New MacBook Pros and MacPro: 4K at high refresh rates via DisplayPort?
Thursday, 07 November 2013
Many Mac users are hoping Apple release a 4K monitor. They want a Thunderbolt-equipped display that can handle resolutions at at least 3840 by 2160 at high refresh rates.
The graphics system on the new MacBook Pros seems like a good intermediate step: They can support 3840 by 2160 at 30Hz and 4096 by 2160 at 24Hz via the built-in HDMI connector.
Today saw the an announcement from Canon of their first 30" 4K display. The DP-3010 is a 16:10 reference display for use in high-end post production. It can display 4096 by 2560 10-bit pixels at up to 60 frames per second.
Although it has two 3G/HD-SDI connections and a DisplayPort connection, it doesn't have an HDMI connector.
The HDMI standard was updated to version 2.0 in September, allowing for higher frame rates at higher resolutions, yet Canon didn't include HDMI. Sony's new Z100 4K camera has an HDMI connector that they plan to upgrade to version 2.0 using a firmware upgrade:
A future firmware upgrade is planned to provide compatibility with the new HDMI 2.0 standard and enable 4K 50fps/60fps output to a wider range of devices.
Up until now I've assumed that 4K at higher refresh rates on MacBook Pros and the new Mac Pro was a matter of waiting for an HDMI software upgrade. But, perhaps we don't have to wait.
There's a good chance that the display limitation MacBook Pros have is that of the connection used. HDMI 1.4 is limited to 24Hz at 4096 by 2160. What if a 4K was connected using the DisplayPort aspect of the Thunderbolt 2 connector?
The DisplayPort standard was last updated in 2009. The big change was to double the effective data rate to 17 Gb/s. It also added Apple's Mini DisplayPort connector design.
Thunderbolt connectors are based on the older Mini DisplayPort connector design. I'd like to see how well a new MacBook Pro connects to a 4K monitor with a DisplayPort connector. As Thunderbolt 2 cables can handle 20 Gb/s in two directions, there's a chance that they can handle the 21.6 Gb/s bandwidth required by by DisplayPort v1.2 (there is a 25% overhead for error correction).
There's a good chance the Mac will be able to drive the display at higher refresh rates: at 50 and 60 frames per second. The refresh rate limit isn't down to the graphics processing power of the Mac, but because of the connection used.
When you set the internal Retina display to be 'Scaled' to show 'More Space' the OS draws to an imaginary 3840 by 2400 pixel screen (double the perceived resolution of 1920 by 1200) and the GPU scales it down to the native 2880 by 1800 screen. The Iris Pro Graphics GPU can handle the high refresh rates expected on computer displays, so 50 or 60Hz might not be a problem
Has anyone tested a DisplayPort-equipped 4K monitor with a new MacBook Pro yet?
The combination of a fast DisplayPort connector plus an SSD that can read and write data at 1.1 GB/s makes me think these new MacBook Pros are a great testbed for making sure 4K works well on the new MacPro.