QVGA V/s VGA for GTA03 (was something about yummy CPU-GPU combos!)

Carsten Haitzler (The Rasterman) raster at openmoko.org
Sat Jun 7 00:19:27 CEST 2008

On Fri, 6 Jun 2008 19:18:43 +0200 "Dr. H. Nikolaus Schaller" <hns at computer.org>

> Hi,
> (I try to cut out some citations).
> > this is my dilemma. win with dpi and sharpness, but then lose in
> > smoothness/speed. i lean a bit to- smoothness myself, but i want to  
> > hear the
> > "peanut gallery" so to speak :) (please don't take offence! i'm  
> > seriously about
> > listening that's why i ask!)
> Someone has already pointed out that the dilemma is more on the  
> processor.
> I.e. the problem should be solved by a faster processor with better  
> GPU rather
> than challenging and and trying to redue user's expectations. Can you  
> build
> container trucks smaller because then they need much less parking space?

but when it has been determined that your cpu is not changing - and there are
no other gpu options to improve things... you only can change resolution or
speed. which is more important?

> > pixels the freerunner/neo1973 have. *IF* we shipped the same screen  
> > - we'd have
> > better performance. i find it interesting how so many peole rave  
> > about how
> > great the iphone screen is - but its tech specs are not so hot. it's  
> > dpi is
> > pretty bad compared to the standard these days. but that sure as  
> > hell has not
> > stopped it selling. :) this is why i ask - actual products and  
> > reality seem to
> > show that dpi is not a major factor. at least as best i can tell.
> I have now done some test with the mySTEP GUI stack which sits on X11.  
> The
> one I have shown during LinuxTag.
> Some application I have choosen makes regular screen updates:
> Neo 1973		every 0.5 seconds (due to more work for the higher
> number of pixels)
> Acer n30		every 0.3 seconds (same CPU but QVGA)
> Zaurus C3100	every 0.3 secons (with X/Qt on VGA)
> So, the difference is not that large by different architectures and  
> display resolutions.
> The astonishing thing is that the C3100 is faster than the Neo with  
> the same display.
> I.e. Display resolution by itself can not be the main issue with speed.
> Well, this is not transferrable to games or video players, but it  
> indicates the direction.

yup. true. these will vary based on what you do. are you mostly memory bus
bound or calculation bound, setup bound etc. if you're memory bound - which a
lot of graphics is (blits, fills etc.) you'e going to see a big difference
based just on pixel count. i.e - closer to 4x for qvga vs vga.

> > but then we have the reverse too. the question is - which is more  
> > important? in
> > the world of phones the mass market is as it is higher volume, but  
> > again - it
> > depends. i am wondering what projects would not be possible at qvga?  
> > seriously?
> > ones you can actually read and use? this is my point. try and actual  
> > 2.8"
> > screen at qvga for a while - try apps on it. they are still quite  
> > usable and
> > visible. you may need to just deal with coarser fonts etc. but -  
> > it's still all
> Yes, they are. But just "Quite". Not excellent. More difficult to  
> read. It is like
> Porsche could reduce one or two gear levels. Can still be used as a  
> car :-)

aah - but openmoko isn't porsche :) well not yet.

> mySTEP has resolution independence so that the identical app binaries  
> work
> on both resolutions and try to show the same size. So it is easy to  
> have both
> (Acer n30 / Neo 1973) sitting next to each other. There are large  
> differences in
> how the same application looks. It is much more crisp on the Neo VGA.
> Let's reverse the question - would you reduce the resolution of your  
> desktop system?
> What do you currently have? 1024*1280 or more?
> You can still do everything like writing software, e-mail, web  
> browsing, gaming.
> Probably even faster. But how would it appear? Future oriented or old  
> fashioned?

this is different - because it's me - my eyesight is better than 20/20 and i
use the highest res i can get, when i can get it as i know i can read my
miniscule 8pt or less fonts. but no one else can read my screen - they all
complain that it's too hard and i am forever upping font sizes if i want anyone
to read something on it. i know *I* am fine with it, but the vast majority of
other people can't read my screen. this is why i am cutting myself out of this
- trying to not be personal about it as i know already i'm an exception to the

> > there. :) i'm serious! if you have examples of projects that would  
> > ONLY work if
> > we shipped a 2.8" 285dpi screen but would not work on the same  
> > screen at all
> > at 143dpi... i want to know! i suspect the reason would just be "bad
> > programming" is why it won't work. and then the next would be "it  
> > may display -
> > but no one will be able to read it..." :) but again - i want to know.
> Some have already been mentioned. What I immediately see (which is not  
> at all exhaustive):
> * viewing pictures (320x240 has just room for a thumbnail but not a  
> viewer)
> * rendering web pages
> * maps / satellite pictures
> * Terminal (QVGA just gives a 40*30 text display where all command  
> line things are used to x * 80 - and the Zaurus delivers that)
> * On-Screen keyboard (without having too much layers)
> * Good monthly overview in a Calendar application (one that says more  
> than some day is busy)
>     QVGA gives max. 46 square pixels per day. Including decoration. If  
> there are buttons to operate
>     the calendar, this reduces to much less, let's say 30 sqp. Quite  
> limited to show all the appointments
>     of one day. And clicking into each day to see if there is  
> something important is quite unfriendly.
>     BTW: that is the main reason why I personally did use a paper  
> calendar until I got a Zaurus with
>     VGA display (the 5500 did also have QGVA...).
> This brings me to a point not discussed so far. IMHO it also depends  
> on whether Finger or Pen
> operation is used. With the finger, you have to reduce the display  
> content anyway - like the iPhone
> working with many sheets moving from left to the right etc. But if you  
> operate by pen, you have a
> much better precision so select something and you expect and can  
> handle a much higher information
> density on a single page. So, a better screen reduces the number of  
> flipping/switching operations.

we are going finger. we have no plans to provide a stylus holder (at this
stage) and the stylus provided is kind of an after thought... :) thus we will
have a grubby smudged screen with fingerprints and need to make buttons and
things to hit big, so your finger can do it.

> Finally, I think since the GTA03 platform should not rule out either  
> finger or pen operation, it must fulfill the higher requirements.

we're aiming for finger.

> I think I have made my reasons and comments clear. So, others should  
> also get a voice and vote...
> Nikolaus

Carsten Haitzler (The Rasterman) <raster at openmoko.org>

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