Connectivity – Last week, VESA released the details of its new 1.3 specification. This week, they revealed the updated protocol will be available in USB Type-C connectors. The protocol will also work on DisplayPort connectors and over HDMI connectors to a certain degree. If all this sounds confusing, it is. While the higher data rates and features are welcome news, the dizzying array of configurations with various levels of support is likely to only add confusion, not clarity. Maybe it is just me, but couple this with all the variations in competing connectivity protocols like HDMI, HDBaseT or USB, and how is any person to know what a source device supports, what the sink device supports or what the cable supports?
On the other hand, DisplayPort has good support in the IT community where it can drive high resolution displays quite easily. HDMI has a stronghold in consumer electronics, an area DisplayPort would like to play in. The new partnership with USB opens up a new way to compete in the CE market. It is now not inconceivable that USB 3.1 – with DisplayPort 1.3 – could become the next de facto connection standard for IT and consumer devices – and maybe even in some professional markets like broadcast and ProAV.
The announcement of the compatibility with the USB Type-C connector means that all the DP1.3 functionality, and more, can now be implemented using USB cables and connectors. And, the USB Type-C connector can also support much faster data transfer (think moving your pictures and videos around) using the SuperSpeed USB (USB 3.1) feature. Plus, the cable can deliver up to 100 Watts of power bidirectionally. USB 3.1 is designed to support device connections for the next 20 years on products like smartphones, tablets, PCs, notebooks, docking stations, cameras and peripherals.
The USB Type-C Alt Mode is an optional feature developed by VESA that can be used drive adaptors (protocol converters) that support the huge installed base of existing DisplayPort, HDMI, DVI and VGA displays. But only portions of the full DP1.3 spec can be supported. This is where it will get very tricky trying to figure out exactly what is supported for your particular devices. DisplayPort is also the transport standard used on DockPort, Thunderbolt, MyDP and Embedded DisplayPort and other wireless multi-function interface standards. Confused yet?
Like USB, DisplayPort uses a packetized data structure and differential AC-Coupled signal lanes that carry high speed data with an embedded clock. SuperSpeed USB data is designed to run at up to 10 Gbps per lane while DisplayPort 1.3 can support AV at up to 8.1 Gbps per lane (50% increase over DP 1.2). To run uncompressed video requires some overhead for the management, so what is available is 25.92 Gbps over all four lanes. This can be allocated in multiple ways, as we will see. The details of the DisplayPort 1.3 spec are available here.
Silicon to support the new 8.1 Gbps receivers and transmitters will not be available until 2015. Early implementations of DisplayPort Alt Mode USB Type-C devices will likely use existing DisplayPort 1.2a capabilities that support up to 5.4 Gbps per lane (another point of potential confusion). In the meantime, DisplayPort will be developing compliance test procedures so they can certify compliant devices and cables.
The new capabilities embodied in the DP1.3 spec and USB compatibility will open up a plethora of enhanced display and device interaction possibilities. For example, there is now enough bandwidth to drive new 5Kx3K (5120×2880) resolution monitors with a single cable without compression at 4:4:4, 8 bits/color and 60 fps.
Want to drive an 8K display? You will be able to do it using a single DP1.3 cable with 8 bits/color and 60 fps, but you have to drop the chroma sampling to 4:2:0.
But the standard allows for this bandwidth and data lanes to be allocated in different ways as well. For example, DP 1.3 has a Multi-Stream feature which means the connector can also drive two UHD (3840 x 2160) monitors at 4:4:4, 10 bits/color and 60 fps, or four FHD (1920 x 1080) monitors. These modes require the VESA video timing mode with reduced blanking.
Or, if using a USB Type-C connection, you could use a dock to drive one UHD monitor using two lanes, while simultaneously moving data using the USB 3.1 protocol on the other two lanes. Or, you can allocate all four lanes for data transfer. The dock can also be configured with DisplayPort protocol converters to support HDMI, VGA and/or DVI monitors. These options could be extremely handy in any home, post production or broadcast environment where ingest of content is an issue.
All this is possible because VESA worked with USB for a year to allow the DisplayPort Alt Mode to re-purpose some or all of the four existing USB SuperSpeed lanes to deliver full DisplayPort performance. It uses other signaling available in the USB Type-C connector for DisplayPort
