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AMD Variable Refresh "FreeSync" Could Be Alternative to NVIDIA G-Sync

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Manufacturer: AMD

DisplayPort to Save the Day?

During an impromptu meeting with AMD this week, the company's Corporate Vice President for Visual Computing, Raja Koduri, presented me with an interesting demonstration of a technology that allowed the refresh rate of a display on a Toshiba notebook to perfectly match with the render rate of the game demo being shown.  The result was an image that was smooth and with no tearing effects.  If that sounds familiar, it should.  NVIDIA's G-Sync was announced in November of last year and does just that for desktop systems and PC gamers.

Since that November unveiling, I knew that AMD would need to respond in some way.  The company had basically been silent since learning of NVIDIA's release but that changed for me today and the information discussed is quite extraordinary.  AMD is jokingly calling the technology demonstration "FreeSync".

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Variable refresh rates as discussed by NVIDIA.

During the demonstration AMD's Koduri had two identical systems side by side based on a Kabini APU . Both were running a basic graphics demo of a rotating windmill.  One was a standard software configuration while the other model had a modified driver that communicated with the panel to enable variable refresh rates.  As you likely know from our various discussions about variable refresh rates an G-Sync technology from NVIDIA, this setup results in a much better gaming experience as it produces smoother animation on the screen without the horizontal tearing associated with v-sync disabled.  

Obviously AMD wasn't using the same controller module that NVIDIA is using on its current G-Sync displays, several of which were announced this week at CES.  Instead, the internal connection on the Toshiba notebook was the key factor: Embedded Display Port (eDP) apparently has a feature to support variable refresh rates on LCD panels.  This feature was included for power savings on mobile and integrated devices as refreshing the screen without new content can be a waste of valuable battery resources.  But, for performance and gaming considerations, this feature can be used to initiate a variable refresh rate meant to smooth out game play, as AMD's Koduri said.

Continue reading our thoughts on AMD's initial "FreeSync" variable refresh rate demonstration!!

All that is needed for this to work, as AMD explained it, was an eDP connection between the discrete GPU and the display, a controller for the screen that understands the variable refresh rate methods of eDP 1.0 specifications and an updated AMD driver to properly send it the signals.  The panel can communicate that it supports this variable refresh technology to the graphics card through the EDID as resolutions and timings are communicated today and then the graphics driver would know to send the varying vblank signals to adjust panel refresh times on the fly.

If you aren't familiar with eDP, don't feel bad.  It's a connection type used in tablets and notebooks and isn't used at all in desktop configurations (some all-in-one designs do use eDP).  But here is where it might get interesting: the upcoming DisplayPort 1.3 standard actually includes the same variable refresh rate specification.  That means that upcoming DP 1.3 panels COULD support variable refresh technology in an identical way to what we saw demoed with the Toshiba laptops today.  DP 1.3 is on schedule to be ratified as a standard in the next 60-90 days and from there we'll have some unknown wait time before we begin to see monitors using DP 1.3 technology in them.

To be clear, just because a monitor would run with DisplayPort 1.3 doesn't guarantee this feature would work.  It also requires the controller on the display to understand and be compatible with the variable refresh portions of the spec, which with eDP 1.0 at least, isn't required.  AMD is hoping that with the awareness they are building with stories like this display designers will actually increase the speed of DP 1.3 adoption and include support for variable refresh rate with them. That would mean an ecosystem of monitors that could potentially support variable speed refresh on both AMD and NVIDIA cards.  All that would be needed on the PC side is a software update for both Radeon and GeForce graphics cards.

Koduri told me that AMD wasn't bringing this demo out to rain on NVIDIA's G-Sync parade but instead to get media interested in learning about this feature of eDP 1.0 and DP 1.3, urging the hardware companies responsible to more quickly produce the necessary controllers and integrate them with upcoming panels in 2014.  While I don't doubt that it is the case for AMD, I'm sure the timing of the demo and NVIDIA's G-Sync releases this week were not an accident.

