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V-sync option?

Posted: Sat Apr 20, 2013 2:20 pm
by saimo
Hello,

while upgrading to Update 6, I've read in a changelog that some component (can't remember which) was changed so that the graphics refresh is now V-synced. I would like to ask: is there any option to switch the synchronization off? The reason is that to me the ensuing loss in smoothness of the refresh is so perceiveable that it greatly affects my user experience (the system constantly seems to be less responsive, and sometimes to crawl, although I'm under the impression that it isn't any/noticeably slower than before).

As an additional note, I believe that the issue is relative to windows only. After the first impressions derived from regular use, I was convinced when I ran a program in a Workbench window, and it appeared surprisingly jerky; as a counter-test, I ran it on a screen of its own (with the same resolution of the Workbench and all other conditions being the same) and it was as smooth as it was supposed to. Prior to Update 6, the program smoothness was basically the same in both modes.

Re: V-sync option?

Posted: Sat Apr 20, 2013 3:27 pm
by Spectre660
Maybe this ?
SYS:Documentation/Picasso96/EnvVars.doc

NoVSync

Re: V-sync option?

Posted: Sat Apr 20, 2013 10:50 pm
by saimo
Spectre660 wrote:Maybe this ?
SYS:Documentation/Picasso96/EnvVars.doc

NoVSync
Tried now, but it makes no difference - which is no surprise since the feature I mentioned has just been introduced.
But thanks for the suggestion anyway :)

Anybody any other idea?

Re: V-sync option?

Posted: Sun Apr 21, 2013 10:16 am
by MichaelMerkel
saimo wrote:Hello,

while upgrading to Update 6, I've read in a changelog that some component (can't remember which) was changed so that the graphics refresh is now V-synced.
check sys:documentation/releasinfo/intuition...
I would like to ask: is there any option to switch the synchronization off?
afaik no. this is not possible...
The reason is that to me the ensuing loss in smoothness of the refresh is so perceiveable that it greatly affects my user experience (the system constantly seems to be less responsive, and sometimes to crawl, although I'm under the impression that it isn't any/noticeably slower than before).

As an additional note, I believe that the issue is relative to windows only. After the first impressions derived from regular use, I was convinced when I ran a program in a Workbench window, and it appeared surprisingly jerky; as a counter-test, I ran it on a screen of its own (with the same resolution of the Workbench and all other conditions being the same) and it was as smooth as it was supposed to. Prior to Update 6, the program smoothness was basically the same in both modes.
can you explain this a little bit further? what exactly happens when you do what?
and which program did you use to test this (on wb or another screen)?

thanks and regards
michael

Re: V-sync option?

Posted: Sun Apr 21, 2013 1:25 pm
by saimo
MichaelMerkel wrote:check sys:documentation/releasinfo/intuition...
I didn't keep the release notes, but good to know it's Intuition. Thank you.
I would like to ask: is there any option to switch the synchronization off?
afaik no. this is not possible...
It would be great if users were given the choice: so everybody can decide whether to avoid the tearing or to have a smoother refresh.
Is it possible to request it?
can you explain this a little bit further? what exactly happens when you do what?
and which program did you use to test this (on wb or another screen)?
I'm talking exclusively about stuff that runs in windows (on the Workbench, but I guess that the same happens on any other screen).
What happens is that the graphics refresh is less smooth than before. It's something that affects all applications, although the effect is (more) perceiveable only with applications that refresh their graphics very often. Of course, the entity of the effect depends on various factors: the refresh rate of the video mode, the refresh rate of the application, the speed of the video data transfer (and of the machine in general)... and on the personal sensitivity of the viewer.

As for programs I noticed the effect with, one is VICE.
Another, as stupid as it might seem, is NotePad: since it refreshes the whole text area at each keypress (I had not noticed this before, but now I did because the refresh is less smooth, so I can see the borders flicker - as a counterproof I tried with different window sizes and, yes, the bigger the area, the slower the cursor movement), if one just keeps an arrow key pressed to move the cursor horizontally through the text (and with a sufficiently high key repeat rate), it's possible to see, besides the borders flickering, that the movement stutters a bit and that the cursor seems to skip characters - before it was much smoother and, unless it's a side effect of some other change, it can be explained by the fact that the graphics are constantly updated with a delay.
For an easier and more evident test, try KOG (being its developer, I can perfectly compare how it behaved before and now): by default it runs in a window with a 2x zoom; if you change the settings to have it running on its own screen (but in the same mode of the Workbench's) and with the same zoom factor, you'll notice a big difference in smoothness (of course, on an A1Xk the behaviour will be different than on an A1 or a SAM, so trying various zoom levels might help).

Additional note: I've just noticed that in VICE the tearing effect is visible anyway. I can't say if it's because the scope of the change doesn't cover it or if the change doesn't work properly, though.