[PD] GEM: forcing the use of Quicktime with pix_flim??

Matteo Sisti Sette matteosistisette at gmail.com
Thu Mar 18 19:15:05 CET 2010

chris clepper escribió:
> On Windows, DirectShow is typically much, much faster than Quicktime 
> (which Apple abandoned a while back).  DirectShow takes advantage of 
> multiple cores/CPUs while Quicktime does not. 
> You can play a lot of Quicktime files using DS provided you have the 
> right codec installed.  I recommend the ffdshow package which covers all 
> of the MPEGs, JPEGs and so on. 
> http://ffdshow-tryout.sourceforge.net/

Hi, I've just installed it and configured it to use ilbavcodec (the only 
available choice except "disabled") for DV video files (which is the 
kind of files I'm using).

I've tested again and nothing has changed: performance is awfully slow, 
compared to that of a 2006 version of GEM (namely 

** Current version (with DS):

- Every [open file.mov( message to a [pix_movie] starts eating up 30% of 
an intel core duo 2.5GHz CPU (two [pix_movie] open -> about 60% cpu; 
three [pix_movie] -> have to open task manager and kill Pd) and it keeps 
consuming that much cpu even if you don't play it _and_ even after 
disconnecting it from the gemhead

- playing back more than one file at a time is impossible (very slow and 
some frames show up black)

** 2006 version (with QT):

- can play up to 6 files at the same time, actually rendering some 
portion of them to some portion of the screen (all at full size, using 

- can "open" as much as 16 files (i guess many more) at the same time 
without any significant increase in cpu consumption; obviously they do 
eat up some cpu at the very moment you send them the open message, but 
only for few seconds.

- with so many files open (and up to 4 playing at the same time) I can 
at any time stop a file (disconnect the gemhead programmatically with a 
spigot) and start playing back another one at an arbitrary frame and I 
almost never get a noticeable delay; i.e. even disk access is as 
efficient and fast as you can conceive it to be. That's where the 
16-open-file limitation comes up. And then I can open 16 more files on 
the same [pix_film]s ("closing" the previously opened ones) and 
everything goes well, so over time I open _literally_ hundreds of files, 
no more than 16 at a time.

I can't believe that DirectShow itself is that bad, or that much worse 
than an old and unupdated QuickTime.
There must be something wrong with [pix_film]...

...Or with my configuration? What could it be? (affecting only DS and 
not QT)??

Can anybody with a Windows machine confirm this issue?

Matteo Sisti Sette
matteosistisette at gmail.com

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