Re: re. sluggish CUSeeMe with 0.80b1

Tim_Dorcey@cornell.edu
Wed, 25 Jan 1995 11:30:29 -0500


>>I recently upgraded from a Macintosh Centris 650, System 7.1 (CUSeeMe ran
>>great with version 68k0.70b13!).
>>
>>Got a PowerMac 8100/80AV, System 7.1 (CUSeeMe version ppc.0.80b1), same
>>thing... very very sluggish! Any thoughts??
>
>Today I compared the maximum frame rate on two systems and two versions:
>
> ver 0.70b15 ver 0.80b1
>Quadra 840AV 23 22 (68k version)
>PowerPC 8100/80AV -- 12 (PPC version)
>
>The settings were the same (CAP rate was set to 150 kbps not to be
>a limit). Unfortunately the PPC didn't have ver 0.70b15, and there
>was no time to fetch it.
>
>But as can be seen the slowiness is more likely to be due to the PPC

The simplest way to compare different machines is without connecting
anywhere. In that case, the CAP is ignored, and CU-SeeMe grabs and
processes video frames as quickly as the machine allows. I get about 28
fps on my PPC7100/66AV, 30 on my Quadra 700 with VideoSpigot, although
applications running in the background can degrade performance. If, in
fact, you were not in the WAITING state, then the 150 kbps CAP would likely
be the limiting factor and could easily explain the difference. E.g., if
there were more motion in the PPC video the frame rate would drop. Even if
the amount of change in the scenes appeared to be equivalent, it is
important to realize that different camera/digitizer combinations record
the same scene differently, which effects CU-SeeMe's notion of what
portions of the video need to be transmitted. You can compensate for this
by adjusting the "Change Tolerance" under the "Compression" controls. To
maximize the frame rate, make it as large as possible without disturbing
the picture quality too much.
That having been said, it is true that the PPC does not perform as
well as a fast 68040 machine. This is partly due to the fact that CU-SeeMe
video processing algorithms were optimized for, no, I should say, designed
for, the 68k architecture. We have recently discovered, however, that
maintaining the user interface is consuming an exhorbitant amount of time,
particularly on the PPC. This is due to some lazy coding practices on our
part and we expect to release a version with enhance performance within the
next day or two.

-Tim
__________________________________________________________________
Tim Dorcey T.Dorcey@cornell.edu
Sr. Programmer/Analyst (607) 255-5715
Advanced Technologies & Planning
CIT Network Resources
Cornell University
Ithaca, NY 14850
__________________________________________________________________