Re: [pygame] PyGame slowdown

[Kevin MacKenzie <kjmacken@xxxxxxxx>]

On 9/27/05 3:42 PM, "Matthew Nuzum" <mattnuzum@xxxxxxxxx> wrote:

> On 9/27/05, Bob the Hamster <Bob-pygame-users@xxxxxxxxxxxxxxxxxxx> wrote:
>> On Tue, Sep 27, 2005 at 07:51:45PM +0100, Michael Sparks wrote:
>>> On Tuesday 27 September 2005 00:20, Rene Dudfield wrote:
>>>> I have no idea what he was doing without seeing his code.
>>>> 
>>>> 23fps for a 2D game is not unheard of on a slow machine.
>>> 
>>> Also, even the best Hollywood film is 24 fps. (Sometimes, an interesting
>>> alternative way of viewing this)
>>> 
>> 
> 
> This is off topic, but to bring it back on topic a bit, I had another
> discussion with someone who said something to the effect of, "people
> can't distinguish between frame rates higher than 24, which is why 24
> is used in movies." This is wrong, as most people on this list know.
> Its just that at about 20 they start to look like real motion. I can
> certainly tell the difference between my computer screen at 60 and 75
> Hz though.
> 
> On a program I worked on with my brother recently we were able to show
> a slide show of images that looked "animated" at only 2 fps. The trick
> was to not blank the canvas between drawing images. It looked
> surprisingly smooth considering the low frame rate. These were low-res
> images from a web-cam and we were performing real-time effects on the
> images. We were trying to determine how much time we could spend
> applying effects without ruining the appearance of animation.
> Obviously faster frame rates were better.
> 

You've hit it right there.  There is a difference between detecting
'flicker' and apparent motion.  The ~20 fps for apparent motion is because
at slower frame rates the motion is not seen as continuous.  Would appear
similar to a strobe light type effect (viewing motion with a strobe light
on).  The movies are "tricking" the brain to see these static images as
apparent motion.  This is vastly different from the flicker you can
experience on a monitor set at to low a refresh rate.  The average critical
flicker frequency (the point at which you stop experiencing this effect) is
somewhere between 55 and 70 Hz for most human observers.  That is why a 75
Hz refresh rate is generally acceptable, but higher is always better.

Kjm


> --
> Matthew Nuzum
> www.bearfruit.org
>