AMD demos FreeSync (free G-Sync alternative) [AnandTech]

Talk about AMD's FreeSync and VESA AdaptiveSync, which are variable refresh rate technologies. They also eliminate stutters, and eliminate tearing. List of FreeSync Monitors.
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nimbulan
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Re: AMD demos FreeSync (free G-Sync alternative) [AnandTech]

Post by nimbulan » 07 Jan 2014, 15:15

Chief Blur Buster wrote:One conceptual example of triple buffering:
(1) Front buffer that the display is reading from, while display is scanning out the refresh.
(2) Back buffer waiting to flip to refresh.
(3) Rendering buffer, which replaces whatever is in the back buffer.
How would this situation of the back buffer waiting for a refresh ever arise when using G-sync? The front buffer is displayed immediately, which will take between 1/60s and 1/144s depending on your settings. It will take longer than that to render to the back buffer unless your PC is capable of generating in excess of the refresh rate, but G-sync caps to the refresh rate anyway so it should never be necessary to have 3 buffers.

Haste
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Re: AMD demos FreeSync (free G-Sync alternative) [AnandTech]

Post by Haste » 08 Jan 2014, 05:46

Interesting article in Pc Perspective by Ryan Shrout:

link: http://www.pcper.com/reviews/Graphics-C ... DIA-G-Sync
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.
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.
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.
AMD is hopeful it will happen in Q3 of 2014 but speed of integration has never been a highlight of the DisplayPort standard.
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.
And another one by Scott Wasson from The Tech Report:

link: http://techreport.com/news/25878/nvidia ... -sync-demo
On the show floor here at CES today, I spoke briefly with Nvidia's Tom Petersen, the executive instrumental in the development of G-Sync technology, about the AMD "free sync" demo we reported on yesterday.
Petersen quickly pointed out an important detail about AMD's "free sync" demo: it was conducted on laptop systems. Laptops, he explained, have a different display architecture than desktops, with a more direct interface between the GPU and the LCD panel, generally based on standards like LVDS or eDP (embedded DisplayPort). Desktop monitors use other interfaces, like HDMI and DisplayPort, and typically have a scaler chip situated in the path between the GPU and the panel. As a result, a feature like variable refresh is nearly impossible to implement on a desktop monitor as things now stand.

That, Petersen explained, is why Nvidia decided to create its G-Sync module, which replaces the scaler ASIC with logic of Nvidia's own creation. To his knowledge, no scaler ASIC with variable refresh capability exists—and if it did, he said, "we would know."
When asked about a potential VESA standard to enable dynamic refresh rates, Petersen had something very interesting to say: he doesn't think it's necessary, because DisplayPort already supports "everything required" for dynamic refresh rates via the extension of the vblank interval. That's why, he noted, G-Sync works with existing cables without the need for any new standards. Nvidia sees no need and has no plans to approach VESA about a new standard for G-Sync-style functionality—because it already exists.
Monitor: Gigabyte M27Q X

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nimbulan
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Re: AMD demos FreeSync (free G-Sync alternative) [AnandTech]

Post by nimbulan » 08 Jan 2014, 13:07

Haste wrote:
Petersen quickly pointed out an important detail about AMD's "free sync" demo: it was conducted on laptop systems. Laptops, he explained, have a different display architecture than desktops, with a more direct interface between the GPU and the LCD panel, generally based on standards like LVDS or eDP (embedded DisplayPort). Desktop monitors use other interfaces, like HDMI and DisplayPort, and typically have a scaler chip situated in the path between the GPU and the panel. As a result, a feature like variable refresh is nearly impossible to implement on a desktop monitor as things now stand.
This is exactly what I was thinking when I first heard about the FreeSync demo, but I will admit my knowledge of laptop display design is lacking.

Morkai
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Re: AMD demos FreeSync (free G-Sync alternative) [AnandTech]

Post by Morkai » 27 Jul 2014, 12:51

Chief Blur Buster wrote:
nimbulan wrote:I'm curious why they are claiming triple buffering is necessary. The whole purpose of triple buffering is to allow the GPU to continue rendering while waiting for the monitor to refresh which will not be necessary when the monitor always refreshes immediately after a frame has been drawn.
It still takes a finite amount of time for a display to refresh. Scanout time for Freesync is currently 1/60sec, so that blocks that buffer. Triple buffering eliminates the blocking overhead, and reduces input lag, which is important.

One conceptual example of triple buffering:
(1) Front buffer that the display is reading from, while display is scanning out the refresh.
(2) Back buffer waiting to flip to refresh.
(3) Rendering buffer, which replaces whatever is in the back buffer.

At high framerates, (3) will run many times, keeping (2) very fresh (low input lag), so that when the refresh is finished (2) will be flipped to (1) for the next refresh pass at the lowest possible latency.
All of the above is true in theory, but directx doesn't implement triple buffering that way, it simply queues 3 frames and uses all of them, so isn't valid for the vast majority of games. It simply adds input lag no matter what, unless directx changes the implementation or game developers implement "correct" triple buffering on a game-to-game basis.

Morkai
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Re: AMD demos FreeSync (free G-Sync alternative) [AnandTech]

Post by Morkai » 27 Jul 2014, 16:16

It seems there is actually some new info, and they now claim it will use single or double buffering:

"We are told you are using triple buffering. There are some obvious drawbacks to this.

– I think this is a misunderstanding derived previous comments that AMD Catalyst can force-enable triple buffering in the driver’s control panel. Let me set the record straight: Project FreeSync does not require extensive buffering, because the need for such techniques is virtually eliminated when you can match the display timings to the framerate of the GPU on the fly. Within the range of refresh rates supported by a compatible display, Project FreeSync will allow the absolute minimum input lag with single- or double-buffered rendering."
http://www.sweclockers.com/artikel/1879 ... freesync/2
This is from 2014-05-21, so relatively fresh info.

I wonder if they say "single- or double-buffered" to avoid confusion, and that they actually mean "real" triple buffering, which is just that.

Edmond

Re: AMD demos FreeSync (free G-Sync alternative) [AnandTech]

Post by Edmond » 28 Jul 2014, 04:12

Morkai wrote:It seems there is actually some new info, and they now claim it will use single or double buffering:

"We are told you are using triple buffering. There are some obvious drawbacks to this.

– I think this is a misunderstanding derived previous comments that AMD Catalyst can force-enable triple buffering in the driver’s control panel. Let me set the record straight: Project FreeSync does not require extensive buffering, because the need for such techniques is virtually eliminated when you can match the display timings to the framerate of the GPU on the fly. Within the range of refresh rates supported by a compatible display, Project FreeSync will allow the absolute minimum input lag with single- or double-buffered rendering."
http://www.sweclockers.com/artikel/1879 ... freesync/2
This is from 2014-05-21, so relatively fresh info.

I wonder if they say "single- or double-buffered" to avoid confusion, and that they actually mean "real" triple buffering, which is just that.
Anything companies say nowadays should be considered worthless in my opinion.
Lets see some prototype monitors for review sites. Until then freesync means nothing.

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