Getting 4K Content to 4K Screens
Athough there is justifiable excitement around 4K or Ultra HD-resolution displays, the screen itself is just the beginning. There is a growing realization that the 4K ecosystem around these displays — made of up of capture devices, players, PCs, content and connectivity — will directly impact the rate of market adoption.
I met with Planar’s Steve Seminario, senior director of product marketing, to discuss what he’s learned about 4K commercial displays.
Question: Working back from the display itself, driving a 4K screen with 4K content is a matter of connectivity and source. What are you seeing as the most popular ways to drive a 4k display or video wall?
Steve: Connecting a 3840 x 2160 resolution source to a 4K display typically involves some combination of HDMI and DisplayPort connections, both of which can receive a 4K signal over a single connection. Beyond resolution, each platform and version of the standard has a supported refresh rate and color depth. We’ve published a table online for reference. As an alternative to single-link 4K connections, some displays are able to receive a synchronized group of two or four connections in order to process and display a 4K source.
While it would be ideal to be able to take a full 60Hz 4K signal with 10-bit color over a single connection, the implementations are really not there yet today, and practically speaking, slower refresh rates and multi-connection configurations that are available now generate excellent 4K results with most content.
Question: You didn’t mention arguably the most popular digital output in the market. What do integrators do if they want to hook up a source with a DVI output to a 4K display?
Steve: With today’s graphics cards, content servers and video processors supporting a combination of HDMI, DVI, SDI and DisplayPort outputs, it is not uncommon to have to covert one signal type to another. Luckily, there are converters available today and those choices continue to grow in the market. Some conversion is passive, meaning there is a compact device requiring no external power. While others are active, or powered, in which case the conversion device will be larger, require a power source and typically be more expensive. The general rule of thumb is that newer, higher-bandwidth connectors like HDMI and DisplayPort can passively convert to older standards like DVI or SDI, but in order to go the other way around, it requires active conversion. Again, we’ve posted a table of common conversion types.
Question: I know integrators are often required to experiment to see what will work to drive different types of content — still imagery, high-speed video thats uses different codecs, processor-intensive applications that utilize real-time rendering or touch interactivity, 3D and beyond. What other things affect 4K performance that integrators should be aware of?
Steve: All the things you mention play a role. We’ve found variations among the playback quality of different operating systems — even on the same PC hardware — different player software, different video codecs or compression algorithms and, naturally, different graphic cards or processors.
Cable length is another factor. HDMI and DisplayPort standards do not specify a maximum cable length, so testing and experimentation are required. In our experience, using good-quality cables, we have been able to successfully support HDMI up to 40 feet at 3840×2160 at 30 or 60 Hz. DisplayPort is more like 10 feet, based on our own testing. Extenders are available in the market for both HDMI and DisplayPort, but today there are certainly more choices available for HDMI because of its widespread use. Extenders utilizing coax, HDBaseT and fiber cabling support different run distances and are priced accordingly.
Question: What’s next for 4K connectivity?
Steve: Another area of rapid development is around network connectivity. For network streaming of 4K, the H.265 HEVC (High Efficiency Video Coding) draft standard approved in July 2012 has set off a flurry of industry development, particularly related to the broadcast industry. Designed with 4K and 8K resolutions in mind, the H.265 HEVC standard promises to double the compression efficiency of H.264 encoding broadly used today. At the NAB 2013 tradeshow, a number of companies discussed or demonstrated prototype implementations. While today, IP network transport of 4K video is still a future, it is one that has a lot of momentum behind it.