also now includes 4K and 3D) and audio (up 8 channels) into single connection, reducing the amount of cable clutter.

Next came the idea of using HDMI as a way to send control signals between connected devices, without having to utilize a separate control system. This is referred to by several names depending on the manufacturer (Sony Bravia Link, Panasonic Viera Link, Sharp Aquos Link, Samsung Anynet+, etc...), but its generic name is HDMI-CEC.

Another idea that is now being implemented successfully is Audio Return Channel, which enables a single HDMI cable to transfer audio signals in both directions, between a compatible TV and Home Theater Receiver, eliminating the need to make a separate audio connection from the TV to a home theater receiver.

Enter MHL

A new feature that has been added to HDMI that extends it capabilities further is MHL, or Mobile High Definition Link.

To put it simply, MHL allows a new generation of portable devices, such as smartphones and tablets to connect to your TV or home theater receiver, via HDMI.

MHL ver 1.0 enables users to transfer up to 1080p high-definition video and 7.1 channel PCM surround audio from the compatible portable device to a TV or home theater receiver, via a mini-HDMI connector on the portable device and a full size HDMI connector on the home theater device that is MHL-enabled.

The MHL-enabled HDMI port also supplies power to your portable device (5 volts/500ma), so you don't have to worry about using up battery power to watch a movie or listen to music. Also, when not using the MHL/HDMI port for connecting portable devices, you can still use it a regular HDMI connection for your other home theater components, such as a Blu-ray Disc player.

MHL and Smart TV

However, it doesn't stop there. There are also has implications for Smart TV capabilities. For example, when you buy a Smart TV, it comes with certain level of media streaming and/or network functionality, and, although new services and features can be added, there is a limitation as to how much upgrading can be accomplished without having to buy a new TV to get more capabilities. Of course, you could connect an additional network media player or streamer, but that means another box connected to your TV and more connection cables.

To solve that problem, Roku has taken its media streamer platform, reduced it down to about the size of the USB Flash Drive, but instead of USB, it has incorporated an MHL-enabled HDMI connector that can plug into any TV that has an MHL-enabled HDMI port and, voila!, you now have a media-streaming capable TV, without that capability even having to be built-into the TV in the first place.

This "Streaming Stick", as Roku, refers to it, even comes with its own built-in Wifi connection interface, so you don't need one on the TV to connect your home network and the internet to access TV and movie streaming content - and you don't need a separate box and more cables either. Find out more about the Roku Streaming Stick.

MHL 3.0

On August 20, 2013, additional upgrades were announced for MHL, which is labeled MHL 3.0. The added capabilities include:

- 4K (Ultra HD/UHD) signal input support up to 30 fps (2160p/30)

- 7.1 channel Dolby TrueHD and DTS-HD surround sound support.

- Simultaneous High-Speed Data Channel accessibility.

- Improved Remote Control Protocol (RCP) with support for external devices such as, touch screens, keyboards, and mice.

- Power and charging up to 10 Watts.

- Compatibility with HDCP 2.2.

- Multiple Simultaneous Display support.

- Backward compatible with previous MHL 1.0 and 2.0 versions (including physical connections). However, devices with MHL versions 1.0 or 2.0 may not be able access version 3.0 capabilities.

MHL Compatibility Issues

Of course, for MHL to work, the HDMI connection your TV, home theater receiver, or Blu-ray Disc player needs to be MHL-enabled, and, although there weren't many as of the beginning of 2013, that number has increased since. In fact, a larger number of home theater receivers introduced during 2013 and 2014 are incorporating this feature, and they are also an increasing number of TVs.

However, even if your TV does not have an MHL-enabled HDMI port, that may not be a problem, if your home theater receiver, Blu-ray Disc player, or even your TV antenna (yes, I said that right - check it out here), has its own MHL-HDMI port, then it will be able to access the content and pass it along to a non-MHL-enabled TV.

More about MHL:

Accell MHL-to-HDMI Adapter

MHL-inputs on Blu-ray Disc Players

MHL-enabled Westinghouse TVs

The Official MHL Consortium Website

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