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Re: MPEG and IDL 5.4

On Thu, 1 Mar 2001 09:20:10 +1300, Mark Hadfield <m.hadfield@niwa.cri.nz> wrote:
>My favourite delivery format for animations is FLC.
>I have written a WWW page with a few notes on the pros & cons of different
>animation formats. The page is a bit sketchy but if you want to read it, see
>Mark Hadfield
>m.hadfield@niwa.cri.nz  http://katipo.niwa.cri.nz/~hadfield
>National Institute for Water and Atmospheric Research

Hi Mark:
	I visited your page, interesting. I've made quite a few scientific
animations, using MPEG. You're right, that the playback for MPEG is fixed 
in the range of 25-30 fps, but many players will allow you to over-ride this.
My favorite for windows is VMPEG, which will do this. I use a 24-bit color
map, but often could get by with 8-bit. Typical compression in MPEG is around
30:1, so seems it should be good for high-color images. On your page, it seems
to indicate that FLC file sizes are more compact, is that right? What is
the compression you achieve? What is the native image file format you build 
your animations with?

MJPEG's also offer good compression, and don't require inter-frame statistics
for compression. This is usefull for long, full-screen animations, where
making all the frames a priori would require a LOT of disk space. This can
be done from IDL by calling a shell-script after generating each frame in IDL,
which does the compression and tacs the frame onto your full-length movie. In
this way, I generate full-screen SVHS 24bit animations at 30fps and dump them 
to a video tape. In this way, you could generate your own feature-length film 
with a 10GB disk :-) ! Maybe this is digressing from the initial thread, but 
it's one of the few IDL topics I can expound on. I don't use the MPEG routines 
in IDL, because I don't like the way they seem to go off into never-never land 
for LONG periods of time and then maybe produce an animation, maybe lock up
your system. That was with IDL 5.2, which I upgraded to specifically for the 
added MPEG routines. I use a freely available MPEG-1 encoder now (Berkley mpeg).

Steve S.

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