Mini DisplayPort to HDMI is a popular adapter because many high-profile computer brands, such as Apple and Dell, support DisplayPort (DP) and mDP. Most television manufacturers, on the other hand, do not. In some cases, such as is common with Dell, the computers have a DP, mDP and HDMI connection, as well as VGA and Mini and standard DVI. With Apple, however, it is very common for the computer to have mDP and Mini DVI and nothing else.
Mini DisplayPort is a scaled down version of the DP digital display interface standard. VESA developed DisplayPort as a digital audio/video intended for a computer and its display, or even a computer and a home-entertainment system. VESA did not develop the DP and mDP standards to compete with HDMI, and in fact, VESA and the rest of the computer industry, perhaps excluding Apple, have worked diligently at maintaining cross-compatibility.
Apple MacBooks do not support HDMI directly. MacBook owners who want to connect their laptops to their televisions must use either the mDP or the mDVI port. The advantage of using Mini DisplayPort to HDMI, as opposed to an mDVI adapter, is that DP and mDP support sound inherently. DVI does not, and in the case of Apple’s mDVI implementation, it operates just like a standard VGA port, meaning no support for sound or advanced features.
One of the most popular adapters on the market is the Kanex mDP-to-HDMI adapter. The only problem with the Kanex is that it tends to be a little on the pricey side, more than $50. On the upside, it is one of the cleanest ways to convert your mDP signal to 1080p and transfer it to your television. It even integrates digital/analog audio, which some Macs require, and you can save $20 or more if you’re willing to settle for analog sound only.
Some DP and mDP adapters, often called booster cables, even incorporate signal-boosting functionality. The purpose of a booster is that DP is susceptible to degradation over long cable stretches, much more so than the high-definition multimedia interface is. For those connecting a laptop to a TV, distance generally isn’t an issue. However, they can be helpful when you want to connect a desktop to a television in another area of the home or office.
Consumers should note that Apple did not always support sound in their mDP implementation, and therefore, you may need an audio cable in addition to the Mini DisplayPort to HDMI connection. Apple began adding sound support to the iMac and Mac Pros with ATI Radeon 5870 GPUs in 2009. For the rest of their lineup, they began adding it in 2010. Before buying anything, make sure you know precisely what your Mac does and doesn’t support.