In case display specifications and dongle-madness wasn’t confusing enough, here’s an example of a dodgy product to watch out for, by LESHP.
I have an older 2015 Macbook Pro 15″. It has 3 display outputs:
- 1x HDMI port (HDMI 1.4)
- 2x mini-displayport ports (DP 1.2)
Now, my laptop supports 4K on all ports. However, the HDMI port is only HDMI 1.4, which means that it only supports 4K at a fairly jittery 30Hz. For the full 4K 60Hz support (that is standard for 4K computer screens) a HDMI 2.0 port is required. Fortunately, the mini-displayport ports are DP 1.2, and that standard is capable of supporting 4K at 60Hz.
Since I wanted to use a HDMI monitor, I need to use an adapter, to convert the mini-displayport signal into to a HDMI signal.
Naturally, I turned to Ebay. Searching “hdmi 60hz 4k mini displayport” quickly reveals a number of cheap adapters for under $6 delivered. Most seem to be branded “LESHP” which is about as recognisable as it is pronounceable. Eventually these adapters arrived, but upon testing, they too would only allow me to select a 4K 30Hz resolution option on my Macbook Pro. What gives? Time for a closer inspection.
Pulling off the cover on the adapter, the main adapter chipset could be identified – a Lontium LT8611SX.
Looking up the datasheet for the LT8611SX chip used on this bargain-basement adapter, we find the specifications for this chip:
• DisplayPort Repeating
• HDMI V1.4/DVI V1.0 Level Shifting
• Support HDMI 2.0 4:2:0 format
Great, so it supports HDMI 2.0, which should mean 4K 60Hz. However, what does 4:2:0 mean? That is a Chroma Subsampling rate. With Chroma Subsampling, a 4K image can be transmitted with a much lower data rate. A normal image is Chroma 4:4:4 – or uncompressed. With Chroma 4:2:0, the information about what colour a pixel is, is shared between 4 other pixels! Or in other words, the colour resolution of the image is 3840×2160 divided by 4 … which is 1920×1080, or 1080P! Now, not all screens support displaying a Chroma 4:2:0 image. While some TV’s may work, very few computer monitors will work. This is because with anything other than Chroma 4:4:4, text on the screen becomes noticably pixelated.
As you can see in the image above, this is a big reduction in the clarity of coloured text, and a big deal for use on a computer. While this LESHP adapter may technically support 4K 60Hz with compressed 4:2:0 colour, this LESHP adapter does not support 4K 60Hz with normal Chroma 4:4:4.
This is deceptive marketing, and this product is wholly unsuitable for use on a computer. As a result, I obtained a refund from the eBay seller for my purchase. However, the product marketing has not changed, so I am writing this article as a warning for those looking for LESHP branded 4K display adapters.