The Video Electronics Standards Association (VESA) has announced the latest release of the DisplayPort dual-mode standard. Among several refinements to improve interoperability, the updated standard enables a higher data rate for DisplayPort-to-HDMI cable adaptors, providing support for HDMI 1.4 display resolutions such as 1080p 3D at 60Hz, and ultra HD (4K-class) up to 30Hz frame rate, as well as 1080p with deep color.
“The first ultra HD displays were introduced in 2012, but today’s dual-mode DisplayPort-to-HDMI cable adaptors limit display resolution to 1080p. For a personal computer to fully support HDMI 1.4 or deep color, today a separate HDMI output is needed. This updated DisplayPort dual-mode standard version 1.1 enables full support of HDMI 1.4 video modes, and 1080p deep color, using a simple cable adaptor plugged into the system’s DisplayPort output. This helps to reduce the number of interface ports needed on a Personal Computer, which is desirable as form factors shrink,” explained Craig Wiley, the chairman of VESA.
Prior to the updated dual-mode standard release, dual-mode cable adaptors were limited to a TMDS clock rate of 165MHz providing support for display resolutions up to 1080p with 60Hz and 24 bits color. In this latest specification, a new dual-mode cable adaptor configuration is defined that enables a TMDS clock rate of up to 300MHz. While the DVI standard limits TMDS clock rates up to 165MHz, the HDMI 1.4 specification allows TMDS clock rates up to 297MHz, enabling the support of 1080p 3D at 60Hz, or ultra HD at up to 30Hz frame rate.
With the release of this new VESA specification, existing adaptors will now be referred to as “Type 1” adaptors, and the new adaptors as “Type 2”. A Type 2 adaptor will be backward compatible with an existing dual-mode DisplayPort source device, but it will only support up to a 165MHz TMDS clock rate unless it is used with a “Type 2 enabled” dual-mode DisplayPort source device. Some existing systems will be software updatable to support Type 2 adaptors. A Type-2 enabled dual-mode DisplayPort Source devices, together with a Type 2 dual-mode DisplayPort-to-HDMI adaptor, will enable support for HDMI 1.4 display modes such 1080p 3D at 60Hz, or UHD/4K at up to 30Hz frame rate, as well as 1080p with deep color. Type 2 adaptor prototypes are currently available from multiple suppliers.
In addition to releasing the DisplayPort dual-mode standard version 1.1, VESA is also releasing an updated DisplayPort dual-mode cable adaptor compliance test specification, version 1.1. Conformance to the updated compliance test specification, or CTS, is required for using the DisplayPort logo with a dual-mode cable adaptor.