AMD asks VESA to allow changes to support FreeSync

AMD Catalyst driver

AMD has demonstrated that it can, with little changes in hardware, emulate the same ability as Nvidia’s GSync technology to allow for variable refresh rates to be opened to any hardware capable of altering the VBLANK refresh interval in supported monitors. Although the idea is old and has been around for quite some time, it’s only taken off very recently, thanks to Nvidia, as a solution to all the aches and pains of being a PC gamer with a regular 60Hz monitor.

Now it seems that waiting for the Displayport 1.3 standard to be adopted will be a slow process and AMD seemingly cannot wait on monitor manufacturers to implement the feature to all future products. It has approached the VESA standards board for approval to a change in the DP 1.2 specification, moving to DP 1.2a for the time being, allowing it to support variable VBLANK intervals in both hardware and software.

The request made by AMD was done on 25 November 2013 and this is only a few weeks out of Nvidia’s GSync reveal at their event held in Montreal, Canada in late October 2013. Its clear that AMD moved a couple of mountains to be able to get their documentation in order so quickly and its likely that the GSync announcement caught them completely off-guard.

Still, they had a working implementation of similar technology already and they also displayed it at CES 2014, running on two low-end laptops with some modified drivers. Implementing FreeSync, as AMD likes to call it, isn’t a difficult thing, but it will take some time for monitor manufacturers to support the VESA standard for it. What AMD hopes to do in the meantime, though, is hack their way into supporting it.

Two AMD-powered laptops - the one on the left has Freesync enabled and no hardware changes were made.
Two AMD-powered laptops – the one on the right has Freesync enabled and no hardware changes were made.

In a notice to the VESA standards body of their intention to add to the Displayport standard, AMD writes that their workaround requires that the GPU and drivers ignore the monitor’s EDID information through the use of Single-Stream Transport (SST) or Multi-Stream Transport (MST) Displayport hubs, currently being sold by a few companies to enable Radeon owners to use three monitors on one Displayport 1.2 connection.

Using a SST or MST hub, AMD would be able to bypass the monitor’s restrictions set in the EDID and enable the ability to ignore the monitor’s internal timing parameters. They would then be able to use timing parameters sent by the GPU which would alter the VBLANK intervals that the monitor uses for internal timing.

Sadly, there’s no guarantee that VESA will allow AMD to move forward with the idea. Displayport hubs are currently over a grand at retail and if you still need to buy another monitor for it, you may as well be looking at GSync instead for all the good this is going to do you. Although this standards change would allow Intel to also take advantage of the feature, Nvidia won’t be supporting it for fear of invalidating the work they’ve put into making their own scaler chips.

FreeSync, then, is only going to be here once new monitors support it after VESA publishes the Displayport 1.3 specification in the second quarter of 2014. We’re all going to have to wait until then to see how things play out.

Further reading: Lets Discuss: Variable Refresh Rates


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