Anandtech freesync review.

Talk about AMD's FreeSync and VESA AdaptiveSync, which are variable refresh rate technologies. They also eliminate stutters, and eliminate tearing.

Re: Anandtech freesync review.

Postby applejack » 23 Mar 2015, 19:56

sharknice wrote:
Sparky wrote:
sharknice wrote:
Sparky wrote:Why not fall back to the monitor's MAX refresh rate?


That would be the same as having a fixed refresh rate. You would always be at 144hz and wouldn't eliminate any stuttering or tearing.

That's better than the current freesync fallback case, which is 40hz without eliminating stuttering and tearing.


No, with the minimum at 40hz you eliminate stuttering and tearing at frame rates from 40-144 fps. With the minimum at 144hz you don't eliminate stuttering or tearing at all because you now have a fixed refresh rate.


Sparky is saying they could theoretically enhance the experience by switching to static 144hz when fps drops below 40 (v-sync on/off fallback), but still return to operate in freesync mode when fps climbs back to 40 and above.
and he is probably right, it should have resulted in a better 'out of range' experience. even better would be to implement a refresh rate multiplication method to preserve a wider VRR range as G-Sync seems to be doing for lower fps, according to pcper.
User avatar
applejack
 
Posts: 13
Joined: 26 Apr 2014, 11:08

Re: Anandtech freesync review.

Postby Sparky » 23 Mar 2015, 22:35

applejack wrote:
sharknice wrote:
Sparky wrote:
sharknice wrote:That would be the same as having a fixed refresh rate. You would always be at 144hz and wouldn't eliminate any stuttering or tearing.

That's better than the current freesync fallback case, which is 40hz without eliminating stuttering and tearing.


No, with the minimum at 40hz you eliminate stuttering and tearing at frame rates from 40-144 fps. With the minimum at 144hz you don't eliminate stuttering or tearing at all because you now have a fixed refresh rate.


Sparky is saying they could theoretically enhance the experience by switching to static 144hz when fps drops below 40 (v-sync on/off fallback), but still return to operate in freesync mode when fps climbs back to 40 and above.
and he is probably right, it should have resulted in a better 'out of range' experience. even better would be to implement a refresh rate multiplication method to preserve a wider VRR range as G-Sync seems to be doing for lower fps, according to pcper.

Exactly, and window shifting should work for the 40-144hz monitor, though 48-75 is too narrow to do that without gaps. (even with perfect prediction, you'd have frames finishing during a forced refresh).
Sparky
 
Posts: 494
Joined: 15 Jan 2014, 02:29

Re: Anandtech freesync review.

Postby sharknice » 23 Mar 2015, 23:54

applejack wrote:Sparky is saying they could theoretically enhance the experience by switching to static 144hz when fps drops below 40 (v-sync on/off fallback), but still return to operate in freesync mode when fps climbs back to 40 and above.
and he is probably right, it should have resulted in a better 'out of range' experience. even better would be to implement a refresh rate multiplication method to preserve a wider VRR range as G-Sync seems to be doing for lower fps, according to pcper.


I don't think you guys quite understand how GSYNC and FreeSync work because that wouldn't make anything better, it would make it worse.

You need to stop thinking of it in terms of refresh rates and think of it as time between frames.

The screen can only hold an image for 25ms (which equates to a minimum of 40hz) and can only switch images up to every 7ms (144hz). So your next frame needs to take between 7ms and 25ms to render to be within that range.

When the frames start taking longer than 25 ms to render (sub 40fps) it will just repeat the same frame every 25 ms. So for example after one repeat the frame needs to finish rendering between 32ms and 57ms to render if you don't want any stuttering. You have 7ms gaps every 25 ms where you could get stutter. You are maximizing your chances of a stutter free experience.

If you max the refresh rate out and repeat the frame every 7 ms you have no window to display the next frame. You guarantee the timing of the next frame will be off which leads to a stutter. Because as soon as you repeat a frame you have to wait at least 7 ms before you can display a new one.
User avatar
sharknice
 
Posts: 230
Joined: 23 Dec 2013, 17:16
Location: Minnesota

Re: Anandtech freesync review.

Postby Sparky » 24 Mar 2015, 00:16

sharknice wrote:
applejack wrote:Sparky is saying they could theoretically enhance the experience by switching to static 144hz when fps drops below 40 (v-sync on/off fallback), but still return to operate in freesync mode when fps climbs back to 40 and above.
and he is probably right, it should have resulted in a better 'out of range' experience. even better would be to implement a refresh rate multiplication method to preserve a wider VRR range as G-Sync seems to be doing for lower fps, according to pcper.


I don't think you guys quite understand how GSYNC and FreeSync work because that wouldn't make anything better, it would make it worse.

You need to stop thinking of it in terms of refresh rates and think of it as time between frames.

The screen can only hold an image for 25ms (which equates to a minimum of 40hz) and can only switch images up to every 7ms (144hz). So your next frame needs to take between 7ms and 25ms to render to be within that range.

When the frames start taking longer than 25 ms to render (sub 40fps) it will just repeat the same frame every 25 ms. So for example after one repeat the frame needs to finish rendering between 32ms and 57ms to render if you don't want any stuttering. You have 7ms gaps every 25 ms where you could get stutter. You are maximizing your chances of a stutter free experience.

If you max the refresh rate out and repeat the frame every 7 ms you have no window to display the next frame. You guarantee the timing of the next frame will be off which leads to a stutter. Because as soon as you repeat a frame you have to wait at least 7 ms before you can display a new one.

You don't understand how freesync is working RIGHT NOW. If you miss the 25ms deadline, it takes a full 25ms to repeat the previous frame. It doesn't let you send a new frame after a 7ms repeat, you have to wait the full 25. Take a look at the PCPer review.
Sparky
 
Posts: 494
Joined: 15 Jan 2014, 02:29

Re: Anandtech freesync review.

Postby nimbulan » 24 Mar 2015, 00:55

Sparky wrote:You don't understand how freesync is working RIGHT NOW. If you miss the 25ms deadline, it takes a full 25ms to repeat the previous frame. It doesn't let you send a new frame after a 7ms repeat, you have to wait the full 25. Take a look at the PCPer review.

I see what you mean. I went back and read through the PC Perspective article closer and they actually have a nice graph of refresh rates now. Where G-Sync will continue to adjust the refresh rate when you're below 30 fps to maintain variable refresh rate functionality, when FreeSync falls below 40 fps (or 48 fps with at least one panel) it will fall back to standard vsync on/off behavior while running at a fixed 40/48Hz. Running at that lower refresh rate will exaggerate the effects of tearing and vsync judder.
User avatar
nimbulan
 
Posts: 316
Joined: 29 Dec 2013, 23:32
Location: Oregon

Re: Anandtech freesync review.

Postby sharknice » 24 Mar 2015, 02:48

Ah okay. What you were saying makes a lot more sense now. That is pretty bad.
User avatar
sharknice
 
Posts: 230
Joined: 23 Dec 2013, 17:16
Location: Minnesota

Re: Anandtech freesync review.

Postby YukonTrooper » 03 Apr 2015, 18:59

I'm not too concerned about the sub 30-40fps behavior, but overdrive being disabled with Freesync enabled is worrisome. Huge deal-breaker if that behavior can't be overcome.
YukonTrooper
 
Posts: 10
Joined: 06 Feb 2014, 23:24

Previous

Return to FreeSync

Who is online

Users browsing this forum: No registered users and 1 guest