The HDMI 2.1 specification was released a long time ago and now, at the end of 2020, the first graphics cards that support it are arriving and the TVs did not reach the market too many months ago, not to mention the consoles. But after this new specification there is still a very interesting question, how does it manage to overcome the 144 Hz barrier? and above all, how have they increased the resolution? There is a technology that makes it possible to a great extent and on which it seems that the next versions of this interface will be built: Fixed Rated Link.
Some time ago we talked about compression technologies for images, frames and others, where, as we have already seen, going from 4K @ 120 requires a method that compresses the data to be able to send it at the maximum speed that the standard supports. In that case it was DSC, but now we have to talk about another technology that does follow the standard and that has managed to do this, but to a lesser extent.
Fixed Rate Link, what is it and how does it help HDMI 2.1?
FRL is the acronym for Fixed Rate Link and as such is a signaling technology that together with the HDMI 2.1 specification makes it possible to increase the resolution and the Hz that the panel will show, all without compressing up to the 48 Gbps of rigor that marks the standard.
According to HDMI, it is also necessary for the transport of compressed video, since it allows the operation of lower data rates, or ultra-high speed video, such as 10K @ 120.
There is not much information on how FRL actually manages to do everything we have discussed, as it seems quite opaque technology, to the point that the organization itself claims that it directly replaces TMDS , although the specification still requires the latter to keep up with it. backward compatibility and millions of HDMI devices.
Will manufacturers add FRL by updating their devices?
Unfortunately, for a team, a component to work with FRL, the manufacturer must design the chip from scratch, that is, it must be supported from the silicon, from the architecture. Therefore, it will not be possible to include FRL in previous specifications of the HDMI standard and we will have to make the leap to HDMI 2.1 at least if we want to enjoy its benefits.
In addition, to support FRL it is necessary that the adjacent hardware also supports it, so it seems that it is a set, an ecosystem that has to define whether it supports it or not, although it is then included as such in plain HDMI 2.1.
Do not confuse or try to compare DSC with FRL, since, although they achieve a similar result in theory, the way to achieve it in practice has nothing to do with it, mainly because one compresses without loss and the other needs to get rid of information to scalar, which generally subtracts colors from the frames represented on the screen.
As we have seen, the problem of HDMI 2.1 starts from 120 Hz up, hopefully the new specification uncompressed achieve up to 240 Hz to 4K with a new version of Rated Fixed Link.
