>the current differential serial bus can do up to 100 Mb/s per ch,
>6-12 lines to bridge 20-bit parallel buses. how would you see
>the bandwith requirement for current and future 3D games?
You can do a quick calculation - a QVGA screen is 320 by 240 pixels, so you
need to write 320*240*2 bytes for a 16 bit display per frame. for 18 bit,
double that because you have to write 32 bits. In addition you have the
z-buffer for any type of sophisticated content (you can use z-sorting, but
content creation is a real pain). So if you want to write a frame of data to
the screen you are writing 153,600 bytes per frame - or 1.5Mbytes per second
for a 10 fps 16 bit display, 3Mbytes for a 18bit display. You also tend to
find that hardware is never running at its full potential for power saving
reasons.
The real killer is actually memory access speed, lots of phones still use
PSRAM, not SDRAM for cost purposes, so the busses and processors are usually
stalled even if they appear to be up to spec. So the real limit is that you
have to read and write the backbuffer and z-buffer, texture maps and scene
data every frame and this is directly linked to memory speed. In other
words, you need to read and write near to 5Mbyte a second for a 10fps game.
Hardware acceleration can help if it is well-designed and attached to fast
busses.
As for which phones will be mass-market in the West - the Siemens and
Motorola phones are attracting a lot of attention and there are more to
come. Pricing will undoubtedly be good and volumes high - I do know, but I
can't reveal the numbers. The K700 is an intermediate step until they have
M3G, so I'm not sure what the volumes or content support will be for that
given that the other top five Western manufacturers are going with M3G. 3D
accelerated handsets with serious acceleration *are* coming too from majors,
so Western phones will be there as well.
As I said, I'm not here to bang the drum for M3G, my company or Western
handsets - I have merely tried to explain what I have personally seen and
heard from developers, manufacturers and operators. I just think it's useful
not to dismiss what happens in the West because in the past Japanese
handsets have undoubtedly been superior. There are things we can learn from
all markets.
regards
Paul
Received on Sun Apr 25 11:00:41 2004