Demand for high resolution across all displays is on the rise, explaining why industry attention today has moved beyond HD to 4K and Ultra HD displays with sights set on the 8K ecosystem ahead.
So why not just add 4 times the pixels of Ultra HD call it a day? Unfortunately, the high data rate required for connectivity makes 8K resolution more complicated than simply adding pixels.
Consider an 8K image may:
- display up to 120 frames per second (fps)
- require a minimum of 10 bit color
- require the color sub-sampling 4:4:4, 4:2:2, or 4:2:0
One common example of this is an RGB signal with 8K pixels, 10 bits of color, 4:2:0 color sub-sampling, and 60 fps equaling 29.86 gigabits per second (Gbps), which would require significant compression to distribute.
So what kind of connectivity options are capable of supporting 8K resolution?
- HDMI version 2.1 will raise the data rate from 18 Gbps to 48 Gbps with four lanes of 12 Gbps, 16-18 bit encoding, reducing the usable bandwidth to 38.4Gbps. Display Stream Compression (DSC) will also be supported, allowing 8K, 16 bit, 4:4:4 at 60 fps or 8K, 16 bit, 4:2:0 at 120 fps. Plus, the connector will remain the same for backward compatibility.
- DisplayPort version 1.3 boasts a transmission bandwidth of 32.4 Gbps with the new HBR3 mode allowing 8.1 Gbps per lane. After considering the 8-10 bit encoding, the total data rate comes to 25.92 Gbps, making it capable of supporting an 8K at 30 fps with either 12 bit 4:2:2 or 16 bit 4:2:0.
- DisplayPort version 1.4 added support for DSC 1.H, Forward Error Correction, static metadata extension support for High Dynamic Range (HDR), and the Rec. 2020 color space. This means that with HBR3 transmission rates, it can support 8K, 16 bit, 4:2:2 at 60 fps or 8K, 12 bit, 4:2:0 at 120 fps with HDR and a wide color gamut (WCG). At this time, don’t count on support for dynamic metadata, but consider it an option in the near future.
- SuperMHL was designed for 8K video support over a single cable. There are 6 data lines each running at 6 Gbps, reaching a raw data rate of 36 Gbps. With the addition of DSC, the bandwidth increases 3x, however when you factor in data error correction, you can expect the useable bandwidth to be about 86.4 Gbps.
- Thunderbolt 3 allows 40 Gbps (doubling the combined data rate of the previous version), while cutting the power consumption in half, allowing up to 100W of power to be delivered via the new USB Type-C connector. (Keep in mind, this is typically used on Apple devices and Apple does not support 8K at this time.)
USB 3.1 includes support for Type-C including Alt Mode, which enables support for the connectivity options we previously discussed (DP 1.3\1.4, SuperMHL and Thunderbolt 3). It also supports DSC. As the demand for 8K increases, we expect to see continuing efforts to improve support for the increased bandwidth requirements within the next few years. While the industry is currently focused more on 4K resolution, 8K is just around the corner and connectivity options are already out there to support the 8K Video Wall of your dreams!