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The question now is one of release windows.  Even if the DisplayPort 1.3 standard supports variable refresh rates and controllers that will understand it are coming down the pipe, we don't know when.  The standard is set to be ratified some time soon but Koduri believes that the various parties involved are going to be ready with hardware to drop in place right away.  I hope he is right, as the mess surrounding support for DisplayPort 1.2 MST hubs to split off display connections from PCs took literal years to be resolved.  If that happens again, AMD Radeon users could be without support for variable refresh rates and NVIDIA GeForce users would be eating up G-Sync panels from the shelf.

Koduri did admit that NVIDIA deserved credit for seeing this potential use of the variable refresh feature and bringing it to market as quickly as they did.  It has raised awareness of the issue and forced AMD and the rest of the display community to take notice.  But clearly AMD's goal is to make sure that it remains a proprietary feature for as little time as possible.

As it stands today, the only way to get variable refresh gaming technology on the PC is to use NVIDIA's G-Sync enabled monitors and GeForce graphics cards.  It will likely take until the ratification and release of DisplayPort 1.3 monitors before AMD Radeon users will be able to enjoy what I definitely believe is one of the best new technologies for PC gaming in years.  AMD is hopeful it will happen in Q3 of 2014 but speed of integration has never been a highlight of the DisplayPort standard.  NVIDIA definitely has an availability advantage with G-Sync but the question will be for how many months or quarters it will last.

Finally, as a last minute stirring of the pot, I received an email from AMD's Koduri that indicated that there might be some monitors already on the market that could support variable refresh rate TODAY with just a firmware update.  This would be possible if a display was shipping with a controller that happened to coincidentally support variable refresh, perhaps in an early stage of development for the upcoming DP 1.3 standard.  We are trying to find a list of these monitors so we can talk with them and ask for these necessary changes.  

January 8, 2014 | 01:02 AM - Posted by JohnGR (not verified)

"the upcoming DisplayPort 1.3 standard actually includes the same variable refresh rate specification"

While the article does have some thoughts about this, I would ask this:

Should we say "thank you Nvidia" for this one?

or should we just start shouting at Nvidia for not promoting something that it is there and free in cooperation with AMD and the monitor manufacturers, but trying to sell another proprietary technology for some extra cash out of something that it is/should be free?

If you do find a couple of monitors that support it and you and the rest of the press make a few articles about freesync around these monitors, things could accelerate fast with no extra help. Those monitors could start selling like hot cakes pushing manufacturers to start putting freesync as an extra feature.

January 8, 2014 | 01:25 PM - Posted by arbiter

Sadly free sync is not as "free" as AMD claims. Need a monitor with a DP it looks like from the info on it first and even then not 100$ sure its support so either way new monitor is likely needed. Won't get in to triple buffering that they say that is needed to use it which does use more vram.

January 9, 2014 | 10:42 AM - Posted by Anonymoose (not verified)

why, thank you sherlock, or shall i say captain obvious?

you need a new monitor. wow.

and with gsync you... need a new monitor as well. which is gonna cost you $100+ (rather 150-200) ...PREMIUM on top of what the monitor normally costs.

i'll take the "free" thing if it "costs" me less and does the same and i have to wait a few more months.

January 8, 2014 | 01:40 AM - Posted by Silver Sparrow

From the way I see it, we should tip one's hat to nvidia by using a tech for power saving to fix a problem that shouldn't have existed with the advent of flat screen panels and highlight how these standards are holding us back from having tear free gaming experience by bringing out G-SYNC promptly.

Also, slap (not a punch, not entirely their fault) them across the face for charging a fistful of dollars (lol!) for proprietary tech that solves the problem that a firmware update and a full/proper adoption of vesa standards by panel manufacturers would solve just as well.

In any case, I'm eagerly awaiting the first 1.3 DP VRR enabled 4k gaming panel for under $1000. Good times ahead :D

Keep up the good CES coverage!

