Parallel video encoding

[rlk-FrUbXkNCsVf2fBVCVOL8/A at public.gmane.org (Robert L Krawitz)]

   Date: Thu, 30 Aug 2007 14:24:04 -0400
   From: Matthew Gillen <me-5yx05kfkO/aqeI1yJSURBw at public.gmane.org>

   Kristian Erik Hermansen wrote:
   > On 8/30/07, Matthew Gillen <me-5yx05kfkO/aqeI1yJSURBw at public.gmane.org> wrote:
   >>  Disk I/O will completely eclipse any context-switching penalty, and even
   > 
   > I've got too many gigs of memory...let's say I MMAP the file, eh?
   > Will that help me out :-)  Do you have experience with using mmap in
   > mencoder?  I went through the man page, but the mmapping support
   > doesn't appear to be for the entire video itself, but for parts of the
   > video when passing it to other apps...

   Sounds like an interesting idea.  I have no experience in that dept.

   If you're going for fastest time of the overall operation though,
   I'm not sure that doing that would buy you much, since to be fair
   you'd have to include both the time to do the mmapping of input and
   un-mmapping of output in the overall time to encode the video.

Memory mapping the file isn't particularly likely to help you, I'd
think.  The filesystem will still cache as much of the file as it can.
It's necessary to balance the I/O -- including distribution of files
on disks -- and processing power, otherwise no matter how much you
optimize the processing you'll be limited by I/O.

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