USB Type-c and HDMI


HDMI Licensing, the company that defines hardware rules for HDMI cables, announced today that it's releasing an HDMI Alt Mode for USB-C products. The specification allows for USB-C-to-HDMI cables to be made with no need for extra dongles or converters, and allow compatible devices to output video directly from a USB-C device to an HDMI display. This means that smartphones, tablets, laptops, cameras, and any other devices with a USB-C port can be built to directly output video to any HDMI display with a single cable.

Alt Mode, which stands for Alternative Mode, allows non-USB signals to be carried through a USB-C cable. Other USB-C Alt Modes support DisplayPort, MHL, and Thunderbolt. USB-C devices that support these Alt Modes can then, with the correct USB-C cable, transfer those signals in addition to regular USB data.


And while the option for USB-C to HDMI connections is certainly convenient, this is significant for another reason as well. While HDMI cables are probably extremely familiar products to most people, there are actually three different consumer HDMI cable types: HDMI Type A, which is the full-size HDMI connector you know and love; HDMI Type C, known as Mini HDMI, a smaller connector designed for smaller portable devices (like cameras and tablets) to be able connect to displays without wasting the physical space of a Type A port; and HDMI Type D, also called Micro HDMI, the smallest physical port that can typically be seen on recent smartphones and cameras. Previously, connecting from a Mini or Micro HDMI device to a larger display required having the specific adaptor handy, as well as requiring an additional port on devices, something that the HDMI Alt Mode could finally solve by offering a consistent and common connection.


There are a few catches to the HDMI Alt Mode, however: the specification uses the older HDMI 1.4b standard, instead of the newer HDMI 2.0b, meaning that HDMI Alt Mode for USB-C connections will be able to output up to 4K resolution, 3D video, and support HDMI-CEC, but won’t offer things like HDR video and other HDMI 2.0b features.

HDMI has already released the specifications for HDMI Alt Mode for USB-C to its manufacturing licensees, so devices and cables supporting the standard could already be in the works.

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