January 8, 2014 | 01:41 AM - Posted by renz (not verified)

is there any real game demo running free sync yet?

January 8, 2014 | 03:56 AM - Posted by Prodeous

Since NVIDIA is involved in VESA consortium, they fully were aware of 1.3 standard and this new feature. The one part that I will grant them is they figured out how to fix something that shouldn't exist in the first place. So kudos to Nvidia for that. But a kick in the shin for overcharging for a upcoming VESA standard>

One thing to keep in mind is that every company will use any opportunity to make money. And this is Nvidia's shot.

Here is hope to 1.3 becoming available soon, and hope that my HP just needs a firmware FLASH :P

January 8, 2014 | 04:16 AM - Posted by Anonymous (not verified)

What Nvidia did is design and implement the first D P1.3 controller that supported variable update rates with minimal buffering. By doing this, it makes more sense for display manufacturers to buy Nvidia IP for their controller rather than developing their own controllers (asynchronous panel updating is much trickier than synchronous updating).

January 8, 2014 | 04:16 AM - Posted by General Lee (not verified)

If there are monitors that have preliminary DP 1.3 support, it will only be the newest monitors.

I'm still a bit confused on the claims by Nvidia that this would require a new ASIC and none exist yet outside G-Sync (even though it's not really an ASIC).

In any case I'm doubtful that even if there was a monitor out there with the necessary support they would be interested in bringing out a firmware update unless AMD makes a deal with them. And AMD still needs to do some work to expose the feature in CCC.

Hopefully though we'll get DP 1.3 quick and the monitor manufacturers will make all the DP 1.3 monitors support the dynamic refresh rates by default.

January 8, 2014 | 04:53 AM - Posted by gamerk2 (not verified)

Anyone with details on how this is actually going to be implemented?

My primary concern here, is since you don't what what FPS you are going to have in games, is that you can't set up the Vblank interval ahead of time. As a result, wouldn't AMD have to wait for the frame to finish to set everything up? That would introduce lag, that wouldn't be present using Gsync (in theory anyway).

January 8, 2014 | 05:47 AM - Posted by Anonymous (not verified)

I may be wrong, but the only difference between Gsync and freesync is that G-sync needs you to buy a 200$ frame buffer to add to a monitor while freesync uses a frame buffer that's already available on the AMD card.
They said that's why G-sync needs the extra hardware, because Nvidia cards don't have the built-in ability to use an extra frame buffer while AMD cards do since the 5000 series. That and AMD has a patent on variable refresh on cards since years ago so Nvidia has to use external hardware to do the job.

Also note: There's no way for Gsync to know what FPS you're going to have in games either, that's what the frame buffer on the monitor is for, to hold the present frame while the monitor draws the previous one.

January 8, 2014 | 08:03 AM - Posted by Ryan Shrout

I don't think the memory on the G-Sync module is used for that exactly, but I'm not sure.  I'll ask today!

January 8, 2014 | 08:40 AM - Posted by Anonymous (not verified)

Thanks!

January 8, 2014 | 02:34 PM - Posted by Anonymous (not verified)

Poor-mans laggy GSYNC imposter.

January 8, 2014 | 02:57 PM - Posted by Anonymous (not verified)

G-Sync is a rip off of

Panel Self Refresh
http://www.hardwaresecrets.com/article/Introducing-the-Panel-Self-Refres...

Intel Seamless Display Refresh Rate Switching
http://liliputing.com/2012/04/intel-future-could-use-less-power-panel-se...

LG wanted to introduce this (G-Sync Module) tech back in 2011
http://www.youtube.com/watch?v=rdfomYGi1dk

All you would need is AMD & Nvidia to have compatible drivers and everyone could enjoy the tech.

January 8, 2014 | 05:10 AM - Posted by Edkiefer (not verified)

From what has been described so far, to me we should check how AMD software mode affects fps hit . It seems there driver would have to guess at frame rate and send signal to display .
If I remember right G-sync had a very small hit of fps .

