USB-C to 4k 120hz HDMI (or HDMI 2.1)

19 replies

I'm really excited about the new CAC-1085 (DisplayPort to 4k 120hz HDMI adapter) that just came out. Are there plans to make a USB-C to HDMI version for laptops with Ice Lake graphics?

Just looked at the catalog -- it looks like the CAC-1585 will be the product. Any thoughts on when this will come out?

I thought you meant it was available for purchase. It's not available yet

End of the month, so soon enough? Anyway, still wondering more about the CAC-1585!

This says something about compression. You can't get a true 4K 120 Hertz at 10 bit. You can however get 98 hz. I hope they haven't compressed the signal

Yes, you need DSC (display stream compression) to get beyond 4K@120hz@8bit or to get to 8K@60hz. DSC should be visually lossless though, and I’m curious to see proof of it.

4:4:4 is referring to the chroma sampling. DSC is totally different. All of the resolutions I mentioned would be at 4:4:4.

any type of compression is going to reduce quality. And yes I could tell the difference between 8-bit 4K 120 and 10-bit 4K 98

You should do your research on DSC, and maybe compression algorithms in general, before making any judgments on compression quality. It's totally orthogonal to chroma sub-sampling, bit depth, and frame rates.

Anyway, back to my original question, @MST1407, any indications as to when the CAC-1585 might come out?

net200777 wrote:

any type of compression is going to reduce quality. And yes I could tell the difference between 8-bit 4K 120 and 10-bit 4K 98

You cannot tell the difference between 8-bit with dithering YCbCr444 / RGB and 10-bit YCbCr444 / RGB in either HDR or SDR. However with YCbCr422 / YCbCr420 subsampling, you cannot use dithering and must use 10-bit for HDR.

the CAC-1585 will have a later delivery time - around end of August 

just curious what system do you want to connect it to? There arent that many USB C DisplayPort 1.4 Alt Mode solutions out there 

Thanks for the info! I was thinking that this adapter is targeted more at laptops that only have USB-C and no DisplayPort ports. Ice Lake supports DSC and DisplayPort 1.4, but I haven’t seen any info about Alt Mode. Tiger Lake is also coming out soon (probably similar August timeframe).

Well it's the end of the month, where is it?

Pittyh wrote:

Well it's the end of the month, where is it?

Looks like it's available at alternate.nl, but it hasn't made it to other countries yet (as of today).

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