Re: DPX Support

On Thu, 7 Apr 2005, Robin Rowe wrote:
>
>> Under UltraSPARC/Solaris I am seeing performance problems when writing, so 
>> with a 2K frame this test is taking 2.620 seconds on Intel Xeon but it 
>> takes 6.732 seconds on UltraSPARC.
>
> Note that's over a minute to write one second of a 24fps movie.

After doing some testing, I see that the "bit stream" algorithm I 
invented (similar to the "word stream" algorithm used by DPX) happens 
to execute almost 1/2 as fast on a 1.2 GHz UltraSPARC as it does under 
a 2.4GHz Intel Xeon.  This core piece of technology is what allowed me 
to write the DPX writing loop in about a day, and the DPX reading loop 
in about 1/2 a day. DPX is a very "difficult" format due to so many 
storage permutations so doing things the hard way (while supporting 
all the permutations) is very hard.

Even though "UltraSPARC" sounds exotic enough that it should make up 
for the 2X difference in CPU clock speed, sometimes that is not 
enough. :-)

The SPARC CPU does about match the faster-clocked Intel Xeon for some 
other image processing operations.

Maybe one or two explicit special cases will help make up for the 
speed difference.  Or maybe the answer is improved optimization in GCC 
4.0.

Bob
======================================
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/


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