I think we need to wait are really use it so compare how each work, performance wise .

January 8, 2014 | 05:50 AM - Posted by Anonymous (not verified)

G-Sync does have a performance hit at the moment. This comes from a polling that occurs in the current implementation. Nvidia have stated that they intend to remove the need for the polling in a future revision.

January 21, 2014 | 02:21 AM - Posted by Relayer (not verified)

Yeah, they'll remove the need with DP1.3 like everyone else. ;)

January 8, 2014 | 05:33 AM - Posted by Anonymous (not verified)

AHHHH we need more info!
Why are AMD always so silent and ambiguous about everything!
Just compare the G-sync and freesync demos:

Gsync: Big HD screens, huge crowds, armies of journalists, and a PR friendly presentation that purely uses nontechnical words: "The world will be a big thuper happy plathe where nobody will ever have thtutter and tearing! Mmm, mmm, mmm!"

Freesync: A couple of laptops on a table and one or two journalists see a small demo, and no info is given whatsoever, even engineers are left to speculate how freesync exactly works (most often incorrectly, like those idiots at TechPowerUp)

January 8, 2014 | 07:21 AM - Posted by Anonymous (not verified)

Does DP 1.3 fix this?

"After the GPU renders a frame with G-Sync enabled, it will start polling the display to see if it’s in a VBLANK period or not to ensure that the GPU won’t scan in the middle of a scan out. The polling takes about 1ms, which translates to a 3 - 5% performance impact compared to v-sync off."

January 8, 2014 | 09:46 AM - Posted by Rickard Eneqvist (not verified)

GSync has the added benefit of being able to shuffle things over to the monitor HW without having to wait for VBlank.

Thus you save some data transfer times and you can do buffer management on the monitor HW which releases some resources on the GPU.

Not sure if this will have a huge impact tho but the argument can be made. Also the argument can be made that this would cause frames to me slightly ouf of sync due to differences in render time and display time (but hey this is true for any prerender system and not something that one should "see").

January 8, 2014 | 02:31 PM - Posted by Anonymous (not verified)

Sounds like you need too much stuff and it`s not as good as GSYNC.

April 15, 2014 | 10:11 AM - Posted by Anonymous (not verified)

Need too much stuff? As in... A DP 1.3 monitor? GSync needs a DP monitor with the special Nvidea chip, it needs more...

January 8, 2014 | 02:32 PM - Posted by Anonymous (not verified)

Reeks of desperation on AMD`s part just to get some press.

January 8, 2014 | 02:57 PM - Posted by Ryan D. (not verified)

And to take away some of the attention around G-Sync lol. Poor AMD...

January 8, 2014 | 05:12 PM - Posted by Anonymous (not verified)

AMD blog response

Doing the work for everyone
http://community.amd.com/community/amd-blogs/amd-gaming/blog/2014/01/08/...

"We’re passionate about gaming, and we know that the biggest advancements come when all industry players collaborate. There’s no room for proprietary technologies when you have a mission to accomplish. That’s why we do the work we do, and if we can help move the industry forward we’re proud to do it for everyone."

Fighting words those are. LOL

January 9, 2014 | 06:39 AM - Posted by Ryan D. (not verified)

They're looking for sympathy? Pathetic...

January 10, 2014 | 09:48 AM - Posted by John D. (not verified)

No, they're looking to offer something for free that Nvidia is trying to charge an arm and a leg for.

As usual.

January 8, 2014 | 10:42 PM - Posted by Snd69 (not verified)

What we need besides of ETA is more gaming oriented tests, if FreeSync has vsync zones(20-30fps for 60hz) just like gsync it may be a huge problem for APU gaming

January 8, 2014 | 11:55 PM - Posted by ThorAxe

DisplayPort has been on GPUs since around 2009 yet how many monitors actually feature it?

Free Sync? More like Wishful Syncing.

January 9, 2014 | 06:40 AM - Posted by Ryan D. (not verified)

LOL

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